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Acylation

The document contains a series of chemistry questions related to acylation, amino acids, and organic synthesis, including mechanisms, observations, and calculations. It covers various reactions involving acyl chlorides, alcohols, and amino acids, as well as practical aspects of purification and yield calculations. The questions are structured to test knowledge on organic chemistry concepts and practical laboratory skills.

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0% found this document useful (0 votes)

24 views95 pages

Acylation

Uploaded by

dzniz.d10

We take content rights seriously. If you suspect this is your content, claim it here.

Available Formats

Download as PDF, TXT or read online on Scribd

You are on page 1/ 95

Name: ________________________

Acylation
Class: ________________________

Date: ________________________

Time: 415 minutes

Marks: 379 marks

Comments:

Page 1 of 95
Q1.
Acyl chlorides are useful reagents in synthesis. They react with aromatic compounds and
also with alcohols.

(a) CH3CH2COCl reacts with benzene in the presence of AlCl3 in an electrophilic

substitution reaction.

Give an equation for the reaction of CH3CH2COCl with AlCl3 to form the electrophile.
Outline a mechanism for the reaction of this electrophile with benzene.

Equation ___________________________________________________________

Mechanism

(4)

(b) The organic product in part (a) can be converted into the alcohol shown.

Give the IUPAC name of the alcohol.

Give the reagent needed for this reaction and name the mechanism.

IUPAC name _______________________________________________________

Reagent ___________________________________________________________

Name of mechanism _________________________________________________

(3)

Describe what would be observed when the alcohol reacts with ethanoyl chloride.
Name the mechanism for the reaction to form the ester.
Draw the structure of the ester.

Observation ________________________________________________________

___________________________________________________________________

Name of mechanism __________________________________________________

Page 2 of 95
Structure of ester

(3)
(Total 10 marks)

Q2.
Use the Data Booklet to help you answer this question.

This question is about amino acids and peptide (amide) links.

(a) Draw the structure of the zwitterion formed by phenylalanine.

(1)

(b) Draw the structure of serine at high pH.

(1)

In each structure show all the atoms and bonds in the amide link.

(2)

Page 3 of 95
(d) An amide link is also formed when an acyl chloride reacts with a primary amine.

Name and outline a mechanism for the reaction between CH3CH2COCl and
CH3CH2NH2

Give the IUPAC name of the organic product.

Name of mechanism __________________________________________________

Mechanism

IUPAC name of organic product _________________________________________

(6)
(Total 10 marks)

Q3.
Benzoic acid can be prepared from ethyl benzoate.

Ethyl benzoate is first hydrolysed in alkaline conditions as shown:

A student used the following method.

Add 5.0 cm3 of ethyl benzoate (density = 1.05 g cm−3, Mr = 150) to 30.0 cm3 of aqueous
2 mol dm−3 sodium hydroxide in a round-bottomed flask.

Add a few anti-bumping granules and attach a condenser to the flask. Heat the mixture
under reflux for half an hour. Allow the mixture to cool to room temperature.

Pour 50.0 cm3 of 2 mol dm−3 hydrochloric acid into the cooled mixture.

Filter off the precipitate of benzoic acid under reduced pressure.

(a) Suggest how the anti-bumping granules prevent bumping during reflux.

___________________________________________________________________

___________________________________________________________________
(1)

Page 4 of 95
(b) Show, by calculation, that an excess of sodium hydroxide is used in this reaction.

(2)

(c) Suggest why an excess of sodium hydroxide is used.

___________________________________________________________________

___________________________________________________________________
(1)

(d) Suggest why an electric heater is used rather than a Bunsen burner in this
hydrolysis.

___________________________________________________________________

___________________________________________________________________
(1)

(e) State why reflux is used in this hydrolysis.

___________________________________________________________________

___________________________________________________________________
(1)

(f) Write an equation for the reaction between sodium benzoate and hydrochloric acid.

___________________________________________________________________
(1)

(g) Suggest why sodium benzoate is soluble in cold water but benzoic acid is insoluble
in cold water.

___________________________________________________________________

___________________________________________________________________
(2)

(h) After the solid benzoic acid has been filtered off, it can be purified.

Describe the method that the student should use to purify the benzoic acid.

Page 5 of 95
___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(6)

(i) In a similar experiment, another student used 0.040 mol of ethyl benzoate and
obtained 5.12 g of benzoic acid.

Calculate the percentage yield of benzoic acid.

Suggest why the yield is not 100%.

Percentage yield ____________________ %

Suggestion _________________________________________________________

___________________________________________________________________

___________________________________________________________________
(3)
(Total 18 marks)

Q4.
Paracetamol is a common analgesic used for the relief of pain. It has the structure shown.

Page 6 of 95
The melting point of paracetamol is 170 °C.
Paracetamol can be prepared from the reaction between 4-aminophenol
(HOC6H4NH2) and ethanoyl chloride.

(a) Write an equation for this reaction.

___________________________________________________________________
(1)

(b) Name and outline the mechanism for this reaction. Use RNH2 to represent
4–aminophenol.

Name of mechanism __________________________________________________

Mechanism

(5)

(c) The paracetamol formed in this reaction is impure. It contains both soluble and
insoluble impurities that must be removed by recrystallisation.

The properties of a suitable solvent for recrystallisation are shown.

• The paracetamol should dissolve when the solvent is hot but be almost
insoluble when the solvent is cold.
• The impurities should either be insoluble in the solvent at all temperatures or
soluble even in cold solvent.
• When a hot saturated solution of the paracetamol is cooled, as much product
as possible should crystallise out, leaving soluble impurities in the solution.

A solvent has been suggested for this recrystallisation. It is a flammable liquid with a
boiling point of 80 °C.

Outline how you would carry out an investigation to show that this solvent is suitable
for the recrystallisation of the impure paracetamol. You should include brief practical
details of how you would carry out your investigation.

You are not required to describe the full recrystallisation procedure.

Page 7 of 95
Explain how you would check that a recrystallisation process had been effective at
producing a pure sample of paracetamol.

___________________________________________________________________

___________________________________________________________________
(6)

(d) When paracetamol is prepared by reacting an excess of 4-aminophenol with

ethanoyl chloride, the expected percentage yield of impure paracetamol is 65%.

An expert practical chemist might expect to lose, at most, a further 20% of the
impure product during recrystallisation.

A student started with 3.87 g of ethanoyl chloride.

After preparation of impure paracetamol followed by recrystallisation, the student

actually obtained 4.07 g of pure paracetamol.

Calculate the mass of impure paracetamol expected from this experiment, based on
a 65% yield.

Use your answer and the actual mass of pure paracetamol obtained, to comment on
the statement that “the student has demonstrated expert practical skills”.

___________________________________________________________________

Page 8 of 95
___________________________________________________________________
(4)

(e) Suggest why the student should not use this sample of paracetamol for the
purposes of pain relief.

___________________________________________________________________

___________________________________________________________________
(1)

(f) Suggest two reasons why, in an industrial situation, ethanoic anhydride would be
preferred to ethanoyl chloride in the production of paracetamol.

1. _________________________________________________________________

___________________________________________________________________

2. _________________________________________________________________

___________________________________________________________________
(2)
(Total 19 marks)

Q5.
1,4-diaminobenzene is an important intermediate in the production of polymers such as
Kevlar and also of polyurethanes, used in making foam seating.

A possible synthesis of 1,4-diaminobenzene from phenylamine is shown in the following

figure.

(a) A suitable reagent for step 1 is CH3COCl

Page 9 of 95
Name and draw a mechanism for the reaction in step 1.

Name of mechanism __________________________________________________

Mechanism

(5)

(b) The product of step 1 was purified by recrystallisation as follows.

The crude product was dissolved in the minimum quantity of hot water and the
hot solution was filtered through a hot filter funnel into a conical flask. This filtration
removed any insoluble impurities. The flask was left to cool to room temperature.
The crystals formed were filtered off using a Buchner funnel and a clean cork was
used to compress the crystals in the funnel. A little cold water was then
poured through the crystals.
After a few minutes, the crystals were removed from the funnel and weighed.
A small sample was then used to find the melting point.

Give reasons for each of the following practical steps.

The minimum quantity of hot water was used

___________________________________________________________________

The flask was cooled to room temperature before the crystals were filtered off

___________________________________________________________________

The crystals were compressed in the funnel

___________________________________________________________________

A little cold water was poured through the crystals

___________________________________________________________________

Page 10 of 95
___________________________________________________________________

___________________________________________________________________
(4)

Suggest the most likely impurity to have caused this low value and an improvement
to the method so that a more accurate value for the melting point would be obtained.

___________________________________________________________________

___________________________________________________________________
(2)

The figure above is repeated here to help you answer the following questions.

(d) In an experiment starting with 5.05 g of phenylamine, 4.82 g of purified product

were obtained in step 1.

Calculate the percentage yield in this reaction.

Give your answer to the appropriate number of significant figures.

Page 11 of 95
Percentage yield = _______________%
(3)

(e) A reagent for step 2 is a mixture of concentrated nitric acid and concentrated
sulfuric acid, which react together to form a reactive intermediate.

Write an equation for the reaction of this intermediate in step 2.

___________________________________________________________________
(1)

(f) Name a mechanism for the reaction in step 2.

___________________________________________________________________
(1)

(g) Suggest the type of reaction occurring in step 3.

___________________________________________________________________
(1)

(h) Identify the reagents used in step 4.

___________________________________________________________________
(1)
(Total 18 marks)

Q6.
Lidocaine is a local anaesthetic used in dentistry and in minor surgical operations.
The synthesis of lidocaine in 2 steps from 2,6-dimethylphenylamine is shown.

Page 12 of 95
(a) (i) Give the IUPAC name of reagent X in Step 1.

______________________________________________________________
(1)

(ii) Outline a mechanism for Step 1.

In your answer, use RNH2 to represent 2,6-dimethylphenylamine.

(4)

(b) Name the mechanism for Step 2.

___________________________________________________________________
(1)

Tick (✔) one box.

8 9 11 12

(1)

(d) Calculate the percentage by mass of hydrogen in a molecule of lidocaine.

___________________________________________________________________

___________________________________________________________________
(2)

Page 13 of 95
(e) Give the name, including the classification, of the functional group that contains the
nitrogen atom labelled b.

___________________________________________________________________
(1)

(f) Lidocaine is used medically as the salt lidocaine hydrochloride.

(i) Suggest which one of the nitrogen atoms labelled a or b is protonated in

lidocaine hydrochloride. Explain your answer.

Nitrogen atom protonated _________________________________________

Explanation ____________________________________________________

______________________________________________________________

______________________________________________________________
(3)

(ii) Suggest why lidocaine hydrochloride is used medically in preference to

lidocaine.
Explain your answer.

______________________________________________________________

______________________________________________________________
(2)
(Total 15 marks)

Q7.
Esters are used as raw materials in the production of soaps and biodiesel.

(a) A student prepared an ester by two different methods.

Method 1 alcohol + acid anhydride

Method 2 alcohol + acyl chloride

(i) An ester was prepared using method 1, by reacting (CH3)2CHOH with

(CH3CO)2O

Write an equation for this reaction and give the IUPAC name of the ester
formed.

Equation

______________________________________________________________

IUPAC name of the ester __________________________________________

Page 14 of 95
(2)

(ii) The same ester was prepared using method 2 by reacting (CH3)2CHOH with
CH3COCl

Outline a mechanism for this reaction.

(4)

(b) The ester shown occurs in vegetable oils.

It can be hydrolysed to make soap and can also be used to produce biodiesel.

(i) Write an equation for the reaction of this ester with sodium hydroxide to form
soap.

______________________________________________________________
(2)

(ii) Give the formula of the biodiesel molecule with the highest Mr that can be
produced by reaction of this ester with methanol.

