They are commonly prepared by the reaction of thionyl chloride with alcohols. The reaction is typically performed at room temperature to prevent the alcohol being converted into a chloroalkane. Bases such as pyridine can also be used to promote the reaction:
- 2 ROH + SOCl2 → (RO)2SO + 2 HCl
The pesticide endosulfan is a sulfite ester. Some simple members include ethylene sulfite, dimethyl sulfite, and diphenylsulfite. Many examples have been prepared from diols, such as sugars. Sulfite esters can be powerful alkylation and hydroxyalkylation reagents.