PURPOSE: To obtain the subject comps. as pigment synthesis intermediates without requiring a solvent and directly by a simple method under specific conditions from a 2,5-dianilino-3,6-dihydroterephthalic acid compd. or 2,5-dianilino- terephthalic acid compd.
CONSTITUTION: The compd. of formula II is obtd. by cyclizing a 2,5-dianilino-3,6- dihydroterephthalic acid deriv. of formula I (R1, R2 are each H, Cl, Br, a 1-10C alkoxy, etc.; R3, R4 are each a 1-10C alkoxy, amino, a 1-10C-mono- or dialkylamino, etc.) in a liquid or solid agglomerated state or as a soln., respectively in a fine form or in a gaseous phase at 350 to 500°C. The compd. of formula IV is obtd. by cyclizing a 2,5-dianilino-terephthalic acid deriv of formula III in a liquid or solid agglomerated state or as a soln., respectively in a fine form or in a gaseous phase at 350 to 700°C.
Colberg, Horst
Teich, Friedhelm
Kemper, Reinhard