______________________________________________________________
(1)

Page 15 of 95
(Total 9 marks)

Q8.
N-phenylethanamide is used as an inhibitor in hydrogen peroxide decomposition and also
in the production of dyes.

N-phenylethanamide can be produced in a laboratory by the reaction between

phenylammonium sulfate and an excess of ethanoic anhydride:

(a) A student carried out this preparation using 1.15 g of phenylammonium sulfate (Mr =
284.1) and excess ethanoic anhydride.

(i) Calculate the maximum theoretical yield of N−phenylethanamide that could be

produced in the reaction. Record your answer to an appropriate precision.

Show your working.

______________________________________________________________

______________________________________________________________
(3)

(ii) In the preparation, the student produced 0.89 g of N−phenylethanamide.

Calculate the percentage yield for the reaction.

______________________________________________________________

______________________________________________________________
(1)

(b) The student purified the crude solid product, N−phenylethanamide, by

recrystallisation.

(i) Outline the method that the student should use for this recrystallisation.

______________________________________________________________

Page 16 of 95
______________________________________________________________

______________________________________________________________

______________________________________________________________
(4)

(ii) Outline how you would carry out a simple laboratory process to show that the
recrystallised product is a pure sample of N−phenylethanamide.

______________________________________________________________

______________________________________________________________
(3)

(iii) Assume that the reaction goes to completion.

Suggest two practical reasons why the percentage yield for this reaction may
not be 100%.

1. ____________________________________________________________

______________________________________________________________

2. ____________________________________________________________

______________________________________________________________
(2)

(c) The reaction to form N−phenylethanamide would happen much more quickly if the
student used ethanoyl chloride instead of ethanoic anhydride.

Explain why the student might prefer to use ethanoic anhydride, even though it has
a slower rate of reaction.

___________________________________________________________________

Page 17 of 95
___________________________________________________________________
(2)
(Total 15 marks)

Q9.
This question is about some isomers of C5H8O2

(a) Compound H is a cyclic ester that can be prepared as shown.

On the structure of H, two of the carbon atoms are labelled.

HOCH2CH2CH2CH2COCl + HCL

(i) Name and outline a mechanism for this reaction.

Use Table C on the Data Sheet to give the 13C n.m.r. δ value for the carbon
atom labelled a and the δ value for the carbon atom labelled b.

______________________________________________________________

Page 18 of 95
(7)

(ii) HOCH2CH2CH2CH2COCl can also react to form a polyester in a mechanism

similar to that in part (i).

Draw the repeating unit of the polyester and name the type of polymerisation
involved.

______________________________________________________________

______________________________________________________________
(2)

(b) State how you could distinguish between compounds J and K by a simple test-tube
reaction.

State how you could distinguish between J and K by giving the number of peaks in
the 1H n.m.r. spectrum of each compound.

J K

___________________________________________________________________

___________________________________________________________________
(5)

(c) Draw the structure of each of the following isomers of C5H8O2

Label each structure you draw with the correct letter L, M, N, P or Q.

L is methyl 2-methylpropenoate.

M is an ester that shows E-Z stereoisomerism.

N is a carboxylic acid with a branched carbon chain and does not show

Page 19 of 95
stereoisomerism.

P is an optically active carboxylic acid.

Q is a cyclic compound that contains a ketone group and has only two peaks in its
1H n.m.r. spectrum.

(5)
(Total 19 marks)

Q10.
(a) During the preparation of aspirin, it is necessary to filter the crude product under
reduced pressure.

Draw a diagram to show the apparatus you would use to filter the crude product
under reduced pressure. (Do not include the vacuum pump.)

(2)

(b) You are provided with a small sample of pure aspirin in a melting point tube.
Describe briefly how you would determine an accurate value for the melting point of
aspirin.

___________________________________________________________________

Page 20 of 95
(2)
(Total 4 marks)

Q11.
Aldehydes can be prepared from acyl chlorides.

State how an aldehyde could be tested to show whether it is contaminated with traces of
unreacted acyl chloride.
State what you would observe.

Test ___________________________________________________________________

Observation _____________________________________________________________

_______________________________________________________________________
(Total 2 marks)

Q12.
Acyl chlorides such as CH3COCl are useful compounds in synthesis.

(a) The acyl chloride CH3COCl reacts with benzene.

(i) Write an equation for this reaction and name the organic product.

Identify a catalyst for the reaction.

Write an equation to show how this catalyst reacts with CH3COCl to produce a
reactive intermediate.

______________________________________________________________

______________________________________________________________
(4)

(ii) Name and outline a mechanism for the reaction of benzene with the reactive
intermediate in part (a)(i).

Name of mechanism _____________________________________________

Mechanism

Page 21 of 95
(4)

(b) Nucleophiles such as alcohols can react with CH3COCl

The ion CH3COO− can act as a nucleophile in a similar way.

State the meaning of the term nucleophile.

Draw the structure of the organic product formed by the reaction of CH3COO− with
CH3COCl

Name the functional group produced in this reaction.

___________________________________________________________________

___________________________________________________________________
(3)
(Total 11 marks)

Q13.
Acyl chlorides and acid anhydrides are important compounds in organic synthesis.

(a) Outline a mechanism for the reaction of CH3CH2COCl with CH3OH and name the
organic product formed.

Mechanism

Name of organic product ______________________________________________

Page 22 of 95
(5)

(b) A polyester was produced by reacting a diol with a diacyl chloride. The repeating
unit of the polymer is shown below.

(i) Name the diol used.

______________________________________________________________
(1)

(ii) Draw the displayed formula of the diacyl chloride used.

(1)

(iii) A shirt was made from this polyester. A student wearing the shirt accidentally
splashed aqueous sodium hydroxide on a sleeve. Holes later appeared in the
sleeve where the sodium hydroxide had been.

Name the type of reaction that occurred between the polyester and the
aqueous sodium hydroxide. Explain why the aqueous sodium hydroxide
reacted with the polyester.

Type of reaction _________________________________________________

Explanation ____________________________________________________

______________________________________________________________

______________________________________________________________
(3)

(c) (i) Complete the following equation for the preparation of aspirin using ethanoic
anhydride by writing the structural formula of the missing product.

......................
(1)

(ii) Suggest a name for the mechanism for the reaction in part (c)(i).

______________________________________________________________
(1)

Page 23 of 95
(iii) Give two industrial advantages, other than cost, of using ethanoic anhydride
rather than ethanoyl chloride in the production of aspirin.

Advantage 1 ___________________________________________________

______________________________________________________________

Advantage 2 ___________________________________________________

______________________________________________________________

______________________________________________________________
(2)

(d) Complete the following equation for the reaction of one molecule of
benzene-1,2-dicarboxylic anhydride (phthalic anhydride) with one molecule of
methanol by drawing the structural formula of the single product

(1)

(e) The indicator phenolphthalein is synthesised by reacting phthalic anhydride with

phenol as shown in the following equation.

(i) Name the functional group ringed in the structure of phenolphthalein.

______________________________________________________________
(1)

(ii) Deduce the number of peaks in the 13C n.m.r. spectrum of phenolphthalein.

______________________________________________________________
(1)

Page 24 of 95
(iii) One of the carbon atoms in the structure of phenolphthalein shown above is
labelled with an asterisk (*).
Use Table 3 on the Data Sheet to suggest a range of δ values for the peak
due to this carbon atom in the 13C n.m.r. spectrum of phenolphthalein.

______________________________________________________________
(1)

(f) Phenolphthalein can be used as an indicator in some acid–alkali titrations.

The pH range for phenolphthalein is 8.3 – 10.0

(i) For each acid.alkali combination in the table below, put a tick ( ) in the box if
phenolphthalein could be used as an indicator.

Acid Alkali Tick

box
( )

sulfuric acid sodium hydroxide

hydrochloric acid ammonia

ethanoic acid potassium hydroxide

nitric acid methylamine

(2)

(ii) In a titration, nitric acid is added from a burette to a solution of sodium

hydroxide containing a few drops of phenolphthalein indicator.
Give the colour change at the end-point.

______________________________________________________________
(1)
(Total 21 marks)

Q14.
Salicylic acid can be used to make aspirin. Before using a sample of salicylic acid to make
aspirin, a student purified the acid by recrystallisation. The method for recrystallisation is
outlined below.

Step 1: The sample is dissolved in a minimum volume of hot water.

Step 2: The solution is filtered hot.
Step 3: The filtrate is cooled in ice to form crystals.
Step 4: The crystals are collected by filtration, washed with cold water and left to dry.

Explain the purpose of each underlined point.

Minimum volume _________________________________________________________

_______________________________________________________________________

Hot water_______________________________________________________________

Page 25 of 95
_______________________________________________________________________

Filtered hot______________________________________________________________

_______________________________________________________________________

Cooled in ice ____________________________________________________________

_______________________________________________________________________

Washed with cold water ____________________________________________________

_______________________________________________________________________
(Total 5 marks)

Q15.
The reactions of molecules containing the chlorine atom are often affected by other
functional groups in the molecule.

Consider the reaction of CH3CH2COCl and of CH3CH2CH2Cl with ammonia.

(a) For the reaction of CH3CH2COCl with ammonia, name and outline the mechanism
and name the organic product.

___________________________________________________________________

___________________________________________________________________
(6)

(b) For the reaction of CH3CH2CH2Cl with an excess of ammonia, name and outline the
mechanism and name the organic product.

___________________________________________________________________

Page 26 of 95
___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(6)

___________________________________________________________________

___________________________________________________________________
(1)
(Total 13 marks)

Q16.
Samples of 1-chloropropane and ethanoyl chloride can be distinguished by the addition of
an aqueous solution of silver nitrate.
State what you would observe with each sample.

Observation with 1-chloropropane

_______________________________________________________________________

Observation with ethanoyl chloride.

_______________________________________________________________________

Page 27 of 95
(Total 2 marks)

Q17.
Esters have many important commercial uses such as solvents and artificial flavourings in
foods.

Esters can be prepared in several ways including the reactions of alcohols with carboxylic
acids, acid anhydrides, acyl chlorides and other esters.

(a) Ethyl butanoate is used as a pineapple flavouring in sweets and cakes.

Write an equation for the preparation of ethyl butanoate from an acid and an alcohol.

Give a catalyst used for the reaction.

___________________________________________________________________

___________________________________________________________________
(4)

(b) Butyl ethanoate is used as a solvent in the pharmaceutical industry.

Write an equation for the preparation of butyl ethanoate from an acid anhydride and
an alcohol.

___________________________________________________________________

___________________________________________________________________
(3)

Page 28 of 95
(5)

(d) The ester shown below occurs in vegetable oils. Write an equation to show the
formation of biodiesel from this ester.

CH2OOCC17H31
│
CHOOCC17H33
│
CH23OOCC17H29

___________________________________________________________________

___________________________________________________________________
(3)

(e) Draw the repeating unit of the polyester Terylene that is made from
benzene-1,4-dicarboxylic acid and ethane-1,2-diol.

Although Terylene is biodegradeable, it is preferable to recycle objects made from

Terylene.

Give one advantage and one disadvantage of recycling objects made from
Terylene.

___________________________________________________________________

Page 29 of 95
___________________________________________________________________
(4)
(Total 19 marks)

Q18.
(a) Name and outline a mechanism for the reaction of CH3CH2NH2 with CH3CH2COCl

Name the amide formed.

(6)

(b) Haloalkanes such as CH3Cl are used in organic synthesis.

Outline a three-step synthesis of CH3CH2NH2 starting from methane. Your first step
should involve the formation of CH3Cl

In your answer, identify the product of the second step and give the reagents and
conditions for each step.

Equations and mechanisms are not required.

___________________________________________________________________

Page 30 of 95
___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(6)
(Total 12 marks)

Q19.
Synthetic dyes can be manufactured starting from compounds such as
4-nitrophenylamine.

A synthesis of 4-nitrophenylamine starting from phenylamine is shown below.

