Investigation on the Gas-Phase Decomposition of Trichlorfon by GC-MS and Theoretical Calculation

Abstract

The gas phase pyrolysis of trichlorfon was investigated by the on-line gas chromatography – mass spectrometry (GC-MS) pyrolysis and theoretical calculations. Two reaction channels were proposed in the pyrolytic reaction, by analyzing the detected pyrolytic products in the total ion chromatography, including 2,2,2-trichloroacetaldehyde, dimethyl phosphite, and dichlorvos. Theoretical calculations showed that there is an intramolecular hydrogen bond between the hydroxyl group and the phosphate O atom in trichlorfon, through which the hydroxyl H atom can be easily transferred to phosphate O atom to trigger two pyrolytic channels. In path-a, migration of H atom results in direct decomposition of trichlorfon to give 2,2,2-trichloroacetaldehyde and dimethyl phosphite in one step. In path-b, migration of H atom in trichlorfon is combined with formation of the O-P bond to give an intermediate, followed by HCl elimination to afford dichlorvos. Path-a is kinetically more favorable than path-b, which is consistent with the GC-MS results.

Biodegradation of the Organophosphate Trichlorfon and Its Major Degradation Products by a Novel Aspergillus sydowii PA F-2

“…Compounds F and G with RTs of 3.558 and 3.083 min showed the same molecular ions at m / z 82, which correspond to chloral hydrate and trichloroethanal, respectively. Among these degradation products, trichloroethanal, dimethyl phosphite, and dimethyl hydrogen phosphite have also been reported during the pyrolytic decomposition of TCF and oxygen plasma treatment of DDCV. , In the control group without PA F-2 inoculates, these metabolites were detected in very low concentrations. This finding suggested that TCF decomposed under aqueous conditions, but the reaction was accelerated by the incubation of PA F-2.…”

“…The GC-MS analysis revealed that the peak at a RT of 10.87 min corresponded to the TCF standard, and the peak at a RT of 9.49 min corresponded to DDCV, an important intermediate product. Metabolite HCl, the main decomposition product from TCF to DDCV, was eluted from the capillary column before methanol because no signal of HCl was detected in the mass spectrum system. TCF and DDCV decreased over time as the five compounds were formed.…”

“…The ion source temperature was 230 °C, and the ionization energy was 70 eV. The solvent cut time was set at 3 min, and the injection volume was 1.0 μL with splitless sampling …”

“…Hydrolysis, photolysis, and biodegradation are the three main degradation pathways of TCF in the environment. TCF and DDCV are easily O-demethylated to desmethyl compounds, dimethylphosphate, and monomethylphosphate through hydrolysis, pyrolysis, and other chemical processes. ,− However, these conventional techniques are limited because of the undesired removal efficiency and toxic organic intermediate products . TCF in soil is initially degraded by the microbial community to produce environmentally friendly and weakly toxic products.…”

Quantum approach to the mechanism of monothiopyrophosphate isomerization

“…This contribution concentrates, however, on methodological aspects of calculations while employing only SMD/M06-2X/ 6311+G9d,p)//SMD/M06-2X/6-31+G(d) level of theory. Some other (non-exhaustive) recent examples of using different theory levels in modeling properties and reactivity of phosphoruscontaining molecules include DFTB3/3OB in structure determination [16,17], B3LYP & MP3 with 6-311G(d,p) basis set in conformational analysis [18], B3LYP/cc-pVTZ/TIP3P and B3LYP-D3/def2-SVP(D) in studies of anharmonicity of phosphate ions in water [19,20], M06-2X, M06L and PBE with 6-31+G(d,p) in lipophilicity calculations [21] ωB97/6-311+ G(3df,2p)//M06-2X/6-311+G(d,p) in investigations of the reaction with OH radical [22], MP3/6-311++G(2d,2p)//B3LYP/6 −31+G(d) in hydrolysis of pesticides [23], PM3/MM, BLYP/6-31G(d)/MM, B3LYP/6-31G*/MM and COSMO/B3LYP/6-31G(d) in hydrolysis of monoesters [24], B3LYP/6-311+ G(d,p) and M06-2X/6-311+G(d,p) in gas-phase decomposition [25], B3LYP/6-311+G(d,p) in metathiophosphate di-and polymerization [26], M06-2X/6-311+G(3df,2p) and B2PLYP/ 6311+G(3df,2p)//(IEFPCM) /M06-2X/6-311+G(d,p) in oxidation [27], PBE-D3/PAW in non-aqueous degradation [28], M06-2X/6-31G(d,p) and BLYP-D3/aug-cc-pVTZ in binding to an enzyme [29], and B97D/6-31+G(d)/AMBER [30], B3LYP/6-31G(d) [31] and PBE0-D3/def2-TZVP [32] in enzymatic catalysis.…”