At low temperature, DIBAL-H reduces ethyl benzoate to which product?

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Multiple Choice

At low temperature, DIBAL-H reduces ethyl benzoate to which product?

DIBAL-H can selectively reduce esters to aldehydes when used at low temperature. It delivers a hydride to the carbonyl carbon, forming a tetrahedral intermediate, and because the reagent is bulky, the reaction typically stops after one hydride transfer rather than proceeding to a second reduction. Upon workup, the alkoxy group leaves as an aluminum alkoxide and the carbonyl ends up as an aldehyde. For ethyl benzoate, this means you obtain benzaldehyde. If you use more DIBAL-H or raise the temperature, the aldehyde can be reduced further to the primary alcohol (benzyl alcohol). Benzoic acid would come from oxidation, not from this reducing setup, and benzene would require removal of the carbonyl entirely, which DIBAL-H does not accomplish under these conditions.

DIBAL-H can selectively reduce esters to aldehydes when used at low temperature. It delivers a hydride to the carbonyl carbon, forming a tetrahedral intermediate, and because the reagent is bulky, the reaction typically stops after one hydride transfer rather than proceeding to a second reduction. Upon workup, the alkoxy group leaves as an aluminum alkoxide and the carbonyl ends up as an aldehyde.

For ethyl benzoate, this means you obtain benzaldehyde. If you use more DIBAL-H or raise the temperature, the aldehyde can be reduced further to the primary alcohol (benzyl alcohol). Benzoic acid would come from oxidation, not from this reducing setup, and benzene would require removal of the carbonyl entirely, which DIBAL-H does not accomplish under these conditions.

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