In organosulfur chemistry, a sulfenyl chloride is a functional group with the connectivity R−S−Cl, where R is alkyl or aryl. Sulfenyl chlorides are reactive compounds that behave as sources of RS⁺. They are used in the formation of RS−N and RS−O bonds. According to IUPAC nomenclature they are named as alkyl thiohypochlorites, i.e. esters of thiohypochlorous acid.

Typically, sulfenyl halides are stabilized by electronegative substituents. This trend is illustrated by the stability of CCl₃SCl obtained by chlorination of carbon disulfide.

Sulfenyl chlorides are typically prepared by chlorination of disulfides:

This reaction is sometimes called the Zincke disulfide reaction, in recognition of Theodor Zincke.

Some thioethers (R−S−R’) with electron-withdrawing substituents undergo chlorinolysis of a C−S bond to afford the sulfenyl chloride.

In a variation on the Reed reaction, sulfur dichloride displaces hydrogen under UV light.

Perchloromethyl mercaptan (CCl₃SCl) reacts with N−H bonds in the presence of base to give the sulfenamides:

This method is used in the production of the fungicides Captan and Folpet.