Dialkyl disulphide

A pletliora of different SA systems have been reported in tire literature. Examples include organosilanes on hydroxylated surfaces, alkanetliiols on gold, silver, copper and platinum, dialkyl disulphides on gold, alcohols and amines on platinum and carboxyl acids on aluminium oxide and silver. Some examples and references can be found in [123]. More recently also phosphonic and phosphoric esters on aluminium oxides have been reported [124, 125]. Only a small selection out of tliis number of SA systems can be presented here and properties such as kinetics, tliennal, chemical and mechanical stability are briefly presented for alkanetliiols on gold as an example. 

The dialkyl disulphides may be prepared by the oxidation of an alkaline solution of a mercaptan with iodine, for example ... 

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... 

Powdered KOH (0.17 g, 3 mmol) is added to the freshly prepared thioiminium halide [MeC(SR)NH2+Cl- or McC(SR)NMc2+C1 ] (3 mmol) and TEBA-C1 (0.12 g, 0.5 mmol) in CH2C12 (30 ml). The mixture is stirred at room temperature until the reaction is complete, as shown by TLC analysis. The organic phase is separated, washed with H20 (2 x 25 ml), dried (Na2S04), and the solvent evaporated under reduced pressure to yield the alkyl aryl thioether and the dialkyl disulphide, which can be separated by chromatography from silica. 

In the reaction of the phenylacetonitrile carbanion with thiocyanates, a major side reaction leads to the formation of the dialkyl disulphides, as a result of the base-catalysed decomposition of the thiocyanate. This side reaction is reported to be insignificant in the reactions of the other carbanions. Phenylacetonitrile reacts with 1,2-ethanyl bisthiocyanate to produce 2-cyano-2-phenyl-1,3-thiolanes [52] under conditions analogous to those used for the synthesis of the thioethers (Scheme 4.12). 

Dialkyl disulphides, of which (S)-cystine above is an example, may be prepared from thiols by mild oxidation, usually with iodine in the presence of alkali. A convenient synthesis of unsymmetrical analogues results when a symmetrical disulphide is heated with thiol to establish an equilibrium mixture. By careful choice of the reactants, fractional distillation then removes the more volatile thiol leaving the mixed disulphide as a residue.240... 

The oxidation of thiols to disulphides by DIB proceeds through the intermediacy of PhI(SR)2, which are homolytically converted into iodobenzene and dialkyl disulphides. These intermediates from 2,3,5,6-tetrafluoro-thiophenol yielded with various terminal alkynes adducts as mixtures of E and Z isomers of varying composition [111] ... 

Sulphur halides and dialkyl disulphides have been used to obtain a variety of aryithk) and alkytthio derivatives of phenols generally by electrophilic substitution. For example, phenol was treated with zirconium tetrachloride, heated to 156°C under nitrogen, kept at this temperature overnight and after reduction of this to 100°C, diethyidisulphide was added. The mixture was heated to remove ethanethiol and the product, 2-(ethylthio)phenol, isolated in 41% yield (ref. 116). 

Franklin and Lumpkinhave used the indirect electron pact method to determine heats of formation of the radicals CH S, CgHgS, and SH. To determine /Ji3 (RS, g) they measured the appearance potential of the RS+ ion by the bombardment firstly of the dialkyl sulphide, and secondly of the dialkyl disulphide., which dissociate according to the equations... 

Some dialkyl disulphides will react directly with white phosphorus at about 200°C (9.463), and phosphorus trichloride will react with thiols in a manner analogous to alcohols (9.464). 

Organosulphur compounds represent the most common class of molecules exploited for formation of monolayers [1-8]. Many different kinds of similar molecules, e.g., aUcanethiols, dialkyl disulphides, dialkyl sulphides, thiophenes (Ths), thiophenols, and cysteines, have been reported to form monolayers on different substrates mainly consisting of (1) metals (e.g., Au, Ag, Cu, Pt, or Hg) or (2) semiconductors, such as indium tin oxide (ITO) and GaAs. Among the possible systems, the most extensively studied are those based on thiols adsorbed on Au. Although fundamental studies have also been carried out on the analogous Se and Te molecules, these have led to a limited number of applications in electroanalysis. 

The synthesis of purine and pyrimidine 2 -deoxynucleosides from a 1,2-dithio-sugar precursor is noted in Chapter 21, which also refers to the alkylation of seleno- and thio-substituted nucleosides using a mixture of a dialkyl disulphide (or diselenide) and tributylphosphine in DMF. Other thio-sugar derivatives are mentioned in Chapter 12. 

A new method of synthesis of substituted cyclohex-1-enyl alkyl sulphides involves the reaction of the appropriate cyclohexanone with a thioacetal or thiol in the presence of aluminium chloride.Aldehydes and ketones give symmetrical dialkyl disulphides on treatment with hydrogen sulphide in the presence of pyridine and triethylamine. ... 

Pyridine 1-oxide reacts with adamantane-1-thiol in acetic anhydride to give 2- and 3-(l-adamantanethio)pyridines and their tetrahydropyridine analogues. Corresponding butylthio-substituted pyridines are obtained using Bu SH or Bu SH in this reaction in the presence of a chloroformic acid derivative. No complications arise in the use of 3-bromopyridine 1-oxide and KSH for the synthesis of 3,3 -dipyridyl sulphide. 2-Methyl- or 2-phenyl-pyridine is converted into its 5-alkylthio-homologue by reaction of the pyridine-MeLi adduct with a dialkyl disulphide. ... 

I.r. and Raman spectra of dialkyl disulphides and benzyl sulphides ... 

Trithiolans, 1,3,5-Trithians, and l,2,4,5 Tetratliians.—new route to 3,5-dialkyl-1,2,4-trithiolans (12Q starting from dialkyl disulphides of the type (127) has been developed "" and is shown in Scheme 2. The method... 

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