23754-87-2Relevant articles and documents
Method for preparing O, O-dimethyl-S-methylcarbamoylmethyl phosphorodithioate
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Paragraph 0114; 0117; 0118, (2019/04/30)
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.
Catalytic pathways in the ethanolysis of fenitrothion, an organophosphorothioate pesticide. A dichotomy in the behaviour of crown/cryptand cation complexing agents
Balakrishnan,Dust,VanLoon,Buncel
, p. 157 - 173 (2007/10/03)
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.
An efficient approach toward the synthesis of phosphorothioate diesters via the Schonberg reaction
Kamer,Roelen,Van den Elst,Van der Marel,Van Boom
, p. 6757 - 6760 (2007/10/02)
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.
