3982-91-0

The present invention discloses an improved process for preparation of acephate and intermediates thereof. More particularly, the present invention relates to a process for preparation of thiophosphoryl chloride useful for commercial production of pesticides and pharmaceutically active compounds.

Preparation of O,O-dimethyl phosphoramidothioate and O,O-dimethyl phosphoroamidothioate. A process of making O,O-dimethyl phosphoroamidothioate is described including reacting sulfur with PCl3 to form PSCl3, reacting the PSCl3 formed with methanol to form O-methyl phosphorodichloridothioate, and reacting the O-methyl phosphorodichloridothioate formed with methyl lye to form O,O-dimethyl phosphorochloridothioate in solution in CH2Cl2, and reacting the O,O-dimethyl phosphorochloridothioate formed with sodium hydroxide and ammonium hydroxide to form O,O-dimethyl phosphoroamidothioate in solution in CH2Cl2. Reacting the O,O-dimethyl phosphoroamidothioate formed with catalytic dimethyl sulfate to form methamidophos, and reacting the methamidophos formed with acetic anhydride to form N-(methoxy-methylsulfanylphosphoryl) acetamide is also described. Throughout the process, the O,O-dimethyl phosphorochloridothioate and the O,O-dimethyl phosphoroamidothioate formed are maintained in solution in CH2Cl2 at all times.

Replacement of the thiol group in polyfluoroarenethiols with chlorine was performed by treating with PCl5 as chlorinating agent. By heating in ampules at 200-220°C polyfluoro- and polyfluorochloroarenethiols with PCl5 mono- and dichloropolyfluoroarenes and also 1,2,4-trifluorotrichlorobenzene were synthesized. Dichloropolyfluoroarenes contain chlorine atoms in ortho- and para-positions.

Exposure of a solid argon matrix containing the molecules OCS and PX3 (X = F or Cl) at ca. 20 K to broad-band ultraviolet radiation leads to the formation of CO and the corresponding thiophosphorus(V) halides SPX3, as witnessed by the infrared spectrum of the matrix.Photolysis of a solid methane matrix containing OCS at 13-20 K on exposure to radiation with wavelengths near 230 nm gives rise to CO, methanethiol, CH3SH, thioformaldehyde, H2C=S, and carbon disulfide, CS2, as the only products to be detected by their infrared spectra.Yet there is no sign of either CH3SH or H2C=S on photolysis of OCS in a CH4-doped argon matrix with the composition Ar:CH4:OCS = 100:20:1.Evidently the photolysis of OCS generates 1D sulfur atoms which add to an adjacent CH4 molecule with the formation of a vibrationally activated intermediate *; this relaxes to give CH3SH or decomposes to give H2C=S.Similar experiments have been carried out with solid argon matrices including OCS and either C2H4 or C2H2.In the presence of C2H4 there is no hint of C-H insertion; instead the C2H4 undergoes sulfur atom addition at the double bond to give thiirane, , as the sole product to be identified by its infrared spectrum.By contrast, C2H2 yields thioketene, H2C=S, ethynethiol, HCCSH, and carbon disulfide, CS2, as the main products, as well as thiirane, , as a minor product.The response of the hydrocarbon molecules in argon matrices can be interpreted in terms of the diffusion and reaction of ground-state 3P sulfur atoms but not of 1D sulfur atoms which are too short-lived to undergo significant migration.It appears that 3P sulfur atoms react with both C2H4 and C2H2 to yield a triplet diradical: that derived from C2H4 favors cyclization, whereas that derived from C2H2 rearranges preferentially to H2C=C=S and this in turn enters into secondary reactions to give HCCSH and CS2.

P4S3 under glass-filtered u.v. irradiation is rapidly cleaved by alkyl and aryl disulphides to give tetrathiophosphate esters, SP(SR)3, and trithiophosphite esters, P(SR)3 (R = Me or Ph), in quantitative yield, as measured in the product mixture by 31P and 1H n.m.r. spectroscopy.No sulphurisation of P4S3 was found.In a competition reaction, MeSSMe and PhSSPh reacted to a similar extent with P4S3 to give all eight possible products SxP(SPh)n(SMe)(3-n) (x = O or 1, n = 0-3) in relative quantities within each oxidation state approximating to a statistical distribution of ligands, but there was more MeS substitution of the phosphorus (V) produts and more PhS substitution of the phosphorus(III) products.Reaction of MeSSPh with P4S3 gave similar results.Redistribution of ligands took place when a mixture of P(SMe)3 and P(SPh)3 was photolysed, and photolysis of a mixture of P(SMe)3 and MeSSPh caused the PhS group to be distributed between the trithiophosphite and disulphide sites.P(SMe)3 and P(SPh)3 were not sulphurised by MeSSMe and PhSSPh respectively, but P(SMe)3 was sulphurised to SP(SMe)3 to a small extent by MeSSPh.P4S3 is similarly cleaved by sulphuryl chloride, but under thermal conditions, to give SPCl3 and PCl3, with no evidence for intermediates.

The reaction of S4N4 with Ph2PCl (1:3 molar ratio) in boiling acetonitrile produces the six-membered ring (Ph2PN)2(NSCl) in excellent yield. The salt [Ph2P(Cl)N(Cl)PPh2]+Cl- is the major product when the molar ratio is increased to 1:12. The reactions of S4N4 with PCl3 or PhPCl2 (1:3 molar ratio) also give heterocycles containing the P2SN3 ring. Derivatives of the type (Ph2PN)2(NSX) (X = I, Ph, NR2 (R = Me, Et, -(CH2)5-)) are obtained by treatment of (Ph2PN)2(NSCl) with KI, Ph2Hg, Me3SiNMe2, Et2NH, or C5H10NH, respectively, in acetonitrile. The cation [(Ph2PN)2(SN)]+ is prepared as a trihalide salt by addition of halogens (Br2 or I2) to (Ph2PN)2(NSCl). Thermolysis at 155°C or treatment with Ph3Sb converts [(Ph2PN)2(SN)]+Br3- to (Ph2PN)2(NSBr). The halides (Ph2PN)2(NSX) (X = Cl, Br, I) are readily hydrolyzed to [Ph2P(NH2)N(NH2)PPh2] +X- in air.

The preparation and identification in solution of several new cyano- and thiocyanato-derivatives of the hexachlorophosphate (PCl6(1-)) ion are described.The cyano-complexes (1-) (n = 1-3) and the hexathiocyanatophosphate ion P(NCS)6(1-) have been isolated as tetra-n-alkylammonium salts and further characterised by elemental analysis, (31)P n.m.r., and (in some cases) vibrational spectroscopy.The mer isomer of the (1-) ion has been obtained pure and the fac isomer in a less pure state (ca. 3:1 fac:mer) by different preparative routes.Isomeric configurations in the chlorothiocyanatophosphate series (1-) have been assigned on the basis of the pairwise interaction method.