A new strategy to generate super and hyper acids with simple organic molecules exploiting σ-hole interaction

Saha, Anusuya; Si, Mrinal Kanti

doi:10.1039/c9cp03881g

Cited by 3 publications

(1 citation statement)

References 27 publications

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“…According to transition state theory, approximate reaction rate constants for elementary reactions could be estimated based on the Eyring-Polanyi equation as follows [26]:…”

Section: Theoretical Computation Methodsmentioning

confidence: 99%

Degradation of Polystyrene Nanoplastics in UV/NaClO and UV/PMS Systems: Insights into Degradation Efficiency, Mechanism, and Toxicity Evaluation

Cai

Fan

Yang

et al. 2023

Water

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Nanoplastics have gradually become a concern due to the wide use of plastics. Nanoplastics in aqueous phase can be exposed to users through water supply networks and cannot be efficiently removed by conventional water treatment processes. This work studied the degradation of polystyrene nanoplastics (PS-NP) by two commonly used advanced oxidation systems: UV/NaClO and UV/peroxymonosulfate (PMS). Results showed that almost no turbidity was detected in the PS-NP solution (5.00 mg/L) after treated by both UV/NaClO and UV/PMS for 360 min, suggesting the excellent turbidity removal ability. Yet, scanning electron microscope (SEM) and total organic carbon (TOC) removal tests demonstrated that PS-NP could not be completely degraded by UV/NaClO. The mineralization rate using UV/NaClO was only 7.00% even when the NaClO concentration increased to 5.00 mM, and many PS-NP particles could still be observed in SEM images. By contrast, the mineralization rate reached 63.90% in the UV/PMS system under the identical experimental conditions, and no spherical particles appeared in the SEM results. Density functional theory (DFT) calculations revealed that the different reaction sites and energy barriers of SO4•− and •Cl on PS-NP resulted in the differences in mineralization rates and degradation intermediates. The degradation pathway of PS-NP by UV/NaClO and UV/PMS was proposed accordingly. Additionally, the intermediates toxicity evaluation by a luminescent bacteria test showed that the inhibition rate in the UV/NaClO system (2.97%) was not markedly different from that in the control group without any treatment (1.98%); while that in UV/PMS system increased sharply to 98.19%. This work demonstrated that UV/PMS was more effective in PS-NP degradation than UV/NaClO, and the chemical risks of degradation intermediates were non-negligible.

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“…According to transition state theory, approximate reaction rate constants for elementary reactions could be estimated based on the Eyring-Polanyi equation as follows [26]:…”

Section: Theoretical Computation Methodsmentioning

confidence: 99%

Degradation of Polystyrene Nanoplastics in UV/NaClO and UV/PMS Systems: Insights into Degradation Efficiency, Mechanism, and Toxicity Evaluation

Cai

Fan

Yang

et al. 2023

Water

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Novel insights into formation mechanism of organic chloramines from pre-oxidized algae-laden water: Multiple roles of dissolved organic nitrogen

Sheng

Zhu

et al. 2022

Science of The Total Environment

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Rational Design of Cyclopentadiene-Based Super- and Hyperacids Based on Aromaticity

Si,

Shigeta

2024

J. Phys. Chem. A

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The design and synthesis of neutral organic superacids have been of interest recently due to their vast applications in chemistry and material sciences, for example, olefinic polymerization, isolation of highly reactive short-lived cations, etc. Cyclopentadiene behaves as a mild organic acid, producing a stable conjugate base by gaining aromaticity and conjugation after deprotonation. To stabilize conjugate bases of organic acids to show superacidities and hyperacidities, we considered aromatic phenyl substituents with cyclopentadiene (mono-, di-, and triphenylsubstituted cyclopentadiene and their cyano derivatives). The MP2, DFT (B3LYP, M06-2X), and CBS-QB3 methods were used to calculate the gasphase proton affinities of the parent cyclopentadiene, and the DFT methods were chosen for the substituted cyclopentadiene as they yield an experimental proton affinity of cyclopentadiene of 253.66 kcal/mol (Expt. 253.6 ± 1.3 kcal/mol). The stable trisubstituted cyclopentadiene derivative shows gas-phase enthalpies of deprotonation (ΔH acid ) of 245 and 239 kcal/mol with DFT B3LYP and M06-2X methods, respectively, with values in the range of hyperacidity. Some of the tautomers of cyclopentadiene derivatives show hyperacidity, with proton affinity values of 205−240 kcal/mol. Triphenyl-substituted cyclopentadiene behaves as a moderate acid but transforms into a superacid after replacing the phenyl group with nitrobenzene, which is a stronger acid than H 2 SO 4 (ΔH acid = 298 kcal/mol). The nucleus-independent chemical shift (NICS) shows the extent of conjugation in the derivatives of cyclopentadienyl anions after deprotonation, which affects the stabilities of conjugate bases, i.e., the acidities of the protonated species. The calculated harmonic oscillator model of aromaticity and NICS indices reveal that the stability of conjugate bases as well as their acidities increase with increasing aromaticity of cyclopentadiene rings after deprotonation in all molecules.

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A new strategy to generate super and hyper acids with simple organic molecules exploiting σ-hole interaction

Abstract: A new strategy can lead to comparable 1st and 2nd ΔHacid values with simple organic acids exploiting σ-hole interaction.

Cited by 3 publications

References 27 publications

Degradation of Polystyrene Nanoplastics in UV/NaClO and UV/PMS Systems: Insights into Degradation Efficiency, Mechanism, and Toxicity Evaluation

Degradation of Polystyrene Nanoplastics in UV/NaClO and UV/PMS Systems: Insights into Degradation Efficiency, Mechanism, and Toxicity Evaluation

Novel insights into formation mechanism of organic chloramines from pre-oxidized algae-laden water: Multiple roles of dissolved organic nitrogen

Rational Design of Cyclopentadiene-Based Super- and Hyperacids Based on Aromaticity

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