"If the phenyl group is substituted, thesubstituents may consist in particular of 1 to 3 halogen atoms such as fluorine, chlorine or bromine atoms, preferably fluorine or chlorine atoms, one to three C.sub.1 -C.sub.3 -alkyl groups, preferably methyl or ethyl groups, and one to three C.sub.1-C.sub.3 -alkoxy groups, preferably methoxy or ethoxy groups." . . . . .