Experiment No.

1
Aim: To prepare urotropine from formaldehyde and report its % yield & Melting point.

Reference – i) Siddiqui. A, Siddiqui, “Experimental Pharmaceutical Chemistry” 3rd edition,

2013, CBS Publication, New Delhi, Page No. 226

Chemicals required: 40%Formaldehyde, ammonia solution.

Chemical reaction involved:

Theory: Hexamethylenetetramine or methenamine is a heterocyclic organic compound with

the formula (CH2)6N4. This white crystalline compound is highly soluble in water and polar
organic solvents. It has a cage-like structure similar to adamantane. It is useful in the
synthesis of other chemical compounds, e.g., plastics, pharmaceuticals, rubber additives. It
sublimes in vacuum at 280 °C

Procedure: Place 10mL of 40% formaldehyde and 9mL of ammonia into a beaker (100mL).
Evaporate the solution on a water bath. During evaporation a white residue (Urotropine) is
formed. Add another portion of ammonia (14mL) to dissolve the solid. Once more place the
flask onto a water bath and evaporate the solvent. Repeat that step once more with an
additional portion of ammonia (14mL). After evaporating, add 15mL of anhydrous ethanol
and dissolve the solid by heating under reflux. Filter the hot mixture on the Büchner funnel.
Add 10mL diethyl ether to the filtrate and cool down. Filter the precipitated urotropine, wash
it with anhydrous ethanol, drain well and then dry on air. Weigh the product, calculate the
yield and measure the melting point. (lit. 214-215

Use: As the mandelic acid salt) it is used for the treatment of urinary tract infection. It
decomposes at an acidic pH to form formaldehyde and ammonia, and the formaldehyde is
bactericidal; the mandelic acid adds to this effect.

Report:
Experiment No.2

Aim: To prepare and submit Benzocaine starting from p-Aminobenzoic acid and report its %
yield and melting point.

Reference: – i) Siddiqui.A, Siddiqui, “Experimental Pharmaceutical Chemistry” 3 rd edition,

2013, CBS Publication, New Delhi, Page No. 230-231.

Chemicals required: Para amino benzoic acid, Absolute ethanol, 5% Sodium bicarbonate
solution.

Apparatus required: Conical flask, measuring cylinder, dropper, reflux assembly, funnel,
beaker, spatula etc.

Chemical reaction:

Procedure: 1) Dissolve 5gm of p-amino benzoic acid and 40ml of absolute ethanol in a conical
flask and dissolve the solid completely.

2) Now cool this mixture over ice bath and slowly add 1ml of concentrated sulphuric acid
carefully. Large amount of precipitate will form when sulphuric acid is added, but this solid
will slowly dissolve during reflux in the next step.
3) Boil the mixture gently over reflux for 75mins and take care of over heating.

4) After completion of reaction allow the mixture to cool down and transfer the content in the
beaker containing 30ml of water.

5) Now add 5% sodium bicarbonate solution slowly until gas is no longer evolved and the pH
becomes around 8.

6) Filter the benzocaine ppt. using vacuum filtration and rinse the ppt. with water.

7) Allow the solid to dry at room temperature over weighed piece of filter paper.

CALCULATION:

Result: The Percentage yield of benzocaine was found to be ___________.

Experiment - 3

Aim:- To prepare and submit Chlorobutanol from acetone and calculate its % yield.

Reference:-Sunila T Patil , mohammad Rageeb & mohammad usman "a practical book of
medicinal chem 3rd " 1st edition ,2020 , Nirali prakshan pune ,pg no. - 9.

Apparatus used:-Beaker, Measuring cylinder, Glass rod, Ice bath, Funnel, Spatula etc.

Chemicals Required:-Acetone, Chloroform, Potassium hydroxide and Ethanol.

Theory:-

Principle:-Chlorobutanol is synthesized by the addition of chloroform to acetone under the

catalytic influence of potassium hydroxide.

Procedure:-1. Take a mixture of 90ml of acetone and 10ml of chloroform and cool this mixture
upto -5*C over ice bath.

2. Now add 2gm powdered KOH slowly to the above mixture with constant stirring.

3. Stir this mixture continously for a 2 has at -5*C.

4. After completion of reaction the suspension was filtered & the filter need to be washed
with acetone.

5. Combine the filterate & distill at 60*C. Untill the weight of the solution is remain constant.

6. Then pour the undistilled chlorobutanol into a beaker containing 100ml of ice cold water.

7. Crystals appeared in the beaker are then filtered off and can be recrystalized from ethanol
to get the pure crystals of chlorobutanol.

8. Chlorobutanol is extremely volatile in nature even at ordinary temperature.

9. Weigh the amount & calculate the %age yield of chlorobutanol.

CALCULATION: Practical yield
Percentage yield = × 100
Theoretical yield

= …………%

Result:-The %age yield of chlorobutanol was found to be……………… .

