NEETChemistryHaloalkanes and Haloarenes
Which of the following gives cyanide when reacted with KCN (A) Chloro benzene (B) Allyl bromide (C) Vinyl chloride (D) Benzyl bromide
Options
- AA, B and C are correct
- BA and B are correct
- CB and D are correct
- DA and C are correct
Correct answer
C. B and D are correct
Step-by-step solution
The reaction with KCN (potassium cyanide) involves an SN1 or SN2 nucleophilic substitution, where the cyanide ion (CN-) replaces a leaving group. (B) Allyl bromide (( CH 2= CH - CH 2 Br ) ) and (D) Benzyl bromide (( C 6 H 5- CH 2 Br ) ) both undergo SN1 or SN2 reactions with KCN to form the corresponding cyanides: - Allyl bromide ( ) Allyl cyanide ( ( CH 2= CH - CH 2 CN )) - Benzyl bromide ( ) Benzyl cyanide (C6H5-CH2CN) (A) Chlorobenzene (C6H5Cl) does not react with KCN because the Cl - is not a good leaving group