Chapter 25, Problem 25.27P

Interpretation Introduction

Interpretation:

When the four aldopentoses are reduced by ${\text{NaBH}}_{\text{4}}$, which yield optically active alditols and which yield optically inactive alditols has to be given.

Concept Introduction:

The reagent ${\text{NaBH}}_{\text{4}}$ is a reducing agent.  In carbohydrates, it reduces the carbonyl group ($\text{-C=O}$) into hydroxyl group ($\text{–OH}$).  The formed reduced products are known as alditols.