Sunday, January 20, 2008

Tests for Organic Compounds having Nitrogen

IIT JEE Chemistry

Tests for Amines:

1. All amines are basic in nature and hence are soluble in dilute HCl. They can be regenerated from acidic medium by adding excess of alkali.

2. Carbylamine test: Primary amines(aliphatic or aromatic) can be detected by heating the amine with chloroform and alkali, as presence of amines produces isocyanides with characteristic foul smell.
3. Aromatic amines give dye test.

Distiction between primary, secondary and tertiary amines

1. carbylamine test
2. Reaction with nitrous acid
3.Hinsberg's tst for amines

Tests for Primary Amine group

Isocyanide Test: A little amount of organic compound to be tested with 2 to drops of chlorogorm and 1 mL of alcoholic KOH is slightly heated. A very unpleasant odour of isocyanide, if comes indicates the presence of primary amine group.

The isocyanide can be destroyed by the adding 2 to 3 mL of concentrated HCL.

Dye Test for aromatic amine: Take 0.2 g or few drops of the organic compound with 1 mL of concentrated HCl and cool it with ice. Add 2 mL of iced-cold dilute NaNO2 solution to it. Shake it well and add 2 to 3 mL of alkaline beta-napathol solution.

A red or orange dye indicates the presence of aromatic amine group.

Test for Secondary Amine Group

Liebermann's Nitroso Reactions

Tests for Nitro Group

1. Dye test
2. Mulliken and Baker's Test

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