. . "se of di-, tri- or tetra-substitution, two vicinal radicals R4 in the phenyl ring are trimethylene or tetramethylene and the other radicals R4 are hydrogen atoms or alkyl with 1 to 6 C atoms, Y is O, S, NH, CO or CH2, R5 is a hydrogen atom or alkyl with 1 to 5 C atoms, R6 is alkyl with 1 to 5 C atoms and Z is a direct bond, O, S, SO, SO2, CO, ##STR60## NR7, CONH, NH, R7 SiR8, R7 OSiOR8, ##STR61##" . .