Abstract
The coloration of ascorbic acid derivatives with pyrrole was studied, and was found that 5,6-diacetylascorbic acid oxidized with iodine produced a blue color with pyrrole, while acetylated dehydroascorbic acid, derived from acetylation of dehydroascorbic acid, unexpectedly did not. On the supposition that this peculiar phenomenon was due to the specific structure of acetylated dehydroascorbic acid, various investigations were performed to elucidate that above acetylated dehydroascorbic acid was a dimer identical with tetraacetyl-bis-dehydroascorbic acid obtained by H. Albers, et al. by acetylating bis-dehydroascorbic acid. Further studies with mass-, infrared- and NMR-spectra did not reveal any fact that deny the proposed structure by H. Albers. In the above dimer, 2 moles of dehydroascorbic acid combined at 2,3'-positions and 2,3'-positions respectively, forming a dioxane ring. These facts would further support the presumed mechanism that the coloration with pyrrole was due to the participation of carbonyl group at 3 position of dehydroascorbic acid, as reported in a preceding paper.
