Sulphur monoxide

I. Cycloaddition of Sulphur Monoxide and Sulphines to Unsaturated Compounds... 

Sulphuranes - see also Dialkoxysulphuranes, Oxysulphuranes as intermediates 406 Sulphur bonding 484-493 Sulphur-containing groups, stereoelectronic effects of 584-594 Sulphur dioxide addition to 215-217 extrusion of 137, 140, 141, 158, 163, 397-402, 801, 805, 962, 1098 Sulphur monoxide, extrusion of 397-402 Sulphur trioxide, reactions of 217, 218 Sultenes, as intermediates 743 Sultines 679, 943 as photolytic products 881, 882... 

S02 and S03 are the only compounds considered in this section. S20 is a well-established356 oxide of sulphur, although there is apparently no information on the kinetics of its decomposition. Sulphur monoxide, SO, is a reactive intermediate which features in the decompositions of S02 and S03. 

The forward reaction is only well known for S02, but even in this case the reverse reaction takes place readily and this property has been applied in the separation and purification of dienes. The addition of sulphur monoxide has also been reported by R.M. Dodson and R.F. Sauers (Chem. Comm. 1967, 1189). Se02 also adds to dienes in a Diels-Alder manner in which Se = 0 acts as dienophile. 

Analogous oxides are known containing one atom of sulphur replaced by selenium or tellurium. The tellurium compound, tellurium sulphoxide, STeOa, decomposes with production of tellurium monoxide, TeO, when gradually heated in a vacuum to 225° C.8 Attempts to produce sulphur monoxide similarly from sulphur sesquioxide have not been successful. 

When heated in toluene, both types of compound form pyrazoles by extrusion of sulphur or sulphur monoxide (equation 158)187. 

The hetero[10]annulenone 2,5-diphenyl-3-thiabicyclo[4.4.1]undeca-l,5,7,9-tetraen-4-one (149) was prepared together with the isomers (150) and (151) by photoelimination of sulphur monoxide from the sulphoxide (152). Extrusion... 

The term sulphur monoxide was originally applied (erroneously) to an equi-molecular mixture of S2O and SO2. The oxide SO is a short-lived radical produced, for example, by the combination of 0 atoms produced in an electric discharge with solid sulphur. By pumping the products rapidly through a wave-guide cell the microwave spectrum can be studied S—0, 1-48 A, p = 1-55D (compare SO2, 1-59D).( >... 

The complex RhCl(PPh3)3 reacts with stilbene episulphoxide in CH2CI2 to yield a dimeric complex (327) with sulphur monoxide ligand. ... 

The first complex of sulphur monoxide (39) has been synthesized by two different routes [reactions (25) and (26)]. It is thought that the structure of (39) will be similar to that of (40), whose structure has been determined. The iridium... 

There is evidence, however, that these reactions may not involve conversion of the iodonium ylide into a carbene which then adds to the relevant substrate, but that this substrate is involved prior to cleavage of the carbon-iodine bond [136]. Other ylide interchange reactions which have been recorded include the conversions of various ylides into an oxosulphonium ylide by reaction with sulphur monoxide, generated in situ [141] ... 

Thiaziridines have been postulated as reactive intermediates in the photochemical rearrangement of thiazoles, isothiazoles, -and 4-aryl-l,3,2-oxathiazolium S-oxide," and in the conversion of oxaziridines into imines and elemental sulphur on treatment with thiourea, potassium thiocyanate, or potassium ethyl xanthate. Irradiation of a mixture of 7V-sulphinyl-aniline and diphenyldiazomethane gave iV-diphenylmethyleneaniline, which was probably formed by extrusion of sulphur monoxide from 2,3,3-triphenyl-thiaziridine 1-oxide formed as an intermediate. ... 

Sulphur monoxide, generated thermally from ethylene sulphoxide, adds to cyclo-octatetraene to give the 1,4-adduct with the oxygen directed towards the butadiene... 

The very unstable sulphur monoxide, generated by thermolysis... 

A novel synthesis of N-sulphinyl-amines (157) utilizes the reaction of the azide (158) with sulphur monoxide [generated in situ from thiiran 1-oxide (159)]. 

Sulphines are formed by the oxidation of thiones with peroxy-acids, but they then react further, albeit much more slowly, to give the ketone, sulphur, and sulphur dioxide. This latter reaction is kinetically similar to many other oxidations with peroxy-acids, and the results are consistent with electrophilic attack of the peroxy-acid on the C=S double bond to give a cyclic sulphinate ester (4), which rapidly decomposes to give the ketone and sulphur monoxide. In contrast, oxidation of thiobenzanilide 5-oxide with m-chloroperoxybenzoic acid gives products derived from the sulphene PhC(NHPh)=SOa. Further examples of the reaction between diarylsulphines and aryldiazomethanes to give epi-sulphoxides have been reported. ... 

The extrusion of sulphur dioxide from a sulphene to give a carbene has been postulated previously, but never authenticated. Flash pyrolysis of a-(toluene-p-sulphonyl)phenyldiazomethane gave i7-tolyl phenyl ketone (15%) and 2-methylfluorene (5%). The former could arise from phenyl-p-tolylsulphene by loss of sulphur monoxide and the latter by loss of sulphur dioxide to give the carbene, which rearranges to the fluorene. Sulphene is postulated as an intermediate in the formation of carbonyl sulphide by the solid-state photolysis of dimethyl sulphone and by various other high-energy processes. 

---