1.

7 Amines and Amides

During a severe allergic reaction, the body’s immune system overreacts to the
presence of a foreign substance. The allergic reaction causes the tissues of the airway
OH to swell and the lungs to fill with fluid. If not treated quickly, this severe reaction can
H
N cause death. The most common treatment for severe allergic reactions is epinephrine,
also known as adrenaline. Epinephrine is a hormone produced naturally by the adrenal
HO glands. The hormone molecules contain a functional group called an amino group, –NH
(Figure 1). Most people who have severe allergies to common substances, such as bee
OH venom or peanuts, carry auto-injection syringes filled with epinephrine with them at
Figure 1  The epinephrine (adrenaline) all times (Figure 2). Amines are one class of organic compounds that contain nitrogen.
molecule. The –NH group on the right
of the molecule is bonded to 2 carbon
atoms, making this compound a
Amines
secondary amine. An amine is a derivative of ammonia in which one or more of the hydrogen atoms are
replaced with alkyl groups. Amines are classified as primary (1°) if one alkyl group
is attached to the nitrogen atom, secondary (2°) if two alkyl groups are present, and
tertiary (3°) if all three hydrogen atoms in ammonia have been replaced by alkyl
groups. Table 1 lists some common amines.
Amines generally have strong, often unpleasant, odours, sometimes described as
“fishy.” Many amine odours resemble ammonia. For example, urine contains amines
that come from the breakdown of proteins. The odours associated with decaying
animal and human tissues are caused by amines such as putrescine, H2N(CH2)4NH2,
and cadaverine, H2N(CH2)5NH2. Notice that these compounds have an amino group
Figure 2  Epinephrine auto-injection
at either end of each molecule. Aromatic amines are used to make dyes. Since many
syringes can be lifesavers for people of them are carcinogenic, they must be handled with great care. CAREER LINK
who are susceptible to severe allergic
reactions. Table 1  Some Common Amines

Formula Systematic IUPAC name Common name Type

amine  an organic compound, related to CH3NH2 methanamine methylamine primary
ammonia, that contains a nitrogen atom CH3CH2NH2 ethanamine ethylamine primary
bonded to one or more alkyl groups on
(CH3)2NH N-methylmethanamine dimethylamine secondary
each molecule
(CH3)3N N,N-dimethylmethanamine trimethylamine tertiary
C6H5NH2 aniline aniline primary
H N-phenylaniline diphenylamine secondary

H Naming Amines
Consider the primary amine with the structure CH3NH2. Using the IUPAC naming
H C N H
system, this molecule would be named by adding the -amine suffix to the name of
H H the chain or ring to which it is attached. The -e is removed from this name, giving the
methanamine name methanamine (Figure 3).
Note that, in Table 1, the IUPAC name for an aromatic amine consisting of an
Figure 3  Alternative names for amine group attached to a benzene ring is aniline, rather than benzamine.
methanamine are methylamine and
To name secondary and tertiary amines, begin with an amine name based on
aminomethane.
the name of the longest alkyl group. We use the locator, N, to indicate the attach-
ment of additional chains to the nitrogen atom, just as we use a number to indicate
a specific carbon atom. For example, an amine with an ethyl group, a propyl group,
and a butyl group, each bonded to the nitrogen atom at carbon number 1, is named
N-ethyl-N-propylbutan-1-amine.

56   Chapter 1 • Organic Compounds NEL

7924_Chem_CH01.indd 56 5/3/12 1:40 PM

 CH2CH2CH3
CH3 CH2 CH2 CH2 N CH2 CH3
N-ethyl-N-propylbutan-1-amine
As you have already read, some compounds contain more than one amino group.
A molecule of cadaverine, for example, is a 5-carbon chain with an amino group at
each end: NH2(CH2)5NH2. This type of compound is called a diamine, so cadaverine’s
IUPAC name is pentane-1,5-diamine.

Tutorial 1  Naming and Drawing Amines

This tutorial will give you practice in drawing and naming amines.

