Mechanisms of abiotic degradation and soil–water interactions of pesticides and other hydrophobic organic compounds. Part 3. Nucleophilic displacement at the phosphorus centre of the pesticide fenitrothion [O,O-dimethyl O-(3-methyl-4-nitrophenyl) phosphorothioate] by oxygen nucleophiles in aqueous solution: α-effect and mechanism†

Nucleophilic substitution reactions of diethyl 4‐nitrophenyl phosphate triester: Kinetics and mechanism

“…On the other hand, attack only on the P center was observed for the reactions of aryl dimethylphosphinothioate and 2-(2,4 -dinitrophenyl)-2-oxo-1,3,2-dioxaphosphinanes with different phenoxide ions and some O-α nucleophiles [3,[11][12][13]. It is known that when the nucleophilic substitution reactions occur at the P center, they can proceed by two main types of mechanism: the stepwise mechanism, involving a trigonal bipyramidal pentacoordinate intermediate, and the concerted mechanism, through a single pentacoordinate transition state [3].…”

Effect of cyclodextrins on the reactivity of fenitrothion

“…10 UV-vis spectroscopy is one of the most frequently used techniques to determine the association constants between an organic guest compound and CDs. 11 We intended to determine the binding constant of 1 with all CDs used in this study by UV-vis spectroscopy. Thus, we recorded the spectra of 1 in the presence of increasing amounts of the appropriate CD.…”

Competing pathways in the reaction of the pesticide Fenitrothion [O,O-dimethyl O-(3-methyl-4-nitro­phenyl) phosphorothioate] with some nitrogen nucleophiles in aqueous solution

“…4 With a series of structurally related phenoxides as nucleophiles, reaction in water occurs exclusively at the P center. 3 Changing the nucleophile to the primary amines used in the present study sets up a competitive process in which attack at the aromatic carbon center is favored to varying extents over the corresponding reaction at P. The behavior of these nucleophiles in alkaline media in their reaction with 1 is amenable to an explanation that is based on the HSAB theory, 41 in which case the "hard" oxygen bases react mainly with the "hard" P center. The fact that "hard" amine nucleophiles, whose basicities are comparable to those of the oxyanions studied previously, show considerable affinity for the aromatic carbon center as well could be attributed to two factors.…”

“…[1][2][3][4] The reaction of the broad spectrum insecticide fenitrothion, 1, with a variety of oxygen-based nucleophiles has engaged our recent attention. 3,4 In aqueous solution, 1 reacts with a variety of oxygen nucleophiles, to include some alpha-nucleophiles and a series of structurally related phenoxides as well as the highly basic nucleophiles OH -and CF 3 CH 2 O -, exclusively at the P center. 3 In other words, products of nucleophilic attack at the alkyl and aromatic carbon centers were not detected.…”

“…3,4 In aqueous solution, 1 reacts with a variety of oxygen nucleophiles, to include some alpha-nucleophiles and a series of structurally related phenoxides as well as the highly basic nucleophiles OH -and CF 3 CH 2 O -, exclusively at the P center. 3 In other words, products of nucleophilic attack at the alkyl and aromatic carbon centers were not detected. Analysis of the kinetic data showed that the thiophosphoryl group transfer proceeds by a concerted mechanism in which bond formation with the incoming nucleophile is slightly ahead of leaving group departure.…”