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

Explanation

corresponding oxime . Thus , glucose contains an aldehydic group. In contrast, when glucose is reacted with acetic anhydride. Anhydride , the OH group at `C-1`, along with the four other OH groups at `C-2,C-3,C-4` and `C-6` form a pentaacetate. Since the pentaacetate of glucose does not contain a free OH group at `C-1` , it cannot get hydrolysed in aqueous solution to produce the open chain aldehydic form and hence glucose this proves that glucose pentaacetate does not contain the aldehyde group.