17659-67-5Relevant academic research and scientific papers
Metal Ion Promoted Phosphate Ester Hydrolysis. Intramolecular Attack of Coordinated Hydroxide Ion
Hendry, Philip,Sargeson, Alan M.
, p. 2521 - 2527 (1989)
The phosphate diesters, ethyl 4-nitrophenyl phosphate, and bis(4-nitrophenyl)phosphate in cis-(1+) (en = 1,2-diaminoethane) react with the cis-hydroxo group at pH 8 to liberate nitrophenolate ion ca. 1E6-fold faster than for the free
Dual function of amino acid ionic liquids (Bmim[AA]) on the degradation of the organophosphorus pesticide, Paraoxon
Morales, Javiera I.,Figueroa, Roberto,Rojas, Mabel,Millán, Daniela,Tapia, Ricardo A.,Pavez, Paulina
, p. 7446 - 7453 (2018/10/24)
The synthesis of a series of ionic liquids using 1-butyl 3-methylimidazolium (Bmim+) as a cation and different amino acids (AA) as anions (Bmim[AA]) is described. These ILs were used for the first time as reaction media to achieve more eco-friendly Paraoxon degradation. The results show that the degradation of Paraoxon in these Bmim[AA]s is accomplished with great efficiency and without an extra nucleophilic agent. Therefore, we propose that all the Bmim[AA]s used in this study have a dual role in the outcome of this reaction; as a nucleophile and a solvent to carry out degradation of the organophosphorous pesticide, Paraoxon. Both kinetics and product distribution results found in this study for Paraoxon degradation turned out to be promising, because this process is achieved in a reaction medium with a better environmental profile.
Kinetics and speciation of paraoxon hydrolysis by zinc(II)-azamacrocyclic catalysts
Kennedy, Daniel J.,Mayer, Brian P.,Baker, Sarah E.,Valdez, Carlos A.
supporting information, p. 123 - 131 (2015/08/24)
Four Zn2+-azamacrocyclic complexes were investigated for their ability to catalyze the hydrolysis of the toxic organophosphate (OP) pesticide diethyl paraoxon. Of the four complexes studied, Zn2+-1,5,9-triazacyclododecane (Zn2+-[12]aneN3) was found to be the most effective catalyst with a pseudo-first order reaction rate of k = 6.08 ± 0.23 × 10-4 min-1. Using 31P nuclear magnetic resonance (NMR) spectroscopy, the two products diethyl phosphate (DEP) and ethyl (4-nitrophenyl) phosphate (E4NPP) were identified for both catalyzed and background hydrolysis of paraoxon. Reaction rate and selectivity for formation of the non-toxic DEP were observed to correlate with catalyst pKa. The rate of formation of toxic E4NPP, however, was independent of both the presence and nature of the catalyst. The potential roles of buffer concentration and product inhibition were also investigated. Background hydrolysis at elevated reaction temperatures (50°C) displayed no preference for DEP over that of E4NPP despite substantial differences between the characteristics (i.e., pKa values) of the two leaving groups (ethoxide vs. 4-nitrophenoxide anions). As with previous observations of these types of metal-catalyzed hydrolyses, we invoke the formation of a trigonal bipyramidal-like transition state involving a Zn-coordinated phosphate bond, with the leaving group at the apical position and the incoming HO- anion approaching from the opposite end. Kinetic rates for catalytic hydrolysis display an overwhelming propensity for DEP formation, and suggest the importance of steric restrictions on transition state structure, namely a concerted arrangement of the azamacrocycle in opposition to the bulky 4-nitrophenoxy group.
Mechanisms of degradation of paraoxon in different ionic liquids
Pavez, Paulina,Millan, Daniela,Morales, Javiera I.,Castro, Enrique A.,Lopez A., Claudio,Santos, Jose G.
, p. 9670 - 9676 (2013/10/22)
Herein, the reactivity and selectivity of the reaction of O,O-diethyl 4-nitrophenyl phosphate triester (Paraxon, 1) with piperidine in ionic liquids (ILs), three conventional organic solvents (COS), and water is studied by 31P NMR, UV-vis, and GC/MS. Three phosphorylated products are identified as follows: O,O-diethyl piperidinophosphate diester (2), O,O-diethyl phosphate (3), and O-ethyl 4-nitrophenyl phosphate diester (4). Compound 4 also reacts with piperidine to yield O-ethyl piperidinophosphate monoester (5). The results show that both the rate and products distribution of this reaction depend on peculiar features of ILs as reaction media and the polarity of COS.
Divalent metal ion-catalyzed hydrolysis of phosphorothionate ester pesticides and their corresponding oxonates
Smolen, Jean M.,Stone, Alan T.
, p. 1664 - 1673 (2007/10/03)
The divalent metal ion-catalyzed hydrolysis of thionate (P=S) and oxonate (P=O) organophosphorus pesticides has been examined in light of three possible catalysis mechanisms: (1) metal ion coordination of the thionate sulfur or oxonate oxygen to enhance the electrophilicity of the phosphorus electrophilic site; (2) metal ion coordination and induced deprotonation of water to create a reactive nucleophile; and (3) metal ion coordination of the leaving group to facilitate its exit. The effect of the following metals at a concentration of 1 mM was examined: Co(II), Ni(II), Cu(II), Zn(II), and Pb(II). These metal ions were chosen for their ability to complex organic ligands and inorganic nucleophiles. Of these metal ions, Cu(II) possesses properties most suitable for all three catalytic mechanisms and serves as the most effective catalyst for the five thionate esters (chlorpyrifos-methyl, zinophos, diazinon, parathion-methyl, and ronnel) and the two oxonate esters (chlorpyrifos-methyl oxon and paraoxon) included in this study. A decrease in the degree of Cu(II) catalysis at high pH arises from solubility limitations. Pb(II) nearly matches Cu(II) as a catalyst for oxonate esters, but is a less effective catalyst for thionate esters. Catalysis by Co(II), Ni(II), and Zn(II) is negligible. Phenolate product analysis indicates that metal catalysis in some instances shifts hydrolysis from alkyl carbon-centered pathways to phosphorus-centered pathways.
A Convenient Preparation of Phosphate Diester Monoanions
Krishnan, B. Radha,Winwood, D.,Bodor, N.
, p. 2653 - 2658 (2007/10/02)
A convenient method is described for the preparation of phosphate diester monoanions.The method uses readily available starting materials and does not require the isolation and handling of highly toxic phosphate triesters.The title compounds are useful as models of aged (poisoned) acetyl cholinesterase systems.
O-Alkyl p,p'-Dianisyl Phosphinite - A New Phosphorylating Reagent
Agrawal, Sudhir,Misra, Krishna
, p. 513 - 515 (2007/10/02)
Phosphorylation of alcohols and phosphates forming mixed esters of phosphoric acid and symmetrical pyrophosphates through O-alkyl p,p'-dianisyl phosphinite in the presence of 2,2'-dipyridyl disulphide has been investigated.
