Refer to the following structures.Which D-aldohexose would react with NaBH4 to yield an optically inactive alditol?

Question

Quizplus · Accepted Answer

A D-aldohexose with a ketone functional group (as in I, II, and IV) would not react with NaBH4 to yield an alditol, as NaBH4 reduces only aldehydes and not ketones. On the other hand, a D-aldohexose with all hydroxyl groups in the equatorial position (as in V) would not have a plane of symmetry and would be optically active. Thus, the only option remaining is III, which has all hydroxyl groups in the axial position and a plane of symmetry, resulting in an optically inactive alditol after reduction with NaBH4.

Refer to the Following Structures