Sample Problem 1: Naming Amines from Their Structures

Name each of the following amines according to the IUPAC system:
(a) H N H   (c)  NH2

CH2CH2CH3

CH3
(b) H   (d)  CH3CH2CH2CH2 N CH2CH3
CH2CH2CH2CH N
CH3
CH3
CH3
hemistry 12 Solution
76504524 (a) The longest carbon chain is a propyl group, whose terminal carbon atom is bonded
N to the nitrogen atom. This is the only alkyl group attached to the nitrogen atom, so
C01-F187-OC12USB
O the compound is a primary amine. The compound’s name is propan-1-amine.
CrowleArt Group
Deborah (b) This compound is a secondary amine with a pentyl group attached at its second
Crowle
carbon atom and a methyl group. The amine’s name is based on the longer group:
ss 1st pass
the pentyl group. The name of the compound is N-methylpentan-2-amine.
pproved
(c) The root name for an amine attached to a benzene ring is aniline. There is also a
ot Approved
substituent methyl group on the third carbon atom. The name of the compound is
3-methylaniline.
(d) This is a tertiary amine whose longest carbon chain has 4 carbon atoms:
butanamine. The two substituents are a methyl group and an ethyl group. The
compound is named N-ethyl-N-methylbutan-1-amine.

Sample Problem 2: Drawing Amines

Draw the structural formula and write the name of each of the following amines, with
ethyl as the attached alkyl group(s):
Chemistry 12 (a) a primary amine (c)  a tertiary amine
0176504524 (b) a secondary amine
FN
8-OC12USBChemistry 12
C01-F190-OC12USB
Solution
Group0176504524
rtCO CrowleArt Group
C01-F189-OC12USB (a) A primary amine has one alkyl group attached to the nitrogen atom.
h CrowleFN Deborah C01-F191-OC12USB
Crowle
CrowleArt
Pass CO Group 1st pass CrowleArt Group CH3CH2 NH2 ethanamine
Deborah Crowle
Approved (b) Deborah
A secondary amine has two alkyl groups and one hydrogen atom bonded to the
Crowle
1stNot
passApproved
Pass nitrogen
2nd pass atom.
Approved
H3C CH2
Not Approved NH N-ethylethanamine
H3C CH2

NEL 1.7 Amines and Amides   57

7924_Chem_CH01.indd 57 5/3/12 1:40 PM

 (c) A tertiary amine has three alkyl groups but no hydrogen atoms bonded to the
nitrogen atom.
CH2 CH3
H3C CH2 N N,N-diethylethanamine
CH2 CH3

Practice
1. Name each of the following compounds:  K/U
(a) H H               (d)  NH2
N
CH3 CH2 CH CH3

(b) CH3CH2CH2CH2 N CH2CH3   (e)  CH3CH2CH NH CH2CH3

CH2CH3 CH3

(c) CH3CH2CH2 N CH2CH2CH3

CH3
2. Draw the structure of each of the following compounds:  K/U C

(a) 2-methylpropan-1-amine
(b) a primary amine with a 2-carbon alkyl group

Chemistry 12
Properties of Amines
0176504524
Small amines are soluble in water. Since nitrogen is more electronegative than either
FN C01-F195-OC12USB
carbon or hydrogen, the N2C bonds and any N2H bonds are polar. This polarity
CO CrowleArt Group increases the strength of the van der Waals forces between molecules so more energy
Deborah Crowle is needed to separate them. That means that amines have higher melting points and
Pass 2nd pass higher boiling points than corresponding hydrocarbon compounds. The series of
CH3 groups
(a)2NH
amines in Figure 4 explains the effect that reducing the number of CH2 hasCH2 NH2
Approved
on the boiling points of amines of similar size.
Not Approved (b) CH3 CH2 NH CH3
(a) CH3 CH2 CH2 NH2

(a) CH3 CH2 CH2 NH2 (b) CH3 CH2 NH CH3 (c) CH3 N CH3

(b) CH3 CH2 NH CH3 CH3

(c) CH3 N CH3
Chemistry 12 primary amine secondary amine tertiary amine
(c) CH N CH3
b.p.3 49 °C CH3
b.p. 37 °C b.p. 3 °C
0176504524
FN C01-F196-OC12USB Figure 4  Boiling
CH3 points (b.p.) for three possible CH isomers of an amine, each with 3 carbon atoms.
CO CrowleArt Group The primary amine, (a), can form two hydrogen bonds and hence has the highest boiling point. The
tertiary amine, (c), cannot form hydrogen bonds at all and hence has the lowest boiling point.
Deborah Crowle
Pass 1st pass
Approved
Not Approved

58   Chapter 1 • Organic Compounds NEL

7924_Chem_CH01.indd 58 5/3/12 2:18 PM

 Amides
Amides are structurally similar to esters, except the two chains are joined by a nitrogen amide  an organic compound that
atom next to a carbonyl group rather than by an oxygen atom (Figure 5). The amide contains a carbonyl group bonded to a
functional group consists of a carbonyl group bonded to a nitrogen atom. nitrogen atom

O O
R C O R (H or) R C N R (or H)
R (or H)
ester amide
Figure 5  General structures of esters and amides illustrate that the compounds include one or
more alkyl groups. These groups, which might be the same or different, are represented in the
diagrams by the symbols R, R r, and Rs.

