|Qu1:||Hydrolysis is a nucleophilic acyl substitution reaction, typical of carboxylic acid derivatives.|
|First task should be to identify the functional groups in each molecule
then use the reactivity order. It can be rationalized based on (i) the
interaction of the substituent and
the carbonyl group, and, (ii) the ability of the substituent
to function as a leaving group.
|Qu2:||All the carboxylic acids in Qu 1 are derivatives of ethanoic acid, so they all give the same carboxylic acid...|
|Qu3:||LiAlH4 is a source of H- (a nucleophile) which functions as a reducing agent.|
|First task should be to identify the functional groups : carboxylic
acid, ketone, aldehyde, ester.
The aldehyde and ketone will undergo nucleophilic addition, the acid and the ester nucleophilic acyl substitution.
Consider the electrophilicity of the carbonyl group in each compound in each pair.
Aldehydes are more reactive than ketones (chapter 17) as they are less hindered and the alkyl group in the ketone is a weak electron donor.
Under the reaction condition s the carboxylic acid will deprotonate to give the carboxylate which is a very poor electrophile (after all, it has a negative charge !) so the ester is more reactive than the acid.
Now combine the two pairs. Since the -OR group is a stronger electron donor (resonance) than the alkyl group of the ketone, the ester is less reactive than the ketone... so we get :
|(b) Each will be reduced to the same product, benzyl alcohol.|
|Qu4:||The answers the these questions involve materials from this chapter and review from chapters 10 and 19|