Electrochemical study of the anodic oxidation of terpinenes at the electrode and by homogeneous redox catalysis

Salah, Nasr Ben; Matoussi, Fatma

doi:10.1016/j.jelechem.2004.08.025

Cited by 9 publications

(5 citation statements)

References 15 publications

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“…First, the generation of a CO 2 · – intermediate in an outer-sphere electron transfer is unfavorable and associated with a high reorganization energy (linear molecule vs bent radical anion). − Second, in the presence of CO 2 , typical outer-sphere reagents such as radical anions of hydrocarbons with extended π-systems (generated in aprotic media) rather undergo carboxylation via electrophilic aromatic substitution than an outer-sphere electron transfer, , whereby an exception from this trend is represented by radical anions of benzoic esters and benzonitriles (see section ). , Consequently, the CO 2 molecule is in most cases activated with a chemical catalyst, whereas redox catalysts/outer-sphere mediators are more suitable for the electroconversion of larger organic molecules. − …”

Section: Fundamentals Of Electrochemical Co2 Reductionmentioning

confidence: 99%

Homogeneously Catalyzed Electroreduction of Carbon Dioxide—Methods, Mechanisms, and Catalysts

2018

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The utilization of CO via electrochemical reduction constitutes a promising approach toward production of value-added chemicals or fuels using intermittent renewable energy sources. For this purpose, molecular electrocatalysts are frequently studied and the recent progress both in tuning of the catalytic properties and in mechanistic understanding is truly remarkable. While in earlier years research efforts were focused on complexes with rare metal centers such as Re, Ru, and Pd, the focus has recently shifted toward earth-abundant transition metals such as Mn, Fe, Co, and Ni. By application of appropriate ligands, these metals have been rendered more than competitive for CO reduction compared to the heavier homologues. In addition, the important roles of the second and outer coordination spheres in the catalytic processes have become apparent, and metal-ligand cooperativity has recently become a well-established tool for further tuning of the catalytic behavior. Surprising advances have also been made with very simple organocatalysts, although the mechanisms behind their reactivity are not yet entirely understood. Herein, the developments of the last three decades in electrocatalytic CO reduction with homogeneous catalysts are reviewed. A discussion of the underlying mechanistic principles is included along with a treatment of the experimental and computational techniques for mechanistic studies and catalyst benchmarking. Important catalyst families are discussed in detail with regard to mechanistic aspects, and recent advances in the field are highlighted.

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Section: Fundamentals Of Electrochemical Co2 Reductionmentioning

confidence: 99%

Homogeneously Catalyzed Electroreduction of Carbon Dioxide—Methods, Mechanisms, and Catalysts

2018

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“…The autoxidation of γ-TH induced by AIBN provides a useful model for the research on the solvent effect (9). Although both Rand γ-TH can be oxidized to form p-cymene (10), it is still an attractive topic for the difference of the bioactivity of Rand γ-TH in biological experimental systems. Presented here is a comparison of the antioxidant effects of Rand γ-TH on the oxidation of methyl linoleate (LH), DNA, and erythrocytes induced by 2,2 0 -azobis (2-amidinopropane hydrochloride) [AAPH, R;NdN;R, R = ;CMe 2 C(dNH)NH 2 ].…”

Section: Introductionmentioning

confidence: 99%

Unusual Antioxidant Behavior of α- and γ-Terpinene in Protecting Methyl Linoleate, DNA, and Erythrocyte

