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Yadav, Ganapati D.; Nair, Jayakrishnan

doi:10.1023/a:1019066131736

Cited by 52 publications

(43 citation statements)

References 13 publications

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“…Several catalysts have been reported for nitration of chlorobenzene which include Cu(NO 3 ) 2 /K-10, HNO 3 /silica-alumina, HNO 3 supported on H-ZSM-5, zeolite b and HNO 3 supported on SiO 2 molecular sieves amongst which zeolite b was reported to give the best para selectivity of about 93%. Yadav and Nair reported a series of supported or modified catalysts such as 20% DTP/K10 and UDCaT-2 to get better selectivity in nitration of chlorobenzene and toluene, the latter being better shape selective catalyst (Table 20) [78]. [79].…”

Section: Nitration Of Chlorobenzenementioning

confidence: 99%

Synergism of Clay and Heteropoly Acids as Nano-Catalysts for the Development of Green Processes with Potential Industrial Applications

Yadav

2005

Catal Surv Asia

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133

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A large number of inorganic oxides, mixed oxides, including alumina, silica, titania, zirconia, zeolites, carbon, clays and ion exchange resins have been employed as both supports and solid acid catalysts. Clay structure collapses at high temperatures and has to be stablilized. The thermal stability and pore size issues were addressed by pillaring of clays. Natural clays are acid treated or ionexchanged to be used as solid acids, and the acidity and pore structure are dependent on the treatment methodology. Another important class of catalysts is the heteropoly acids (HPA), which are employed as homogeneous or heterogeneous catalysts, having both acid and redox properties. The focus of the current paper is to address the work done in our laboratory on the synergism between clays and heteropoly acids for the development of green processes. A comparison is also provided for the activity of these catalysts with other solid acids. Several alkylation, acylation, isomerization, condensation, dehydration, esterification, nitration and oxidation reactions which are useful in a wide spectrum of industries such as bulk, intermediates, dyes, plasticizer, pharmaceuticals, perfumes, flavours and other fine chemicals were investigated to improve the selectivity of the desired products.

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Section: Nitration Of Chlorobenzenementioning

confidence: 99%

Synergism of Clay and Heteropoly Acids as Nano-Catalysts for the Development of Green Processes with Potential Industrial Applications

Yadav

2005

Catal Surv Asia

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133

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“…A Brønsted acid (Zr-OH) site on the ZrO 2 surface is considered to act as an activator for Qs as electrophiles. 30,54,55) …”

Section: Cmentioning

confidence: 99%

Reactions of 1-Naphthols with .PI.-Acceptor p-Benzoquinones: Oxidative Aryl Coupling vs. Non-Oxidative Electrophilic Arylation

Takeya

Kondo

Otsuka

et al. 2005

CHEMICAL & PHARMACEUTICAL BULLETIN

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We investigated the reactions of various 1-naphthols (NPOHs; 1) with p-benzoquinones (Qs), such as 1,4-benzoquinone (BQ) and p-chloranil (CA), as p p-electron acceptors. With electron-rich NPOHs 1a-c, oxidative biaryl coupling and subsequent dehydrogenation reaction took place selectively to give the corresponding 2,2Ј-binapthyl-1,1Ј-quinones 3a-c in excellent yield. In the case of electron-deficient NPOHs 1e, f, two different types of reactions occurred in the presence of SnCl 4 and ZrO 2 under similar conditions: SnCl 4 mediated oxidative dimerization and trimerization of NPOH, while ZrO 2 promoted electrophilic arylation of Qs with NPOH. The resulting products 3 would be useful synthetic intermediates for naturally occurring diosindigo B, biramentaceone and violet-quinone.

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“…Its activity at temperatures as low as room temperature [1] has evoked commercial interest. In the past decades, extensive efforts have been devoted to the investigation of those bulk structural and surface properties of sulfated zirconia that affect the catalytic activity [4,5]. It has been demonstrated that the zirconia phase composition, the sulfur content, the surface area, and the addition of a second metal oxide component as a promoter are all properties that influence the maximum activity of this type of catalyst [1][2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Characterization of catalysts in their active state by adsorption microcalorimetry: Experimental design and application to sulfated zirconia

Wrabetz

Yang

Tzolova-Müller

et al. 2010

Journal of Catalysis

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A method to characterize the surface sites of catalysts in their active state by adsorption microcalorimetry was developed. A calorimeter cell was used as a flow-type reactor, and the skeletal isomerization of n-butane (1 kPa) at 378 K and atmospheric pressure proceeded at comparable rates and with the same states of induction period, maximum and deactivation phase as in a tubular reactor. The reaction was run for selected times on stream and after removal of weakly adsorbed species, n-butane or isobutane were adsorbed at 313 K. The surface of activated sulfated zirconia was characterized by at least two different sites for n-butane adsorption, a small group of sites (about 20 µmol g -1 ) that yielded heats of 5060 kJ mol -1 and sites that were populated at higher pressures (above about 5 hPa n-butane) and yielded heats of about 40 kJ mol -1 . The strongly interacting sites disappear during the induction period and are proposed to be the sites where the isomerization reaction is initiated.

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Cited by 52 publications

References 13 publications

Synergism of Clay and Heteropoly Acids as Nano-Catalysts for the Development of Green Processes with Potential Industrial Applications

Synergism of Clay and Heteropoly Acids as Nano-Catalysts for the Development of Green Processes with Potential Industrial Applications

Reactions of 1-Naphthols with .PI.-Acceptor p-Benzoquinones: Oxidative Aryl Coupling vs. Non-Oxidative Electrophilic Arylation

Characterization of catalysts in their active state by adsorption microcalorimetry: Experimental design and application to sulfated zirconia

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