Chapter 16, Problem 24P

Interpretation Introduction

Interpretation:

Whether  maltose, lactose, and sucrose undergo mutaroration or not has to be identified.

Concept introduction:

Mutarotation is the change in the specific rotation that occurs when an $\alpha$ or $\beta$ form of a carbohydrate is converted to an equilibrium mixture of the two.

If the oxygen on the anomeric carbon (the carbonyl group) of a sugar is not attached to any other structure, that sugar can be considered as a reducing sugar. Only the state of the oxygen on the anomeric carbon determined if the sugar is reducing or nonreducing, the other hydroxyl groups on the molecule are not involved. Without this hydroxyl group, the ring cannot open and close and so it cannot undergo mutarotaion.

Reducing sugars can undergo Mutarotation while nonreducing sugars cannot undergo Mutarotation.