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Chapter 17 Amines and Amides
17.1 Amines
17.2 Naming Amines
17.3 Physical Properties of Amines
Copyright © 2004 Pearson Education Inc., publishing as Benjamin Cummings.
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Amines

Amines are organic compounds in which one
or more H in ammonia, NH3, is replaced with
alkyl or aromatic groups.
H
|
H—N—H
H
|
CH3—N—H
H
|
CH3—N—CH3
ammonia
Copyright © 2004 Pearson Education Inc., publishing as Benjamin Cummings.
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Classification of Amines



Amines are classified as primary, secondary, or
tertiary.
In a primary (1°) amine, one carbon group is
bonded to the nitrogen atom.
A secondary (2°) amine has two carbon groups.
A tertiary (3°) amine has three carbon groups.
H
CH3
CH3
|
|
|
CH3—N—H
CH3—N—H
CH3—N—CH3
1°
2°
3°
Copyright © 2004 Pearson Education Inc., publishing as Benjamin Cummings.
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Models of Amines

The threedimensional
models show the
shapes of amine
molecules with
one or more
alkyl groups
bonded to the
nitrogen atom.
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Common Names of Amines


Simple amines are named as alkylamines.
The alkyl groups bonded to the N atom are listed in
alphabetical order in front of amine.
CH3—CH2—NH2
CH3—NH—CH3
Ethylamine
Dimethylamine
CH3
|
CH3—N—CH2—CH3
Ethyldimethylamine
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IUPAC Names of Amines



In the IUPAC system, amines are named as
alkanamines.
The –e in the alkane name of the longest chain
is changed to –amine.
The chain is numbered to locate the amine
group and substituents.
NH2
|
CH3—CH2—NH2
CH3—CH—CH3
Ethanamine
2-Propanamine
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Naming Secondary and Tertiary
Amines

Each alkyl groups bonded to the N atom is
named as N-alkyl groups in front of the amine
name for the longest chain.
CH3—CH2—CH2—NH—CH3
N-Methyl-1-propanamine
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HN—CH3
|
CH3—CH—CH2—CH3
N-Methyl-2-butanamine
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Learning Check
Give the common and IUPAC names and
classify as primary, secondary, or tertiary:
A. CH3—CH2—CH2—NH2
CH3
|
B. CH3—CH2—N—CH3
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Solution
A. CH3—CH2—CH2—NH2
1-propylamine, 1-propanamine, 1°
CH3
|
B. CH3—CH2—N—CH3
ethyldimethylamine,
N,N-dimethylethanamine, 3°
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Learning Check
Write a structural formula for
A. 2-pentanamine
B.
N-methyl-1-butanamine
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Solution
A.
2-pentanamine
NH2
|
CH3—CH—CH2—CH2—CH3
B.
N-methyl-1-butanamine
CH3—CH2—CH2—CH2—NH—CH3
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Aromatic Amines
 The amine of benzene is named aniline.
NH2
NH2
NH CH3
Cl
 Aniline
3-Chloroaniline
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N-Methylaniline
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Boiling Points of Amines, Alcohols,
and Alkanes
The boiling points of amines are higher than
alkanes, but lower than alcohols of similar mass.
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13
Hydrogen Bonding for Amines


The polar N-H bond provides hydrogen bonding in
1°and 2° amines, but not 3°.
However, the N-H bonds in amines are not as polar
as the O-H bonds in alcohols.
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Solubility in Water


Amines with 1-5 carbon atoms are soluble in
water.
The N atom in amines forms hydrogen bonds
with the polar O-H bond in water.
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Learning Check
Consider the following compounds:
1) CH3—CH2—CH2—NH2
2) CH3—CH2—NH—CH3
3) CH3—CH2—CH2—CH3
A. Which compound has the highest boiling point?
B. Which compound is soluble in water?
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Solution
Consider the following compounds:
1) CH3—CH2—CH2—NH2
2) CH3—CH2—NH—CH3
3) CH3—CH2—CH2—CH3
A. Which compound has the highest boiling point?
1) CH3—CH2—CH2—NH2
B. Which compound is soluble in water?
1) CH3—CH2—CH2—NH2
2) CH3—CH2—NH—CH3
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17
Chapter 19 Amines and Amides
19.4 Amines React as Bases
19.5 Heterocyclic Amines and Alkaloids
Copyright © 2004 Pearson Education Inc., publishing as Benjamin Cummings.
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Amines React as Bases

Like ammonia, amines are weak bases in water.
NH3 + H2O
NH4+ + OH–
ammonium
hydroxide
CH3—NH2 + H2O
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CH3—NH3+ + OH–
methylammonium
hydroxide
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Neutralization forms Amine Salts
An amine salt:
 Forms when an amine is
neutralized by acid.
 Is named by replacing the
amine part of the name with
ammonium followed by the
name of the negative ion.
CH3—NH2 + HCl
CH3—NH3+ Cl–
Methylamine
methylammonium chloride
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Properties of Amine Salts
Amine salts are:
 Solids at room temperature.
 Soluble in water and body fluids.
 The form used for drugs.
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Cocaine


Cocaine is sold illegally as an amine salt.
Cocaine is reacted with NaOH to produce the
free amine form known as “crack.”
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Heterocyclic Amines