(a) An equation for formation of N-phenylethanamide in Step 1 of the synthesis is

shown below.

2C6H5NH2 + CH3COCl → C6H5NHCOCH3 + C6H5NH3Cl

N-phenylethanamide

(i) Calculate the % atom economy for the production of N-phenylethanamide

(Mr = 135.0).

______________________________________________________________

______________________________________________________________
(3)

(ii) In a process where 10.0 kg of phenylamine are used, the yield of

N-phenylethanamide obtained is 5.38 kg.

Calculate the percentage yield of N-phenylethanamide.

______________________________________________________________

Page 31 of 95
______________________________________________________________

______________________________________________________________

______________________________________________________________
(2)

(iii) Comment on your answers to parts (i) and (ii) with reference to the
commercial viability of the process.

______________________________________________________________

______________________________________________________________
(2)

(b) Name and outline a mechanism for the reaction in Step 1.

___________________________________________________________________

___________________________________________________________________
(5)

(c) The mechanism of Step 2 involves attack by an electrophile. Write an equation

showing the formation of the electrophile. Outline a mechanism for the reaction of
this electrophile with benzene.

___________________________________________________________________

Page 32 of 95
___________________________________________________________________

___________________________________________________________________
(4)
(Total 16 marks)

Q20.
(a) Write an equation for the formation of methyl propanoate, CH3CH2COOCH3, from
methanol and propanoic acid.

___________________________________________________________________
(1)

(b) Name and outline a mechanism for the reaction between methanol and propanoyl
chloride to form methyl propanoate.

Name of mechanism _________________________________________________

Mechanism

(5)

(c) Propanoic anhydride could be used instead of propanoyl chloride in the preparation
of methyl propanoate from methanol. Draw the structure of propanoic anhydride.

(1)

(d) (i) Give one advantage of the use of propanoyl chloride instead of propanoic
acid in the laboratory preparation of methyl propanoate from methanol.

______________________________________________________________

(ii) Give one advantage of the use of propanoic anhydride instead of propanoyl
chloride in the industrial manufacture of methyl propanoate from methanol.

______________________________________________________________

Page 33 of 95
______________________________________________________________
(2)

(e) An ester contains a benzene ring. The mass spectrum of this ester shows a
molecular ion peak at m/z = 136.

(i) Deduce the molecular formula of this ester.

______________________________________________________________

(ii) Draw two possible structures for this ester.

(3)
(Total 12 marks)

Q21.
Consider the sequence of reactions below.

(a) Name and outline a mechanism for Reaction 1.

Name of mechanism _________________________________________________

Mechanism

(5)

(b) (i) Name compound Q

______________________________________________________________

Page 34 of 95
(ii) The molecular formula of Q is C4H7NO. Draw the structure of the isomer of Q
which shows geometrical isomerism and is formed by the reaction of ammonia
with an acyl chloride.

(3)

(c) Draw the structure of the main organic product formed in each case when R reacts
separately with the following substances:

(i) methanol in the presence of a few drops of concentrated sulphuric acid;

(ii) acidified potassium dichromate(VI);

(iii) concentrated sulphuric acid in an elimination reaction.

(3)
(Total 11 marks)

Q22.
(a) Name the compound (CH3)2NH

___________________________________________________________________
(1)

(b) (CH3)2NH can be formed by the reaction of an excess of CH3NH2 with CH3Br. Name
and outline a mechanism for this reaction.

Name of mechanism _________________________________________________

Mechanism

Page 35 of 95
(5)

(c) Name the type of compound produced when a large excess of CH3Br reacts with
CH3NH2 Give a use for this type of compound.

Type of compound ___________________________________________________

Use _______________________________________________________________
(2)

(d) Draw the structures of the two compounds formed in the reaction of CH3NH2 with
ethanoic anhydride.

(2)
(Total 10 marks)

Q23.
(a) Name and outline a mechanism for the reaction between propanoyl chloride,
CH3CH2COCl, and methylamine, CH3NH2
Draw the structure of the organic product.

___________________________________________________________________

Page 36 of 95
(6)

(b) Benzene reacts with propanoyl chloride in the presence of aluminium chloride.
Write equations to show the role of aluminium chloride as a catalyst in this reaction.
Outline a mechanism for this reaction of benzene.

___________________________________________________________________

___________________________________________________________________
(5)

(c) Write an equation for the reaction of propanoyl chloride with water. An excess of
water is added to 1.48 g of propanoyl chloride. Aqueous sodium hydroxide is then
added from a burette to the resulting solution.
Calculate the volume of 0.42 mol dm–3 aqueous sodium hydroxide needed to react
exactly with the mixture formed.

___________________________________________________________________

___________________________________________________________________
(5)
(Total 16 marks)

Q24.
(a) Addition reactions to both alkenes and carbonyl compounds can result in the

Page 37 of 95
formation of isomeric compounds.

(i) Choose an alkene with molecular formula C4H8 which reacts with HBr to form
two structural isomers. Give the structures of these two isomers and name the
type of structural isomerism shown.

Outline a mechanism for the formation of the major product.

______________________________________________________________

______________________________________________________________
(7)

(ii) Using HCN and a suitable carbonyl compound with molecular formula C3H6O,
outline a mechanism for an addition reaction in which two isomers are
produced.
Give the structures of the two isomers formed and state the type of isomerism
shown.

______________________________________________________________

Page 38 of 95
______________________________________________________________

______________________________________________________________

______________________________________________________________
(7)

(b) Explain why ethanoyl chloride reacts readily with nucleophiles.

Write an equation for one nucleophilic addition–elimination reaction of ethanoyl
chloride.
(A mechanism is not required.)

___________________________________________________________________

___________________________________________________________________
(4)
(Total 18 marks)

Q25.
(a) Ester X, CH3CH2COOCH3, can be produced by the reaction between propanoyl
chloride and methanol. Name X and outline a mechanism for this reaction. Name
the mechanism involved.

___________________________________________________________________

Page 39 of 95
___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(6)

(b) The proton n.m.r. spectrum of X is shown below together with that of an isomeric
ester, Y. Deduce which of Spectrum 1 and Spectrum 2 is that obtained from X. Use
Table 1 on the Data Sheet and the integration data on the spectra to help you to
explain your deduction. Suggest a structure for Y.

___________________________________________________________________

Page 40 of 95
___________________________________________________________________

___________________________________________________________________

___________________________________________________________________
(4)
(Total 10 marks)

Q26.
(a) The gaseous reactants W and X were sealed in a flask and the mixture left until the
following equilibrium had been established.

2W(g) + X(g) 3Y(g) + 2Z(g) ΔH = –200 kJ mol–1

Write an expression for the equilibrium constant, Kp, for this reaction.
State one change in the conditions which would both increase the rate of reaction
and decrease the value of Kp. Explain your answers.

___________________________________________________________________

___________________________________________________________________
(7)

(b) Ethyl ethanoate can be prepared by the reactions shown below.

Page 41 of 95
Reaction 1
CH3COOH(l) + C2H5OH(l) CH3COOC2H5(l) + H2O(l) ∆H = –2.0 kJ mol–1

Reaction 2
CH3COCl(l) + C2H5OH(l) → CH3COOC2H5(l) + HCl(g) ∆H = –21.6 kJ mol–1

(i) Give one advantage and one disadvantage of preparing ethyl ethanoate by
Reaction 1 rather than by Reaction 2.

______________________________________________________________

______________________________________________________________
(2)

(ii) Use the information given above and the data below to calculate values for the
standard entropy change, ∆S , and the standard free-energy change, ∆G ,
for Reaction 2 at 298 K.

CH3COCl(l) C2H5OH(l) CH3COOC2H5(l) HCl(g)

S /JK1mol1 201 161 259 187

______________________________________________________________

______________________________________________________________
(6)
(Total 15 marks)

Q27.
(a) Use the following data to show the stability of benzene relative to the hypothetical
cyclohexa-1,3,5-triene.

Page 42 of 95
Give a reason for this difference in stability.

___________________________________________________________________

___________________________________________________________________
(4)

(b) Consider the following reaction sequence which starts from phenylamine.

(i) State and explain the difference in base strength between phenylamine and
ammonia.

______________________________________________________________

______________________________________________________________
(3)

Page 43 of 95
(ii) Name and outline a mechanism for the reaction in Step 1 and name the
organic product of Step 1.

______________________________________________________________

______________________________________________________________
(6)

(iii) The mechanism of Step 2 involves attack by an electrophile. Give the

reagents used in this step and write an equation showing the formation of the
electrophile.
Outline a mechanism for the reaction of this electrophile with benzene.

______________________________________________________________

______________________________________________________________
(6)

Page 44 of 95
(iv) Name the type of linkage which is broken in Step 3 and suggest a suitable
reagent for this reaction.

______________________________________________________________

______________________________________________________________
(2)
(Total 21 marks)

Q28.
(a) Outline a mechanism for the reaction of CH3CH2CH2CHO with HCN and name the
product.

Mechanism

Name of product ____________________________________________________

(5)

(b) Outline a mechanism for the reaction of CH3OH with CH3CH2COCl and name the
organic product.

Mechanism

Name of organic product _______________________________________________

(5)

(c) An equation for the formation of phenylethanone is shown below. In this reaction a
reactive intermediate is formed from ethanoyl chloride. This intermediate then reacts
with benzene.

Page 45 of 95
(i) Give the formula of the reactive intermediate.

______________________________________________________________

(ii) Outline a mechanism for the reaction of this intermediate with benzene to form
phenylethanone.

(4)
(Total 14 marks)

Q29.
(a) A flask containing a mixture of 0.200 mol of ethanoic acid and 0.110 mol of ethanol
was maintained at 25 °C until the following equilibrium had been established.

CH3COOH(l) + C2H5OH(l) CH3COOC2H5(l) + H2O(l)

The ethanoic acid present at equilibrium required 72.5 cm3 of a 1.50 mol dm–3
solution of sodium hydroxide for complete reaction.

(i) Calculate the value of the equilibrium constant, Kc, for this reaction at 25 °C.

______________________________________________________________

Page 46 of 95
______________________________________________________________

______________________________________________________________

______________________________________________________________
(7)

(ii) The enthalpy change for this reaction is quite small. By reference to the
number and type of bonds broken and made, explain how this might have
been predicted.

______________________________________________________________

______________________________________________________________
(2)

(b) Aspirin can be prepared by acylation using either ethanoyl chloride or ethanoic
anhydride, as represented by the equations shown below.

CH3COCl + HOC6H4COOH → CH3COOC6H4COOH + HCl

(CH3CO)2O + HOC6H4COOH → CH3COOC6H4COOH + CH3COOH

(i) By a consideration of the intermolecular forces involved, explain why the

product HCl is a gas but the product CH3COOH is a liquid at room
temperature.

______________________________________________________________

______________________________________________________________
(2)

(ii) Give two industrial advantages of using ethanoic anhydride rather than
ethanoyl chloride in the manufacture of aspirin.

______________________________________________________________

______________________________________________________________
(2)
(Total 13 marks)

Q30.

Page 47 of 95
Which one of the following types of reaction mechanism is not involved in the above
sequence?

CH3CH2CH3 (CH3)2CHCl (CH3)2CHCN

(CH3)2CHCH2NHCOCH3 (CH3)2CHCH2NH2

A free-radical substitution

B nucleophilic substitution

C elimination

D nucleophilic addition-elimination
(Total 1 mark)

Page 48 of 95
Mark schemes

Q1.

(a)
Allow + on C or O in equation –
But must be on C in mechanism
M1

M2 Arrow from inside hexagon to C or + on C

1
M3 Structure of intermediate
• horseshoe centred on C1 and must not extend beyond C2
and
C6, but can be smaller
• + in intermediate not too close to C1 (allow on or “below” a
line
from C2 to C6)
1
M4 Arrow from bond into hexagon (Unless Kekule)
• Can allow M4 arrow independent of wrong M3 structure
• + on H in intermediate loses M3 not M4
• Ignore Cl– and AlCl4–
- used in M4
1

(b) Either...

