Trialkyl phosphorothioates

Q/Q/Q Trialkyl phosphorothioates and selenoates are efficiently converted into the corresponding phosphates by trifluoroacetic anhydride in dichloromethane, a process rendered easier in the presence of pyridine. Cyclic thiophosphates yield cyclic phosphates with retention of configuration, and the reaction... 

With alkylating agents, the salts of dialkyl phosphorothionates form 0,0,S-trialkyl phosphorothioates. Dialkyl phosphonate can also be used as an alkylating agent (Melnikov et al., 1965). 

In the group of phosphorothioates, an increase in the number of sulfur atoms linked to the phosphorus atom increases the fungicidal effect of the aliphatic esters (Hacskaylo and Stewart, 1962). Thus, simple trialkyl phosphorodithioates are more efficient than trialkyl phosphorothioates, and the fungicidal activity of phosphorotrithioates and tetrathioates is even more potent (Mandelbaum et al.,... 

Pistschimuka (253), who first investigated the reaction between alkyl halides and trialkyl phosphorothioate, demonstrated the stoichiometry to be ... 

Walling and Rabinowitz observed (299,300) that, in the presence of appropriate initiators, trialkyl phosphites can undergo a free radical chain reaction with alkyl disulfides to yield an 0,0,0-trialkyl phosphorothioate and an alkyl sulfide (eq. 11a). Because of the strength of the aryl-sulfur bond in phenyl disulfide, an ethyl rather than an aryl radical would be eliminated from the radical intermediate (eq. 11b) in this instance. 

Trialkyl phosphorothioates can be made to isomerize to the 0,0,5 -trialkyl compounds in a process which can be thermally initiated and which may occur during distillation. A similar rearrangement, coupled (evidently) with an allylic rearrangement, occurs... 

Dinsdale, D.. and Vcrschoylc, R. D. (1988). Comparative toxicity of two trialkyl phosphorothioates to rat lung and the effects of atropine sulfate pretrealrncm. Arc/i. Toxicol. Suppl. 12,432-434. 

The metabolic and/or hydrolytic products of parathion encountered as residues in the urine include both diethyl phosphoric acid and diethyl phosphorothioic acid, most probably as their salts (potassium or sodium). Derivatization of these residues with diazomethane would result in the formation of three trialkyl phosphate compounds, namely, 0,0-diethyl O-methyl phosphate (DEMMP), 0,0-diethyl 0-methyl phosphoro-thionate (DEMMTP), and 0,0-diethyl S-methyl phosphorothiolate (DEMMPTh). Earlier (15), it had been shown by combined gas chromatography-mass spectrometry and other analytical data that a later-eluting major product ca. 85%) of the methylation of diethyl phosphorothioic acid formed under the conditions of the analytical method was DEMMPTh, and the minor product formed (ca. 15%) was DEMMTP. Accordingly, all three trialkyl phosphates were observed and confirmed by mass spectrometry in the analysis of the human urine extract. Sufficient internal bond energy differences are associated with the isomeric structures DEMMPTh and DEMMTP that qualitatively and quantitatively dissimilar fragmentation patterns are observed for both isomers as can be seen from the mass spectra of these compounds shown in Figure 4. 

At a simpler level, descriptions have been of convenient syntheses of S-alkyl phosphorodichloridothioates from sulphenyl chlorides and methyl phosphorodichloridite in liquid S02 " of dialkyl S-phenyl phosphorothioates from trialkyl pho.sphites and phenylsulphenyl chloride of S -[2-(dialkylamino)ethyl] dialkyl phosphorothioates by a... 

Phosphorothioate esters. Mixtures of thiols and trialkyl phosphites react by a redox pathway in the presence of TeCl and lutidine (9 examples, 90-96%). 

Methods of preparing O-S esters are numerous and very varied (9.396-9.402). They include heating an alkyl halide with sodium phosphorothioate (9.396) or a diester (9.397), and heating a trialkyl phosphite with sulphenyl chloride (9.398). 

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