Uses:-1. It is used as a preservative, sedative, hypatic, and has a week local anaesthatic effect
also. 2. It has anti-bacterial and anti-fungal properties also.
Experiment 4

Aim:- To prepare and submit Wintergreen oil (methylsalicylate) from salicylic acid its % yield

Reference:- Siddiqui AA, Siddiqui S, “Experimental p’ceutical chemistry”, 3rd edition , 2013 ,
CBS Publisher, New Delhi Pg no. 230.

Chemical used:- Salicylic acid, Methanol or sulphuric acid , diethyl ether & 5% NahCO 3
solution.

Glass wear used:- Beaker , Large test tube, Glass road , Funnel, Separating Funnel, Spatula
etc.

Chemical Reaction:

Procedure:-

1. Weigh 3gm of salicylic acid and transfer to a dry large test tube and add 10 ml of
methanol to dissolve the salicylic acid completely.

2. Carefully add 1 ml of concentrated H2SO4 drop wise to the mixture in the fuming hood
and mix well.

3. Now place this mixture in a hot water bath for about 20 mint to complete the reaction.

4. After that remove the test tube from water bath and allow it to cool.

5. After it has cooled, smell or aroma of oil of winter green appears.

6. Now pour this mixture into cold water taken in a beaker and add 30 ml diethyl ether
to it.

7. Now transfer this content in to a separating funnel and remove the aqueous layer.

8. Take the organic layer into a separate conical flask and add 5 ml of 5% NAHCO3 solution
and mix well this will neutralized the unreacted acid.

9. Now transfer the ether layer to another dry flask and add sodium sulphate to make
product dry.

10. Filter out the drying agent and evaporate the ether layer, the oil of winter green
appear in the glass.

11. Calculate the % age yield and report.

 CALCULATION: Practical yield
Percentage yield = × 100
Theoretical yield

= …………%

Result:-The % age yield of oil of winter green was found to be……………….

Experiment – 5

Aim:-To synthesized Chalcone from acetophenone and benzaldehyde and report its %age
yield.

Reference:-www.labmonk.com.

Apparatus required:-beaker, glass rod, measuring cylinder, ice bath, funnel, filter paper,
spatula, dropper etc.

Chemicals required:-benzaldehyde, acetophenone, 50%naoh solution.

Theory :- Principle :- Aromatic aldehyde condensed with aliphatic or mixed arylalkalie ketone
in the presence of aqueous alkali to form alfa-beta unsaturated ketone which is also known
as Claisen – Schimidt condensation reaction. Benzaldehyde react to form benzyledene
acetophenone ( chalcone ).

Procedure:-1. Dissolve 2.4gm of actophenone & 2.1gm of benzaldehyde in 15ml of methanol

and maintain in the temperature between 0-50c.

2. Then slowly add 15ml of 50% naoh.

3. Now stirr this mixture for 3 hour and then allow to stand over night.

4. on next day pour this mixture over 10-20ml ice – cold water & neutralize the solution using
dil. HCL , crystals of chalcone appeared, filter them & dry them.

CALCULATION: Practical yield

Percentage yield = × 100
Theoretical yield

= …………%
Result:-The % age yield chalcone was found to be …………

Experiment No.6

Aim: To synthesis and submit sulphanilamide from p-acetamido benzene sulphanilamide

and calculate its percentage yield.
Principle:

Sulphanilamide can be prepared by the reaction of P-acetamido benzene

sulphanilamide with Hydrochloric acid or ammonium carbonate. The acetamido
groups are easily undergo acid catalysed hydrolysis reaction to form p-amino
benzene sulphonamide.

Chemical Required:

Resorcinol-1.2 g, Ethyl acetoacetate-2.4 ml, Conc. Sulphuric acid-7.5 ml

Chemical reaction:

Procedure:

1.5 gm of 4- acetamido benzene sulphonamide is treated with a mixture of 1 ml of

conc. Sulphuric acid diluted with 2 ml water. This mixture is gently heated under
reflux for 1 hour. Then 3ml of water is added and the solution is boiled again, with
the addition of a small quantity of activated charcoal. The solution is filtered while
hot, and the filtrate is neutralised with powdered sodium carbonate with stirring until
all effervescence ceases and the sulphanilamide is precipitated as a white powder.
The solution is cooled filtered, the sulphanilamide wash with water and dried.
Finally, crude sulphanilamide is recrystallized from hot water, to get colourless
crystals.

CALCULATION: Practical yield

Percentage yield = × 100
Theoretical yield

= …………%
Result: The % age yield of 1,2,3,4-Tetrahydrocarbazole was found to be ………

Experiment No. 7

Aim : To perform the Assay of Dapsone.

