| abstract |
Compounds of the general formula <IMAGE> (I) wherein R represents hydrogen or alkyl and A represents a radical of the formula <IMAGE> <IMAGE> <IMAGE> <IMAGE> +TR <IMAGE> wherein the rings D can carry up to 4 alkyl radicals, R1 and R2 independently of one another represent alkyl, alkenyl, cycloalkyl, aryl or aralkyl and R3 represents hydrogen, alkyl or aryl, and the said cyclic and acyclic radicals and the rings B and C may carry nonionic substituents, are used as color-forming agents. |