Bivalent Sulphur

Sulphur—Compounds containing Bivalent Sulphur. The synthesis of sulphides via attack of thiols or thiolates on unsaturated substrates is covered in Chapter 2, and oxidation reactions are dealt with in the next two sections of this chapter a representative selection of information gleaned from patent literature is incorporated in the appendix to this chapter. 

CF2-CC1 CC1-CF2-S (p. 153) . ii further (cf. Vol. 2, p. 443) studiesS on the epithiocyclobutadiene (a Dewar thiophen ) obtainable by photoisomraization of tetrakis(trifluoromethyl)thiophen are dealt with in Chapter 6 (p. 463). Information 

CFa-CFa-CCFCLi (from CFaCFaCCl Ca -i- Bu Li (see Vol. 1, p. 86)] with sulphur mono- or di-chloride in ether at —78 °C yields the 1,4-dithiocin (82) plus the bis(cyclobutenyl) sulphide (83) separate treatment of the latter product with its lithio-precursor, followed by sulphur monochloride then the lithio-precursor, yields more of the dithiocin (82).  

Hexafluorothietan (90) [from pyrolysis of poly(tctrafluoroethylene-thio-carbonyl fluoride) (see Vol. 1, p. 154)] undergoes ring-opening polymerization when irradiated with u.v. light in the presence of CjFsI. Treatment of hexafluorothioacetone dimer (91) with ROH (R = Me, Et, Pr, Me CH, Bu, or MeiCH CHj) and KF-DMF yields (CF,)jC(OR) S S C(ORKCF, and (CF,),C(OR)SR.  

Exothermic secondary reactions occur when the mixture obtained by addition of the disulphide (CFaCl CFa)3S2 (from CFj CF2 + SaCla at 120 °C) to a solution of aziridine in methylene chloride at — 40 °C is evaporated at -10 °C, and the residue is found to contain the triaziridinyletbane (92) and the thiazoline (93). These products are believed to arise via initial stepwise nucleophilic displacement of both fluorines from an ot-CFt group, followed by a final attack by aziridine leading to (92) and CF2CI-CF2 S SH, 

and tris-(chlorofluoromethylsulphenyl)amines have been prepared by stepwise introduction of S CFiCla- (x = 1 or 2) groups into ammonia through the agency of the corresponding sulphenyl chlorides. Similarly, the amines (CFs-SlaN-S CF CIa-a (x = 0, 1, or 2) have been produced via the interaction of (CFg SlaNH [from CFa-S NHa + CFa SCl 

The new unsymmetrical perfluorinated sulphides CF3 S C2F5 and CFs S-CFa CFj CFa have been synthesized by photodecarboxylation of the appropriate 5-trifluoromethyl thio-perester CFs-SCl + RpC02Ag----------  

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Reid, E. E. Organic Chemistry of Bivalent Sulphur 1962, Vol. 4 Chemical Publishing New York. 

SeS206, Se2S40e , and aromatic sulphinates of bivalent sulphur and selenium.S(CN)2 and Se(CN)2 react quantitatively with CN in the mole ratio 1 3, according to reaction (28). The reaction between TeS406" and CN" [reaction (29)] is completely different to that between SsO " or SeS40fi and CN" [reaction (30)]. The overall reaction, of both SeS206 and 8028206" with CN" [reactions (31) and (32)] has also been ascertained. Complete reaction mechanisms have been proposed for all seven reactions. " ... 

The orientation of the Friedel-Crafts reaction is correct since the lone pairs of electrons on bivalent sulphur direct o,p. 

From a graphical study of positional isomers containing bivalent sulphur, it was predicted that (2a) should be more stable than (2b). The former has been synthesized, whereas the latter is not a known compound. 

Although there are no mechanistic studies in this area, schemes equivalent to equation (20) have been proposed for the halogenolysis of sulphides and other bivalent sulphur compounds . The reaction goes to completion to the right with chlorine and bromine, but takes a more complex course with iodine. With fluorine the reaction yields higher oxidation products with extensive fluorination at the hydrocarbon moiety. ... 

Sulphenamides.—A variety of bivalent sulphur compounds act as sulphenyl-ating reagents towards amines, giving sulphenamides, and most routes to these compounds are of this type. The copper(i)-catalysed reaction of azides with alkanethiols gives sulphenamides, in addition to the corre> sponding primary amine and disulphide arenethiols give only amine and disulphide, the sulphenamide being entirely converted into these products. 

Sulphur.—Compounds containing Bivalent Sulphur. The use of such compounds in transition-metal chemistry is dealt with in the next chapter. Work on bis(perfluoroisopropylideneimino) disulphide, [(CFj)jC N]2S2, and derived compounds has already been covered (Scheme 20, p. 214 (ref. 137)] so has... 

Sulphur.—Compounds Containing Bivalent Sulphur. Attempts to oxidize bistrifluoromethyl sulphide (conveniently prepared by pyrolysis of commercial bistrifiuoromethyl disulphide at 425—435 °C) to either the sulphoxide or the sulphone using the reagents ( i-(n C H4-CO)sOa-100°C, NOjCIO, NOa-u.v., or NOa-Oa-350°C have proved unsuccessful fluorination of the monosulphide with hot argentic or cobaltic fluoride gave trifluoromethyl-sulphur pentafluoride, while bis(trifluoromethyl)sulphur difluoride was formed at low temperatures with fluorine itself. " Bis(trifluoromethyl)-sulphur difluoride and several other bis(perfluoroalkyl)sulphur difluorides, obtained from the corresponding sulphides and chlorine monofluoride (see p. 162), have been converted into bisperfluoroalkyl sulphoxides ... 

Electron-diffraction studies for dimethyl sulphone and polarographic data for alkenes and alkynes bearing sulphoniiim, sulphinyl, and sulphonyl groups are reported. Data of practical importance in analysis have been obtained for the relationship of structure of bivalent sulphur compounds to the temperature-dependence of the electron-capture mechanism. ... 

Di-(2-hydroxy-2-propylphenyl) selenide gives the selenurane analogue (45a CH, in place of CF H in place of Bu ) of the sulphurane (45a) through a simple procedure (Brz followed by EtjN). Easy access to higher valency states for selenium derivatives may account for some differences in properties of bivalent sulphur compounds compared with their selenium analogues for example, phenyl vinyl selenide PhSeCH=CH2 does not polymerize with benzoyl peroxide, as does the vinyl sulphide, but gives the dibenzoate PhSeCH(OCOPh)CH2(OCOPh) via the selenurane PhSe-(OCOPh)2CH=CH2. ... 

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