Requirement: aspirin, sodium hydroxide solution, hydrochloric acid, phenol red indicator

Principle:

Dapsone is a diamino diphenyl sulphone. It is assayed by direct diazotization titration.

The free primary amino group present in dapsone is diazotized by nitrous acid and
hydrochloric acid to form arene diazonium compound. The end point can be
determined by using external indicator i.e. starch iodide paper, during titration with
sodium nitrite an aromatic primary amine is diazotized. After the end point the drug
solution containing a slight excess of nitrite comes in contact with starch iodide
paper. It oxidizes iodide into iodine which gives blue colour with starch indicating the
end point.

Procedure:

Preparation of 0.1M Sodium nitrite solution:

7.5g of sodium nitrite was dissolved in sufficient water to produced 1000ml.

Standardisation of 0.1M Sodium nitrite:

0.3g of sulphanilic acid was dissolved in 50ml of 2M hydrochloric acid, 3g of

potassium bromide was added, cool in ice and titrate with 0.1M sodium nitrite
solution using starch iodide paper as external indicator.
 Each ml of 0.1M Sodium nitrite= 0.01732g of C6H7NO3S.
Assay of Dapsone tablet:
20 tablets were weighed and powered. Tablet powder equivalent to 0.25gm dapsone
was weighed and dissolved in a mixture of 15ml of 2M hydrochloric acid. The solution
was cooled to about 15oC and carry out sodium nitrite titration using starch iodide
paper as an external indicator. End point is immediate appearance of blue colour.

Each ml of 0.1M sodium nitrite= 0.01241g of C12H12N2O2S.

Report:

The Molarity of 0.1M sodium nitrite=

The percentage purity of given dapsone tablet was found to be=

Experiment 8

Aim :- To perform the assay of chlorpheniramine and report its % purity.

Principle:

Chlorpheniramine maleate chemically known as 3-(4-chlorophenyl) N, N- Dimethyl-

3-(2-pyridyl) propylamine hydrogen maleate is an anti-histamine H1 receptor
antagonist. Mineral acid salts of weak nitrogen bases hydrolyse so extensively in
aqueous or hydro-alcoholic solution that is possible to titrate the liberated acid with
a strong mineral base. Titration of the maleate salt of the drug in water against the
sodium hydroxide leads to the formation of water turbidity as the titration proceeds.
To prevent this precipitation, alcohol has been used. Since alcohol is basic with
respect to water as a solvent, dissolved bases react less strongly alkaline, their salts
react more strongly acid, and the end points of the titrations are greatly sharpened,
here an aqueous solution of Chlorpheniramine maleate was titrated with aqueous
NaOH, the turbidity was formed with appearance of pink is the end point.
Procedure:

Preparation of 0.01M Sodium hydroxide:

Weighed accurately about 0.4gm of Sodium hydroxide pellet in a clean 1000ml

standard flask then completely dissolved with 100ml distilled water, and make up to
1000 ml with distilled water.
Standardisation of 0.01M sodium hydroxide:

Weighed accurately about 0.5gm of potassium hydrogen phthalate and transferred

into 1000ml conical flask. Then add 75ml of distilled water to dissolve and titrated
with 0.01M sodium hydroxide solution using 0.1ml phenolphthalein as an indicator.
The end point is appearance of permanent pale pink colour.
Each ml of 0.01M Sodium hydroxide= 0.002042g of C8H5KO4
Assay of Chlorpheniramine maleate

Twenty tablets were weighed and grind into a fine powder. An amount of power
equivalent to 200mg of chlorpheniramine maleate was weighed accurately into
100ml standard flask, 70ml of neutral alcohol was added and shaken for about 20
min. Then, the volume was made up to mark with neutral alcohol, mixed well and
filtered using whatmann No 42 filter paper. The first 10 ml portion of the filtrate was
discarded. An aliquot of the drug solution containing 2.0-20.0 mg of
chlorpheniramine maleate was measured accurately and transferred into a clean 100
ml conical flask and the total volume was brought to 10 ml with neutral alcohol. Then
2 drops of 0.5% phenolphthalein indicator was added and the solution was titrated
with standard 0.01M Sodium hydroxide solution until a permanent pink colour was
obtained.
Each ml of 0.01M Sodium hydroxide= 0.002042g of C8H5KO4.

Report:

The molarity of 0.01M Sodium hydroxide=

The percentage purity of given Chlorpheniramine maleate tablet was found
to be=

Experiment 9

Aim :- To perform the assay of metronidazole and report its % purity.

Requirements:

Apparatus: Volumetric flask, Measuring cylinder, Analytical balance, Weight box, Beaker,
Burette and Conical flask.

