Question

How do you explain the absence of aldehyde group in the pentaacetate of d-glucose?

Answer 1

$\huge\rm{Answer :-}$

The pentaacetate of glucose does not react with hydroxylamine ($NH_2OH$) which shows that aldehyde(—CHO) group is present in glucose pentaacetate.

Answer 2

Answer:

Pentaacetate of glucose does not contain a free —OH group at C-1 position. Therefore, in aqueous solution it cannot get hydrolysed to form the open chain aldehydic form and thus it does not react to form glucose oxime. Hence, glucose pentaacetate does not contain the aldehyde group.