Alpha-methylene-6-styryl-acrylic acid derivatives

All possible stereoisomer forms and mixtures of a compound of the formula ##STR7## wherein X is a halogen, R.sub.2 and R.sub.3 are individually selected from the group consisting of alkyl and cycloalkyl of up to 8 carbon atoms optionally substituted with at least one halogen, R.sub.1 is selected from the group consisting of alkyl, alkenyl, alkynyl and cycloalkyl of up to 12 carbon atoms optionally substituted with at least one halogen, hydrocarbyl aryl and heterocycle selected from the group consisting of pyridyl, pyrimidyl, pyridazinyl, oxazolyl, thiazolyl, isoxazolyl, isothiazolyl, (1,3,4)-oxadiazolyl, (1,2,4)-oxadiazolyl, thiadiazolyl and triazolyl optionally substituted with at least one member of the group consisting of halogen, alkyl, alkenyl, alkynyl and cycloalkyl of up to 8 carbon atoms optionally substituted with at least one member of the group consisting of --NO.sub.2 --NH.sub.2, --CN, --OR', --SR", --SOR", --SO.sub.2 R", --NR"'.sub.2, --Ar, --OAr.sub.1 and SAr.sub.2, R', R" and R"' are individually selected from the group consisting of alkyl, alkenyl alkynyl and cycloalkyl of up to 12 carbon atoms optionally substituted by at least one halogen, Ar, Ar.sub.1 and Ar.sub.2 are hydrocarbyl aryl of up to 14 carbon atoms or heteroaryl selected from the group consisting of pyridyl, pyrimidyl, pyridazinyl, oxazolyl, thiazolyl, isoxazolyl, isothiazolyl, (1,3,4) -oxadiazolyl, (1,2,4) -oxadiazolyl, thiadiazolyl and triazolyl optionally substituted with at least one member of the group consisting of halogen and alkyl, alkenyl, alkynyl and cycloalkyl of up to 8 carbon atoms optionally substituted by at least one member of the group consisting of --NO.sub.2, --NH.sub.2, --CN, --OR', --SR", --SOR", --SO.sub.2 R", --NR"'.sub.2, R', R" and R"' have the above definitions.