CBSE Class 12 Chemistry 2016 Outside Delhi Set 1 Solved Paper

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Question : 10
Total: 26
Write the chemical equations involved in the following reactions:
(i) Hoffmann-bromamide degradation reaction,
(ii) Carbylamine reaction.
Solution:  
(i) Hoffmann - bromanide degradation reaction: When an amide is treated with bromine in aqueous or ethanolic solution fo sodium hydroxide, a primary amine with one carbon atom less than the origin amide is produced. This degradation is known as Hoffmann bromamide degradation reaction.
R
O
C
NH2+Br2+4NaOHRNH2
(Aqueousoralcoholic)1Amine
+Na2+Na2CO3+2NaBr+2H2O
Example,
CH3CH2
O
C
NH2
Propanamide
+
Br2+4NaOH
(Aqueousoralcoholic)
CH3CH2NH2
Ethanamine
+Na2CO3
+
2NaBr+2H2O
(ii) Carbylamine reaction: It is used as a test for detection of primary amines. When aliphatic or aromatic primary amines are heated with chloroform and alcoholic potassium hydroxide, carbylamines or isocyanides having foul smell are formed. Secondary and tertiary amines do nnot respond to this test.
RNH2+
CHCl3+3KOH
(Alcoholic)
Heat
RNH+3KCl
Alkylisocyanide
+3H2O
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