how is the cabonyl group of aldehyde/ketone affected in the presence of electron donating group like metyl in cyanohydrin reaction?

Asked by prakriti12oct | 14th Feb, 2020, 12:09: PM

Expert Answer:

(a)  Formation of cyanohydrins:

  • On addition of HCN to aldehydes and ketones they yield cyanohydrins.
  • Since the reaction is very slow with pure HCN, it is catalysed with the help of a base and the cyanide ion (CN-) generated as a strong nucleophile adds to carbonyl compounds to give cyanohydrins.
  • The C-O double bond is polarised since oxygen is electronegative than carbon.
  • So the carbonyl carbon is an electrophilic centre and the carbonyl oxygen is a nucleophilic centre.
  • If an electron donating group is present next to carbonyl group then it will slow down the reaction or will retard the rate of reaction.

Answered by Ramandeep | 14th Feb, 2020, 05:57: PM