Sulfenyl chloride

Trichloromethane­sulfenyl chloride is a stable sulfenyl chloride

Sulfenyl chlorides are typically prepared by chlorination of disulfides:[2][3]

${\displaystyle {\ce {R2S2 + Cl2 -> 2 R-SCl}}}$

This reaction is sometimes called the Zincke disulfide reaction, in recognition of Theodor Zincke.[4][5] Typically, sulfenyl halides are stabilized by electronegative substituents. This trend is illustrated by the stability of CCl₃SCl obtained by chlorination of carbon disulfide.

Some thioethers (R−S−R’) with electron-withdrawing substituents undergo chlorinolysis of a C−S bond to afford the sulfenyl chloride.[6][7]

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

${\displaystyle {\ce {CCl3SCl + R2NH -> CCl3SNR2 + HCl}}}$

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

Sulfenyl chlorides add across alkenes, for example ethylene:[8]

${\displaystyle {\ce {CH2=CH2 + R-SCl -> R-SC2H4Cl}}}$

They undergo chlorination to the trichlorides:[3]

${\displaystyle {\ce {R-SCl + Cl2 -> [R-SCl2]Cl}}}$

Sulfenyl chlorides react with water and alcohols to give sulfenyl esters (R−SO−R′):[9]

${\displaystyle {\ce {R-SCl + H2O -> R-SOH + HCl}}}$

${\displaystyle {\ce {R-SCl + R'-OH -> R-SO-R' + HCl}}}$

Route to sulfinyl halides

Sulfenyl chlorides can be converted to sulfinyl chlorides (RS(O)Cl). In one approach, the sulfinyl chloride is generated in two steps starting with reaction of a thiol (−SH) with sulfuryl chloride (SO₂Cl₂). In some cases the sulfenyl chloride results instead, as happens with 2,2,2-trifluoro-1,1-diphenylethanethiol. A trifluoroperacetic acid oxidation then provides a general approach to formation of sulfinyl chlorides from sulfenyl chlorides:[10]

Sulfenyl fluorides and bromides are also known.[11] Simple sulfenyl iodides are unknown because they are unstable with respect to the disulfide and iodine:

${\displaystyle {\ce {2 R-SI -> (R-S)2 + I2}}}$

Sulfenyl iodides can be isolated as stable compounds if they bear alkyl steric protecting groups as part of a cavity-shaped framework, illustrating the technique of kinetic stabilization of a reactive functionality, as in the case of sulfenic acids.[12]

A related class of compounds are the alkylsulfur trichlorides, as exemplified by methylsulfur trichloride, CH₃SCl₃.[13]

The corresponding selenenyl halides, R−SeCl, are more commonly encountered in the laboratory. Sulfenyl chlorides are used in the production of agents used in the vulcanization of rubber.