Reactions of Amines

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