Question

Amines can be considered as derivatives of ammonia.

a) Arrange the following in the increasing order of their basic strength.

C₆H₅NH₂, C₂H₅-NH₂(C₂H₅)₂NH, NH₃.

b) Represent a reaction of explain the basic character of aniline.

c) Name the reagents used in Hoffmann bromamide reaction.

d) What is the significance of the above reaction?

e) Give one chemical test to distinguish between methyl amine and diethyl amine.

Answer 1

a) C₆H₅NH₂ < NH₃ < C₂H₅NH₂, (C₂H₅)₂NH

b) Aniline, being basic reacts with hydrochloric acid to form anilinium chloride salt.

c) An amide, bromine, aqueous or ethanolic solution of NaOH.

d) It is a method for preparation of primary amines. The amine so formed contains one carbon less than that present in the amide.

e) Hinsberg’s test – When methyl amine (1° amine) is treated with Hinsberg’s reagent (benzene suiphonyl chloride), N-Methylbenzene suiphonamide is formed which is soluble in alkali due to the presence of acidic hydrogen.

When dimethyl amine (2° amine) is treated with Hinsberg’s reagent N,N-dimethyl benzene shlphonamide is formed which is insoluble in alkali due to the absence of acidic hydrogen.