Insecticidal Phosphates Obtained by a New Rearrangement Reaction<sup>1a</sup>

Barthel, W. F.; Alexander, B. H.; Giang, P. A.; Hall, S. A.

doi:10.1021/ja01614a019

Cited by 77 publications

(19 citation statements)

References 3 publications

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“…Ethephon is not the only example of an organophosphorus compound that must be activated in order to become a cholinesterase inhibitor. Trichlorphon is an insecticide that rearranges to dichlorvos under slightly alkaline conditions. , Trichlorphon itself does not inhibit cholinesterases. Its inhibitory properties are due to non-enzymatic conversion to dichlorvos .…”

Section: Discussionmentioning

confidence: 99%

Newly Observed Spontaneous Activation of Ethephon as a Butyrylcholinesterase Inhibitor

Liyasova

Schopfer

Kodani

et al. 2013

Chem. Res. Toxicol.

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The plant growth regulator ethephon (2-chloroethylphosphonic acid) inhibits human butyrylcholinesterase (BChE) by making a covalent adduct on the active site serine 198. Our goal was to extend earlier studies on ethephon inhibition. Addition of freshly prepared ethephon to BChE in buffered medium, at pH 7.0 and 22 °C, resulted in no inhibition initially. However, inhibition developed progressively over 60 min of incubation. Preincubation of ethephon in pH 7-9 buffers increased its initial inhibitory potency. These observations indicated that ethephon itself was not the inhibitor. About 3% of the initial ethephon could be trapped as a BChE adduct. Mass spectral analysis of the active site peptide from inhibited BChE showed that the inhibitor added a mass of 108 Da to the active site serine on peptide FGES198AGAAS. This result rules out a previous hypothesis that ethephon adds HPO3 to BChE (added mass of 80 Da). To accommodate these observations, we propose that in aqueous media at neutral to slightly alkaline pH about 3% of the ethephon is converted (t1/2 = 9.9 h at pH 7.0) into a cyclic oxaphosphetane which is the actual BChE inhibitor forming the 2-hydroxyethylphosphonate adduct on BChE at Ser198 while about 97% of the ethephon breaks down to ethylene (t1/2 = 11-48 h at pH 7.0) which is responsible for plant growth regulation.

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Section: Discussionmentioning

confidence: 99%

Newly Observed Spontaneous Activation of Ethephon as a Butyrylcholinesterase Inhibitor

Liyasova

Schopfer

Kodani

et al. 2013

Chem. Res. Toxicol.

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“…The sites of attack in this reaction remained uncertain and were the subject of debate among the experimenters 8 . According to them, it is possible to propose two hypotheses comparable to the reaction of Perkow [10][11][12] , concerning the conversion of an αhalogenated ketone to enol phosphate by a trialkyl phosphite. The first hypothesis proposes that the sodium hydrogen sulfite would be added to the most α-reactive carbonyl of the ester to give a bisulfite combination which would then evolve through an intermolecular rearrangement to an enol sulfate.…”

Section: Introductionmentioning

confidence: 99%

Reactivity Indices related to DFT Theory, the Electron Localization Function (ELF) and Non-Covalent Interactions (NCI) Calculations in the Formation of the non-Halogenated Pyruvic Esters in Solution

et al. 2019

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The non-halogenated pyruvic esters are essential compounds, considering that they exhibit particular properties, due to the proximity of two functional groups: carbonyl and ester. These molecules can be obtained from the approach of the Lewis acid MgI2 on the iodinated pyruvic ester by using sodium hydrogen sulfite in aqueous solution, which selectively reduces the carbon-iodine bond of the iodinated pyruvic ester. The sites of attack of hydrogen sulfite of this reaction remained uncertain and were the subject of a debate between the experimenters. Our aim in this work is to determine the more favorable sites of attack by using the local indices (Parr functions). To approve the structure of the reagents, we have conducted a topological analysis of electron localization function (ELF). To reveal the type of interaction in the "ester pyruvic-hydrogen sulfite" complex, we have performed a non-covalent interactions (NCI) calculation. The analysis of local indices and NCI analysis of electron density indicate that the approach of the hydrogen sulfite ion will take place on the iodine atom elucidating the preferable site of the attack.

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“…To our knowledge, no research has been reported previously on supervised trials for the trichlorfon residue and its dissipation product on rice. Trichlorfon can easily be degraded to the highly toxic insecticide dichlorvos (Barthel et al 1955;Liu 2012). Both trichlorfon and dichlorvos are highly polar organophosphorus pesticides (Figs.…”

Section: Introductionmentioning

confidence: 99%

Dissipation kinetics, safety evaluation, and preharvest interval assessment of trichlorfon application on rice

Chen

Ren

Meng

et al. 2016

Environ Monit Assess

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Nowadays, there is an urgent need for the investigation of the field dissipation and assessment of the preharvest interval for trichlorfon residues on rice. To protect consumers from potential health risks, this study can provide references for the safe application of trichlorfon in the rice fields. Results of the field dissipation study showed that the dissipation dynamic equations of trichlorfon were based on the first-order reaction dynamic equations and that the dissipation rates vary among rice plant, brown rice, rice bran, soil, and water. The 2-year field trials conducted in Yangzhou and Xiaogan suggested the interval of each application for trichlorfon on rice to be at least 7 days when 80 % trichlorfon SP was sprayed with a dose ranges between 80 and 160 a.i g/667 m(2). Additionally, the preharvest interval of the last application should be at least 15 days to ensure the amounts of residues below the maximum residue limits of trichlorfon on brown rice (0.1 mg/kg).

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Insecticidal Phosphates Obtained by a New Rearrangement Reaction^1a

Cited by 77 publications

References 3 publications

Newly Observed Spontaneous Activation of Ethephon as a Butyrylcholinesterase Inhibitor

Newly Observed Spontaneous Activation of Ethephon as a Butyrylcholinesterase Inhibitor

Reactivity Indices related to DFT Theory, the Electron Localization Function (ELF) and Non-Covalent Interactions (NCI) Calculations in the Formation of the non-Halogenated Pyruvic Esters in Solution

Dissipation kinetics, safety evaluation, and preharvest interval assessment of trichlorfon application on rice

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Insecticidal Phosphates Obtained by a New Rearrangement Reaction1a

Cited by 77 publications

References 3 publications

Newly Observed Spontaneous Activation of Ethephon as a Butyrylcholinesterase Inhibitor

Newly Observed Spontaneous Activation of Ethephon as a Butyrylcholinesterase Inhibitor

Reactivity Indices related to DFT Theory, the Electron Localization Function (ELF) and Non-Covalent Interactions (NCI) Calculations in the Formation of the non-Halogenated Pyruvic Esters in Solution

Dissipation kinetics, safety evaluation, and preharvest interval assessment of trichlorfon application on rice

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Insecticidal Phosphates Obtained by a New Rearrangement Reaction^1a