Hydride as a nucleophile reduction of carboxylic acid derivatives

11 Hydride as a nucleophile reduction of carboxylic acid derivatives 

We have already noted the ability of complex metal hydrides like lithium aluminium hydride and sodium borohydride to reduce the carbonyl group of aldehydes and ketones, giving alcohols (see Section 7.5). These reagents deliver hydride in such a manner that it appears to act as a nucleophile. However, as we have seen, the aluminium hydride anion is responsible for transfer of the hydride and 

Acyl halides, anhydrides, esters and acids all react with LAH to give a primary alcohol. Amides (see later) behave differently. 

The initial reaction is effectively the same as with an aldehyde or ketone, in that hydride is transferred from the reducing agent, and that the tetrahedral anionic intermediate then complexes with the Lewis acid aluminium hydride. However, the typical reactivity of the carboxylic acid derivatives arises because of the presence of a leaving group. 

Although LAH will reduce carboxylic acids, it is not usually employed for this purpose, since salt 

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