1-phenylpropan-1-ol
1
NaBH4 / LiAlH4
1
Nucleophilic addition
1

Or...

1-phenylpropan-1-ol
1
H2 with Ni/Pd/Pt

Page 49 of 95
1
Addition/hydrogenation
1
Both numbers needed for names
Ignore solvents

(c) Misty fumes / steamy fumes

Allow sweet/fruity smell / white fumes
Not smoke
1

(Nucleophilic) addition-elimination
1

1
[10]

Q2.
(a)

Allow −CO2−
Allow +H3N− and NH3+−
1

(b)

(c)

Page 50 of 95
1
If same wrong amino acid twice – max 1

(d) (nucleophilic) addition-elimination

Not electrophilic addition-elimination.
M1

M2 for arrow from lp on N to C

(or to space half way between N and C)
Ignore δ+ and δ− unless wrong

M3 for arrow from C=O bond to O

Not score M3 as an independent first step, but can allow M2
for attack on C+ produced
If Cl lost at this stage, Max 1 for mechanism for M2

M4 for structure of ion including 2 charges

(+ on N must be correct in both cases if drawn twice)

M5 for 3 arrows and lp on O

- may be scored in two steps

Ignore use of RNH2 to remove H+ in M5, but penalise use of

Cl−
M2-5

N-ethylpropanamide
M6
[10]

Page 51 of 95
Q3.
(a) allows smaller bubbles to form / prevents the formation of (very) large bubbles
ALLOW provides large surface area for bubbles to form on
IGNORE ‘air’
NOT no bubbles form / prevents bubbles forming
1

(b) (Mass of ester = 1.05 × 5.0 = 5.25g)

amount of ester = 5.25 / 150.0 = 0.0350 mol
1

amount of NaOH = 30 × 2 / 1000 = 0.06 mol

(Mass of ester = 1.05 × 5.0 = 5.25g)

amount of ester = 5.25 / 150.0 = 0.0350 mol
1

Vol of 0.035 mol of NaOH = (0.035/2) × 1000 = 17.5 cm3

(so 30 cm3 used is an excess)
1

amount of NaOH = 30 × 2 / 1000 = 0.06 mol

0.06 mol of ester = 9 g = 8.57 cm3

(only 5 cm3 used so NaOH in excess)
1
Mark independently
Max 2

(c) To ensure that the ester is completely hydrolysed / to ensure all the ester
reacts
ALLOW to ensure the other reagent has completely reacted
1

(d) Many organic compounds / the ester / ethanol are flammable

ALLOW prevent ignition of any flammable vapours formed
1

(e) Reflux allows reactant vapours (of volatile organic compounds) to be returned
to the reaction mixture / does not allow any reactant vapour to escape
IGNORE reference to products
1

(f) C6H5COONa + HCl → C6H5COOH + NaCl

Allow ionic equation.
ALLOW molecular formulae (C7H5O2Na and C7H6O2 )
ALLOW skeletal benzene ring
1

(g) Sodium benzoate soluble because it is ionic

IGNORE polar

Page 52 of 95
1

Benzoic acid insoluble because: despite the polarity of the COOH group /
ability of COOH to form H-bonds, the benzene ring is non-polar.
ALLOW ‘part of molecule’ or ‘one end’ for COOH
1

(h) Dissolve crude product in hot solvent/water

ALLOW ethanol
If no M1 max = 4
1

of minimum volume
ALLOW reference to saturated soln as alternative to ‘min vol’
1

Filter (hot to remove insoluble impurities)

IGNORE use of Buchner funnel here
1

Cool to recrystallise
apply list principle for each additional process in an incorrect
method but IGNORE additional m.pt determination
1

Filter under reduced pressure / with Buchner/Hirsch apparatus

wash (with cold solvent) and dry

(i) 5.12 / 122 (= 0.042 mol)

method mark
1

(0.042/0.04) × 100 = 105 %

ecf for M1/0.04
or calculation that 0.04 mol of benzoic = 4.88 g (M1) so
% yield = (5.12/4.88) × 100 = 105%
1

Product not dried / impurities present in product

Only allow M3 if M2>100%
1
[18]

Q4.
(a) 2HO–C6H4–NH2 + CH3COCl ⟶ HO–C6H4–NHCOCH3 + HO-C6H4-NH3+Cl−
HO–C6H4–NH2 + CH3COCl ⟶ HO–C6H4–NHCOCH3 + HCl
1

(b) (Nucleophilic) Addition-elimination.

Page 53 of 95
M2 = Arrow from lone pair on N to carbon in C=O.
1
M3 = Arrow from the bond in CO to the O.
1
M3 = Correct intermediate with + on N and − on O.
1
M4 = Three arrows and lone pair.
1

(c) This question is marked using levels of response. Refer to the Mark Scheme
Instructions for Examiners for guidance on how to mark this question.

Level 3

Outlines a workable process with clear decision-making process. Gives a method for
melting point determination with detailed reference to the melting point of 170 ± 2
°C.
5-6 marks

Level 2

Outlines a workable process with some indication of decision-making. Gives a

method for melting point determination without detailed reference to the melting
point of 170 ± 2 °C.
3-4 marks

Level 1

Partially outlines a potentially workable process. Suggests need for melting point
determination.
1-2 marks

Level 0

Insufficient correct chemistry to warrant a mark.

0 marks
Indicative Chemistry content
• Place a small amount of pure paracetamol in a
test-tube.
• Add small volume (0.5–1.0 cm3) of possible solvent
• Shake/stir.
• If paracetamol dissolves then solvent unsuitable.
• Heat (with suitable awareness of flammability and
boiling point; e.g. hot − not boiling − water bath).
• If paracetamol does not dissolve = unsuitable.
• If paracetamol dissolves partially try adding more

Page 54 of 95
solvent.
• If/when completely dissolved place test-tube in
ice-water bath.
• If crystals form = suitable.
• Effectiveness determined by measuring melting point.
• Purity indicated by melting point being sharp and close
to 170 °C.
6

(d) Amount of ethanoyl chloride = 3.87 / 78.5 = 0.0493 mol

(Theoretical mass of paracetamol = 0.0493 × 151 = 7.44 g)

Mass expected = (65/100) × 7.44 = 4.84 g
1

Loss in mass on recrystallisation = 4.84 − 4.07 = 0.77

Percentage loss in mass = (0.77 / 4.84) × 100 = 15.9 %

This suggests that the student has demonstrated expert practical skills as less than
20 % loss during recrystallisation.
Allow comment that it is unlikely student would be better
than expert chemist so final product may not be dry thus
increasing apparent mass obtained.
1

(e) There may still be small amounts of impurities.

(f) Any two from:

• less exothermic reaction

• easier to control

• dangerous gas not evolved

• ethanoic anhydride is a cheaper or more easily recycled reagent.

2
[19]

Q5.
(a) (nucleophilic) addition-elimination
Not electrophilic addition-elimination
1

Page 55 of 95
Allow C6H5 or benzene ring
Allow attack by :NH2C6H5
M2 not allowed independent of M1, but allow M1 for correct
attack on C+
M3 for correct structure with charges but lone pair on O is
part of M4
M4 (for three arrows and lone pair) can be shown in more
than one structure
4

(b) The minimum quantity of hot water was used:

To ensure the hot solution would be saturated / crystals would form on cooling
1

The flask was left to cool before crystals were filtered off:

Yield lower if warm / solubility higher if warm

The crystals were compressed in the funnel:

Air passes through the sample not just round it

Allow better drying but not water squeezed out
1

A little cold water was poured through the crystals:

To wash away soluble impurities

Press the sample of crystals between filter papers

Allow give the sample time to dry in air
1

(d) Mr product = 135.0

Expected mass = 5.05 × = 7.33 g

Page 56 of 95
Percentage yield = × 100 = 65.75 = 65.8(%)

Answer must be given to this precision

(e)

C6H5NHCOCH3 + NO2+ C6H4(NHCOCH3)NO2 + H+

(f) Electrophilic substitution

(g) Hydrolysis
1

(h) Sn / HCl
Ignore acid concentration; allow Fe / HCl
1
[18]

Q6.
(a) (i) (2-)chloroethan (-1-) oyl chloride
2 not required but penalise 1- or other numbers at start.
Ignore 1 in ethanoyl
Ignore hyphens, commas, spaces
1

(ii)

M1 for arrow from lp on N to C

(or to space half way between N and C)
If full amine drawn, ignore slips except in –NH2
M2 for arrow from C=O bond to O
Not score M2 as an independent first step, but can allow M1
for attack on C+ produced
If Cl lost at this stage, Max 1 for M1

Page 57 of 95
M3 for structure of ion including 2 charges
M4 for 3 arrows and lp on O
- may be scored in two steps
Ignore use of RNH2 to remove H+ in M4, but penalise use of
Cl-
4

(b) Nucleophilic substitution

Allow minor spelling errors e.g. nucleophyllic
1

(d) Mr = 234(.0)
9.4 scores 2 marks
1

% H = 9.4(0)

M2 =
If Mr = 234 not shown, can score M1 if their answer × 234 =
their no of H
1

(e) Tertiary amine OR 3o amine OR IIIo amine

Ignore N- substituted
1

(f) (i) If a given: CE=0, can only score if answer given is b

M1 lp on Nb or on b

M2 alkyl groups donate electron density or positive inductive effect or electron

donating groups attached

M3 (lp on Nb) more available or protonated amine stabilised or better lp donor/H+

acceptor

Ignore reference to nucleophiles

NOTE – there is NO mark for b alone
Alternatives
M1 lp on Na or on a
M2 lp or electrons (on Na) delocalised into ring /towards O in
C=O
M3 (lp on Na) less available (to bond to H+/accept proton)
1
1
1

(ii) Salt is ionic

Independent marks
1

(More) soluble (in blood/body fluids/water)

Page 58 of 95
[15]

Q7.
(a) (i) (CH3)2CHOH + (CH3CO)2O → CH3COOCH(CH3)2 + CH3COOH
Allow CH3CO2CH(CH3)2 and CH3CO2H
Ignore (CH3)2 −C in equation
1

(1)-methylethyl ethanoate OR

Propan-2-yl ethanoate
Ignore extra or missing spaces, commas or hyphens
1

(ii)

M4 for 3 arrows and lp

NO Mark for name of mechanism

M1 for lone pair on O and arrow to C or to mid-point of space
between O and C
M2 for arrow from C=O bond to O
• M2 not allowed independent of M1, but
allow M1 for correct attack on C+
• + rather than δ+ on C=O loses M2
• If Cl lost with C=O breaking, max1 for M1
M3 for correct structure with charges (penalise wrong alcohol
here) but lone pair on O is part of M4
Penalise (CH3)2 −C in M3
M4 for lone pair on O and three arrows
• Only allow M4 after correct / very close M3
• M4 can be gained over more than one structure
• Ignore Cl− removing H+
4

(b) (i)

Page 59 of 95
Penalise covalent Na e.g. -O-Na
LHS 1
RHS 1

(ii) C17H33COOCH3
Allow C19H36O2
1
[9]

Q8.
(a) (i) Mr N−phenylethanamide = 135.0
1

Theoretical yield = 135.0 × 2 (1.15 / 284.1) = 1.09 g

Answer recorded to 3 significant figures.

(ii) × 100

= 81.4 %
Mark consequentially to (a)
Allow 81 to 82
1

(b) (i) Dissolve the product in the minimum volume of water / solvent (in a
boiling tube / beaker)
If dissolving is not mentioned, CE = 0 / 4
1

Hot water / solvent

Steps must be in a logical order to score all 4 marks
1

Allow the solution to cool and allow crystals to form.

