sulfenyl chloride
{{Short description|Chemical group (R–S–Cl)}}
File:Sulfenyl chloride.svg of sulfenyl chlorides, RSCl]]
In organosulfur chemistry, a sulfenyl chloride is a functional group with the connectivity {{chem2|R\sS\sCl}}, where R is alkyl{{ cite book | last1= Drabowicz |first1=J. |last2=Kiełbasiński |first2=P. |last3=Łyżwa |first3=P. |last4=Zając |first4=A. |last5=Mikołajczyk |first5=M. | editor-last = Kambe |editor-first=N. | year = 2008 | title = Alkanesulfenyl Halides | series = Science of Synthesis | volume = 39 | pages = 544–550 | isbn = 9781588905307}} or aryl. Sulfenyl chlorides are reactive compounds that behave as sources of {{chem2|RS+}}. They are used in the formation of {{chem2|RS\sN}} and {{chem2|RS\sO}} 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 {{chem2|CCl3SCl}} obtained by chlorination of carbon disulfide.
Preparation
File:Perchloromethyl mercaptan.svg is a stable sulfenyl chloride]]
Sulfenyl chlorides are typically prepared by chlorination of disulfides:{{OrgSynth | first= Max H.|last= Hubacher | year = 1943 | title = o-Nitrophenylsulfur chloride| collvol = 2 | collvolpages = 455 | prep = CV2P0455}}{{OrgSynth | first1= Irwin B. |last1=Douglass |first2=Richard V.|last2= Norton | year = 1973 | title = Methanesulfinyl Chloride| collvol = 5 | collvolpages = 709–715 | prep = CV5P0709}}
: {{chem2 | R2S2 + Cl2 -> 2 R\sSCl}}
This reaction is sometimes called the Zincke disulfide reaction, in recognition of Theodor Zincke.{{cite journal
| title = Über eine neue Reihe aromatischer Schwefelverbindungen
| last = Zincke | first= Th. | author-link = Theodor Zincke
| journal = Chemische Berichte
| volume = 44
| issue = 1
| pages = 769–771
| year = 1911
| language = de
| doi = 10.1002/cber.191104401109| url = https://zenodo.org/record/1426425 }}{{cite journal
| title = Über o-Nitrophenylschwefelchlorid und Umwandlungsprodukte
| last1 = Zincke | first1= Th. | author-link1 = Theodor Zincke | first2= Fr. | last2= Farr
| journal = Justus Liebig's Annalen der Chemie
| volume = 391
| issue = 1
| pages = 57–88
| year = 1912
| language = de
| doi = 10.1002/jlac.19123910106| url = https://zenodo.org/record/1427597 }}
Some thioethers ({{chem2|R\sS\sR’}}) with electron-withdrawing substituents undergo chlorinolysis of a {{chem2|C\sS}} bond to afford the sulfenyl chloride.{{cite journal |doi=10.15227/orgsyn.015.0022|title=2,4-Dinitroaniline |author=F. B. Wells, C. F. H. Allen|journal=Organic Syntheses |year=1935 |volume=15 |page=22 }}{{cite journal |doi=10.15227/orgsyn.044.0047|title=2,4-Dinitrobenzenesulfenyl Chloride |author=Norman Kharasch, Robert B. Langford|journal=Organic Syntheses |year=1964 |volume=44 |page=47 }}
In a variation on the Reed reaction, sulfur dichloride displaces hydrogen under UV light.Smith (2020), March's Organic Chemistry, rxn. 14-9.
Reactions
Perchloromethyl mercaptan ({{chem2|CCl3SCl}}) reacts with {{chem2|N\sH}} bonds in the presence of base to give the sulfenamides:
:{{chem2 | CCl3SCl + R2NH -> CCl3SNR2 + HCl }}
This method is used in the production of the fungicides Captan and Folpet.
