1,1-Bis(chloromethyl)ethylene is the organic compound with the formula CH2=C(CH2Cl)2.

It is a colorless liquid.

Featuring two allylic chloride substituents, it is dialkylating agent.

It is prepared from pentaerythritol via a multistep procedure, beginning with the partial chlorination.

[2][3] The compound reacts with diiron nonacarbonyl to give the complex of trimethylenemethane Fe(η4-C(CH2)3)(CO)3.