Filter off the pure product under reduced pressure / using a Buchner
funnel and side arm flask
Ignore source of vacuum for filtration (electric pump, water
pump, etc.)
1

(ii) Measure the melting point

Use of melting point apparatus or oil bath

Sharp melting point / melting point matches data source value

(iii) Any two from:

Product left in the beaker or glassware
Sample was still wet
Sample lost during recrystallisation.

Page 60 of 95
Do not allow “sample lost” without clarification.
2 Max

(c) An identified hazard of ethanoyl chloride

E.g. “Violent reaction”, “harmful”, “reacts violently with water”
Do not allow “toxic”, “irritant” (unless linked with HCl gas).
1

HCl gas / fumes released / HCl not released when ethanoic anhydride used
1
[15]

Q9.
(a) (i) (nucleophilic) addition-elimination
Not electrophilic addition-elimination
Ignore esterification
1

M3 for structure
• If wrong nucleophile used or O–H broken in first step,
can only score M2.
• M2 not allowed independent of M1, but allow M1 for
correct attack on C+
• + rather than δ+ on C=O loses M2.
• If Cl lost with C=O breaking lose M2.
• M3 for correct structure with charges but lone pair on O
is part of M4.
• Only allow M4 after correct / very close M3.
• Ignore HCl shown as a product.
4

a 20-50 (ppm) or single value or range entirely within this range

If values not specified as a or b then assume first is a.
1

b 50-90 (ppm) or single value or range entirely within this range

(ii)

Must have trailing bonds, but ignore n.

Page 61 of 95
OR –OCH2CH2CH2CH2CO– OR –CH2CH2CH2CH2COO–
Allow

but not - C4H8−

one unit only

Condensation
1

(b)

Tollens’ Fehling’s / Benedicts Acidified potassium

dichromate

Penalise wrong formula for Tollens or missing acid with

potassium dichromate but mark on.
1

J No reaction / no No reaction / no No reaction / no

(visible) change (visible) change (visible) change /
/ / stays
no silver mirror stays blue / no r orange / does not turn
ed green
ppt

Ignore ‘clear’, ‘nothing’.

Penalise wrong starting colour for dichromate.
1

K Silver mirror / Red ppt (orange) turns

grey ppt green
(allow brick red
or
red-orange)
1

J Two (peaks)
Allow trough, peak, spike.
1

K Four (peaks)
Ignore details of splitting.
If values not specified as J or K then assume first is J.
1

(c) If all the structures are unlabelled, assume that the first drawn ester is L, the
second ester is M; the first drawn acid is N, the second P. The cyclic
compound should be obvious.

L
ester

Page 62 of 95
OR H2C=C(CH3)COOCH3
All C5H8O2 L to P must have C=C.
Allow CH3−.
Allow -CO2CH3 etc.
Allow CH2C(CH3)COOCH3.
1

M
ester

CH3CH=CHCOOCH3 CH3CH=CHOOCCH3 CH3CH=C(CH3)OOCH

CH3CH=CHCH2OOCH CH3CH2CH=CHOOCH
Allow either E–Z isomer.
Allow CH3− or C2H5− but not CH2CH3−.
Allow CH3CHCHCOOCH3 etc.
1

N
acid

(CH3)2C=CHCOOH H2C=C(CH3)CH2COOH H2C=C(COOH)CH2

CH3
Allow CH3− or C2H5− but not CH2CH3−.
Allow −CO2H.
Not cyclic isomers.
Not the optically active isomer.

Allow (CH3)2CCHCOOH etc.

Page 63 of 95
acid

Allow −CO2H.

CH3CH(COOH)CH=CH2
Allow CH3CH(CO2H)CHCH2 or
CH3CH(CO2H)C2H3.
1

Not cyclic esters.

1
[19]

Q10.
(a) Side-arm flask / side-arm test tube
Do not allow sealed side-arm flask.
1

Flat-bottomed filter funnel with filter paper clearly shown

Either Buchner or Hirsch versions are suitable.
Allow Hirsch funnel and horizontal filter paper.
Allow three-dimensional filter funnels.
Do not allow standard Y-shaped funnel.
Do not allow sealed funnel.
If it is not clearly air-tight between the funnel and the flask,
maximum 1 mark.
1

(b) Heat melting point tube in an oil bath

Accept ‘melting point apparatus’ or Thiele tube.
Do not accept water bath.
1

slowly near the melting point

Ignore any additional correct details.
Apply list principle for additional incorrect details.
1
[4]

Q11.
Test silver nitrate (solution) (M1)
Allow an alternative soluble silver salt eg fluoride, sulfate.

Page 64 of 95
Do not allow ‘silver ions’ but can access second mark.
Incorrect formula loses this mark but can access second
mark.
Do not allow ‘silver’ or an insoluble silver salt and cannot
access second mark.
Ignore references to acidification of the silver nitrate.
If an acid is specified it should be nitric acid, but allow
sulfuric acid in this case as there are no metal ions present.
If hydrochloric acid is used, CE = 0 / 2.
Do not allow ‘add water’.
1

Observation white precipitate (M2)

Ignore ‘cloudy’.
Do not allow ‘white fumes’ or ‘effervescence’.
Do not allow this mark if test reagent is incorrect or missing.
Allow named indicator paper or named indicator solution for
M1.
Allow correct colour change for M2.
1
[2]

Q12.
(a) (i) CH3COCl + C6H6 → C6H5COCH3 + HCl
Not molecular formulae Not allow C6H5CH3CO
1

phenylethanone
Ignore number 1 in name but penalise other numbers
1

AlCl3 can be scored in equation

Allow RHS as

Allow + on C or O in equation but + must be on C in

mechanism below
Ignore curly arrows in balanced equation even if wrong

Page 65 of 95
1

(ii) Electrophilic substitution

• M1 arrow from within hexagon

to C or to + on C
• + must be on C of CH3CO in mechanism
• + in intermediate not too close to C1
• Gap in horseshoe must be centred approximately around
C1
• M3 arrow into hexagon unless Kekulé
• Allow M3 arrow independent of M2 structure,
• ie + on H in intermediate loses M2 not M3
• Ignore base removing H for M3
3

(b) Electron pair donor or lone pair donor

Allow donator
Allow lone pair used in description of (dative) bond formation
1

Allow (CH3CO)2O
1

(acid) anhydride
Allow ethanoic anhydride but not any other anhydride
1
[11]

Page 66 of 95
Q13.
(a)

• M2 not allowed independent of M1, but allow M1 for

correct attack on C+
• + rather than δ+ on C=O loses M2
• If Cl lost with C=O breaking, max1 for M1
• M3 for correct structure with charges but lp on O
is part of M4
• only allow M4 after correct/very close M3
• ignore Cl – removing H+
4

(b) (i) pentane-1,5-diol

Second ‘e’ and numbers needed
Allow 1,5-pentanediol but this is not IUPAC name

(ii)

Must show ALL bonds

(iii) All three marks are independent

M1 (base or alkaline) Hydrolysis (allow close spelling)

1
Allow (nucleophilic) addition-elimination or saponification

M2 δ+ C in polyester
1

M3 reacts with OH– or hydroxide ion

1
Not reacts with NaOH
1

Allow CH3COOH or CH3CO2H

Page 67 of 95
(ii) (nucleophilic) addition-elimination
Both addition and elimination needed and in that order

(nucleophilic) addition followed by elimination

Do not allow electrophilic addition-elimination / esterification
Ignore acylation
1

(iii) any two from: ethanoic anhydride is

• less corrosive

• less vulnerable to hydrolysis

• less dangerous to use,

• less violent/exothermic/vigorous reaction OR more controllable rxn

• does not produce toxic/corrosive/harmful fumes (of HCl) OR does not

produce HCl

• less volatile
NOT COST
List principle beyond two answers
2

(d)

(e) (i) ester

Do not allow ether
Ignore functional group/linkage/bond
1

(ii) 12 or twelve (peaks)

(iii) 160 – 185

Allow a number or range within these limits
Penalize extra ranges given
Ignore units
1

Page 68 of 95
(f) (i)

sulfuric acid sodium hydroxide

hydrochloric acid ammonia X or blank

ethanoic acid potassium hydroxide

nitric acid methylamine X or blank

4 correct scores 2
3 correct scores 1
2 or 1 correct scores 0
2

(ii) Pink to colourless

Allow ‘red’ OR ‘purple’ OR ‘magenta’ instead of ‘pink’
Do not allow ‘clear’ instead of ‘colourless’
1
[21]

Q14.
Minimum volume and hot water:
Note that this question is worth a total of 5 marks.

Any two from:

to obtain saturated solution

to increase yield / reduce amount left in solution

enable crystallisation (on cooling)

Do not allow ‘because acid doesn’t dissolve well in cold
water’.
Max 2

Filtered hot: to remove insoluble impurities / to prevent crystals forming during

filtration
1

Cooled in ice: to increase amount of crystals that are formed

Do not allow ‘to cool quickly’.
1

Washed with cold water: to remove soluble impurities

Allow ‘washing with hot water would dissolve some of the
crystals’.
1
[5]

Q15.
(a) (Nucleophilic) addition-elimination
• Minus sign on NH3 loses M1(but not M4 also)

Page 69 of 95
• M2 not allowed independent of M1, but
1

• allow M1 for correct attack on C+

• + rather than δ+ on C=O loses M2
• If Cl lost with C=O breaking, max1 for M1
• M3 for correct structure with charges but lp on O is part of
M4
• only allow M4 after correct/very close M3
• For M4, ignore NH3 removing H+ but lose M4 for Cl–
removing
H+ in mechanism,
• but ignore HCl shown as a product
4

propanamide (Ignore -1- )

penalise other numbers
penalise propaneamide and N-propanamide
1

(b) Nucleophilic substitution

• Minus sign on NH3 loses M1 (not M4 also)
• + rather than δ+ on C=O loses M2
1

• ALLOW SN1 so allow M2 for loss of Cl– before attack of

NH3 on C+ for M1
• only allow M4 after correct/very close M3
• For M4, ignore NH3 removing H+ but lose M4 for Cl–
removing H+ in mechanism,

Propylamine (ignore number 1)

• but ignore HCl shown as a product
4

Page 70 of 95
or propan-1-amine or 1-aminopropane (number 1 needed)
penalise other numbers
allow 1-propanamine
1

(c) electron rich ring or benzene or pi cloud repels nucleophile/ammonia

Allow
• C–Cl bond is short/stronger than in haloalkane
• C–Cl is less polar than in haloalkane
• resonance stabilisation between ring and Cl
1
[13]

Q16.
1-chloropropane no visible change
Accept ‘small amount of precipitate’ or ‘precipitate forms
slowly’.
1

ethanoyl chloride white precipitate

Accept ‘large amount of precipitate’ or ‘precipitate forms
immediately’.
1
[2]

Q17.
(a) M1 CH3CH2CH2COOH
not C3H7COOH
1

M2 CH3CH2OH or C2H5OH
1

M3 CH3CH2CH2COOCH2CH3 + H2O
allow C3H7COOC2H5
penalise M3 for wrong products and unbalanced equation
1

M4 H2SO4 or HCl or H3PO4 conc or dil or neither

not HNO3
1

(b) M1 CH3CH2CH2CH2OH
1
not C4H9OH

M2 (CH3CO) 2O
1

M3 → CH3COOCH2CH2CH2CH3 + CH3COOH
allow CH3COOC4H9
penalise M3 for wrong products and unbalanced equation
1

Page 71 of 95
(c) (nucleophilic) addition-elimination

not acylation alone

M2 not allowed indep of M1 but allow M1 for correct attack
on C+
+C=O loses M2
only allow M4 after correct or v close M3
ignore Cl– removing H+
5

(d)

(1) (1) (1)

ignore errors in initial triester
First mark for 3CH3OH
Third mark for all three esters
3

(e)

First mark for correct ester link second mark for the rest
including trailing bonds
If ester link wrong, lose second mark also
2

Adv reduces landfill

saves raw materials
lower cost for recycling than making from scratch
reduces CO2 emissions by not being incinerated
not allow cost without qualification
ignore energy uses
1

Disad difficulty/cost of collecting/sorting/processing

product not suitable for original purpose, easily contaminated

Page 72 of 95
not allow cost without qualification
ignore energy uses
1
[19]

Q18.
(a) (nucleophilic) addition-elimination
1

N-ethylpropanamide
minus on NH2 loses M1
M2 not allowed independent of M1, but allow M1 for correct
attack on C+
+C=O loses M2
only allow M4 after correct or very close M3
lose M4 for Cl– removing H+ in mechanism, but ignore HCl as
a product
Not N-ethylpropaneamide
1

(b) CH3CN or ethan(e)nitrile or ethanonitrile

not ethanitrile
but allow correct formula with ethanitrile
1

for each step wrong or no reagent loses condition mark

contradiction loses mark
1

Step 1 Cl2
uv or above 300 °C
wrong or no reagent loses condition mark
1

Step 2 KCN
1

aq and alcoholic (both needed)

allow uv light/(sun)light/uv radiation
1

Step 3 H2/Ni or LiAlH4 or Na/C2H5OH

Page 73 of 95
not CN– but mark on
NOT HCN or KCN + acid, and this loses condition mark
NOT NaBH4
Sn/HCl (forms aldehyde!)
ignore conditions
1
[12]

Q19.

