Phototransformation of Pesticides in the Environment

Vione, Davide; Minella, Marco; Minero, Claudio

doi:10.1201/b18481-14

Cited by 2 publications

(3 citation statements)

References 60 publications

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“…For 24D-CPA and 245T-CPA the pKa values are 2.77 and 2.88 respectively. 24 Thus, the anionic forms of 24D-CPA and 245T-CPA are predominant at pH values bigger than 2.77 and 2.88 respectively. On the other hand, to the best our knowledge, the pKa value for 34-CPA has not been reported in the literature.…”

Section: Global and Local Reactivity Descriptors For Anionic Cpas At mentioning

confidence: 94%

“…Under these conditions the anionic forms of 4-CPA, 24D-CPA, 34-CPA and 245T-CPA are predominant at pH values bigger than 3.56, 2.77, 2.77 and 2.88, respectively. 24 . In order to analyze the chemical reactivity of the anionic forms.…”

Section: Global and Local Reactivity Descriptors For Anionic Cpas At mentioning

confidence: 99%

“…It is important to mention that only the free radical attacks on these CPAs have been analyzed in the literature by which the electrophilic and nucleophilic chemical reactivity exhibited by these acid herbicides are missing. Under these conditions the proposal of new efficient degradation methods employing electrophiles and nucleophiles is a topic of interest Moreover, if one considers that in an aqueous environment at pH > 7 carboxyl groups are usually deprotonated; then the anionic forms of chlorophenoxy acetic acids may be predominant under the pH conditions of surface waters, 24 and a change on the chemical reactivity; in comparison to the neutral forms may be expected. To the best of our knowledge, the global and local reactivity descriptors, of 4-CPA, 24D-CPA, 3,4-dichlorophenoxy acetic acid (34-CPA) and 2,4,5-trichlorophenoxy acetic acid (245T-CPA), in their neutral and anionic forms are still missing.…”

Section: Introductionmentioning

confidence: 99%

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Electrophilic and Nucleophilic Chemical Reactivity of Neutral and Anionic Forms of 4-Cpa, 24d-Cpa, 34-Cpa and 245t-Cpa Through Conceptual DFT Reactivity Descriptors

Mendoza-Huízar

Ríos-Reyes

Álvarez-Romero

et al. 2017

J. Chil. Chem. Soc.

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In the present work, we have analyzed the electrophilic and nucleophilic chemical reactivity of the neutral and anionic chlorophenoxyacetic acid herbicides, 4-CPA, 24D-CPA, 34-CPA and 245T-CPA at the X/6-311++G(2d,2p) level of theory (where X= wB97XD, MPW91B1K and MP2). Chemical reactivity was analyzed in the aqueous phase and employing global and local DFT reactivity descriptors. The structural parameters derived from DFT calculations are equivalent to those obtained at the MP2 level. The Fukui Function values suggest that nucleophilic attacks to the neutral and anionic forms would cause dechlorination on 24D-CPA, 34-CPA and 245T-CPA and hydrogen abstraction in 4-CPA. At pH values lower than 2.7, electrophilic attacks would cause the cleavage of the ether bond in 4-CPA, 24D-CPA and 34-CPA and dechlorination in 245T-CPA. But, at pH > 3.6, electrophiles may cleave the ether bond to start the degradation of the four CPAs.

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Section: Global and Local Reactivity Descriptors For Anionic Cpas At mentioning

confidence: 94%

Section: Global and Local Reactivity Descriptors For Anionic Cpas At mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Electrophilic and Nucleophilic Chemical Reactivity of Neutral and Anionic Forms of 4-Cpa, 24d-Cpa, 34-Cpa and 245t-Cpa Through Conceptual DFT Reactivity Descriptors

Mendoza-Huízar

Ríos-Reyes

Álvarez-Romero

et al. 2017

J. Chil. Chem. Soc.

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Occurrence and transformation of phenoxy acids in aquatic environment and photochemical methods of their removal: a review

Muszyński

Brodowska

Paszko

2019

Environ Sci Pollut Res

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The article presents the behavior of phenoxy acids in water, the levels in aquatic ecosystems, and their transformations in the water environment. Phenoxy acids are highly soluble in water and weakly absorbed in soil. These highly mobile compounds are readily transported to surface and groundwater. Monitoring studies conducted in Europe and in other parts of the world indicate that the predominant phenoxy acids in the aquatic environment are mecoprop, 4-chloro-2-methylphenoxyacetic acid (MCPA), dichlorprop, 2,4-dichlorophenoxyacetic acid (2,4-D), and their metabolites which are chlorophenol derivatives. In water, the concentrations of phenoxy acids are effectively lowered by hydrolysis, biodegradation, and photodegradation, and a key role is played by microbial decomposition. This process is determined by the qualitative and quantitative composition of microorganisms, oxygen levels in water, and the properties and concentrations of phenoxy acids. In shallow and highly insolated waters, phenoxy acids can be decomposed mainly by photodegradation whose efficiency is determined by the form of the degraded compound. Numerous studies are underway on the use of advanced oxidation processes (AOPs) to remove phenoxy acids. The efficiency of phenoxy acid degradation using AOPs varies depending on the choice of oxidizing system and the conditions optimizing the oxidation process. Most often, methods combining UV radiation with other reagents are used to oxidize phenoxy acids. It has been found that this solution is more effective compared with the oxidation process carried out using only UV.

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Phototransformation of Pesticides in the Environment

Cited by 2 publications

References 60 publications

Electrophilic and Nucleophilic Chemical Reactivity of Neutral and Anionic Forms of 4-Cpa, 24d-Cpa, 34-Cpa and 245t-Cpa Through Conceptual DFT Reactivity Descriptors

Electrophilic and Nucleophilic Chemical Reactivity of Neutral and Anionic Forms of 4-Cpa, 24d-Cpa, 34-Cpa and 245t-Cpa Through Conceptual DFT Reactivity Descriptors

Occurrence and transformation of phenoxy acids in aquatic environment and photochemical methods of their removal: a review

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