Question

a) i) Explain Hoffmann bromamide degradation for the preparation of Aniline.
ii) Give the IUPAC name of
$H_{3}C-\underset{\underset{H}{|}}{N}-C{H}_2-C{H}_3$.
b) What is Hinsberg reagent? Between $C{H}_{3}N{H}_2$ and $C_6{H}_{5}N{H}_2$ which is more basic?

Answer 1

a) i) When an amide is treated with bromine inv aqueous or ethanolic solution of sodium hydroxide, a primary amine with one carbon atom less than the original amide is released. This degradation reaction is called as Hoffmann bromamide reaction. This reaction involves the migration of an alkyl or aryl group from the carbonyl carbon atom of the amide to the nitrogen atom.

$C_6{H}_5-CO-N{H}_2+B{r}_2+4NaOH\to C_6{H}_5-N{H}_2+N{a}_{2}C{O}_3+2NaBr+2H_{2}O$

ii) The IUPAC name is Ethyl methyl amine.

b) It is an excellent test for distinguishing primary, secondary and tertiary amines. In this test, the amine is shaken well with Hinsberg reagent in the presence of aqueous alkali (either KOH or NaOH). A reagent containing an aqueous sodium hydroxide solution and benzenesulfonyl chloride is added to a substrate.

Benzene sulphonyl chloride.$C_6{H}_{5}N{H}_2$ is more basic due to resonance.