Amides and Amines: Organic
Nitrogen Compounds
Chapter 25
Hein * Best * Pattison * Arena
Version 1.0
Colleen Kelley
Chemistry Department
1 College
Pima Community
© John Wiley and Sons, Inc.
Chapter Outline
25.1 Amides: Nomenclature
and Physical Properties
25.2 Chemical Properties of
Amides
25.3 Polyamides:
Condensation Polymers
25. 4 Urea
25.5 Amines: Nomenclature
and Physical Properties
25.6 Preparation of Amines
25.7 Chemical Properties of
Amines
25.8 Sources and Uses of
Selected Amines
2
Nitrogen-Containing Compounds
• The amines and amides are the two major
classes of nitrogen-containing compounds.
• Amines isolated from plants form a group
of compounds called alkaloids.
– Quinine, caffeine
• Amides are nitrogen derivatives of
carboxylic acids.
– Nylon, proteins
3
Amides: Nomenclature
and Physical Properties
4
• Carboxylic acids react with ammonia to form
ammonium salts.
• When heated, ammonium salts of carboxylic
acids lose a molecule of water and are converted
to amides:
O
C
R
ammonia
+ NH3
OH
carboxylic
acid
R
O
O
C
C
-
O NH4+
ammonium
salt
R
+ H2O
NH2
amide
5
IUPAC Rules for Naming Amides
1. The IUPAC name is based on the longest
carbon chain that includes the amide
group.
2. Drop the –oic acid ending from the
corresponding IUPAC acid name.
3. Add the suffix –amide.
6
Naming Amides
O
O
C
H
NH2
methanamide
O
C
H3C
NH2
ethanamide
C
NH2
benzamide
7
Naming Amides
• When the nitrogen of an amide is
connected to an alkyl or aryl group, the
group is named as a prefix preceded by
the letter N:
O
C
H3C
NHCH3
N-methylethanamide
8
9
Physical Properties of Amides
• Except for formamide (methanamide), a
liquid, all other unsubstituted amides are
solids at room temperature.
• Many are odorless and colorless.
• Low molar-mass amides are soluble in
water, but solubility decreases quickly as
molar-mass increases.
10
• The amide functional group is polar, and
nitrogen is capable of hydrogen bonding.
11
Chemical Properties
of Amides
12
Hydrolysis of Amides
under acidic conditions:
O
O
C
C
NH2 + H2O + HCl
H3C
H3C
OH
+ NH4Cl
under basic conditions:
H3C
O
O
C
C
NH2 + NaOH
H3C
-
O Na+
+ NH3 (g)
13
Polyamides:
Condensation Polymers
14
Polyamides
• Polyamides are condensation polymers.
• Proteins are biological polyamides.
• Nylon-66 is a synthetic polyamide.
O
C
R
O
H2
C
OH H
carboxylic
acid group
N
R'
H
amine group
H2
C
C
R
HN
+ H2O
R'
amide linkage
15
Urea
16
Urea
• The body disposes of nitrogen by the
formation of a diamide known as urea.
• Urea is a white solid that melts at 133 C.
• It is soluble in water and therefore is
excreted from the body in the urine.
O
C
H2N
NH2
17
Amines: Nomenclature
and Physical Properties
18
H
H
H
CH3
CH3
N
N
N
N
H
ammonia
H
CH3
H
methylamine
primary amine
CH3
H3C
dimethylamine
secondary amine
trimethylamine
tertiary amine
H
H
N
N
H
cyclohexylamine
primary amine
CH3
H
aniline
primary amine
19
IUPAC System for Naming Amines
1. The IUPAC system names simple
amines by using the name of the
alkane (omitting the final –e) and
adding the ending –amine.
CH3CH2NH2 ethanamine
CH3CH2CH2NH2 1-propanamine
20
2. Secondary and tertiary amines are named as
N-substituted primary amines by using the
longest carbon chain as the parent name.
H
CH3
CH2CH3
N
N
CH2CH2CH3
N-methyl-1-propanamine
H3C
CH2CH2CH2CH3
N-ethyl-N-methyl-1-butanamine
CH3
N
CH3
21
N,N-dimethylcylcohexanamine
Common Names of Amines
H
H
H
H
N
N
N
CH2CH2CH3
CHCH3
H
C
H3C
propylamine
CH3
isopropylamine
NH2
aniline
H
CH3
CH3
tert-butylamine
N(CH3)2
N,N-dimethylaniline
22
Heterocyclic Compounds
• Ring compounds in which the atoms in the ring
are not all alike are known as heterocyclic
compounds.
•The most common heteroatoms are oxygen,
nitrogen, and sulfur.
H
N
N
N
N
N
N
N
H
N
pyrrole
pyridine
pyrimidine
purine
23
Physical Properties of Amines
• Amines are capable of hydrogen bonding
with water.
• They have odors:
– Methylamine and ethylamine = strong
ammoniacal odor
– Trimethyamine = ‘fishy’ odor
– High molar-mass amines = obnoxious
odors
24
Preparation of
Amines
25
Preparation of Amines
1. Alkylation of ammonia and amines
2. Reduction of amides and nitriles
3. Reduction of aromatic nitro compounds
26
Alkylation of Ammonia and Amines
• The substitution of alkyl groups for hydrogen
atoms of ammonia can be done by reacting
ammonia with alkyl halides.
NH3+CH3Br
CH3NH2+CH3Br
(CH3)2NH
27
Reduction of Amides and Nitriles
O
C
H3C
NH2
LiAlH 4
CH3CH2NH2
CH3CH2CN  CH3CH2CH2NH2
H2/Ni
28
Reduction of Aromatic Nitro Compounds
NO2
Sn
HCl
-
NH3+Cl
NH2
NaOH
29
Chemical Properties
of Amines
30
Chemical Properties of Amines
1. Alkaline properties of amines
2. Salt formation
3. Formation of amides
31
Alkaline Properties of Amines
Amines are bases and produce OH- ions in
water.
CH3NH2 + H-O-H
+
CH3NH3 + OH
32
Salt Formation
• An amine reacts with a strong acid to
form a salt.
CH3NH2 + H-Cl
+
CH3NH3Cl
33
Formation of Amides
• Primary and secondary amines react
with acid chlorides to form substituted
amides.
H3C
O
O
C
C
Cl + 2 (CH3CH2)2NH2
H3C
N(CH2CH3)2
+
-
+ (CH3CH2)2NH2Cl
34
35