1. Amines are organic compounds derived from ammonia by replacing one or more hydrogen atoms with alkyl groups. This document discusses the nomenclature, preparation, and reactions of amines. 2. Amines are named based on whether they contain one, two, or three alkyl groups bonded to the nitrogen atom (primary, secondary, tertiary). Aromatic amines are named after the parent aromatic compound with the suffix -amine. 3. Amines can be prepared through reduction of nitro compounds, halides, amides, nitriles, or amides via Hoffman degradation. Common reducing agents include lithium aluminum hydride and catalytic hydrogenation.

1. ORGANIC CHEMISTRY II
CHM301
AMINES
1
NURUL’ AIN BINTI JAMION

2. INTRODUCTION

Amines are similar to ammonia (base) with one or more
alkyl groups bonded to the nitrogen atom.
H

The classification:
N
H Ammonia
H
 1o, 2o, or
3o corresponding to the number of hydrogen atoms
or alkyl replaced.
 General structure:
R
N
H
H
R
N
R'
R''
R
N
R'
H
2

3. OH
NH
N
N
CH3
H3C
Cl
Hydroxychloroquine

Identify whether the amino group shown by the arrow is
primary, secondary or tertiary.
3

4. 4

5. NOMENCLATURE OF
AMINES
Count the carbons in the longest chain containing the amine
 Drop the –e ending for the parent name and add –amine
 For a secondary amine an N prefixes the compound giving the
shorter carbon chain its side chain prefix name
 For a tertiary amine an N,N prefixes the compound giving the
two shorter carbon chains their side chain prefix names

Structural
Formula
H
H C N H
H H
H H
H C C N CH3
H H H
H H
H C C N CH3
H H CH3
Condensed
Structural
Formula
CH3NH2
CH3CH2NHCH3
CH3CH2N(CH3)2
CA format
methanamine
N-methylethanamine
5
N,N-dimethylethanamine

6. NOMENCLATURE OF
AMINES
Aromatic amines belong to specific families, which act as
parent molecules.
 For example, an amino group (—NH ) attached to benzene
2
produces the parent compound aniline.

phenylamine
6

7. NOMENCLATURE OF
AMINES

The prefix ‘amino’ is used to indicate the presence of an
–NH2 group in a molecule containing more than one
functional group.
1
1
7

8. NOMENCLATURE OF
AMINES

Compounds with two –NH2 groups are named by adding
the suffix ‘diamine’ to the name of the corresponding alkane
or aromatic compounds.
H2N
(CH2)6 NH2
hexane-1,6-diamine
(1,6-hexanediamine)
H 2N
NH2
benzene-1,4-diamine
(1,4-benzenediamine)
8

9. PREPARATION OF
AMINES
1.
2.
3.
4.
5.
Reduction of nitro compounds
Reduction of halides with ammonia
Reduction of amides
Reduction of nitriles
Hoffmann degradation of amides
9

10. PREPARATION OF
AMINES
1.
Reduction of nitro compounds – gives 1o amines



Aromatic amines are normally prepared by reduction of the
corresponding aromatic nitro compound.
Aniline is prepared from nitrobenzene.
Reducing agents: Fe/H+, Sn/H+ or catalytic hydrogenation (example,
H2/Pd or Pt or Ni).
10

11. PREPARATION OF
AMINES

Another example:
11

12. PREPARATION OF
AMINES
2.
Reduction of halides with ammonia

The reaction of ammonia with an alkyl halide leads to the
formation of a primary amine.

The primary amine that is formed can also react with the alkyl
halide, which leads to a disubstituted amine.(2o amine)
12

13. PREPARATION OF
AMINES

Further reaction can form a trisubstituted amine.(3o amine).

In general:
13

14. PREPARATION OF
AMINES
3.
Reduction of amides

Amides yield primary amines on reduction by lithium aluminum hydride,
LiAlH4.

The oxygen atom is replaced by two hydrogen atoms.
2o and 3o amides produce 2o and 3o amines, respectively.
Reaction occurs via nucleophilic acyl substitution then nucleophilic addition.


14

15. PREPARATION OF
AMINES
4.
Reduction of nitriles


Nitriles can be reduced by strong reducing agent like H2 with
catalyst (example Ni) or LiAlH4 to yield primary amines via
nucleophilic addition reaction.
Example:
2H2, catalyst
R CN
R CH NH
or LiAlH4, ether
2
2
15

16. PREPARATION OF
AMINES
5.



Hoffmann degradation of amides
Heating the amides with a mixture of bromine and KOH
or NaOH.
amides will change to amines.
is used to shorten the chain by one carbon.
∆
16

17. REACTION OF
AMINES
1.
2.
3.
4.
5.
Formation of amides
Amine alkylation: formation of quarternary
salts
With nitrous acid
Isocyanides (nitrile compound)
Benzenediazonium salts
1. Preparation of Benzenediazonium chloride
2. Reaction of Benzenediazonium chloride
17