Sulfenyl chlorides add across alkenes, for example cyclohexene{{cite book |doi=10.1002/9780470842898.rn00720 |chapter=4-Nitrobenzenesulfenyl Chloride |title=Encyclopedia of Reagents for Organic Synthesis |date=2007 |last1=Kim |first1=Sunggak |isbn=978-0-471-93623-7 }} and ethylene{{cite journal | doi = 10.1002/cber.19540870306| title = Synthesen mit Alkylschwefelchloriden (X. Mitteil. über organische Schwefelchloride)| date = 1954| last1 = Brintzinger| first1 = Herbert| last2 = Langheck| first2 = Malte| journal = Chemische Berichte| volume = 87| issue = 3| pages = 325–330}}
:{{chem2 | CH2\dCH2 + R\sSCl -> R\sSC2H4Cl }}
They undergo chlorination to the trichlorides:
:{{chem2 | R\sSCl + Cl2 -> [R\sSCl2]Cl }}
Sulfenyl chlorides react with water and alcohols to give sulfenyl esters ({{chem2|R\sS\sO\sR′}}):{{cite journal |doi=10.15227/orgsyn.081.0244|title=Phenylsulfenylation of Nonactivated Carbon Atom by Photolysiis of Alkyl Benzenesulfenated: Preparation of 2-Phenylthio-5-heptanol|journal=Organic Syntheses|year=2005|volume=81|page=244|first1=Goran|last1=Petrovic|first2=Radomir N.|last2=Saicic|first3=Zivorad|last3=Cekovic|doi-access=free}}
:{{chem2 | R\sSCl + H2O -> R\sSOH + HCl }}
:{{chem2 | R\sSCl + R'\sOH -> R\sSO\sR' + 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 ({{chem2|\sSH}}) with sulfuryl chloride ({{chem2|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:{{cite book|pages = [https://archive.org/details/comprehensiveorg0000unse/page/113 113–276]|chapter = Alkyl Chalcogenides: Sulfur-based Functional Groups|chapter-url = https://books.google.com/books?id=BPcxrmIgLKMC&pg=PA173|title = Synthesis: Carbon with One Heteroatom Attached by a Single Bond|editor-first = Steven V.|editor-last = Ley|editor-link = Steven V. Ley|publisher = Elsevier|year = 1995|series = Comprehensive Organic Functional Group Transformations|isbn = 9780080423234|last1 = Page|first1 = P. C. B.|last2 = Wilkes|first2 = R. D.|last3 = Reynolds|first3 = D.|url = https://archive.org/details/comprehensiveorg0000unse/page/113}}
:File:Conversion of F3CCPh2SH to F3CCPh2SCl and on to F3CCPh2S(O)Cl.png{{clear-left}}
Related compounds
Sulfenyl fluorides and bromides are also known.{{OrgSynth | first1= Daniel S.|last1= Reno |first2= Richard J.|last2= Pariza
| year = 1998 | title = Phenyl Vinyl Sulfide| collvol = 9 | collvolpages = 662 | prep = CV9P0662}} Simple sulfenyl iodides are unstable with respect to the disulfide and iodine, gradually decomposing over the course of several hours at low temperature:
:{{chem2 | 2 R\sSI -> (R\sS)2 + I2 }}
They can be formed metastably from metal mercaptides and iodine, and even form fleetingly when iodine oxidizes neutral thiols to the disulfide. Indeed, sulfenyl iodides are believed to be the active iodinating agents in iodotyrosine biosynthesis.{{cite book|title=Sulfur in Organic and Inorganic Chemistry|volume=1|editor-first=Alexander|editor-last=Senning|year=1971|publisher=Marcel Dekker|location=New York|lccn=70-154612|isbn=0-8247-1615-9|first=James P.|last=Danehy|chapter=The Sulfur–Iodine Bond|pages=331–335}} Sulfenyl iodides that are heavily sterically hindered from dimerization are stable.{{cite journal |last1=Sase |first1=S. |last2=Aoki|first2= Y. |last3=Abe |first3=N. |last4=Goto|first4= K.|year=2009|title=Stable Sulfenyl Iodide Bearing a Primary Alkyl Steric Protection Group with a Cavity-shaped Framework|journal=Chemistry Letters|volume= 38|issue= 12|pages= 1188–1189|doi =10.1246/cl.2009.1188}}
A related class of compounds are the alkylsulfur trichlorides, as exemplified by methylsulfur trichloride, {{chem2|CH3SCl3}}.{{cite journal |last1=Braverman |first1=S. |last2=Cherkinsky |first2=M. |last3=Levinger |first3=S. |title=Alkylsulfur Trihalides |journal =Sci. Synth. |year=2008 |volume=39 |pages=187–188|isbn = 9781588905307}}
The corresponding selenenyl halides, {{chem2|R\sSeCl}}, are more commonly encountered in the laboratory. Sulfenyl chlorides are used in the production of agents used in the vulcanization of rubber.