Sydnon‐äthylene. III. Chemische Reaktionen elektronisch angeregter 4‐Styryl‐sydnone

Abstract

Sydnone Ethylenes. III. Chemical Reactions of Excited 4‐Styryl‐sydnones Dependent on the character of the substituents in the photo reactions of 4‐styryl sydnones Z / E ‐isomerism competes with CO 2 ‐elimination. Excited p‐nitrostyryl sydnones exhibit a relatively strong degradation of the bond order in the CC region. Their quantum yields of Z / E ‐isomerism are therefore much higher than those of compounds with p‐substituents of lower acceptor effect. In these compounds the cleavage of the sydnone ring with elimination of carbon dioxide is favoured especially if a methyl group is in 3‐position of the sydnone.