a colourless, dense, toxic, volatile, flammable liquid belonging to the family of organic halogen compounds, used principally in combination with vinyl chloride, acrylonitrile, or methyl methacrylate for the manufacture of a class of plastics called saran. Vinylidene chloride is also used as a starting material for making methylchloroform, or 1,1,1-trichloroethane, a solvent useful in cleaning electrical machinery.

Vinylidene chloride is produced by the reaction of 1,1,2-trichloroethane (itself derived from acetylene or ethylene) with lime or with caustic soda; it usually is prepared only as it is needed because it is rapidly attacked by oxygen to form peroxides that catalyze the formation of undesired polymers.