Chapter 19.SE, Problem 37MP

Interpretation Introduction

Interpretation:

A mechanism for the formation of an acetal when α-glucose is treated with an acid catalyst is to be proposed. The structure of the stereoisomeric acetal that can be expected as a product also is to be given.

Concept introduction:

The acid will protonate one of the –OH groups in glucose. An internal nucleophilic attack of the oxygen present will eliminate water to produce an alkene. The addition of methanol to alkenes can take place from both sides of the planar double bond leading to the formation of two stereomeric acetals one woth axial –OCH₃ and other with equtorial –OCH₃.

To propose:

A mechanism for the formation of an acetal when α-glucose is treated with an acid catalyst and to give the structure of the stereoisomeric acetal that can be expected as a product.