Which of the following is both a D-sugar and an epirner of glucose? A B C D Both A and B Both C and D

Question

Anu Bhardwaj · Accepted Answer

B

Reason: A D-sugar has the OH on the penultimate carbon (C-5) on the right in the Fischer projection.

Comparing each option to D-glucose (C2–C5: R–L–R–R):

A: OH pattern R–R–L–R → differs at two centers → not an epimer.
B: OH pattern R–R–R–R → differs from glucose at only C-3 and has C-5 OH on the right → D-sugar and an epimer.
C: Penultimate OH on the left → L-sugar.
D: Penultimate OH on the left → L-sugar.

So only B is both a D-sugar and an epimer of glucose.

Chemistry