Processes for the preparation of 1,1'-dinaphthyl-4,4',5,5',8,8'-hexacarboxylic acid derivatives

The invention relates to processes for the preparation of derivatives of the polynuclear, polybasic aromatic carboxylic acids, in particular to a process for the preparation of 1,1'-dinaphthyl-4,4',5,5',8,8'-hexacarboxylic acid derivatives of the general formula in which X represents oxygen or N-C6H3RR', R represents H or alkyl having 1 to 4 carbon atoms, R' represents H, alkyl having 1 to 4 carbon atoms, alkoxy having 1 to 4 carbon atoms or halogen. The process consists according to the invention of diazotising 1-aminonaphthalene-4,5,8-tricarboxylic acid derivatives of the general formula in which X has the above-mentioned meanings, with an alkali metal nitrite at a temperature of 0 to 15 DEG C and a pH of the medium of 0 to 2 and then subjecting the diazo compound obtained to a diaryl condensation under the action of a copper(I)/ammonia complex in an amount from 2 to 2.5 mol, relative to copper(I), per 1 mol of compound of the general formula II at a temperature of 5 to 25 DEG C and a pH of the medium of 8 to 10 and then isolating the final product by treatment with an inorganic acid. The said compounds are dyes which are used for the printing of fabrics made of cotton, flax fibre, viscose or acetate staple fibre, synthetic fibres and blends thereof, and for the dyeing of the fabrics composed of the said fibres.