Carboxylic acids react with alcohols to produce esters. Carboxylic acids react in
a similar way with ammonia, primary amines, and secondary amines to produce
amides. You will learn more about these reactions a little later in this section.

Naming Amides
Naming amides is similar to naming esters. The name of an amide has three parts:
the first part from the amine; the second part from the acid; and the ending, which
is always the suffix -amide. For example, the reaction of methanamine and butanoic
acid will produce an amide: N-methylbutanamide (Figure 6).

O H O H
CH3CH2CH2C OH  CH3NH CH3CH2CH2C N CH3  HOH
butanoic acid methanamine N-methylbutanamide water
Chemistry 12 acid amine amide
0176504524 Figure 6  Note how to derive the name of the amide from the names of the amine and the
FN C01-F199-OC12USB
carboxylic acid.
CO CrowleArt Group
Deborah Crowle
Tutorial 2  Naming and Drawing Amides
Pass 1st pass
This tutorial will give you practice in naming and drawing amides.
Approved
Not Approved
Sample Problem 1: Naming Amides from Their Structures
Name each of the following amides:
(a) O (c) O
CH3CH2CH2 C NH CH3 CH3C N CH2CH3

(b) O CH2CH3

CH3CH2CH2 C NH CH2CH2CH3

Solution (a)
The first part of the compound came from a carboxylic acid, with 4 carbon atoms:
butanoic acid. The second part of the compound came from a primary amine with
Chemistry 12 1 carbon atom: methanamine. The name of the amide is N-methylbutanamide.
0176504524
FN C01-F200-OC12USB
CO CrowleArt Group
Deborah Crowle
NEL 1.7 Amines and Amides   59
Pass 2nd pass
Approved
Not Approved
7924_Chem_CH01.indd 59 5/3/12 1:40 PM
 Solution (b)
The carboxylic acid had a chain with 4 carbon atoms: butanoic acid. The amine was a primary
amine with 3 carbon atoms: propanamine. The name of the amide is N-propylbutanamide.
Solution (c)
The carboxylic acid had 2 carbon atoms: ethanoic acid. The amine was a secondary amine:
N-ethylethanamine. The name of the amide is N,N-diethylethanamide.

Sample Problem 2: Drawing Amides

Draw the structure of N-ethylpropanamide.

Solution
The alkyl group bonded to the nitrogen atom (from the amine) O
is ethyl. It therefore has 2 carbon atoms. The carbonyl group
CH CH C N CH2CH3
from the carboxylic acid is attached to a propan- chain, so has 3 3 2
carbon atoms. Therefore, the structure is as shown at right: H
Practice
Investigation 1.7.1
1. Name each of the following amides:  K/U

Building Organic Molecular (a) O   (c)  O

Models (page 69)
This investigation gives you an CH3 CH2 CH2 C N H CH3 CH2 CH2 C N CH3
opportunity to put into practice H CH3
your knowledge of the names and (b) O  
properties of amines and amides. You
will have the opportunity to build and CH3C NH
explore models of these compounds.
CH2CH2CH3
2. Draw the structure of each of the following amides:  K/U C
(a) N,N-diethylethanamide (b) N-methylbutanamide

Properties of Amides
The smaller amides are somewhat soluble in water. This can be explained by the mol-
ecules’ structure: the –NH groups form hydrogen bonds with water molecules. As
the length of the carbon chain increases, solubility decreases. Primary amides, with
their nitrogen atoms each bonded to 2 hydrogen atoms, have higher melting points
and boiling points than similar amides. This is likely due to more hydrogen bonding
between primary12
Chemistry amide molecules.
0176504524
Reactions
FN Involving Amines and Amides
C01-F203-OC12USB
CO can generally be
An amine CrowleArt Group
synthesized from an alkyl halide and ammonia. For example,
Deborah Crowle
Pass CH3CH2 I1st H passN H CH3CH2 N H  HI
Approved H H
Not Approved
iodoethane ammonia ethanamine
1° amine

Ethanamine is a primary amine. It reacts with additional iodoethane to form a

secondary amine, N-ethylethanamine, and hydrogen iodide:
CH3CH2 I  CH3CH2 N H CH3CH2 N CH2CH3  HI
H H
iodoethane ethanamine N-ethylethanamine
1° amine 2° amine

60   Chapter 1 • Organic Compounds NEL

7924_Chem_CH01.indd 60 5/3/12 1:40 PM

 N-ethylethanamine also reacts with iodoethane, this time forming a tertiary
amine, N,N-diethylethanamine, along with hydrogen iodide.

