Question

Give three reactions of glucose which cannot be explained by its chain structure.

Answer 1

There are following three reactions of glucose which cannot be explained by its chain structure.

(1) Glucose doesn’t undergo 2,4-DNP test, schiff’s test. Actually, aldehyde gives 2,4-DNP test , Schiff’s test and react with NaHSO₄ forms hydrogen sulphite addition product.

(2) the pentaacetate of glucose doesn’t react with hydroxylamine. This indicates that free -CHO group is absent from glucose molecule.

(3) Glucose doesn’t form the hydrogen sulphite addition product of NAHSO₃

Answer 2

Glucose is nothing but the polyhydroxy aldehyde.It is a type of aldohexose.It can also exist in chain structure.Three reactions of glucose which cannot be explained by its chain structure are,

(1) Glucose doesn’t give 2,4-DNP test, schiff’s test. Actually, aldehyde and ketones give 2,4-DNP test , Schiff’s test.

(2) the pentaacetate of glucose doesn’t react with hydroxylamine to give oxim.This indicates that free -CHO group is not present in glucose molecule.

(3) Glucose doesn’t react with NaHSO3.