Question

When an aldehyde or ketone undergo a nucleophilic attack, the reaction follows a nucleophilic addition mechanism. Conversely, carboxylic acids and their derivatives are known to undergo nucleophilic acyl substitution. Even though all of these functional groups are defined by the carbonyl group, they react very differently. In 1-3 sentences, explain why an aldehyde and a carboxylic acid derivative follow different mechanistic pathways in the presence of a nucleophilic species.

Answer 1

The answer is explained in detail in the attached image.

bergo a nucleophilie | 1 Nga nuclea phim is because of the icked by a nucleophile, and oxygen op When an aldehyde ao attack the reaction follows a nu addition mechanism. This is because of fact that aldehydes and ketones do not any good learing group and thus when the Carbonyl carbon is attacked by am it pushes the electrons toward onygon a form a new bond with the carbon atoom. The Duygen atom which just develops a negative charge, can pick up a hydrogen atom and finally give rise to an alcohol. Thus aldehyde and ketones undergo nucleophilec addition mechanism rather than nucleophilica substitution mechanism. R thH/R + Nuh ħ Rt Nu aldeky de or ketone But carboxylic acides and their dentratives are known to undergo nucleophilie acyl substitution. Carboxylic acids have an toh) which can act as a leaving group which a facilitate the substitution mechanism by an nucleophile. Dertratives of carboxylic acids also have leaving groups unlike aldehydes or ketones and this they also prefer to undergo nucleophilic substitution Nu 7 RILA О[4 HiR RaOH Nu carboxylla hacia + OH(-)