on radical of 1 to 20 carbon atoms, R4 and R5 are each independently of the other hydrogen, halogen, C1 -C5 alkyl, C1 -C5 alkoxy, phenoxy or substituted phenoxy, and X is a direct single bond or a methylene or ethylene bridge; and Z is either a direct single bond or may be a member selected from the group consisting of: --S--; --O--; --SO--; --SO2 --; --CO--; --C(R6)(R7)--, where R6 is hydrogen, m