Sulfite ester

A sulfite ester is a functional group with the structure (RO)(R'O)SO. When substituents R and R' differ, the compound is chiral owing to the stereogenic sulfur centre. They are commonly prepared by the reaction of thionyl chloride with alcohols in the presence of a base such as pyridine:

2 ROH + SOCl₂ + 2 C₅H₅N → (RO)₂SO + 2 C₅H₅NH⁺Cl^-

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.