Which reagent is commonly used for the reduction of ketones to secondary alcohols?

The correct answer for the reduction of ketones to secondary alcohols is sodium borohydride (NaBH4). Sodium borohydride is a milder reducing agent that specifically targets ketones and aldehydes, providing a straightforward pathway for converting these carbonyl compounds into their corresponding alcohols.

NaBH4 donates a hydride ion (H-) to the carbonyl carbon of the ketone, breaking the π bond and reforming a single bond while concurrently generating an alkoxide intermediate. Subsequent protonation of the alkoxide leads to the formation of the secondary alcohol.

Although lithium aluminum hydride (LiAlH4) is also a potent reducing agent capable of reducing ketones to alcohols, it is more reactive and can reduce a wider variety of carbonyl compounds, including esters and carboxylic acids. This level of reactivity may lead to undesired side reactions when a more selective approach (like that with NaBH4) is preferred.

Grignard reagents can also be used to form alcohols through a reaction with ketones, leading to tertiary alcohols rather than secondary alcohols. Therefore, while both Grignard reagents and lithium aluminum hydride can reduce ketones, they do not