GB272528A - - Google Patents

Abstract

272,528. I. G. Farbenindustrie Akt.- Ges. June 9. 1926, [Convention date].. Samples furnished. Ferylene derivatives. - Perylene carboxylic acids, their imides and halogen substitution products, are decarboxylated by heating them under pressure in aqueous solution or suspension in the presence of an acid-binding agent, or by heating their salts under pressure in neutral or alkaline aqueous solution or suspension. By selection of the reaction conditions, the degree of decarboxylation can be regulated; for this purpose the use of an excess of alkali has the same effect as raising the temperature or increasing the concentration. Thus, from perylene-3 : 4 9 : 10-tetracarboxylic acid are obtained the 3 : 4: 9-tricarboxylic acid, the 3 : 9- or 3 : 10-dicarboxylic acid, the 3-monocarboxylic acid, and finally perylene itself, and examples are given of their preparation. Similarly, perylene-3 : 4 : 9 : 10-tetracarboxylic acid monoimide yields either the 3: 4-dicarboxylic acid imide or a dicarboxylic acid, the imide ring being ruptured in the latter case, whilst perylene-3 : 4- dicarboxylic acid imide gives the 3-monocarboxylic acid: wording conditions are given for these reactions. In the case of chlorinated perylene carboxylic acids, the decarboxylation is generally accompanied by replacement of the chlorine by hydroxyl groups. Perylene-3 : 4 : 9- tricarboxylic acid readily forms both an imide and an anhydride. The products are useful as intermediates for the manufacture of dyes. Specification 221,008 is referred to. The Specification as open to inspection under Sect. 91 (3) (a) refers to the decarboxylation of derivatives and substitution products in general of perylene carboxylic acids; this subject-matter does not appear in the Specification as accepted.