CH3CH2 I  CH3CH2 N CH2CH3 CH3CH2 N CH2CH3  HI

H CH2CH3
iodoethane N-ethylethanamine N,N-diethylethanamine
2° amine 3° amine

Amides can be synthesized by the condensation reaction of a carboxylic acid with

ammonia or primary or secondary amines (Figure 7).
O
 NH3 R C NH2  H2O
ammonia primary amide

O
O
 R NH2 R C N R  H2O
R C OH
H
carboxylic
primary amine secondary amide
acid
O
 R N R R C N R  H2O
H R
secondary amine tertiary amide

Figure 7  The structure of the amide product depends on whether the carboxylic acid reacts with
ammonia, a primary amine, or a secondary amine.

An example of the synthesis of an amide is the reaction of butanoic acid with

methanamine to produce N-methylbutanamide plus water.
The reactions above are reversible: Amides can be hydrolyzed in acidic or basic
conditions to produce the carboxylic acid and the amine.

Chemistry 12
0176504524
FN C01-F208-OC12USB
CO CrowleArt Group
Deborah Crowle
Pass 2nd pass
Approved
Not Approved

NEL 1.7 Amines and Amides   61

7924_Chem_CH01.indd 61 5/3/12 1:40 PM

 1.7 Review
Summary
• Amines can be viewed as alkyl groups bonded to a nitrogen atom or an amino
group bonded to an alkane. Primary amines have one alkyl group attached to
the nitrogen atom; secondary amines have two; tertiary amines have three.
• Amines are named by adding the suffix -amine to the root of the name of the
longest alkyl group attached to the nitrogen atom. The prefix N- indicates that
a second (and third) alkyl group is also attached to the nitrogen atom.
• Amides are formed from the reaction of carboxylic acid and amines. Amides
can be hydrolyzed to re-form the amine and carboxylic acid.
• Amides are named with the root of the name of the carboxylic acid first,
followed by the root of the name of the amine, and ending with -amide.
Questions
1. Name each of the following compounds:  K/U 3. Draw the structural formulas for the isomers of
(a) O   C3H9N. Show at least one primary, one secondary,
and one tertiary amine.  K/U C
CH3CH2C NH2
4. Write a structural formula equation that represents
(b) CH3CH2CH2 N CH3   the formation of N,N-diethylpropanamide.  K/U
CH3 5. Identify the reaction type and write the structures
(c) O   and names for the products you would expect for
each of the following reactions:  K/U C
CH3CH2C N CH2CH3 (a) H3C CH2 Br H3N CH2 CH3  
CH2CH3
(b) H3C CH2 Br H3C NH CH2 CH3
(d) Cl  
CH3CHCH2CHCH2CH2CH3 (c) ethanoic acid and propan-1-amine
6. Create a flow chart showing how you would
NH2 synthesize N,N-dimethylethanamide from an
(e) NH2   alkane, an alkene, a halogen, and ammonia. Draw
CH3CHCH2CHCH2CH CH2 and name each compound.  T/I C
7. Several amines are used in natural gas processing.
NH2 Research how these amines reduce air pollution.
2. Copy and complete Table 2 in your Create a storyboard or diagram to communicate
notebook.  K/U C your findings.  T/I C A

WEB LINK
Table 2

Name Condensed structure Line diagram or structural formula Type of compound

N,N-dimethylbutanamide
CH3CH2CH2NH2
H
N

O
Chemistry 12
CH3CH2CH2CH2CH2NHCH3
0176504524
N-methylbutan-1-amine
FN C01-F219-OC12USB
Chemistry 12 H
CO CrowleArt Group
0176504524
Deborah Crowle N
FN C01-F220-OC12USB
Pass 3rd pass
CO CrowleArt Group
Approved
62   Chapter 1 • Organic Compounds NEL
Deborah Crowle
Not Approved
Pass 3rd pass
Approved
7924_Chem_CH01.indd 62 5/3/12 1:40 PM
Not Approved