597-84-2Relevant academic research and scientific papers
1,2,4-Dithiazole-5-ones and 5-thiones as efficient sulfurizing agents of phosphorus(iii) compounds - A kinetic comparative study
Ponomarov, Oleksandr,Laws, Andrew P.,Hanusek, Ji?í
supporting information, p. 8868 - 8876 (2013/01/15)
The sulfurization efficiency of 25 3-substituted-1,2,4-dithiazole-5-ones and 5-thiones towards triphenyl phosphite in acetonitrile, DCM, THF and toluene at 25 °C was evaluated. All the 1,2,4-dithiazoles are much better sulfurizing reagents than commercially available agents (PADS, TETD, Beaucage's reagent). The most efficient sulfurizing agents in all solvents are 3-phenoxy (4), 3-phenylthio (5) and 3-ethoxy-1,2,4-dithiazole-5-one (1) whose reactivity is at least two orders of magnitude higher than that of other 1,2,4-dithiazoles. Contrary to a previous report, the sulfurization with 1 does not yield carbonylsulfide and ethyl cyanate as the additional reaction products but unstable ethoxythiocarbonyl isocyanate which has been trapped with 4-methoxyaniline. Similar trapping experiments have proven that the site of attack is at the sulfur adjacent to the CO group for compounds 4 and 5. The reaction pathway involves rate-limiting initial nucleophilic attack of the phosphorus at sulfur followed by decomposition of the phosphonium intermediate to the corresponding phosphorothioate and isocyanate/isothiocyanate species. The existence of the phosphonium intermediate during sulfurization of triphenyl phosphine with 3-phenyl-1,2,4-dithiazole-5-thione (7a) was proven using kinetic studies. From the Hammett and Bronsted correlations and from other kinetic measurements it was concluded that the transition-state structure is almost apolar for the most reactive 1,2,4-dithiazoles whereas a polar structure resembling a zwitter-ionic intermediate may be more appropriate for the least reactive 1,2,4-dithiazoles. The extent of P-S bond formation and S-S bond cleavage is very similar in all reaction series but it gradually decreases with the reactivity of the 1,2,4-dithiazole derivatives.
Mechanism of the sulfurisation of phosphines and phosphites using 3-amino-1,2,4-dithiazole-5-thione (xanthane hydride)
Hanusek, Jiri,Russell, Mark A.,Laws, Andrew P.,Jansa, Petr,Atherton, John H.,Fettes, Kevin,Page, Michael I.
, p. 478 - 484 (2008/03/27)
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.
Substituent effects on the 31P NMR chemical shifts of arylphosphorothionates
Hernández, Javier,Goycoolea, Francisco M.,Zepeda-Rivera, Denisse,Juárez-Onofre, Josué,Martínez, Karla,Lizardi, Jaime,Salas-Reyes, Magali,Gordillo, Bárbara,Velázquez-Contreras, Carlos,García-Barradas, Oscar,Cruz-Sánchez, Samuel,Domínguez, Zaira
, p. 2520 - 2528 (2007/10/03)
Six tris(aryloxy)phosphorothionates substituted in the para position of the aromatic rings were synthesized and studied by 31P NMR, X-ray diffraction techniques and ab initio calculations at a RHF/6-31G** level of theory, in order to find the main structural factors associated with the δ31P in these compounds. As the electron-withdrawing (EW) ability of the substituents was increased, an 'abnormal' shielding effect on δ31P of the arylphosphorothionates was observed. The analyses of the geometrical properties obtained through both experimental and theoretical methods showed that a propeller-type conformation is preferred for the arylphosphorothionates, except in the case of the tris(O-4-methylphenyl) phosphorothionate, since one of the aromatic rings is not rotated in the same direction as the other two in the solid state. The main features associated with the δ31P NMR of compounds 1-6 were a decrease of the averaged O-P-O angle and mainly the shortening of the PS bond length, which is consistent with an increase of the thiophosphoryl bond order as δ31P values go upfield. On the other hand, comparison of the experimental and calculated bond lengths and bond angles involving α bonded atoms to phosphorus of the six compounds suggested that stereoelectronic interactions of the type nπO-σ*PS, nπO- σ*P-OAr and nπS-σ* P-OAr could be present in the arylphosphorothionates 1-6.
Synthesis of O,O,O-triaryl phosphorothioates and O-aryl phosphorodichloridothioates using poly(ethylene glycol) as a phase transfer catalyst
Jadhav,Wadgaonkar,Salunkhe
, p. 1473 - 1475 (2007/10/03)
O,O,O-Triaryl phosphorothioates and O-aryl phosphorodichloridothioates have been prepared in good yields and purity from thiophosphoryl chloride and phenol using poly(ethylene glycol)-400 (PEG-400) as a phase transfer catalyst.
THIONO COMPOUNDS. 9. USE OF SPECTRA TO STUDY INTERMEDIATES IN THE OXIDATION OF THIONO PHOSPHORUS COMPOUNDS
Swinson, Joel,Field Lamar,Heimer, Norman E.,Michalska, Danuta,Muccio, Donald D.,et al.
, p. 159 - 172 (2007/10/02)
Intermediates in the oxidation by m-chloroperoxybenzoic acid (MCPBA) of 13 structurally different thiophosphoramides and phosphorothioates were studied at -25 deg C to 0 deg C using NMR, EPR, UV, IR and Raman spectra.The lifetimes of intermediates ascertained by NMR varied from a few minutes to many hours at the same temperature and were longer for thiono esters than for amides, for aryl than for alkyl constituents, and for electron-donating substituents on aryl groups than for electron-withdrawing groups.The major 31P NMR peaks for all intermediates appeared in the same region, about midway between the resonances of the P(S) starting materials and the P(O) products, indicating close structural similarly to one another for the intermediates; the range of 13-33 ppm for the major peaks indicates that the intermediates are tetracoordinate and supports phosphonium polysulfide structures for them of the type R3PSx (26, Scheme 1), or perhaps R3POSx.UV spectra also afforded support for polysulfide structures, since typical absorption develops and then disappears.Raman, 31P NMR, and UV spectra are consistent with longer-term presence of bisphosphonium species (e.g. 25, from reactions of 26; Scheme 1).EPR spectra gave no indication of homolysis. - Key words: Phosphorothioates, Raman Spectra, Infrared Spectra, Thionophosphorus, NMR Spectra, Thiophosphoramides
Phase-Transfer-Catalyzed Preparation of Triaryl Phosphorothionates
Talley, John J.,Berman, Carol B.
, p. 279 - 280 (2007/10/02)
Triaryl phosphorothionates have been prepared in good yield from thiophosphoryl chloride and three equivalents of a phenol by a phase-transfer-catalyzed process.
