Derivate des 5, 6‐Dihydro‐p‐dithiin‐2, 3‐dicarbonsäure‐anhydrids, I: Imide

Abstract 5. 6‐Dihydro‐ p ‐dithiin‐2. 3‐dicarboxylic anhydride reacts with primary amines quite readily to form the substituted imides. The imide formation occurs much more easily than with maleic or phthalic anhydride. The imide and all N‐substituted imides have a fairly strong, bright yellow colour. Their absorption spectra differ considerably from those of the anhydride, ester and dinitrile. Electron‐attracting substituents on the imide nitrogen increase the absorption maximum somewhat, while strongly electron‐releasing groups decrease it, and may even shift it to a shorter wave‐length. It is therefore concluded that the imide nitrogen is part of the election acceptor group of the chromorphoric system.