Question

The $\alpha -$ and $\beta -$ forms of glucose are

• A. isomers of $D(+)$ glucose and $L(-)$ glucose respectively
• B. diastereomers of glucose
• C. anomers of glucose
• D. isomers which differ in the configuration of $C-2$.

Answer 1

Answer: (C)

$\alpha$-D-glucose and $\beta$-D-glucose are stereoisomers - they differ in the 3 -dimensional configuration of atoms/groups at one or more positions. More specifically, they are a class of stereoisomer called an anomer. Anomers are capable of interconverting in solution. All cyclic structures of monosaccharides exhibit anomeric $\alpha \alpha$ (down) and $\beta \beta$ (up) versions. These differences occur at the anomeric acetal carbon (the only carbon with two $C-OC-O$ bonds.