ne, and their lower alkyl-substituted derivatives, by removal of two or more of their hydrogen atoms, each R4 is independently an alkylene moiety with 2 to 10 carbon atoms, or a cycloalkylene moiety with 6 to 10 carbon atoms, each R5 is independently a phenyl moiety or methyl, each R6 is independently a lower alkyl with 1 to 4 carbon atoms,g is zero or a number up to 5, h is an integer of 1 to 10,