The Enhancement of Formose Formation with 2-Hydroxyacetophenone. A mechanism Involving Aldol and Retro-aldol Reactions

Article abstract of DOI:10.1246/bcsj.55.2409

The rapid aldol addition of formaldehyde to 2-hydroxyacetophenone (HAP), an efficient accelerator for formose formation, took place to yield addition products of HAP with one and two molecules of formaldehyde at 35 deg C in an aqueous 40percent methanol mixture of formaldehyde, HAP, and Ca(OH)2.No further addition product with more than two molecules of formaldehyde attached to HAP was detected throughout the reaction.On the contrary, benzaldehyde and benzoic acid were formed, accompanied by formose sugars.The initial molar amount of HAP corresponded to the sum of the compounds substituted with the phenyl group including benzaldehyde and benzoic acid.The retro-aldol reaction of the HAP derivatives is likely to be involved in the overall reaction to yield glycolaldehyde or trioses, which are good accelerators for formose formation.