chlorohydrins

Chlorohydrins are a class of halohydrins in which a chlorine atom and a hydroxyl group reside on adjacent carbon atoms within the same molecule. The general motif is a vicinal chlorohydrin with the structure R-CH(OH)-CH2Cl, though many variants exist depending on the substituents on the carbon skeleton. They are typically colorless to pale liquids or viscous liquids.

Most chlorohydrins are prepared by the halogenation of alkenes in water. When an alkene is treated with chlorine (Cl2) in aqueous solution, the halohydrin formation reaction adds Cl to the less substituted carbon and OH to the more substituted carbon, producing a chlorohydrin such as 1-chloro-2-propanol from propene or 2-chloroethanol from ethene. The resulting compounds are versatile intermediates in organic synthesis.

One major use of chlorohydrins is as precursors to epoxides. Treatment with base induces intramolecular substitution (dehydrohalogenation) to form an epoxide, releasing a chloride ion. This halohydrin-to-epoxide transformation is a standard route to many epoxides, including those used to make epoxy resins and glycidyl derivatives. Chlorohydrins also serve as intermediates in the production of glycols and various chlorine-containing building blocks for polymers and specialty chemicals.

Safety and handling considerations are important: chlorohydrins are typically corrosive and can be toxic or irritant to skin, eyes, and the respiratory tract. They may hydrolyze or decompose under certain conditions, releasing hydrochloric acid or chlorine. They should be handled with appropriate protective equipment and waste treated to minimize environmental impact.