Question

Identify the major product 'B' in the following reaction: \[ \text{But-2-ene} \xrightarrow{\text{HBr, Peroxide}} \text{A} \xrightarrow{\text{AgCN, } \Delta} \text{B} \]

• A. n - butyl isocyanide
• B. n - butyl cyanide
• C. sec. butyl isocyanide
• D. isobutyl cyanide

Hint:

In reactions involving peroxides, the addition of HBr follows an anti-Markovnikov rule, and AgCN is used to form isocyanides from alkyl halides.

Answer 1

The Correct Option is A

Step 1: Understanding the reaction.
The reaction involves the formation of a product through two steps. The first step is the addition of HBr to but-2-ene in the presence of peroxides, which follows an anti-Markovnikov addition mechanism, leading to the formation of a secondary radical. In the second step, silver cyanide (AgCN) reacts with the alkyl halide to form an isocyanide.
Step 2: Analyzing the options.
(A) n - butyl isocyanide: Correct. The product 'B' formed in this reaction is n-butyl isocyanide, a result of the reaction with AgCN.
(B) n - butyl cyanide: Incorrect. The product is an isocyanide, not a nitrile.
(C) sec. butyl isocyanide: Incorrect. The primary product is n-butyl isocyanide, not sec-butyl.
(D) isobutyl cyanide: Incorrect. This is the wrong product formed in this reaction. The correct product is n-butyl isocyanide.
Step 3: Conclusion.
The correct answer is (A) n - butyl isocyanide, which is the major product of the reaction.