A compound having the vinyl grouping (CH2═CH), specifically vinyl chloride, vinyl acetate, and similar esters but also referring more generally to compounds such as styrene C6H5CH═CH2, methyl methacrylate CH2═C(CH3) COOCH3, and acrylonitrile CH2═CHCN. The vinyl compounds are highly reactive, polymerize easily, and the basis of a number of important plastics.