NaBH4 reduces acetophenone to which product?

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Multiple Choice

NaBH4 reduces acetophenone to which product?

NaBH4 is a mild reducing agent that converts ketones and aldehydes into alcohols by delivering a hydride to the carbonyl carbon, followed by protonation. In acetophenone, the carbonyl carbon is attached to a phenyl group on one side and a methyl group on the other. Reducing this C=O bond adds a hydrogen to the carbonyl carbon and, after workup, introduces a hydroxyl group, turning the carbonyl carbon into a secondary alcohol center. The product is 1-phenylethanol (Ph-CH(OH)-CH3), a secondary alcohol where the OH-bearing carbon is connected to a phenyl group and a methyl group. This explains why other possibilities don’t fit: the molecule still has its carbonyl group after NaBH4 reduction only if it’s reduced to an alcohol, which would give the secondary alcohol shown. A product without a carbonyl bond, like ethylbenzene, would require breaking the carbonyl entirely, which NaBH4 does not do under typical conditions. Benzaldehyde would be reduced to benzyl alcohol, not the ketone starting material.

NaBH4 is a mild reducing agent that converts ketones and aldehydes into alcohols by delivering a hydride to the carbonyl carbon, followed by protonation. In acetophenone, the carbonyl carbon is attached to a phenyl group on one side and a methyl group on the other. Reducing this C=O bond adds a hydrogen to the carbonyl carbon and, after workup, introduces a hydroxyl group, turning the carbonyl carbon into a secondary alcohol center. The product is 1-phenylethanol (Ph-CH(OH)-CH3), a secondary alcohol where the OH-bearing carbon is connected to a phenyl group and a methyl group.

This explains why other possibilities don’t fit: the molecule still has its carbonyl group after NaBH4 reduction only if it’s reduced to an alcohol, which would give the secondary alcohol shown. A product without a carbonyl bond, like ethylbenzene, would require breaking the carbonyl entirely, which NaBH4 does not do under typical conditions. Benzaldehyde would be reduced to benzyl alcohol, not the ketone starting material.

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