23754-87-2

The invention belongs to the technical field of pesticides, and particularly relates to a method for preparing O, O-dimethyl-S-methylcarbamoylmethyl phosphorodithioate. Chloroacetyl chloride and dimethyl phosphite are used as raw materials to prepare the O, O-dimethyl-S-methylcarbamoylmethyl phosphorodithioate for the first time, the product prepared by using the method is high in yield and purity, no waste liquid is generated in the preparation process, the preparation process is simple, and reaction mother liquor, such as the mother liquor in the step 1 and the step 3, does not need to be treated and can be recycled 6-8 times; while the yield of the product is further improved, the product keeps a high purity, and the quality of the product is ensured. By using the method, through optimization of a reaction system and selection of reaction details, the yield in the reaction in each step can be high. Besides, by using the method, after the reaction is completed, through simple aftertreatment steps, the water content of the obtained product can be as low as 0.032%, and the problem is solved that the product is decomposed due to high water content.

A novel rearrangement of S-(2-aminoethyl) thiophosphates to N-(2-mercaptoethyl)phosphoramidates was discovered and developed. The reaction proceeds smoothly at room temperature under basic conditions and the resulting thiol could subsequently be alkylated. The reaction mechanism is investigated by electron structure calculations using density functional theory at the B3LYP/6-31G(d) and B3LYP/6-311+G(d,p) levels. The calculations indicate that the reaction proceeds in a two step process when two explicit solvent molecules are included. In the presence of water the rearrangement reaction proceeds in competition with hydrolysis. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.

The rates of displacement of 3-methyl-4-nitrophenoxide ion from the pesticide, fenitrothion, by alkali metal ethoxides in anhydrous ethanol were followed spectrophotometrically. Through product analysis experiments, which included 31P NMR and GC-MS, as well as spectrophotometric analysis, three reaction pathways were identified: nucleophilic attack at the phosphorus centre, attack at the aliphatic carbon, and a minor SNAr route (≤7%). Furthermore, a consecutive process was found to occur on the product of attack at the phosphorus centre. For purposes of kinetic treatment, the processes at the aliphatic and aromatic carbon were combined (i.e., the minor SNAr pathway was neglected), and the observed reaction rate constants were dissected into rate coefficients for nucleophilic attack at phosphorus and at aliphatic carbon. Attack at phosphorus was found to be catalyzed by the alkali metal ethoxides in the order KOEt > NaOEt > LiOEt. Catalysis arises from alkali metal ethoxide aggregates in the base solutions used (0-1.8 M); treatment of the system as a mixture of free ethoxide, ion-paired metal ethoxide, and metal ethoxide dimers resulted in a good fit with the kinetic data. An unexpected dichotomy in the kinetic behaviour of complexing agents (e.g., DC-18-crown-6, [2.2.2]cryptand) indicated that the dimers are more reactive than free ethoxide anions, which are in turn more reactive than ion-paired metal ethoxide. The observed relative order of reactivity is explained in the context of the Eisenman theory in which the free energy of association of the metal ion with the rate-determining transition state is largely determined by the solvent reorganization parameter. In contrast with displacement at the phosphorus centre, attack at the aliphatic carbon was not found to be catalyzed by alkali metals. In this case, the free ethoxide anion was more reactive than either the ion-paired metal ethoxide or the dimeric aggregate. The differing effects of alkali metals on the two pathways is ascribed largely to the leaving group pKa. For carbon attack, the pKa value estimated for demethyl fenitrothion, 2.15, is sufficiently low that metal ions are not required to stabilize the rate-determining transition state. In contrast, for phosphorus attack, 3-methyl-4-nitrophenoxide, with a pKa of 7.15, requires stabilization by metal ion interactions. Hence, alkali metal ions catalyze attack at phosphorus, but not attack at the carbon centres.

O-Methylmethylphosphatotriphenyltin(IV) (II) is synthesized by treating stoichiometric amounts of O,O'-dimethylmonothiophosphatotriphenyltin(IV) (I) with mercury.The negative 119Sn chemical shift in solution relative to tetramethyltin for I corresponds to higher than four coordination (at tin) in solution.The values of the 119Sn Moessbauer isomer shift for I and II confirm the presence of tin as tin(IV).The magnitudes of the quadrupole splitting and the ratios of the QS to the IS of both compounds reveal that tin is higher than four coordinated.The solid state structure of II was determined by X-ray diffraction.The compound crystallized in the trigonal space group R3 with a, b 31433(15), c 10.259(3) Angstroem, V 8778.2 Angstroem3, Z = 18, Dx 1.56 g cm-3 at 138 K.In the solid state compound II exists as a highly symmetric cyclic hexamer in which planar trimethyltin(IV) groups are axially bridged by O-P-O linkages.The geometry about tin is trigonal bipyramidal with an axial O-Sn-O angle of 177.1(2) deg and average C-Sn-C angle of 120.0(2) deg.The structure of the hexameric ring is linear at tin but bent at phosphorus with an O-P-O angle of 117.1(2) deg.

Easily accessible phenacetyl or benzoyl disulfide proved to be very conventional ragents for a rapid P-sulfurization of phosphite-triesters and H-phosphonate diesters, respectively.

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