Chemicals:

Metronidazole tablets, 0.1 N Perchloric acid, Anhydrous glacial acetic acid, Brilliant green,
Potassium hydrogen phthalate and Crystal violet.

Principal:

Metronidazole tablets are assayed by non-aqueous titration in which the tertiary amine group
is titrated with perchloric acid using brilliant green as indicator.

Preparation of Perchloric acid, 0.1 M:

Mix 8.5 ml of perchloric acid with 500 ml of anhydrous glacial acetic acid and 25 ml of acetic
anhydride, cool and add anhydrous glacial acetic acid to produce 1000 ml. The prepared
solution is allowed to stand for 1 day and again titrate the water content. The solution so
obtained should contain between 0.02% and 0.05% of water.

Weigh accurately about 0.35 gm of Potassium hydrogen Phthalate and dissolve in 50 ml of

anhydrous glacial acetic acid. Add 0.1 ml of crystal violet solution as indicator and titrate with
the perchloric acid solution until the violet colour changes to emeraid-green. Perform a blank
determination. Each ml of 0.1 M Perchloric acid is equivalent to 0.02042 g of C 8H3KO4 .

Procedure:

• Weigh and powder of 20 tablets of Metronidazole.

• Weigh accurately a quantity of the powder containing about 0.2 g of Metronidazole transfer
to a glass crucible and extract with six quantities, each of 10 ml, of hot aceton.

• Cool it and add 50 ml of acetic anhydride to the combined extracts.

• Titrate with 0.1 M perchloric acid, using 0.1 ml of 1% w/v solution of brilliant geen in
anhydrous glacial acetic acid as indicator to a yellowish-green end point. Carry out a blank
titration.

• Each ml of 0.1 M perchloric acid is equvalent to 0.01712 g of C6H9N303.

Result:

The given sample contains……………………..mg of Metronidazole.

Experiment No.10

Aim: To draw the chemical Structures and Reactions by using ChemDraw.

Reference: Sunita N Patil, “A Practical book of medicinal chemistry-III” First edition, 2019,
Nirali prakashan, Pune, page no. 35-40.

Theory: ChemDraw program is developed by David A. Evans and Stewart Rubenstein in 1985,
later by the chem informatics company Cambridge Soft. ChemDraw is a simple-to- use
program that allows drawing efficiently simple two-dimensional representations of organic
molecules. It is available for the PC as well as for the Mac platform. The drawing of chemical
formulae and reaction schemes is a repetitive task for chemists on all levels of their education.

ChemDraw is used by all over the world to quickly and effectively draw molecules, reactions
and biological pathways for use in documents and electronic lab notebooks.

Features of ChemDraw 12.0:

1) Chemical structure to name conversion.

2) Chemical name to structure conversion.

3) NMR spectrum simulation ('H and 1C).

4) Mass spectrum simulation.

5) Structure cleanup.

ChemDraw Toolbars:

> The Main Toolbar: The main toolbar includes the tools used for drawing structures including all
selection bond tools

>Tearing off Toolbars: Tearing off toolbars are indicated by a small black triangle in the lower right
corner example:

Creating a New Document:

To create a document, go to File>New Document.

Using Styles:

> To create a new document using a different style sheet or stationery pad:

1. Go to File>Open Style Sheets.

2. Choose a Style Sheet from the list.

Opening a Document:
(a) Navigate to File>Open. From the Open dialog, select the file name and location of
the file and click Open.

OR

(b) From the File menu, choose the document from the list at the bottom.

Chemical Properties Window:

> Chemical Properties view for Methane:

The Analysis Window:

The Analysis window displays the chemical anaiysis of the selected structure. Window can

Activate from the View menu.

The Analysis Window View for Methane:

Importing and Exporting Data from ChemDraw:

• Chemical drawing programs enable scientists to communicate chemical structures.

• ChemDraw includes many of the standard file formats for transferring information
between ChemDraw and documents created using other applications.

Exporting Graphics from ChemDraw:

Method 1:

• To insert the ChemDraw. wmf image file into a Microsoft Word document, position
the cursor at the appropriate location on the page. Then use INSERT > PICTURE >
FROM
FILE.
• Select the file and click insert to insert the drawing to the document.

Method 2 (Direct Export Method):

• To export diagrams from Chem Draw into Word (or other programs): select the diagram.
Copy it to the clipboard (Edit-Copy or Command-C), go to Word and do Edit-Paste or
Command-V to paste it into the document.

Importing Graphics to ChemDraw:

• Diagrams that have been placed in a Word file can be edited. If double click on the
diagram in the Word file, it will extract it into a little window in ChemDraw where it
can be edited. Just close the window to put the edited diagram back into the Word
file.
 • If right-click on the diagram in the Word file, it will see the edit and open options under
the CS ChemDraw Drawing Object option.
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