Reactions of Amines

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Trapal, Mariel B.Prof. T.D. Macasil
BSE Physical Science

Reactions of amines
Reaction of amines with acids – acids and amines form ammonium salts.

R – NH2 + HCl → R – NH3+ + OH –
Amine acid amine salt
Example 1
CH3 – NH2 + HCl → CH3 – NH3 + Cl-
Methylamine Methylammonium
Example 2
CH3CH2 – NH3 + Cl → CH3CH2NH2 . HCl
Ethylammonium Ethylamine

Reaction of amine with water – when amines react with water, they produce hydroxide ( OH )

R – NH2 + H2O ⇄ R – NH3+ + OH-
Amine water Hydroxide
Example
CH3 – NH2 + H2O ⇄ CH3 – NH3+ + OH-
Methylamine methylammonium
Oxidation – all amines can be oxidize, only tertiary amines give easily isolated products. The oxidation of a tertiary amine leads to the formation of an amine oxide.

Example
H2O2
(CH3)3N (CH3)N+ O-

Reaction of amines with nitrous acid – Nitrous acid ( HNO2) reacts with amines to distinguish primary, secondary, tertiary amines. Primary amines react with nitrous acid to yield a diazonium salt, which is highly unstable. Example

NaNO2 +
CH3CH2CH2 CH3CH2 – N ≡ NCl
Ethanamine HCl ethyl diazonium chloride
HOH
CH3CH2OH
CH3CH2N≡NCl→ [ CH3CH2+] + N2 Cl CH3CH2Cl
CH2=CH2 + H +

Secondary aliphatic and aromatic amines form nitrosoamine with nitrous acid Example
NaNO2
CH3 – NH2 – CH3 (CH3)2 – N – N=O
dimethylamine HCl N, Nitrosodimethylamine
N=O
Example N
CH3
NH – CH3

NANO2

HCl

Tertiary amine forms only salt
Example
(CH3)3 + NaNO2 + HCl → [ ( CH3) NH ] – NO2 + NaCl
HCl
Reaction with acid halides – Acid halides react with amines to form substituted amides. Example
Cl O
| CH3NH2 ∥ . .
CH3 – CH2 – C = O CH3 –...
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