2-Chloromethyl-2,3-dihydrothieno[3,4-b]-1,4-dioxine (EDOT-Cl) can be prepared by reacting 3,4-dimethoxythiophene with 3-chloro-1,2-propanediol via transesterification. The six-memebered ring of the molecule exhibits twisted conformation. It acts as an intermediate during the multi-step synthesis of poly(sulfobetaine-3,4-ethylenedioxythiophene) (PSBEDOT), a conjugated polymer.