GB683770A - Improved process for the manufacture of 4:5-diphenylphthalic acids and anhydrides - Google Patents

Abstract

A process for the manufacture of 4 : 5-diphenyl-phthalic acid and substituted 4 : 5-diphenylphthalic acid and the anhydrides of these acids comprises heating anhydroacetone benzil or a substitution derivative thereof with a monochloro- or monobromo-maleic acid or a monochloro- or monobromo-fumaric acid or a functional derivative of these acids. The reactants may be heated together, e.g. at 150 DEG -250 DEG C. in a solvent, e.g. nitrobenzene or o-dichlorobenzene. A dehydrating agent, e.g. potassium bisulphate, may be added to the reaction mixture. It is suggested that in the mixture anhydroacetonebenzil, i.e. 1 : 2-diphenylcyclo - pent - 2 - en - 4 - one - 1 - ol) is dehydrated to 1 : 2 - diphenyl - cyclopent - 2 : 5-dien-4-one which undergoes a Diels-Alder reaction with the halogenomaleic acid, and the adduct by loss of halogen acid and endocarbonyl group yields the desired product. In examples: (1) to (5) 4 : 5-diphenylphthalic acid or anhydride is obtained by reacting anhydroacetonebenzil with (1-4) chlormaleic anhydride, (5) chlorfumaric acid, with different solvents and isolation methods. Similarly to (2) are prepared (no solvents and addition of alkali to yield the acid salt): (6) 4 : 5-di-(p-methylphenyl) phthalic acid; (7) 4 : 5-di-(p-chlorphenyl) phthalic acid; (8) and (9) 4 : 5-diphenyl-3-methylphthalic acid (from 1 : 2-diphenyl-3-(or 5-) methyl-cyclopent-2-en-4-one-1-ol); (10) 3 : 4 : 5-triphenyl-phthalic acid (from 1 : 2 : 3-triphenylcyclopent-2-en-4-one-1-ol. For use in examples (6) and (7) are prepared 1 : 2 - di - (p - methylphenyl) - cyclopent - 2 - en - 4 - one-1-ol from acetone and p : p1-dimethylbenzil, and 1 : 2 - di - (p - chlorophenyl) - cyclopent - 2 - en-4-one-1-ol from p : p1-dichlorobenzil and acetone.