The Thermal Decompositions and Mass Spectral Studies of the Cyclic Anhydrides of Some β-Sulfocarboxylic Acids

Abstract

Abstract The thermal decompositions of the cyclic anhydrides of β-sulfopivalic acid (III) and β-sulfoisobutyric acid (IV) have been studied. The pyrolysis of III without a solvent gave pivalic acid, isobutene, isobutane, water, and a mixture of trimers of isobutene, while the pyrolysis of IV resulted in the formation of methacrylic acid and acetone. In the case of III, the evolution of sulfur dioxide and carbon dioxide occurred mainly. On the contrary, in the case of IV, the carboxylic acid derivative was the predominant product. These results might be interpreted in terms of a decomposition mechanism in which the compound (IV) having α-hydrogen to a carbonyl group undergoes thermal decomposition via a concerted mechanism. In the case of IV, it should be noted that acetone was formed. This paper will also be concerned with the mass spectra of III and IV and with the cyclic anhydride of β-sulfopropionic acid.