18. REACTION OF AMINES
1.
Formation of amides
a.
From acyl chlorides
Addition of 1o , 2o (or ammonia) to acid chlorides results in
amides.
18

19. REACTION OF AMINES

Example:
19

20. REACTION OF AMINES
Formation of amides
1.
a.
From acid anhydride
O
R C O
C R
acid anhydride
O
R C O
O
O
2RNH2
R
O
2R2NH
R C O RNH3
+
amide
amine
O
C R
C NHR
O
R
C NR2
O
+
R C O R2NH2
20

21. REACTION OF AMINES
Formation of amides
1.
From ester
Esters reacts with ammonia, primary and secondary
amines to produce amides and alcohols.
a.
O
R
C O R
ester
C O R
ester
R
H N R
C NH
primary amine
secondary amide
R
R OH
O R
O
R
O R
H
R
H N R
secondary amine
C N R
R OH
tertiary amide
EXAMPLE
O
H3C
C O CH2CH3
H
H N H
O
O
0-5 C
H3C
C NH2
CH3CH2 OH 21

22. REACTION OF AMINES
2.
Amine alkylation: formation of quarternary salts
 Reaction
of amines and acid will give amine salt (an ammonium ion).
CH3CH2NH2 + HCl  CH3CH2NH3+ + Cl -
CH3CH2CH2 NH2
HCl
n-propylammonium chloride
n-propylamine
(CH3CH2)3 N
triethylamine
CH3CH2CH2 NH3Cl
HCl
(CH3CH2)3 NH Cl
22
triethylammonium chloride

23. REACTION OF AMINES

Amine alkylation: formation of quarternary salts
 Examples:
CH3CH2CH2 NH2
HCl
n-propylammonium chloride
n-propylamine
(CH3CH2)3 N
triethylamine
CH3CH2CH2 NH3Cl
HCl
(CH3CH2)3 NH Cl
triethylammonium chloride
23

24. REACTION OF AMINES
3.
With nitrous acid
 Nitrous
acid is unstable and must be prepared in the reaction solution by
mixing sodium nitrite with acid.
 Primary
amines react with nitrous acid to yield a diazonium salt, which is
highly unstable and degradates into a carbocation that is capable of
reaction with any nucleophile in solution. Therefore, reacting primary
amines with nitrous acid leads to a mixture of alcohol, alkenes, and alkyl
halides.
24

25. REACTION OF AMINES

With nitrous acid
 Primary
aromatic amines form stable diazonium salts at zero
degrees.
25

26. REACTION OF AMINES

With nitrous acid
 Secondary
aliphatic and aromatic amines form nitrosoamine (yellow
oils) with nitrous acid.
26

27. REACTION OF AMINES

With nitrous acid
 Tertiary
amines react with nitrous acid to form N-nitrosoammonium
compounds (ammonium salts).
27

28. REACTION OF AMINES

Reaction of nitrous acid with aliphatic amines in cold acidic solution
can be used to distinguish between primary, secondary and tertiary
amines.
RNH2 + HNO2 → N2 gas evolution from a clear solution.
(1° amines)
R2NH + HNO2 → An insoluble yellow oil formed (N-nitrosoamine)
(2° amines)
R3N + HNO2 → A clear solution (ammonium salt formation)
(3° amines)
28

29. REACTION OF AMINES
Isocyanides (nitrile compound)
4.
Primary amines heated with trichloromethane (CHCl3) and
alcoholic KOH solution will produce a foul odor of isocyanide,
RNC.
• Isocyanide:
- an organic compound with functional group R N C
- The CN functionality is connected to the organic
fragment via the nitrogen atom, not via carbon atom.
- a zwitterion (nitrogen atom carries positive charge,
carbon atom carries negative charge).
•
29

30. REACTION OF AMINES
4.
Isocyanides (nitrile compound)
examples:
30

31. REACTION OF AMINES
5.
Benzenediazonium salts
1. Preparation of Benzenediazonium chloride
 Structure
• has the formula C6H5N2+Cl¯
• a diazonium group is attached to the benzene ring
• the aromatic ring helps stabilise the ion
31

32. REACTION OF AMINES
5.
Benzenediazonium salts
1. Preparation of Benzenediazonium chloride
 From phenylamine (which can be made by reduction of
nitrobenzene)
 Reagents: nitrous acid and hydrochloric acid
 Conditions: keep below 10°C
 Equation:
C6H5NH2 + HNO2 + HCl  C6H5N2 + Cl¯+ 2H2O

32

33. REACTION OF AMINES
5.
Benzenediazonium salts
2. Reaction of Benzenediazonium chloride
 Diazonium salts of aromatic amines are very useful as
intermediates to other compounds.
 Aromatic diazonium salts are only stable at very low
temperatures (zero degrees and below), warming these
salts initiates decomposition into highly reactive cations.
 These cations can react with any anion present in
solution to form a variety of compounds. Figure
illustrates the diversity of the reactions.
33

34. REACTION OF AMINES
5.
Benzenediazonium salts
2. Reaction of Benzenediazonium chloride
•
The nitrogen gas is released.
34