Which one of the following reactions is not explained by the open chain Structure of glucose:

Options

A. Formation of pentaacetate of glucose with acetic anhydride
B. Formation of addition product with 2, 4 DNP reagent
C. Silver mirror formation with Tollen's reagent
D. Existence of alpha and beta forms of glucose.

Answer

D

Explanation

Glucose exist in two different crystalline forms which are named as `alpha and beta`. The `alpha`-form of glucose (m.p. 419 K) is obtained by crystallisation from concentrated solution of glucose at 303 K while the `beta`-form (m.p. 423 K) is obtained by crystallisation from hot and saturated aqueous solution at 371 K. This behaviour could not be explained by the open chain structure for glucose.