The marking scheme for this part of the question includes an

overall assessment for the Quality of Written Communication
(QWC). There are no discrete marks for the assessment of QWC
but the candidates’ QWC in this answer will be one of the criteria
Mark used to assign a level and award the marks for this part of the
Range question

Descriptor
an answer will be expected to meet most of the criteria in the level
descriptor

4-5 – claims supported by an appropriate range of evidence

– good use of information or ideas about chemistry, going

beyond those given in the question

– argument well structured with minimal repetition or irrelevant

points

– accurate and clear expression of ideas with only minor errors

of grammar, punctuation and spelling

2-3 – claims partially supported by evidence

– good use of information or ideas about chemistry given in the

question but limited beyond this

– the argument shows some attempt at structure

– the ideas are expressed with reasonable clarity but with a few
errors of grammar, punctuation and spelling

0-1 – valid points but not clearly linked to an argument structure

– limited use of information or ideas about chemistry

– unstructured

– errors in spelling, punctuation and grammar or lack of fluency

(a) (i) Mr of C6H5NH2 = 93 Mr of CH3COCl = 78.5

total Mr of reagents = 264.5
1

Page 74 of 95
% atom economy = × 100 QWC
1

= × 100 = 51.0 %
1

(ii) expected yield = × 0.5 × 135 = 7.26 kg

% yield = × 100 = 74.1 %

(iii) Although yield appears satisfactory (74%) % atom economy

is only 51% QWC
1

nearly half of the material produced is waste and must be

disposed of QWC
1

(b) (nucleophilic) addition-elimination

QWC (2)
4

(c) HNO3 + 2H2SO4 → NO2+ + H3O+ + 2HSO4–

3
[16]

Q20.
(a) CH3OH + CH3CH2COOH → CH3CH2COOCH3 + H2O
1

Page 75 of 95
(b) (nucleophilic) addition–elimination NOT acylation
1

ignore use of Cl– to remove H+

M3 for structure
M4 for 3 arrows and lone pair
4

(c)

allow C2H5 and –CO2–

allow CH3CH2COOCOCH2CH3
or (CH3CH2CO)2O
1

(d) (i) faster/not reversible/bigger yield/purer product/no(acid) (catalyst)

required
1

(ii) anhydride less easily hydrolysed or reaction less violent/exothermic

no (corrosive) (HCl) fumes formed or safer or less toxic/dangerous
expense of acid chloride or anhydride cheaper
any one
1

(e) (i) C8H8O2

(ii) any two from

Allow –CO2– allow C6H5

2
[12]

Q21.

Page 76 of 95
(a) nucleophilic addition
1

(b) (i) 2-hydroxybutanenitrile

(ii)

(allow 1 for amide even if not C4H7NO, i.e. RCONH2)

(if not amide, allow one for any isomer of C4H7NO which shows
geometric isomerism)
2

(ii)

(iii) CH3CH=CHCOOH
1
[11]

Q22.
(a) dimethylamine
1

(b) nucleophilic substitution

Page 77 of 95
1

(c) quaternary ammonium salt

(cationic) surfactant / bactericide / detergent / fabric softener or

conditioner/hair conditioner
1

(d)

(allow CH3COOH or CH3COO– NH4+)

2
[10]

Q23.
(a) (nucleophilic) addition-elimination;

(M3 for structure)

(M4 for 3 arrows and lone pair)
(M2 not allowed independent of M1, but allow M1 for correct
attack
on C+ if M2 show as independent first.)
(+on C of C=O loses M2 but ignore δ+ if correct)
(Cl– removing Ft loses M4)
1

Page 78 of 95
(If MS lost above for wrong C chain, do not penalise same
error again here)
5

(b) CH3CH2COCl + AlCl3 → [CH3CH2CO]+ + AlCl4–;

(penalise wrong alkyl group once at first error)
(position of + on electrophile can be on O or C or outside [ ])
(penalise wrong curly arrow in the equation or lone pair on
AlCl3)
1

(horseshoe must not extend

beyond C2 to C6 but can be
smaller)

(+ not too close to C1)

(penalise M2 if CH3 chain

wrong again but allow M1 and
M3)

(M3 arrow into hexagon unless

Kekule)

(M1 arrow from within hexagon to C (allow M3 arrow independent

or to + on C) of M2 structure)

(don’t penalise position of + on C of

RCO+)
3

(or can be gained in mechanism);

(c) M1 CH3CH2COCl + H2O → CH3CH2COOH + HCl 1

(penalise wrong alkyl group once at first error)
1

M2 Mr of CH3CH2COCl = 92.5 1
(if Mr wrong, penalise M2 only)
1

M3 moles of CH3CH2COCl = 1.48/92.5 = 0.016 1

M4 moles NaOH = 2 × 0.016 = 0.032 1

(allow for × 2 conseq to wrong no of moles)
1

M5 volume of NaOH = 0.032/0.42 = 0.0762 dm3 or 76.2 cm3 1

(with correct units)
(if ×2 missed in M4 lose M5 also)

Page 79 of 95
1
[16]

Q24.
(a) (i) An appropriate alkene; CH3CH2CHCH2 or (CH3)2CCH2
1

Isomer 1
1

Isomer 2
1

Position isomerism
1

Mechanism

electrophilic attack and electron shift to Br (Unless H+ used)

carbocation
1

reaction with carbocation

[Allow mechanism marks for the alkene CH3CHCHCH3]
[Allow one mark if mechanism for minor product given]
1

(ii) An appropriate carbonyl; CH3CH2CHO

Mechanism nucleophilic attack and electron shift to O

anion intermediate
1

reaction with anion

[Allow mechanism marks for the carbonyl (CH3)2CO]
1

Isomer 1
1

Isomer 2
1

Optical isomerism
NB Isomer structures must be tetrahedral
NB Penalise “stick” structures once in part (a)
1

(b) QoL
Large charge on carbonyl carbon atom due to bonding
to O and Cl
1

Page 80 of 95
Nucleophiles have electron pairs which can be donated
1

Equation Species
1

Balanced
1
[18]

Q25.
X is methyl propanoate

M1 for arrow and lone pair,

M2 for arrow
addition-elimination
1

Spectrum 2
if thinks Spectrum 1 = X can only score for structure of Y
1

Y is CH3COOCH2CH3
1

The two marks for explanation are awarded for discussing one or more of the
four peaks (not those for the CH3 of the ethyl groups)
for stated δ values the integration or the splitting should be related to the
structure: e.g. structure of X shows that
at δ 3.7 – 4.1 (1) spectrum of X should have integration 3 / singlet (1)

at δ 2.1 – 2.6 (1) spectrum of X should have integration 2 / quartet (1)

Spectrum 2 has these

[OR Spectrum 1 has
at 3.7 – 4.1 (1) quartet / integration 2 (1) so not X
at 2.1 – 2.6 (1) singlet / integration 3 (1) so not X]
2
[10]

Q26.
(a) M1 Kp = (PY)3. (PZ)2/ (PW)2.( PX) NB [ ] wrong

Page 81 of 95
1

M2 temperature
1

M3 increase
1

M4 particles have more energy or greater velocity/speed

M5 more collisions with E > Ea or more successful collisions

M6 Reaction exothermic or converse

M7 Equilibrium moves in the left

Marks for other answers

Increase in pressure or concentration allow M1, M5, M6 Max 3
Addition of a catalyst; allow M1, M5, M6 Max 3
Decrease in temperature; allow M1, M2, M6 Max 3
Two or more changes made; allow M1, M6 Max 2

(b) (i) Advantage; reaction goes to completion, not reversible

or faster
1

Disadvantage; reaction vigorous/dangerous

(exothermic must be qualified)

or HCl(g) evolved/toxic
or CH3COCl expensive
NB Allow converse answers
Do not allow reactions with other reagents e.g. water
or ease of separation
1

(ii) ΔS = ΣS products – ΣS reactants

ΔS = (259 + 187) – (201 + 161)

ΔS = 84 (JK–1 mol–1) (Ignore units)

Allow – 84 to score (1) mark
1

ΔG = ΔH – TΔS
1

= – 21.6 – 298 × 84/1000

= – 46.6 kJ mol–1 or – 46 600 J mol–1
1
Allow (2) for – 46.6 without units
(Mark ΔG consequentially to incorrect ΔS)
(e.g. ΔS = –84 gives ΔG = +3.4 kJ mol–1)

Page 82 of 95
1
[15]

Q27.
(a) Cyclohexane evolves 120 kJ mol–1

(expect triene to evole) 360 kJ mol–1 (1) or 3 × 120

360 – 208 = 152 kJ (1) NOT 150

152 can score first 2
QofL: benzene lower in energy / more (stated) stable (1)
Not award if mentions energy required for bond
breaking
due to delocalisation (1) or explained
4

(b) (i) phenylamine weaker (1)

if wrong no marks

lone pair on N (less available) (1)

delocalised into ring (1) or “explained”
3

(ii) addition – elimination (1)

structure (1) M3
3 arrows (1) M4

N-phenyl ethanamide (1)

(iii) conc HNO3 (1)

conc H2SO4 (1)

HNO3 + 2H2SO4 → O2 + H3O+ + 2HSO4– (1)

(iv) peptide / amide (1)

NaOH (aq) (1)

Page 83 of 95
HCl conc or dil or neither
H2SO4 dil NOT conc
NOT just H2O
2

Notes

(a) • 360 or 3 × 120 or in words (1);

• 152 NOT 150 (1); (152 can get first two marks)
• Q of L benzene more stable but not award if ΔH values used to say
that more energy is required by benzene for hydrogenation compared with
the triene or if benzene is only compared with cyclohexene (1);
• delocalisation or explained (1)

(b) (ii) or N-phenylacetamide or acetanilide

mechanism: if shown as substitution can only gain M1
if CH3CO+ formed can only gain M1
lose M4 if Cl– removes H+
be lenient with structures for M1 and M2 but must be correct for M3
alone loses M2

(iii) No marks for name of mechanism in this part

if conc missing can score one for both acids (or in equation)
allow two equations

allow HNO3 + H2SO4 → NO2+ + HSO4– + H2O

ignore side chain in mechanism even if wrong
arrow for M1 must come from niside hexagon
arrow to NO2+ must go to N but be lenient over position of +
+ must not be too near “tetrahedral” Carbon
horseshoe from carbons 2-6 but don’t be too harsh

(iv) reagent allow NaOH

HCl conc or dil or neither
H2SO4 dil or neither but not conc
not just H2O
[21]

Q28.
(a) Mechanism

Allow C3H7 if structure shown elsewhere

penalise HCN splitting if wrong

Name of product: 2-hydroxypenta(neo)nitrile (1)

Page 84 of 95
or 1-cyanobutan-1-ol
5

(b) Mechanism

Name of organic product: methylpropanoate (1)

(c) (i) ([) CH3CO (])+ (1)

(ii)

Notes

(abc) extra curly arrows are penalised

(a) be lenient on position of negative sign on : CN– but arrow must come from lp

(a)/(b) alone loses M2 but can score M1 for attack on C+, similarly

(a) allow 2-hydroxypentanonitrile or 2-hydroxypenta(ne)nitrile ... pentylnitrile

(b) in M4, allow extra: Cl– attack on H, showing loss of H+

(c) (i) allow formula in an “equation”(balanced or not)

be lenient on the position of the + on the formula

(ii) for M1 the arrow must go to the C or the + on the C

don’t be too harsh about the horseshoe, but + must not be close to the
saturated C
M3 must be final step not earlier; allow M3 even if structure (M2) is wrong
[14]

Organic points

(1) Curly arrows: must show movement of a pair of electrons,

i.e. from bond to atom or from lp to atom / space
e.g.

