Hoffmann's method for the separation of amines

Class XII- Chemistry

HSEB NOTES

This method helps in the separation of primary, secondary and tertiary amines.

       For this the mixture of amines is treated with diethyl oxalate. Primary, secondary and tertiary amines react with these to produce solid, liquid and gaseous products.

       Primary amines on reaction with diethyl oxalate gives solid oxamide, secondary amine gives liquid oxamic ester and tertiary amine remains unreacted in gaseous form.

1. The gaseous tertiary amine is separated out.

 2. The solid oxamide is filtered out of the liquid oxamic ester.

3. These products are added to the alkaline solution of NaOH.

 In this way, Primary, secondary and tertiary amines are separated by Hoffmann's Method.

Note :

Primary Amine  = 1^o Amine

Secondary Amine = 2^o Amine

Tertiary Amine = 3^o Amine