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Which of the following reagents will convert acetophenone (C6H5COCH3) to C6H5C(OH)(CH3)D, where D is deuterium?

1. NaBD4 in CH3OH
2. LiAlH4, then D2O
3. NaBO4 in CH3OD
4. LiAlO4, then D2O

Correct answer: NaBD4 in CH3OH

Solution

The target molecule C6H5C(OH)(CH3)D has deuterium on the alpha-carbon (the former carbonyl carbon) and a normal OH group. NaBD4 in CH3OH: BD4- delivers D- to the electrophilic carbonyl carbon (C=O of acetophenone), and the alkoxide oxygen picks up a proton from CH3OH. This directly gives C6H5C(OH)(CH3)D. LiAlH4 followed by D2O would deliver H- to the carbonyl carbon giving C6H5C(O-)(CH3)H, and D2O would exchange the O-H to give C6H5C(OD)(CH3)H — the D is on oxygen, not carbon. NaBO4 is sodium perborate, an oxidant, not a reductant. LiAlO4 is not a real reagent. Hence NaBD4 in CH3OH is correct.

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