Question

What is the correct name of the following compound?

(a) D-(+)-fructose

(b) D-(-)-fructose

(c) L-(+)-fructose

(d) L-(-)-fructose

The question was asked during an interview.

This interesting question is from Biomolecules Carbohydrates topic in division Biomolecules of Chemistry – Class 12

Answer 1

Right answer is (b) D-(-)-fructose

The best I can explain: Since the OH group on the carbon adjacent to the last CH2OH group is on the right-hand side, it is of D configuration. Also, fructose is naturally a laevorotatory compound, hence the (-) sign.