Proton dissociation properties of arylphosphonates: Determination of accurate Hammett equation parameters

Dargó, Gergő; Bölcskei, Adrienn; Grűn, Alajos; Béni, Szabolcs; Szántó, Zoltán; Lopata, Antal; Keglevich, György; Balogh, György Tibor

doi:10.1016/j.jpba.2017.05.038

Cited by 9 publications

(10 citation statements)

References 38 publications

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“…S2 †. The initial shift to lower ppm over time is consistent with initial aggregation of the linker (as per the control experiments just described and in agreement with conclusions from the SAXS experiments described below), but is also consistent with the direction of anticipated peak shifts on deprotonation of the BTPPA phosphonic acid groups, 41–44 most notably observed in H c at the ortho position with respect to the phosphonic acid substituents. 41,45–47 Subsequent to these two combined effects, and on a more rapid timescale with increasing temperature, a marked swing in the other direction downfield to higher ppm is observed for all the aromatic protons, in line with metal coordination counteracting and exceeding the effects of deprotonation in particular.…”

Section: Resultssupporting

confidence: 86%

Exploiting in situ NMR to monitor the formation of a metal–organic framework

et al. 2021

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Section: Resultssupporting

confidence: 86%

Exploiting in situ NMR to monitor the formation of a metal–organic framework

et al. 2021

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“…This allows a quantitative description of the molecule by showing the influence of the substituents. For aromatic rings with more than one substituent, the additive nature of the σ coefficients can be assumed (with some caution) [29,30]. The substituent constants found in the literature are presented in Table 3 [31,32].…”

Section: The Hammett Constantmentioning

confidence: 99%

Heterogeneous Oxidation of Phenolic Compounds with Photosensitizing Catalysts Incorporated into Chitosan

et al. 2019

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The increasing amount of hazardous micropollutants in the aqueous environment has recently become a concern, especially because they are not usually included in environmental monitoring programs. There is also limited knowledge regarding their behavior in the environment and their toxicity. This paper presents results regarding the heterogeneous photosensitized oxidation of 10 phenolic compounds under visible light. All of the selected compounds are classified as pollutants of emerging concern. For the first time, the application of photosensitizing catalysts incorporated into a chitosan carrier was investigated from several points of view, namely, structure characterization, singlet oxygen generation potential, photodegradation ability, biodegradability, and toxicity assessment. It was found that compounds of different origins were degraded with high effectivity. Photoactive chitosan was stable and could be reused for at least 12 cycles without losing its photocatalytic activity. The Hammett constants for all of the degraded compounds were determined. Improved biodegradability after the treatment was achieved for almost all compounds, apart from 4-hydroxybenzoic acid, and only slightly for 2-phenylphenol. The acute toxicity was assessed using bioluminescent Vibrio fischeri bacteria, indicating lower toxicity than the parent compounds.Photosensitized oxidation is undoubtedly one of the most important photochemical methods, since it does not generate any additional pollutants [5]. Moreover, the advantage of photosensitized oxidation is the photooxidation of hard-degradable compounds by singlet oxygen generated in the presence of air and solar radiation [5][6][7], therefore, photosensitized oxidation is classified as a green chemistry process. Moreover, because the heterogeneous process is considered to leave no residue, no sludge is produced from the process. Furthermore, if the immobilized photosensitizer remains unchanged throughout the process, the photocatalyst can easily be reused.Two general mechanisms of photosensitized oxidation for such reactions are well-known as Type I, also called the radical-involving mechanism, and Type II, the singlet oxygen mechanism [8,9]. Our previous research showed that singlet oxygen could be used for water purification. For this kind of area, the immobilization of photosensitizers onto various materials (heterogeneous system) is a desirable approach due to the easy separation from the reaction mixture and the preparation for reuse. Moreover, in homogenous systems (where the photosensitizer is dissolved in a water solution), the photosensitizer undergoes photobleaching, resulting in a rapid decrease in yield. Immobilized photosensitizers exhibit the advantages of good activity, stability against photobleaching, and repeated use [10]. Immobilization of a photosensitizer is associated with a decrease in the quantum yield of singlet oxygen [8,9]. This may be due to limitations in oxygen diffusion into and from the carrier material [9]. These disadvantages can be overcome by reusi...

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“…Arylphosphonates are the products of another approach comprising the MW‐assisted catalytic Arbuzov reaction of aryl bromides with triethyl phosphite. In the presence of a Ni salt catalyst, the phosphonates could be prepared in yields of 67–86 % ,. The MW irradiation “overcame” the decreased reactivity of aryl bromides (Scheme ).…”

Section: The Substitution or Simplification Of Catalyst Systems By/unmentioning

confidence: 99%

The Impact of Microwaves on Organophosphorus Chemistry

Keglevich

2018

The Chemical Record

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A personal account on the pioneering results on microwave (MW)-assisted organophosphorus syntheses obtained in the last decade is presented. The broad spectrum of the reactions studied exemplifies the advantages of the MW technique as a green tool regarding efficiency and the simplification of catalyst systems. Theoretical calculations for a few typical models helped us to explore the scope and limitations of the application of MW irradiation.

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Proton dissociation properties of arylphosphonates: Determination of accurate Hammett equation parameters

Cited by 9 publications

References 38 publications

Exploiting in situ NMR to monitor the formation of a metal–organic framework

Exploiting in situ NMR to monitor the formation of a metal–organic framework

Heterogeneous Oxidation of Phenolic Compounds with Photosensitizing Catalysts Incorporated into Chitosan

The Impact of Microwaves on Organophosphorus Chemistry

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