Diaryl pigments with improved heat stability obtained by coupling bis-diazotized diamines with acetoacetanilides

Claim 1

A diaryl pigment obtained by coupling bis-diazotized 3,3'-dichloro-4,4'-diaminobiphenyl with an acetoacetanilide of the formula I ##STR30## in which the Rs are identical or different and each of the Rs represents a member selected from the group consisting of hydrogen, chlorine, methyl, methoxy and ethoxy, and n denotes an interger from 1 to 3, the coupling being carried out in the presence of about 1 to 3 mole %, relative to said acetoacetanilide of formula I of a component consisting essentially of a compound of the formula II ##STR31## in which R 1 and r 2 each denote the radical ##STR32## or one of the radicals R 1 and R 2 denotes hydrogen and the other denotes a radical selected from the group consisting of ##STR33## and -SO 2 NH 2 , or R 1 and R 2 linked to one another denote a divalent radical selected from the group consisting of ##STR34## the CO group being attached to the phenyl nucleus either via the 3-position or via the 4-position.