4. acrylates, for example ethyl or isooctyl ??-cyano-??,??-diphenylacrylate, methyl ??-carbo-methoxy-cinnamate, methyl or butyl ??-cyano-??-methyl-p-methoxy-cinnamate, methyl ??-carbomethoxy-p-methoxy-cinnamate and N-(??-carbomethoxy-??-cyanovinyl)-2-methylindoline.