Final answer:
Hydride reduction of aldehydes and ketones involves the nucleophilic addition of a hydride ion to the carbonyl carbon, converting it to an alcohol. Reagents like NaBH4 and LiAlH4 serve as hydride donors, with NaBH4 being selective for certain functional groups, while LiAlH4 is more reactive.
Step-by-step explanation:
The process used for the hydride reduction of aldehydes and ketones, as well as the nucleophilic addition of carbanions, involves the transfer of a hydride ion (H⁻) to the carbon atom of the carbonyl group (C=O). This reaction converts the carbonyl group into a hydroxyl group (C-OH), effectively reducing the aldehyde or ketone to an alcohol.
When utilizing reagents like NaBH4 or LiAlH4, the hydride ion serves as a potent nucleophile that attacks the electrophilic carbon atom in a direct [1,2]-addition. In biological systems, a similar reduction process occurs with reagents like NADH serving as the hydride donor. Moreover, NaBH4 selectively reduces aldehydes, ketones, and acid halides, while LiAlH4 can also reduce carboxylic acids and their derivatives including esters and amides.