Sulfenyl chloride explained

In organosulfur chemistry, a sulfenyl chloride is a functional group with the connectivity, where R is alkyl^[1] or aryl. Sulfenyl chlorides are reactive compounds that behave as sources of . They are used in the formation of and 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 obtained by chlorination of carbon disulfide.

Preparation

Sulfenyl chlorides are typically prepared by chlorination of disulfides: R2S2 + Cl2 -> 2 R-SCl This reaction is sometimes called the Zincke disulfide reaction, in recognition of Theodor Zincke.^{[2] [3]}

Some thioethers with electron-withdrawing substituents undergo chlorinolysis of a bond to afford the sulfenyl chloride.^{[4] [5]}

In a variation on the Reed reaction, sulfur dichloride displaces hydrogen under UV light.^[6]

Reactions

Perchloromethyl mercaptan reacts with bonds in the presence of base to give the sulfenamides:

CCl3SCl + R2NH -> CCl3SNR2 + HClThis method is used in the production of the fungicides Captan and Folpet.

Sulfenyl chlorides add across alkenes, for example ethylene:^[7]

CH2=CH2 + R-SCl -> R-SC2H4Cl

They undergo chlorination to the trichlorides:

R-SCl + Cl2 -> [R-SCl2]Cl

Sulfenyl chlorides react with water and alcohols to give sulfenyl esters :^[8]

R-SCl + H2O -> R-SOH + HCl

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 with sulfuryl chloride . 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:^[9]

Related compounds

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

2 R-SI -> (R-S)2 + I2Sulfenyl 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.^[10]

A related class of compounds are the alkylsulfur trichlorides, as exemplified by methylsulfur trichloride, .^[11]

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

Notes and References

1. Book: Drabowicz . J. . Kiełbasiński . P. . Łyżwa . P. . Zając . A. . Mikołajczyk . M. . Kambe . N. . 2008 . Alkanesulfenyl Halides . Science of Synthesis . 39 . 544–550 . 9781588905307.
2. Über eine neue Reihe aromatischer Schwefelverbindungen . Zincke . Th. . Theodor Zincke . . 44 . 1 . 769–771 . 1911 . de . 10.1002/cber.191104401109.
3. Über o-Nitrophenylschwefelchlorid und Umwandlungsprodukte . Zincke . Th. . Theodor Zincke . Fr. . Farr . . 391 . 1 . 57–88 . 1912 . de . 10.1002/jlac.19123910106.
4. 10.15227/orgsyn.015.0022. 2,4-Dinitroaniline . F. B. Wells, C. F. H. Allen. Organic Syntheses . 1935 . 15 . 22 .
5. 10.15227/orgsyn.044.0047. 2,4-Dinitrobenzenesulfenyl Chloride . Norman Kharasch, Robert B. Langford. Organic Syntheses . 1964 . 44 . 47 .
6. Smith (2020), March's Organic Chemistry, rxn. 14-9.
7. Brintzinger, H.; Langheck, M., "Synthesen mit Alkylschwefelchloriden (X. Mitteil. über organische Schwefelchloride)", Chemische Berichte 1954, volume 87, 325-330.
8. 10.15227/orgsyn.081.0244. Phenylsulfenylation of Nonactivated Carbon Atom by Photolysiis of Alkyl Benzenesulfenated: Preparation of 2-Phenylthio-5-heptanol. Organic Syntheses. 2005. 81. 244. Goran. Petrovic. Radomir N.. Saicic. Zivorad. Cekovic. free.
9. Book: 113–276. Alkyl Chalcogenides: Sulfur-based Functional Groups. https://books.google.com/books?id=BPcxrmIgLKMC&pg=PA173. Synthesis: Carbon with One Heteroatom Attached by a Single Bond. Steven V.. Ley. Steven V. Ley. Elsevier. 1995. Comprehensive Organic Functional Group Transformations. 9780080423234. Page. P. C. B.. Wilkes. R. D.. Reynolds. D..
10. Sase . S. . Aoki. Y. . Abe . N. . Goto. K.. 2009. Stable Sulfenyl Iodide Bearing a Primary Alkyl Steric Protection Group with a Cavity-shaped Framework. Chemistry Letters. 38. 12. 1188–1189. 10.1246/cl.2009.1188.
11. Braverman . S. . Cherkinsky . M. . Levinger . S. . Alkylsulfur Trihalides . Sci. Synth. . 2008 . 39 . 187–188. 9781588905307.