Chlorosulfate

Chlorosulfate is a chemical term used to describe a class of compounds and functional groups that originate from chlorosulfuric acid (ClSO3H). In organic chemistry, chlorosulfates most often refer to esters of chlorosulfuric acid with alcohols, having the general structure R-O-S(=O)2-Cl. These are called alkyl or aryl chlorosulfates and are used as sulfonylating reagents and intermediates in various synthetic sequences.

Preparation and properties tend to be moisture sensitive. They are typically prepared by treating alcohols with chlorosulfuric acid or via related chlorosulfonylation routes. Due to the reactive S–O–Cl linkage, chlorosulfates readily hydrolyze in the presence of water, giving sulfuric acid derivatives and hydrogen chloride. They are generally stored under strictly dry conditions and handled with appropriate protective equipment because of their corrosive and irritant properties.

Reactivity and applications in organic synthesis include the introduction of the sulfonyl or sulfate-related functionality into substrates. Chlorosulfates can serve as leaving groups or as activated sulfonylating agents in the formation of sulfate esters and related structures. Because of their high reactivity with nucleophiles, they are typically used in controlled, dry environments and are often replaced by more stable sulfonylating reagents when possible.

In inorganic chemistry, the term chlorosulfate can also refer to salts containing the chlorosulfate anion, ClSO4−, though these are far less common in routine practice than the organic chlorosulfate esters.

Safety considerations are important: chlorosulfates are corrosive and moisture reactive. Proper handling includes use of fume hoods, gloves, and dry solvents and equipment.