Esterification of ascorbic acid

Cousins et al. (38) have reported the formation of ascorbic acid 6-0-sulfate, 27, from the esterification of ascorbic acid with sulfur trioxide in sulfuric acid. The 6-sulfate derivatives have been proposed for use as anti-cholesteremics and as inhibitors of nitrosamine formation. 

Acid-catalysed esterification of ascorbic acid, e.g. acetylation, produces initially the O-6-acylated derivative and, under more stringent conditions, a 5,6-diester. Fhe crystalline 5,6-diacetate is well known. More vigorous conditions still are needed to obtain the 2,3,4,6-tetra-acetate. 

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