Electrophilic Reactions of Phenols

Reddy, V. Prakash; Prakash, G. K. Surya

doi:10.1002/9780470682531.pat0285

Cited by 4 publications

(4 citation statements)

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“…The electrophilic-mediated pathway involving hydroxyl radicals or direct hole oxidation is also confirmed by the predominance of the ortho-dihydroxylated degradation intermediate (catechol). The preferential formation of hydroquinone over benzoquinone was also quite expected, considering the hydrophilic character of all the catalysts (Prakash Reddy and Surya Prakash, 2003;Matos et al, 2010). As for the catalyst loading, it seemed to have a small effect on the photocatalytic efficiency (though more pronounced for WO3/CNT), other than a slight increase in the amount of intermediates.…”

Section: Phenol Photodegradationmentioning

confidence: 63%

“…According to literature, phenol is preferentially adsorbed on hydrophobic carbon surfaces via the interaction between the aromatic ring with the adsorbent's surface. Thus, the aromatic ring is easily oxidized via an electrophilic attach of hydroxyl radicals formed upon oxidation of water by the holes, inducing the opening of the aromatic ring to preserve the double bond conjugation (Prakash Reddy and Surya Prakash, 2003). The electrophilic-mediated pathway involving hydroxyl radicals or direct hole oxidation is also confirmed by the predominance of the ortho-dihydroxylated degradation intermediate (catechol).…”

Section: Phenol Photodegradationmentioning

confidence: 96%

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Carbon Materials as Additives to WO3 for an Enhanced Conversion of Simulated Solar Light

et al. 2016

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We have explored the impact of the incorporation of nanoporous carbons as additives to tungsten oxide on the photocatalytic degradation of two recalcitrant pollutants: rhodamine B (RhB) and phenol, under simulated solar light. For this purpose, WO3/ carbon mixtures were prepared using three carbon materials with different properties (in terms of porosity, structural order and surface chemistry). Despite the low carbon content used (2 wt.%), a significant increase in the photocatalytic performance of the semiconductor was observed for all the catalysts. Moreover, the influence of the carbon additive on the performance of the photocatalysts was found to be very different for the two pollutants. Carbon additives of hydrophobic nature increased the photodegradation yield of phenol compared to bare WO3, likely due to the higher affinity and stronger interactions of phenol molecules toward basic nanoporous carbons. Oppositely, the use of acidic carbon additives led to higher RhB conversions due to increased acidity of the WO3/carbon mixtures and the stronger affinity of the pollutant for acidic catalyst's surfaces. As a result, the photooxidation of RhB is favored by means of a coupled (photosensitized and photocatalytic) degradation mechanism. All these results highlight the importance of favoring the interactions of the pollutant with the catalyst's surface through a detailed design of the features of the photocatalyst.

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Section: Phenol Photodegradationmentioning

confidence: 63%

Section: Phenol Photodegradationmentioning

confidence: 96%

Carbon Materials as Additives to WO3 for an Enhanced Conversion of Simulated Solar Light

et al. 2016

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“…La escoria granulada de alto horno (del inglés "granulated blast furnace", GBFS) es un subproducto de la industria del acero. Se compone principalmente de silicatos y aluminosilicatos cálcicos y es de particular interés por sus propiedades hidráulicas latentes que se pueden desarrollar al combinarse con cemento Portland, cal o agentes alcalinos Prakash;Reddy, Misra, 2007;Gutt;Nixon, 1979). GBFS se ha utilizado con éxito en la estabilización de suelos expansivos.…”

Section: Estabilización De Suelos Utilizando Escorias Siderúrgicas Deunclassified

Estabilización química de suelos - Materiales convencionales y activados alcalinamente (revisión)

Rivera

Aguirre-Guerrero

Gutiérrez

et al. 2020

Inf.Tec

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El creciente interés por el desarrollo de alternativas frente al uso masivo de cementantes tradicionales en aplicaciones geotécnicas, tales como cemento y cal, se debe en gran medida a los retos ambientales y costos asociados en este tipo de aplicaciones. Los cementantes activados alcalinamente surgen como una de las alternativas de mayor sostenibilidad, particularmente por su bajo consumo energético y en teoría la baja huella de carbono en su fabricación; además, tienen la posibilidad de utilizar residuos y subproductos industriales como materiales precursores en su fabricación. Este artículo presenta un estado del arte de los diversos materiales empleados convencionalmente en la estabilización química de suelos y realiza una revisión de los artículos publicados en relación con la implementación de cementantes activados alcalinamente, su viabilidad técnica, los impactos ambientales asociados y los retos que se deben superar para lograr posicionarlos como una alternativa sostenible para procesos geotécnicos.

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“…Data also showed a marked accumulation of phenol degradation subproducts in the solution during the consecutive photocatalytic runs. The lower photooxidation extent of polyhydroxylated intermediates -compared to phenol itself-indicates the preferential reactivity of the radicals towards the monosubstituted aromatic ring [85], which is characteristic of electrophilic mediated mechanisms. The higher concentrations of catechol over the cycles confirmed the regioselective oxidation mechanism via the preferential substitution in ortho-(i.e., catechol) over meta-or para-(i.e.…”

Section: Photocatalytic Cyclesmentioning

confidence: 99%

Metal‐Free Nanoporous Carbons in Photocatalysis

Gomis‐Berenguer

Ania

2018

Carbon‐Based Metal‐Free Catalysts

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Evidences on the photochemical activity of semiconductor and metal-free nanoporous carbons upon irradiation in aqueous environments have opened new opportunities for these materials in photocatalysis, beyond their conventional use as inert supports of semiconductors. The aim of this chapter is to review the recent progress on the photocatalytic performance of nanoporous carbons under different illumination conditions, discussing the photochemical quantum yield of carbons of varied nature and physicochemical features towards the photodegradation of pollutants in water. The tight confinement inside the nanopores is important to minimize surface recombination and to increase the lifetime of the excitons photogenerated upon irradiation of the nanoporous carbons. Furthermore, matching of the molecular dimensions of the compound confined in the porosity of the carbon boosts the light conversion towards the visible spectrum. The composition of the nanoporous carbon is also essential for the stabilization of the charge carriers, and to promote additional transfer reactions involving chromophoric surface moieties decorating the carbon matrix that are capable of generating vacancies upon irradiation under sunlight. Some progress is yet to be done towards the understanding of the fundamentals of the light/carbon/molecule interactions to design photoactive nanoporous carbons with optimized features for an enhanced photocatalytic response under solar light.

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Electrophilic Reactions of Phenols

Abstract: Introduction F riedel– C rafts Alkylation F riedel– C rafts Acylations Nitration and Nitrosation F ries and Related Rearrangements Electrophilic Halogenation … Show more

Cited by 4 publications

References 152 publications

Carbon Materials as Additives to WO3 for an Enhanced Conversion of Simulated Solar Light

Carbon Materials as Additives to WO3 for an Enhanced Conversion of Simulated Solar Light

Estabilización química de suelos - Materiales convencionales y activados alcalinamente (revisión)

Metal‐Free Nanoporous Carbons in Photocatalysis

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