Thiophosphoric esters

Ketelaar, J.A.A., Gersmann, H.R., and Beck, M.M. 1956. Metal-catalyzed hydrolysis of thiophosphoric esters. Nature, 111 392-393. 

Phosphoric, or, better, thiophosphoric, esters alkylate ethers smoothly to tertiary oxonium salts in the presence of antimony pentachloride.213... 

JO Sulfur and Selenium Containing Compounds. - The interaction of 0,0-dialkyl methylphosphonothioates acid with POCI3 to give the chloridates (286) and alkyl phosphorodichloridates parallels reactions of thiophosphoric esters already encountered. The use of Lawesson s reagent to replace the phosphoryl bond in (l,l-difluoroalkyl)phosphonic esters by thiophosphoryl, has been noted (see also reference 258). - ... 

Dialkyl thiophosphites Thiolphosphonic O-monoesters Thionophosphonic acid esters Thiophosphonic acids and esters Thiophosphorous esters... 

Compound (1) phosphorylates phosphate monoesters and alcohols, although with the latter a considerable excess of alcohol is necessary to obtain satisfactory yields. In the absence of mercuric ions the milder phosphorylating species (3) can be isolated which converts monoalkyl phosphates to pyrophosphate diesters in good yield but does not react appreciably with alcohols unless catalytic amounts of boron trifluoride are added. Amine salts of (3) are converted to phosphoramidates on heating. In the presence of silver ions, O-esters of thiophosphoric acid behave as phosphorylating agents and a very mild and convenient procedure suitable for preparing labile unsymmetrical pyrophosphate diesters, such as the... 

Parathion (0,0-diethyl 0-p-nitrophenyl thiophosphate) is an ester of thiophosphoric acid with the empirical formula C10H14NO5PS. It is a high boiling deep-brown to yellow liquid, some samples of which possess a characteristic odor. Its boiling point has been calculated to be 375 0 C. or higher, at 760 mm. pressure its refractive index is n 5 1.15360 specific gravity is 1.26. The vapor pressure is 0.0006 mm. of mercury at 24° C. The technical grade has a purity of approximately 95%. 

The foregoing reaction scheme had been described in a patent issued in 1934 to Clemmensen (9), who prepared certain organic esters of thiophosphoric acid embodying both aromatic and aliphatic radicals. These esters are claimed as new compositions of matter useful as fire retardants. Parathion itself is not specifically described in the patent. 

Recent kinetic studies on thiophosphoric aryl ester dianilides suggest analogous decomposition. The rate law observed is in agreement with a hydrolysis scheme in which both the monoanion and the dianion decompose to metaphosphorothioimi-date and its anion, respectively, which then react fast with water133). 

Dithiophosphoric acids, (RO)2PS2H, have been used for the thionation of carbonyl groups in certain aldehydes, ketones, amides, esters, thio-carboxylates and other organics.163 The mechanism for this reaction proceeds via a reversible nucleophilic attack of the thioacid on the carbonyl compound, which can then rearrange by way of a four-membered PSCO cyclic intermediate into the desired C=S containing molecule and thiophosphoric acid (Equation 81).163... 

The IR and Raman spectra of the thiophosphoric acid ester 14 are consistent with a polymeric structure including tetra- and pentacoordinated tin atoms128. 

Virtually all that tested positive are methyl or ethyl esters of phosphoric or thiophosphoric acids, and are electrophilic and mutagenic (e.g., dichlorvos, tetrachlorvinphos Figure 14.12). 

Hydrolytic Reactions of Phosphoric and Thiophosphoric Acid Esters... 

Figure 13.17 General structure of phosphoric and thiophosphoric acid (thio)esters. Note that often Ri = R2 = CH3 or C2H5.

As for other esters, hydrolysis of phosphoric and thiophosphoric acid triester occurs via acid-catalyzed, base-catalyzed, and neutral mechanisms (Table 13.12). We note that in the following discussion we are concerned primarily with acid triesters, although the hydrolysis products of these compounds, that is, the di- and monoesters, are also of environmental concern inasmuch as they usually seem to react at slower rates as compared to the triesters (Mabey and Mill, 1978 Wolfe, 1980). 

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