Question

Which d-aldopentoses are reduced to optically inactive alditols using ${\mathbf{NaBH}}_{\mathbf{4}}\mathbf{,}\mathbf{}{\mathbf{CH}}_{\mathbf{3}}\mathbf{OH}$?

Short answer

Answer

D-ribose and D-xylose are the two d-aldopentose that reduce to optically inactive alditols using${\mathrm{NaBH}}_4,{\mathrm{CH}}_3\mathrm{OH}$ .

Step-by-step solution

Optically inactive compound

The compound is inactive which means it is incapable of rotation of the plane-polarized light of plane, i.e., achiral compound. Aldopentose is a type of sugar that contains the aldehyde group.

D-ribose

D-ribose treated with ${\mathrm{NaBH}}_4$ followed by ${\mathrm{CH}}_3\mathrm{OH}$forms a compound which forms an optically inactive alditol.

Reduction of D-ribose to optically inactive alditol

D-xylose

D-xylose treated with ${\mathrm{NaBH}}_4$ followed by${\mathrm{CH}}_3\mathrm{OH}$ forms a compound which forms an optically inactive alditol.

Reduction of D-xylose to optically inactive alditol