78-47-7

Reactions of Group 16 elements involving the addition of atoms such as sulfur, selenium or tellurium to organic or inorganic molecules comprising use of an ionic liquid as a reaction medium.

Contrary to a previous report, the sulfurisation of phosphorus(iii) derivatives by 3-amino-1,2,4-dithiazole-5-thione (xanthane hydride) does not yield carbon disulfide and cyanamide as the additional reaction products. The reaction of xanthane hydride with triphenyl phosphine or trimethyl phosphite yields triphenyl phosphine sulfide or trimethyl thiophosphate, respectively, and thiocarbamoyl isothiocyanate which has been trapped with nucleophiles. The reaction pathway involves initial nucleophilic attack of the phosphorus at sulfur next to the thiocarbonyl group of xanthane hydride followed by decomposition of the phosphonium intermediate formed to products. The Hammett ρ-values for the sulfurisation of substituted triphenyl phosphines and triphenyl phosphites in acetonitrile are ～ -1.0. The entropies of activation are very negative (-114 ± 15 J mol-1 K-1) with little dependence on solvent which is consistent with a bimolecular association step leading to the transition state. The negative values of ΔS ≠ and ρ values indicate that the rate limiting step of the sulfurisation reaction is formation of the phosphonium ion intermediate which has an early transition state with little covalent bond formation. The site of nucleophilic attack has been also confirmed using computational calculations. The Royal Society of Chemistry 2007.

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Kinetic data and activation parameters are reported for the reactions of a series of phosphites, arylphosphonites, diarylphosphinites, and triarylphosphines with octasulphur (S8) in toluene as solvent.For the phosphites the data are explained in terms of changes in p-character of the Ione-pair orbital on phosphorus and inductive electron donation by the alkyl groups.The rates of reaction of series of arylphosphonites, diarylphosphonites, and triarylphosphones correlate with the Hammett ? constants to give ? values of -3.0, -3.0, and -2.5, respactively, and the results are discussed in terms of the Reactivity-Selectivity Principle and the biphilic mechanism or insertion of trico-ordinate phosphorus into ?-bonds.

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Trialkylphosphines react with equimolar amounts of sulfuric trioxide to form the 1:1 adducts R3P(1+)-SO3(1-).Trialkylarsines and -stibines undergo sulfur trioxide insertion reaction across the metal-carbon bond to give the trisulfonates of the metal M(OSO2R)3 (M=As,Sb).The reactions of trialkyl phosphites, with sulfur trioxide yield trialkyl phosphonates, trialkyl thiophosates, dialkyl alkylphosphonates, dialkyl sulfates, and polymers which contain phosphorus atoms.The reactions of trialkoxyarsines and -stibines result in the insertion of sulfur trioxide across the metal-oxygen bond to form the alkoxymetal alkylsulfates (RO)3-nM(OSO3R)n (M=As,Sb; n=1,2,3) depending on the stoichiometric ratios of the reagents used.Pyrolysis of the metal sulfates gives dialkyl sulfates and undistillable residues containing the metals.