Liu

2009

J. Agric. Food Chem.

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The antioxidant effects of alpha-terpinene (alpha-TH) and gamma-terpinene (gamma-TH) on the oxidation of methyl linoleate (LH), DNA, and erythrocytes induced by 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH) were investigated. The results from erythrocytes and DNA were treated by means of chemical kinetic equations. It was found that either alpha- or gamma-TH was able to scavenge approximately 0.4 radicals when they protected DNA. alpha-TH can trap approximately 0.7 radicals when protecting erythrocytes and can trap approximately 0.5 radicals when protecting LH. gamma-TH can trap approximately 1.2 radicals when protecting erythrocytes and LH. Therefore, the antioxidant effectiveness of gamma-TH was higher than alpha-TH. gamma-TH contained a nonconjugated diene, and the diene in alpha-TH was conjugated. The obtained results implied that the nonconjugated diene benefited for antioxidant capacity more than a conjugated diene. Moreover, the reactions of alpha- and gamma-TH with 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) cation radical (ABTS(+) (*)) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) implicated that alpha- and gamma-TH were able to scavenge radicals directly. However, alpha- and gamma-TH promoted AAPH-induced hemolysis with a high concentration employed.

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“…The formation of a phenoxenium cation via phenoxy radical that subsequently evolves through other chemical processes such as loss of a proton. 28,29…”

Section: Phenolic Substances Flavonoid Content and Antioxidant Activitymentioning

confidence: 99%

Investigation of Antioxidant Activity, Acute Toxicity and Anticholinesterasic Potential of Lippia hirta (Verbenaceae)

Oliveira

Zapp²,

Brondani³

et al. 2019

Rev. Virtual Quim.

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Investigação da Atividade Antioxidante, Toxidade Aguda e do Potencial Anticolinesterásico de Lippia hirta (Verbenaceae) Resumo: O gênero Lippia, o segundo maior da família Verbenaceae, possui aproximadamente 200 espécies, das quais aproximadamente 120 espécies encontram-se no Brasil. Uma vez que a espécie Lippia hirta não tem sido documentada na literatura, o objetivo deste trabalho foi analisar a atividade antioxidante, a toxicidade aguda e a atividade de inibição da acetilcolinesterase (AChE) por parte do óleo essencial, extrato bruto e frações provenientes desta espécie vegetal. Com relação à atividade antioxidante, avaliada pelo poder redutor, foi possível observar um excelente comportamento antioxidante, especialmente para o óleo essencial (IC50= 6,26 µg.mL-1), e frações butanólica (BuOH, IC50= 7,26 µg.mL-1) e acetato de etila (EtOAc, IC50= 8,09 µg.mL-1), superiores ao padrão quercetina (IC50= 9,43 µg.mL-1) utilizado neste ensaio. Observou-se uma baixa toxicidade para todas as amostras e grande potencial inibitório para a AChE, pela maioria das frações e especialmente para a fração rica em alcaloides (FRA), que foi capaz de inibir a enzima em até 100 % em uma concentração de 0,5 μg.mL-1 , o que representa uma atividade de elevada potência. Ainda que a FRA seja uma matriz complexa, o efeito sinérgico é elevado quando comparado ao padrão utilizado no teste, Reminyl-contendo galantamina (IC50=17,8 μmol.L-1). Estes resultados incentivaram o fracionamento cromatográfico de FRA que permitiu a caracterização de três alcaloides, até então não relatados na espécie, dihidrocorinanteol, vincamina and dexoxicordifolina. A baixa toxicidade, a boa atividade antioxidante e o excelente resultado para a inibição da AChE incentivam outras análises para determinação dos compostos ativos nas demais frações, sugerindo o fracionamento bioguiado como uma ferramenta de suma importância na análise fitoquímica e biológica de Lippia hirta.

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Electrochemical study of the anodic oxidation of terpinenes at the electrode and by homogeneous redox catalysis

Cited by 9 publications

References 15 publications

Homogeneously Catalyzed Electroreduction of Carbon Dioxide—Methods, Mechanisms, and Catalysts

Homogeneously Catalyzed Electroreduction of Carbon Dioxide—Methods, Mechanisms, and Catalysts

Unusual Antioxidant Behavior of α- and γ-Terpinene in Protecting Methyl Linoleate, DNA, and Erythrocyte

Investigation of Antioxidant Activity, Acute Toxicity and Anticholinesterasic Potential of Lippia hirta (Verbenaceae)

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