In a heterocyclic amine, a five- or six-atom ring
contains one or more nitrogen atoms.
N
N
H
Pyrrolidine
N
H
Pyrrole
N
H
Imidazole
N
H
Piperidine
N
N
N
N
N
N
N
H
Pyridine
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Pyrimidine
Purine
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Alkaloids
Alkaloids are:
 Physiologically active nitrogen-containing
compounds.
 Produced by plants.
 Used as stimulants, anesthetics, and
antidepressants.
 Often habit forming.
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Caffeine
Caffeine:
 Is a stimulant of the
central nervous
system.
 Is found in coffee
beans, tea, chocolate,
and soft drinks.
 Contains an imidazole
ring.
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Nicotine
Nicotine:
 Increases the adrenaline level in the blood.
 Causes addiction to tobacco.
 Contains a pyrrolidine ring.
N
CH3
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Alkaloids Related to Morphine



Alkaloids such as morphine and codeine are
produced by the poppy.
For centuries, morphine and codeine have been
used as painkillers.
Heroin is a modification of morphine.
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Pharmacology


An area of research in pharmacology is to
design drugs with some of the characteristics
of alkaloids.
The structures of cocaine and morphine are
modified to produce anesthesia, but without
the addictive side effects.
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Pharmacology

Parts of the morphine structure that produce
anesthesia are found in procaine, lidocaine,
and demerol.
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Learning Check
Identify the heterocyclic amine in serotonin.
CH2
CH2
NH2
HO
N
N
serotonin
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Solution
Identify the heterocyclic amine in serotonin.
CH2
CH2
NH2
HO
N
H
Copyright © 2004 Pearson Education Inc., publishing as Benjamin Cummings.
pyrrole
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Chapter 17 Amines and Amides
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Amides

In amides, an amino group replaces the –OH
group of carboxylic acids.
O
O
||
||
CH3 — C — OH
CH3 — C — NH2
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Preparation of Amides
Amides are produced by reacting a carboxylic acid
with ammonia or an amine (1° or 2°).
O
O


CH3—C—OH + NH3
CH3—C—NH2 + H2O

O

CH3—C—OH + CH3—NH2
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O

CH3—C—NH—CH3
+ H2O
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Naming Amides


Amides are named as alkanamides.
In the IUPAC and common names, the –oic acid or ic acid endings are replaced by –amide.
O

Methanamide (IUPAC)
H—C—NH2
Formamide (common)
O

Propanamide (IUPAC)
CH3—CH2—C —NH2 Propionamide (common)
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Naming Amides with N Groups
An alkyl group bonded to the N atom is named as
N-alkyl in front of the amide name.
O

CH3—C—NH —CH3 N-methylethanamide (IUPAC)
N-methylacetamide (common)
O CH3


CH3—CH2—C —N —CH3
N,N-dimethylpropanamide
N,N-dimethylpropionamide
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Aromatic Amides

The amide of benzene is named benzamide.
O
O
C NH2
C NH CH3
Benzamide
N-methylbenzamide
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Classification of Amides
Amides are classified according to the number of
carbon atoms bonded to the nitrogen atom.
O H
|| |
CH3—C—N—H
Primary (1°) amide
O H
|| |
CH3—C—N—CH3 Secondary (2°) amide
O CH3
|| |
CH3 —C—N—CH3 Tertiary (3°) amide

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Learning Check
Give the common and IUPAC names for the
following amides and classify as primary,
secondary, or tertiary:
O
||
A. CH3—CH2—CH2—C—NH2
O CH3
|| |
B. CH3—C—N—CH2—CH3
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Solution
O
||
A. CH3—CH2—CH2—C—NH2
butryamide (common);
butanamide (IUPAC) primary(1°) amide
O CH3
||
|
CH3—C—N—CH2—CH3
N-ethyl-N-methylacetamide (common);
N-ethyl-N-methylethanamide (IUPAC)
tertiary (3°) amide
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Learning Check
Draw the condensed structures of
A. Pentanamide
B. N-methylbenzamide
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Solution
A. Pentanamide
O
||
CH3—CH2—CH2 —CH2—C—NH2
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Amides in Health and Medicine




Urea is the end product of protein
metabolism.
Saccharin is an artificial sweetener.
Some amides such as phenobarbital,
Nembutal and Seconal are barbiturates.
Acetaminophen is used to reduce fever and
pain.
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Amides in Health and Medicine
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Physical Properties of Amides




Hydrogen bonds form in primary and secondary
amides, but not tertiary amides.
The melting points of primary amides are higher
than secondary amides, which have higher
melting points than tertiary amides.
All amides can form hydrogen bonds with water.
Amides with 1–5 carbon atoms are soluble in
water.
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Hydrogen Bonding of Amides
O
||
CH3—C—N—H
|
H
Hydrogen bonding occurs
between primary amides.
O
||
CH3—C—N—H
|
H
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Reactions of Amides
Amides undergo:
 Acid hydrolysis to produce a carboxylic acid and
ammonium salt.

Base hydrolysis to produce the salt of a carboxylic
acid and an amine or ammonia.
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47
Hydrolysis Reactions
O
||
CH3—C—OH + NH4+Cl-
acid hydrolysis
O
HCl + H2O
||
CH3—C—NH2
NaOH
O
||
CH3—C—O-Na+ + NH3
base hydrolysis
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48
Learning Check
Write the products of the hydrolysis of
N-ethylpropanamide with NaOH.
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Solution
Write the products of the hydrolysis of
N-ethylpropanamide with NaOH.
O
||
CH3—CH3—C—O-Na+ + CH3 —CH2 —NH2
Copyright © 2004 Pearson Education Inc., publishing as Benjamin Cummings.
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