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Question:

Which of the following is NOT a correct method of the preparation of benzylamine from cyanobenzene?

(i)HCl/H2O(ii)NaBH4

(i)LiAlH4(ii)H3O+

(i)SnCl2+HCl(gas)(ii)NaBH4

H2/Ni

Solution:

Correct option is A. (i)HCl/H2O(ii)NaBH4
Hence option A is correct. The reaction of cyanobenzene with HCl/H2O followed by NaBH4 is not a correct method for the preparation of benzylamine. While LiAlH4 reduces the nitrile group to a primary amine, and SnCl2/HCl followed by reduction also works, the combination of HCl/H2O and NaBH4 is not effective in this conversion. HCl/H2O would protonate the nitrile, but NaBH4 is not a strong enough reducing agent to reduce the resulting iminium ion to benzylamine.