GB421813A - Manufacture of napthelene-1:4:5:8-tetracarboxylic acid - Google Patents

Abstract

Naphthalene-1 : 4 : 5 : 8-tetracarboxylic acid is prepared by heating with concentrated sulphuric acid a di-, tri- or tetrachloro- or -bromopyrene compound which contains at least one halogen atom in 8- or 10-position and at least one further halogen atom of the same kind in 3- or 5-positions and oxidizing, with or without previous isolation the pyrenequinones thus obtained. In examples (1) 3 : 5 : 8 : 10-tetrachlorpyrene is heated with concentrated sulphuric acid to obtain the sulphate of di-perinaphthindandione (3 : 4 : 5 : 8 : 9 : 10-hexahydro3 : 5 : 8 : 10-tetraoxopyrene) which is oxidized by means of sodium hypochlorite or nitric acid to yield naphthalene-1 : 4 : 5 : 8-tetracarboxylic acid; (2) 3 : 5 : 8 : 10-tetrabromopyrene is heated with sulphuric acid to yield dibromodiperinaphthindandione which may be oxidized by means of sodium hypochlorite, nitric acid or pyrolusite to naphthalene-1 : 4 : 5 : 8-tetracarboxylic acid. 3 : 5 : 8 : 10-Tetrachlorpyrene is prepared by chlorination of pyrene in trichlorobenzene or tetrachlorethane with chlorine, or in nitrobenzene with sulphuryl chloride, or by reacting tetranitropyrene with phosphorous pentachloride in trichlorobenzene. 3 : 5 : 8 : 10-Tetrabrompyrene is prepared by bromination of pyrene in nitrobenzene. Di-acetoxypyrenequinone and its dibromo derivative are prepared by heating diperinaphthindandione or its dibromo derivative with acetic anhydride. The Specification as open to inspection under Sect. 91 refers also to the use of fuming sulphuric acid and to the treatment of more highly halogenated pyrenes. In examples, 3 : 5 : 8 : 10-tetrachlorpyrene, or hexachlorpyrene, or decachlorpyrene, is heated with fuming sulphuric acid to yield the di-peri-naphthindandione and then oxidized to yield naphthalene-1 : 4 : 5 : 8-carboxylic acids or chloro derivatives thereof. Hexachlorpyrene is obtained by chlorinating pyrene to yield 1 : 2 : 3 : 5 : 6 : 7 : 8 : 10-octochloro-1 : 2 : 6 : 7-tetrahydropyrene and splitting off 2 molecules of hydrochloric acid by means of an alcoholic alkali. Decachlorpyrene is obtained by chlorinating hexachlorpyrene by means of chlorosulphonic acid in the presence of iodine and heating to split off hydrochloric acid. This subject-matter does not appear in the Specification as accepted.