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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
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Amides: Nomenclature
and Physical Properties
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• 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
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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.
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Naming Amides
O
O
C
H
NH2
methanamide
O
C
H3C
NH2
ethanamide
C
NH2
benzamide
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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
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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.
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• The amide functional group is polar, and
nitrogen is capable of hydrogen bonding.
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Chemical Properties
of Amides
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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)
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Amines: Nomenclature
and Physical Properties
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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
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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
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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
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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
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Do You
?
N
Know
What
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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
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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
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Amines are responsible for the strong odors of decaying flesh which
are produced by bacterial decomposition. Two of these compounds
are actually diamines as shown here.
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Preparation of
Amines
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Preparation of Amines
1. Alkylation of ammonia and amines
2. Reduction of amides and nitriles
3. Reduction of aromatic nitro compounds
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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
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Reduction of Amides
O
C
H3C
NH2
LiAlH 4
CH3CH2NH2
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Reduction of Aromatic Nitro Compounds
Nitrobenzene is reduced to aniline which is a common aromatic
amine.
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Chemical Properties
of Amines
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Chemical Properties of Amines
1. Alkaline properties of amines
2. Salt formation
3. Formation of amides
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Alkaline Properties of Amines
Amines are bases and produce OH– ions in
water.
CH3NH2 + H-O-H
+
CH3NH3 + OH
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Salt Formation
• An amine reacts with a strong acid to
form a salt.
CH3NH2 + H-Cl
+
CH3NH3Cl
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Formation of Amides
Amides are produced when primary and secondary amines
react with acid chlorides
.
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Sources and Uses of
Selected Amines
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Many antibacterial agents include nitrogen containing compounds
such as those shown here.
Amines and amides are found in the B-complex vitamins B1 and B3.
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Alkaloids are a class of compounds derived from plants that show
biological activity. Procaine is an example of a local anesthetic.
An alkaloid like nicotine stimulates the nervous system while the
opium alkaloids like methadone and cocaine have morphine-like
activity ( i.e. sleep inducing and analgesic properties).
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Amphetamines are a class of compounds that stimulate the central
nervous system. Amphetamines like methamphetamine mimics the
action of epinephrine which produces a feeling of well-being and
increased alertness.
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Barbiturates are a class of compounds that depress the central
nervous system. These sedatives contain amide groups. An example
is pentobarbital.
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Other examples of drugs containing the amine/amide functional groups
include tranquilizers like Valium and antidepressants like Prozac.
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