JEE MainChemistryBiomolecules
Which of the following statements about the cyclic structure and stereochemistry of D-glucose is incorrect?
Options
- A-D-glucopyranose and -D-glucopyranose differ in configuration only at C-1
- BThe cyclic hemiacetal structure of glucose is a six-membered ring called pyranose
- C-D-glucose and -D-glucose are enantiomers of each other
- DAn aqueous solution of D-glucose undergoes a spontaneous change in specific rotation known as mutarotation
Correct answer
C. -D-glucose and -D-glucose are enantiomers of each other
Step-by-step solution
-D-glucose and -D-glucose are anomers, which means they differ in configuration only at the anomeric carbon (C-1). Since they are not non-superimposable mirror images of each other, they are diastereomers, not enantiomers. Glucose forms a six-membered cyclic hemiacetal ring, which is analogous to pyran, hence called a pyranose ring. When either the or form is dissolved in water, it slowly converts into an equilibrium mixture of both forms, leading to a change in specific rotation. This phenomenon is called mutarota