Doubt by khadijah

Just as addition of sodium hyrogensulphite is used for sepration of aldehydes and ketones can addition of alcohol do same???

Answers

Answer by Rishikant Pandey

yes,

Addition of Alcohols

Aldehydes undergo reaction with the monohydric alcohol to produce hemiacetals or alkoxyalcohol intermediate. The hemiacetal will further undergo reaction with an alcohol to produce gem-dialkoxy compound or acetal. The reaction is carried out in the presence of dry hydrogen chloride. On application of similar conditions, ketone undergoes reaction with ethylene glycol to produce cyclic compounds or ethylene glycol ketals.

The dry hydrogen chloride present in the reaction protonates the oxygen atom present in the carbonyl structure thereby increasing the electrophilicity of the carbonyl carbon. Thus, it helps in the nucleophilic attack of ethylene glycol. Further hydrolysis of acetals and ketals with mineral acids (aqueous) will help in retrieval of respective aldehydes and ketones.