Thermal Decomposition of Lichen Depsides

Abstract

The thermal decomposition of the following lichen depsides has been described: lecanoric acid, gyrophoric acid, evernic acid, perlatolic acid, planaic acid, confluentic acid, atranorin, 4-O-de-methylbarbatic acid, and sekikaic acid. Main reaction products are decarboxylated compounds, phenolic units, rearranged depsides, and xanthones. Triethylammonium salts of depside carboxylic acids decompose at reasonably lower temperature than the corresponding free acids. © 1989, Walter de Gruyter. All rights reserved.