Page 85 of 95
(2) Structures

penalise sticks (i.e. ) once per paper

Penalise once per paper

allow CH3– or –CH3 or or CH3

or H3C–

Q29.
(a) (i) Moles NaOH = mv/1000 = 1.50 × 72.5/1000 = 0.108 to 0.11 (1)
Moles of ethanoic acid at equilibrium = moles sodium hydroxide (1)
Moles ester = moles water (=moles acid reacted) (1)
= 0.200 – 0.108 = 0.090 to 0.092 (1)
Moles ethanol = 0.110 – 0.091 = 0.018 to 0.020 (1)
KC = [Ester] [Water]/[Acid] [Alcohol] (1)
Allow if used correctly

= (0.091)2/0.109 × 0.019 = 3.7 to 4.9 (1)

Ignore units
NB Allow the answer 4 one mark as correct knowledge
7

(ii) Similar (types) of bond broken and made (1)

Same number of the bonds broken and made (1)
any number if equal
NB If a list given then the total number of each type of bond
broken and made must be the same
2

(b) (i) (Weak) dipole-dipole attraction between HCl molecules (1)

(Strong) hydrogen bonds between CH3COOH molecules (1)
NB Ignore van der Waals forces
2

(ii) Ethanoic anhydride is

Page 86 of 95
cheap compared to ethanoyl chloride (1)

less corrosive than ethanoyl chloride or HCl evolved (1)

reaction less violent or vigorous or exothermic or dangerous

or safer to use (1)

less vulnerable to hydrolysis (1)

reaction more easily controlled (1)

Max 2
[13]

Q30.
C
[1]

Page 87 of 95
Examiner reports

Q1.
(a) This was a straightforward question on a familiar topic and many good students
(46.5%) scored full marks. However, some drew structures, such as the horseshoe
in the mechanism, with insufficient care and consequently failed to gain marks.
Others omitted charges on the ions in the equation (especially on AlCl4–), or in the
mechanism did not draw the + on the carbonyl carbon in the electrophile.

(b) In this question, although some students struggled with the name, a number failed
to gain the mark due to a failure to label 1-phenyl in an otherwise correct name.
Most identified a correct reagent but “electrophilic addition” and “reduction” were
frequent wrong answers for the name of the mechanism.

(c) This question was generally answered well, especially the name of the mechanism
and the structure of the ester. A common error was to give the name of the product,
i.e. ‘HCl gas’, rather than an observation as required, or alternatively to describe this
as a ‘white precipitate’.

Q2.
(a) The zwitterion was drawn correctly by all except the weakest students.

(b) The structure of the negative ion formed by serine in alkali was less well known and
occasionally the response showed a hydrogen removed from the alcohol group, as
well as from the acid.

(c) Although the questions asked for ‘both dipeptides’, several students drew only one.
The amide link was also occasionally drawn with an extra oxygen atom included,
and occasionally cysteine was used instead of serine.

(d) This question was well answered and 25% of students scored all six marks. The
name of the organic product was the most common mark lost, closely followed by
slips in the third or fourth marks in the mechanism.

Q3.
(a) This part, and others in this question, illustrate the importance of students paying
attention to why certain techniques and processes are used during practicals. The
role of anti-bumping granules was not as well understood as expected, with only
30% of students gaining this mark. Incorrect suggestions included that they slow the
reaction down by preventing the reactant particles from bumping into each other.

(b) This proved to be an easy question for most, although there were issues with the
layout of the calculation; it was not always clear which calculation related to which
reactant.

(c) Nearly 60% of students gained this mark but a lack of specific clarity cost many
dearly. Many students apparently did not retain an awareness of the context of a
question as they worked through the stages. They did not appear to recall, from the
stem of the question, that the reaction was between NaOH and ethyl benzoate. This
recall should have enabled students to make the specific statement that the excess
of sodium hydroxide was to ensure that all the ethyl benzoate would react.

(d) Answers here often incorrectly referred to the ‘control’ of the temperature rather than

Page 88 of 95
recognising the risk of flammability of organic reagents. Clarity is again key,
because any suggestion that NaOH is flammable is incorrect.

(e) As was also evident in part (f), some students thought that reflux is a separation
method. A specific answer was again the key here, with a need to mention the fact
that reactant/organic vapours are returned to the reaction mixture. Suggestions that
reflux prevents vapour forming were incorrect.

(f) This was answered best by students who used structural or partial skeletal formulas.
Many students, who attempted to use molecular formulas, often miscounted the
number of hydrogens or carbons. Care was needed to avoid any suggestion that
there is an O−Na bond in sodium benzoate.

(g) As mentioned previously, this proved to be the trickiest question on the paper, with
only 1% of students earning both marks. Most could state that sodium benzoate is
ionic – although there were also many incorrect references to it being ‘polar’ or ‘a
molecule’. However, a proper description of why benzoic acid is insoluble was
beyond most students. Many stated that it is non-polar, while others suggested that
its ability to hydrogen-bond with itself is what prevents it dissolving. Very few were
able to clearly explain that, despite the polarity (and hence the ability to form
hydrogen bonds with water), the large non-polar benzene ring prevented dissolving.

(h) About a third of students earned 4 or more marks here, but about the same number
failed to score. Despite a statement in the stem that benzoic acid is a solid, many
answers referred incorrectly to methods based on distillation and/or solvent
extraction. Some answers implied that a solid would be expected to run through the
tap of a separating funnel! For those students who correctly recognised that
recrystallization was the correct method, there was often confusion in the order of
the steps, which prevented potentially good answers gaining full marks. An example
seen quite often was the suggestion that the solid obtained after
cooling/crystallisation should be washed before filtering. The steps most often
missing were the need for hot filtration after dissolving the impure solid in hot
solvent, and the final wash and dry after Buchner filtration.

(i) This was another tricky question, with only 10% of students earning full marks. It
seemed that many were thrown by the realisation that the answer was over 100%,
with many students responding by doing the percentage calculation the wrong way
round, because they seemed to feel that the answer must be less than 100%.
Relative molecular masses were often calculated incorrectly despite that for ethyl
benzoate being given in the stem. The Mr of ethyl benzoate was sometimes used in
place of the Mr of benzoic acid.

Q6.
The IUPAC name in part (a)(i) proved harder than expected with answers including
1-chloro or ethyl. The mechanism in part (a)(ii) was well known with over half of students
gaining full marks. There was a wide range of answers to part (d) with both the number of
hydrogens and the overall Mr proving harder than expected, but, even so, nearly half of all
students scored both marks. Many students knew (e) was tertiary but some thought it was
an amide rather than an amine.

Part (f)(i) was generally well done and in the correct responses there was a fairly even
distribution between those describing why b is a stronger base or why a is a weaker base.
Part (f)(ii) proved more difficult and only the best students scored any marks. The term
salt was given in the question and so just that link was not credited. Few stated that the
ionic character of the salt would make it more water-soluble than lidocaine itself.

Page 89 of 95
Q7.
The equation in part (a)(i) was fairly well written. By comparison, few students could name
the ester correctly. The more common errors in the equation were to give a straight chain
alkyl group in the ester, or to give the second product as water or to leave it out
altogether. In part (a)(ii), the nucleophilic addition-elimination mechanism was well done
with over half of the students scoring full marks.

In part (b)(i), the mark for 3NaOH was frequently scored, whereas the mark for the right
hand side of the equation was often lost mainly due to mistakes in the salts, such as an
incorrect number of hydrogen atoms, a covalent bond from O to Na, or covalent bonds
between the three salts. Almost half of the students gained the mark in part (b)(ii). Those
who lost it gave the carboxylic acid instead of the methyl ester or misread the question
and calculated the Mr of the molecule rather than giving its formula.

Q8.
The skill of chemical communication is one which is being assessed here. Parts (a)(i) and
(ii) were frequently well done with, occasionally the usual difficulty with what is expected
for precision – this cannot be ignored by centres. Many good answers were seen for part
(b)(i) but only the best students got full marks with parts of the detail missing. There
appeared, for some centres, to be an obsession with washing, even ‘washing solutions’!
Part (b)(ii) was well answered by many, especially where they had carried out the
procedure but M3 was occasionally lost through a lack of clarity regarding the required
‘match’ with data values. Part (b)(iii) was well answered but part (c) was marked too
generously; again a lack of clarity was often evident and centres were frequently too
generous, misapplying the Marking Guidelines e.g. HCl is not toxic.

Q9.
The nucleophilic addition-elimination mechanism in part (a)(i) presented a real challenge
to many students, who were confused by the cyclic nature of the product, failed to identify
the correct nucleophile and suggested either separate nucleophiles such as H2O, CH3OH
and OH– or alternatively loss of the proton from the OH group before nucleophilic attack.
Most students gave the correct range for the carbon atom labelled b, but often the range
for the carbon atom labelled a was given as 160–185 as for a carbonyl carbon. In part
(a)(ii), the repeating unit for the polyester was answered well although some students
gave twice the repeating unit.

The distinguishing test in part (b) was well done, although a significant number of students
thought that substance K was an acid and wrongly suggested NaHCO3 or Na2CO3 to
distinguish between the compounds. It was common for students to fail to see the
symmetry of J and so to predict, incorrectly, three peaks in its proton n.m.r. spectrum.
Five peaks was a common incorrect answer for K, suggesting that students had misread
the question and given the 13C n.m.r. result.

Part (c) of this question proved to be very challenging and fewer than 10% of students
scored full marks. Isomer Q was found particularly difficult where many students omitted
one of the O atoms from their suggested structure. Other common errors included missing
the double bond in L, giving the structure of P as the structure of N (which suggests a
failure to recognise that optical isomerism is a form of stereoisomerism) or writing an
unbranched carbon chain for the acid N. Answers to part (c) were often very badly
presented, with a great deal of crossing out, duplication of answers and poor labelling of
structures.

Q10.

Page 90 of 95
(a) This part proved very challenging, with many students failing to draw apparatus for
filtering under reduced pressure. Of those who did choose appropriate equipment, it
was common to see sealed flasks and funnels, rendering them incapable of being
used.

(b) About half of the students were able to state a suitable piece of apparatus in this
part. However, only a very small number were able to describe clearly the process
of heating slowly near to the melting point. A number of very vague answers were
seen in response to this question, as well as simple restating of the question itself.

Q11.
In this Question, a number of students spoiled their answer by including sodium hydroxide
in the test reagent. The use of water was occasionally allowed even though it was
specifically disallowed in the Marking Guidelines.

