. "tic radical, R3 is an aliphatic radical having at least 2 C atoms, R4 is alkyl having 1-4 C atoms, cycloalkyl having 5-7 C atoms, aralkyl having 7 or 8 C atoms or aryl having 6-10 C atoms, R5 and R6 independently of one another are hydrogen or methyl, Z1 and Z3 are each hydrogen, Z2 is hydrogen, chlorine or methyl and Z4 is hydrogen, methyl, chlorine, --CN, --COOH, --CONH2, phenyl, methylphenyl, m" . . . .