Thermal decomposition of ascorbic acid

Thermal degradation of l-ascorbic acid at 300 °C in the absence of a solvent yielded mostly furan derivatives and α,β-unsaturated cyclic ketones with a five-membered ring. Some of the furan derivatives are the same as those obtained in the Maillard reaction, with the reductones undergoing retroaldol reaction, decarboxylation, oxidation, and hydrolysis. In propylene glycol, under milder conditions (180 °C), the carbonyl and dicarbonyl derivatives resulting from the decomposition react with the solvent and give cyclic acetals and ketals (1,3-dioxolanes). The products were identified by GC-MS using the SPECMA data bank.