Q12.
In part (a)(i), only the most able could write a correct overall equation and name the
product correctly. Marks awarded for the electrophilic substitution mechanism were high
although some students were careless in their drawing of the Wheland intermediate,
particularly the position of the + in the hexagon.

The definition of a nucleophile was not well answered in part (b). Many realised that
nucleophiles have a lone pair but failed to mention that they could donate them; others
offered a description in terms of attraction to an electron rich area.

The structure of the organic product was well attempted but many failed to recognise it as
an acid anhydride, often suggesting that it was an ester.

Q13.
In part (a), the mechanism was frequently correct and well presented, but some students
lost a mark by writing a minus charge on the oxygen of methanol. Methyl ethanoate was a
common wrong name for the product ester.

There were few correct answers to part (b)(i); IUPAC nomenclature requires an ‘e’ before
the numbers. Many correctly identified the diacyl chloride in part (b)(ii) but some failed to
give its displayed formula. Although hydrolysis was often correctly identified, part (b)(iii)
proved to be difficult, with many offering the breaking of peptide bonds as an explanation
and very few identifying attack by the hydroxide ion on the electron deficient carbon as a
contributory factor. Part (c)(i) was very well done although a few lost the mark by drawing
incomplete structures, notably by omitting the oxygen in the OH of the acid group so
giving an aldehyde.

Despite the question in part (c)(iii) stating ‘other than cost’, many students still gave the
answer that the anhydride is cheaper. Another common wrong answer was to describe
the loss of chlorine rather than hydrogen chloride. Part (d) was correctly answered by half
of the students; some of the others lost the mark by careless omission of an oxygen atom
and so drew a ketone rather than an ester.

Only the weakest students failed to answer parts (e)(i) and (e)(iii) correctly, but only the
top 20% were able to deduce the number of 13C peaks correctly in part (e)(ii).

Q14.
This Question discriminated well between students that could express scientific ideas

Page 91 of 95
logically, concisely and accurately and students who could not. The question would have
discriminated well if some schools and colleges had been less keen on awarding a mark
for incomplete answers or answers which were disallowed in the Additional Guidance. A
vague reference to removing impurities was often credited twice. Schools and colleges
are reminded that when the answer in the Marking Guidelines includes words which have
been underlined, all of these words, or their very close equivalents, must be present if an
answer is to be credited.

Q15.
These mechanisms were well done and clearly presented with about a third of students
scoring full marks. However, many struggled to name both compounds correctly.
Propanamide proved especially difficult, with incorrect names based on aminoketone
appearing very frequently. There were some good answers to part (c), but many others
involved comments about ammonia not being attracted to the benzene ring rather than
actively being repelled by it. ‘Ammonia is a nucleophile’ was another frequent wrong
answer.

Q16.
Questions that require identification of a reagent and a subsequent observation defeat
many candidates. Providing the reagent in the rubric for the question did not seem to help
and correct answers to this Question were rare. Most candidates realised that one of the
reactions would produce a white precipitate but often chose the wrong one. The
production of a silver mirror was often given.

Overall, the scheme seems to have gone well once again. Given the pressures on centres
to deliver the teaching programme, this was a very positive and encouraging outcome.
Centres are once again warmly commended for their efforts.

Q17.
A few candidates were unsure of the names of the esters involved and confused butyl
ethanoate with ethyl butanoate. In parts (a) and (b) a common error was the failure to
balance the equations due to the omission of water or ethanoic acid respectively. Weaker
candidates were also unsure of the structure of ethanoic anhydride.

The mechanism in part (c) was well answered although several omitted to give its name.
The reaction in part (d) proved unfamiliar to many candidates; some attempted to answer
the question in terms of alkaline hydrolysis of the ester to form soap rather than the
reaction with methanol to form the mixture of methyl esters which make up biodiesel. The
repeating unit was well answered in part (e).

Q18.
In part (a), a significant number missed out the name of the mechanism and also could
not name the product correctly. However, better candidates scored well in this question.

Part (b) required synoptic understanding and knowledge of some reactions from AS as
well as knowledge of the chemistry of amines from A2. A surprising number could not give
the correct reagent for the formation of CH3Cl from methane. Although many realised that
the second step in the synthesis required use of a cyanide to increase the carbon chain
from one to two, many confused the use of HCN in nucleophilic additions with the use of
aqueous/alcoholic KCN without any acid in the nucleophilic substitution needed here.

Page 92 of 95
Q20.
Good candidates were able to score high marks in this question.

The equation in part (a) was well answered; leaving out H2O was the most common error.
The mechanism in part (b) was well done by many, although several weaker candidates
persist in writing a negative charge as well as a lone pair on nucleophiles such as
methanol used here. Incorrect structures for propanoic anhydride were common in part
(c); many contained only three carbon atoms in total. By contrast, most candidates were
able to answer part (d) correctly. In part (e)(i) many did not understand the meaning of the
term “molecular formula” and wrote semi-structural formulae instead. However many
correct structures were written in part (e)(ii).

Q21.
As usual, better candidates find organic mechanisms straightforward and many good
answers were seen to part (a). In part (b)(i) the name 2–hydroxybutanenitrile, was usually
given correctly. The abbreviation 2–hydroxybutanitrile was not allowed.

The structure of the isomer of C4H7NO was found difficult. It was possible to score one
mark for a structure with the correct molecular formula which showed geometric
isomerism. Sadly many candidates did not recognise that an acyl chloride reacts with
ammonia form an amide.

In part (c), there were many pentavalent carbons shown in the structures drawn,
especially in part (ii). The elimination of water in part (iii) to form an alkene was the least
well-known reaction.

Q22.
A disappointingly small number of candidates could name the secondary amine correctly
in part (a), although the mechanism was well answered by the better candidates. The
name quaternary ammonium salt was well known and many uses for such compounds
were allowed. Part (d) was found difficult by many candidates who seemed unfamiliar with
anhydrides and their reactions.

Q23.
The better candidates often gained full marks in part (a). The most common errors were
similar to those described in Question 3(a) above. In part (b), despite the request to write
equations to show the role of aluminium chloride, many drew a mechanism often
containing incorrect curly arrows and were penalised. The electrophilic substitution
mechanism was generally well answered although careless drawing of the electrophile
with wrong position of the + charge often led to incorrectly linked COCH2CH3 side chains,
with CH3 or O joined to benzene ring. Many failed to write an equation for the regeneration
of the A1C13 catalyst. In part (c), few realised that hydrolysis of propanoyl chloride forms
both propanoic and hydrochloric acids, both of which react with sodium hydroxide. Hence
the most common answer was half the correct value. A disappointing number also failed
to calculate the correct Mr of propanoyl chloride, the formula for which was given at the
start of the question.

Q24.
Part (a)(i) was well answered. Many candidates chose a correct alkene, gave two
structural isomers formed in the reaction with HBr and named the type of structural
isomerism. Candidates who chose an incorrect alkene were able to score three marks for
a correct mechanism. In (a)(ii) choosing a carbonyl compound with the molecular formula

Page 93 of 95
C3H6 O which forms two isomers when HCN is added proved more difficult and many
candidates gave the incorrect carbonyl (CH3)2CO. Marks were again allowed for a correct
mechanism even when the carbonyl was incorrect. Candidates were only allowed to score
a mark for stating that the isomers formed were optically active if the isomers given had
an asymmetric carbon. As square planar molecules are not optically active, structure
marks were only awarded when isomers were shown as tetrahedral arrangements. Almost
all candidates were able to write an equation for a nucleophilic addition-elimination
reaction of ethanoyl chloride but equations involving NH3 were only given full marks if
NH4CI rather than HCl was given as a product. Many candidates omitted to state the
polarising effects of both the oxygen and the chlorine atoms when explaining why the
reactions occur readily. Most also failed to state that nucleophiles are able to react
because they have a lone electron pair which they can donate.

Q25.
Many candidates were able to name ester X correctly but fewer could give the correct
name for the mechanism involved in the formation of X from an acid chloride and an
alcohol. Too many candidates also forgot that the mechanism initially involves addition in
which the C=O bond becomes C-O and then, subsequently, the C=O bond is reformed in
the second step which involves elimination. Better candidates were able to state that
Spectrum 2 was that of ester X, but many did not explain their deduction clearly. Both
spectra contain a peak in the δ range 3.7 - 4.1 which could apply to an ester, and this
statement alone was insufficient. It was necessary to state that for X, the absorption in this
region must be a singlet or have an integration value 3. Despite the statement in the
question that Y was “an isomeric ester”, many suggestions for the structure of Y were not
those of esters.

Q26.
Many candidates gave a correct expression for the equilibrium constant, Kp, for the
reaction given in part (a). Some, who gave correct indices, lost a mark as they included
square brackets, which are specific used to indicate concentration, in their expression.
Identifying the one change which would increase the rate of reaction and decrease the
value of Kp proved challenging but part marks were awarded for answers which addressed
either of the two required changes. Candidates who gave more than one change of
condition were able to score one mark for a correct Kp expression. There were many
vague answers to part (b)(i), some of which assumed there were other reactants present
with the most common example being water in Reaction 2. By contrast, (b)(ii) was very
well answered with many candidates scoring full marks. Most candidates now remember
to use either kJ mol–1 or J mol–1 throughout these calculations but a small number still
failed to do this. Consequential marks were awarded in each part of the calculation.

Q27.
In part (a), not all candidates noted the requirement in the question to “Use the data”. The
numerical difference of 152 kJ mol-1 between the expected enthalpy of hydrogenation of
-360 kJ mol-1 and the actual value of –208 kJ mol-1 was rarely noted. Weaker candidates
also thought that the data given was of the energy required to cause the reaction, rather
than that evolved in the reaction. In part (b), weaker candidates muddled the expected
addition-elimination reaction of an acid chloride and an amine with a Friedel Craft’s
substitution in the benzene ring and frequently gained no marks for the section. The
correct name for the product, N-phenylethanamide was rarely seen. Part (c) was better
answered; most candidates were able to discuss nitration correctly and the mechanism
was better answered than that in part (b)(ii). The amide or peptide link was not always
named correctly in part (iv) and many did not state that acidic or alkaline hydrolysis is
required to break the bond.

Page 94 of 95
Q28.
In organic mechanisms, a curly arrow must start at a lone pair or at a bond. This idea was
still forgotten by some candidates. In part(a), several used a lone pair on the nitrogen
atom rather than one on the carbon of the cyanide ion. A few confused the nucleophilic
addition in part (a) with the addition-elimination in part (b) and tried in part (a) to reform a
carbon to oxygen double bond. An appreciable number thought that the name of the
product was a propanenitrile instead of 2-hydroxypentanenitrile. In both parts (a) and (b)
the C=O bond should not be shown breaking before the nucleophile attacks. The ester
was often correctly named as methyl propanoate but many other suggestions were also
seen. Part (c) discriminated well. Only the better candidates were able to identify the
correct electrophile, join it correctly to the benzene ring, draw the correct intermediate and
show the loss of H+ correctly.

Q29.
The calculation of the equilibrium constant, Kc, required in part (a)(i) was generally well
done. The most common error was made by candidates who subtracted the equilibrium
moles of ethanoic acid from the initial moles of alcohol when calculating the moles of
alcohol at equilibrium. Consequential marks were awarded after any arithmetic error. In
answer to (a)(ii), most candidates recognised that similar bonds were being broken and
made during the formation of the ester, but not all stated that the same number of these
bonds was involved. Part (b)(i) most candidates stated correctly that hydrogen bond
between ethanoic acid molecules explains why it is a liquid at room temperature but rather
less candidates referred to the weaker dipole-dipole attractive forces between molecules
of hydrogen chloride. Almost all candidates were able to give two advantages of using
ethanoic anhydride rather than ethanoyl chloride in the manufacture of aspirin.

Page 95 of 95

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