2,2 -Diphenyl disulphide

Rajanikanth and Ravindranath44 have recently published a deoxygenation reaction for sulphoxides that uses metallic lithium in refluxing dimethoxyethane. Dialkyl and alkyl phenyl sulphoxides were reduced cleanly in yields around 70%, even if sterically hindered, but benzyl sulphoxides gave mixtures of products. For example, benzyl phenyl sulphoxide gave frans-stilbene (33%), benzyl phenyl sulphide (20%) and diphenyl disulphide (47%). These products can be rationalized by reaction pathways such as in equation (17) ... 

Phosphinyl radicals, obtained by hydrogen abstraction from dialkyl phosphites, have been trapped with t-nitrosobutane and the resultant nitroxyl radicals examined by e.s.r, The reaction of phosphinyl radicals, e.g. (5) and (6), with olefins has been shown to occur with retention of configuration at phosphorus. " These radicals have also been postulated as intermediates in the reactions of dialkyl disulphides and diaryl disulphides with phosphinates. " From the reaction of diphenyl disulphide... 

Solutions of diphenyl disulphide (13) are found to become yellow on heating, the colour disappearing again on cooling ... 

A rather complex mixture of products is obtained from the reaction of benzyl-idenetriphenylphosphorane and CS2.48 The major product from the reaction of diphenyl disulphide with methylenetriphenylphosphorane is tris(phenylthio)-methane (44) and only a trace of the insertion product bis(phenylthio)methane is isolated.49 Presumably the salt (45) is deprotonated before it can react with the phenylthioate anion (Scheme 12). a-Thiocarbonyl-stabilized ylides (46) are obtained from the reaction of ylides with S-alkyl thiolcarboxylates.50... 

These two classes of compounds can be prepared by treating diphenyl disulphide and aryl sulphonyl chlorides with sodium telluride followed, respectively, by a-halocarbonyl compounds and alkyl halides. 

It oxidizes thiophenol to diphenyl disulphide, hydroquinone to p-benzoquinone, benzoin to benzyl, benzylic alcohols to the corresponding carbonyl compounds and cleaves hydrobenzoin to benzaldehyde. 

The formed acyl radicals are reactive towards efficient radical trapping reagents such as 2,2,6,6-tetramethylpiperidine-l-oxyl radical (TEMPO), diphenyl diselenide and diphenyl disulphide, and A-f-butyl-a-phenylnitrone giving the respective adducts. ... 

S-phenyl thiobenzoate typical procedure in the presence of diphenyl disulphide. Photolysis of the telluroester (Ar = 4-FCgH4) in the presence of 6 equiv of diphenyl disulphide according to the standard for the formation of selenoesters gave 71% of the thiobenzoate after chromatography on silica gel (eluent hexane/ ethyl acetate, 9 1). The product had a melting point and spectral characteristics in accordance with those described in the literature. 

Diphenyl disulphide has been shown to be a poor radical captor. 

Thiotelluration of 1-styrylcyclopropane In a Pyrex glass tube were placed 1-styrylcy-clopropane (0.2 mmol, 28.8 mg, 0.4 M), diphenyl disulphide (0.2 mmol, 43.7 mg, 0.4 M), diphenyl ditelluride (0.2 mmol, 81.9 mg, 0.4 M) and CDCI3 (0.5 mL). The tube was filled with Ar, and the mixture was irradiated at 40°C for 7 h through a filter (hv >400 nm) with a tungsten lamp (500 W). The solvent was evaporated in vacuo. Purification by a recycling preparative HPLC (CDCI3) yielded 77 mg (84%, E/Z= 14 86) of 2-phenyl-l-(phenylthio)-5-(phenyltelluro)-2-pentene as a pale yellow oil. 

Homogeneous reductive cleavage of the sulphur-sulphur bond in some diphenyl disulphides by electron transfer from added radical-anions in the solution illustrate points from the two previous paragraphs [32], Rate data for two diphenyl disulphides are given in Figure 4.6. The variation in electron transfer rate with electron... 

Figure 4.6. Homogeneous dissociative electron transfer reaction between aromatic radical-anions and (a) di-(4-cyanophenyl) disulphide, (b) diphenyl disulphide in dimethyl formamide. Data from ref [31J.

Diphenyl disulphide [882-33-7] M 218.3, m 60.5". Crystd from MeOH. [Alberti et al. JACS 108 3024 1986]. Crystd repeatedly from hot ethyl ether, then vac dried at 30° over P2O5, fused under nitrogen and re-dried, the whole procedure being repeated, with a final drying under vac for 24h. Also recrystd from hexane/EtOH soln. [Burkey and Griller JACS 107 246 7985]. 

Reactions 20 and 21 are interesting in their use of the oxidizing properties of an iV-chloro derivative. In reaction 22, the two Cl atoms on the P(III) compound play a somewhat similar role, while in reaction 23 oxidizing power is provided by the S—S bond of diphenyl disulphide. 

DIB in combination with sodium azide and diphenyl disulphide or diphenyl diselenide can replace the methinic hydrogen of aliphatic, aromatic and heteroaromatic aldehydes by the phenylthio or phenylseleno group. The corresponding esters were obtained in moderate (for unsaturated aldehydes) to very good yields [109] ... 

There is no need to isolate this compound in order to effect addition of diphenyl disulphide (and dimethyl disulphide) to alkenes in this way tran. -l,2-bis-phe-nylthio (and methylthio) adducts were formed from cycloalkenes and 1-hexene. 

To a stirred suspension of IOB (110 mg, 0.5 mmol) in dichloromethane (20 ml) was added triflic acid (0.044 ml, 0.5 mmol) at 0°C. After 2 h at room temperature, a solution of diphenyl disulphide (238 mg, 1.09 mmol) in dichloromethane (6 ml) was added dropwise at 0°C. After 2 h at room temperature, the alkene (5 mmol) was added at 0°C and the mixture was stirred for 12 h. The reaction mixture was poured into water and extracted with ether. The organic layer was washed with water, dried and concentrated to an oil from which iodobenzene was removed in vacuo at 70-80°C. Purification was effected using preparative centrifugal TLC yields of bis phenylsulphides were near 90%. 

The required ketone 91 is formed almost intantaneously the other product is diphenyl disulphide. We have some evidence57 for a mechanism involving PhS migration for this reaction. As examples, ketones 92 (64% yield) and 93 (88%) can be made this way57. ... 

Oxidation with p-phenoxyphenyltellurinic anhydride diphenyl disulphide (typical procedure) Thiophenol (0.215 g, 2 mmol) is added to a stirred solution of the anhydride (0.210 g, 0.33 mmol) in HOAc (2 ml,) under argon. The mixture is stirred for 1 h at room temperature. After evaporation under vacuum, the residue is extracted with CHjClj. The organic phase is washed with H2O, 5% aqueous Na2C03 and HjO. SiOj column chromatography yields diphenyl disulphide (0.154 g (86%)) as colourless crystals (from CH2Cl2/EtOH) (m.p. 58-60°C) and the ditelluride (0.167 g (83%)) as purple crystals (from CH2Cl2/EtOH) (m.p. 93-95°C). 

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