Aqueous medium Ullmann reaction over a novel Pd/Ph–Al-MCM-41 as a new route of clean organic synthesis

Li, Hexing; Chen, Jia; Wan, Ying; Chai, Wei; Zhang, Fang; Lu, Yunfeng

doi:10.1039/b612370h

Cited by 46 publications

(22 citation statements)

References 29 publications

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“…A similar result has been obtained by Li et al during the Ullmann reaction over a Pd-containing Al-MCM-41 catalyst. [30] This observation is in contrast to the results of Neri et al [9] who observed a significant decrease in the se- Figure 6. Effect of Pd dispersion and Si/Al ratio on phenol conversion and cyclohexanone selectivity over Pd catalyst.…”

Section: Effect Of Si/al Ratiocontrasting

confidence: 65%

Hydrogenation of Phenol in Supercritical Carbon Dioxide Catalyzed by Palladium Supported on Al‐MCM‐41: A Facile Route for One‐Pot Cyclohexanone Formation

Chatterjee¹,

Kawanami²,

Sato³

et al. 2009

Adv Synth Catal

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The hydrogenation of phenol has been carried out in supercritical carbon dioxide (scCO 2 ) under very mild reaction conditions at the temperature of 50 8C over palladium supported Al-MCM-41 (metal loading~1%). This palladium catalyst is shown to be highly active and promotes the selective formation of cyclohexanone (~98%), an industrially important compound, in a "one-pot" way. The effects of different variables like carbon dioxide and hydrogen pressure, reaction time and also silica/alumina ratio of the MCM-41 support along with palladium dispersion are presented and discussed. The pressure effect of carbon dioxide is significantly prominent in terms of conversion and cyclohexanone selectivity. Moreover, the silica/alumina ratio was also found to be an important parameter to enhance the effectiveness of the catalyst as it exhibits a remarkable increase in phenol conversion from 20.6% to 98.4% as the support changes from only silica MCM-41 to Al-MCM-41. A plausible mechanism for the hydrogenation of phenol to cyclohexanone over the palladium catalyst has been proposed. The proposition is validated by transition state calculations using density functional theory (DFT), which reveal that cyclohexanone is a favorable product and stabilized by < 19 kcal mol À1 over cyclohexanol in scCO 2 medium. Under similar reaction conditions, phenol hydrogenation was also carried out with rhodium, supported on Al-MCM-41. In contrast to the palladium catalyst, a mixture of cyclohexanone (57.8%) and cyclohexanol (42.2%) was formed. Detailed characterization by X-ray diffraction and transmission electron microscopy confirmed the presence of metal nanoparticles (palladium and rhodium) between 10-20 nm. Both the catalysts exhibit strikingly different product distributions in solventless conditions compared to scCO 2 . This method can also be successfully applied to the other hydroxylated aromatic compounds.

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Section: Effect Of Si/al Ratiocontrasting

confidence: 65%

Hydrogenation of Phenol in Supercritical Carbon Dioxide Catalyzed by Palladium Supported on Al‐MCM‐41: A Facile Route for One‐Pot Cyclohexanone Formation

Chatterjee¹,

Kawanami²,

Sato³

et al. 2009

Adv Synth Catal

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“…A number of reports have been published till date about Ullmann reaction in aqueous media to provide a green route for synthesis of biphenyls over heterogeneous catalysts. Ullmann reaction of iodobenzene to form biaryl with maximum ~80% yield and high selectivity in water as solvent was carried out over a novel Pd doped Ph and Al-functionalized MCM-41 catalyst 137. Coupling of substituted chlorobenzene over heterogeneous palladium catalysts, supported on ordered mesoporous silica-carbon nanocomposites was carried out both at normal and elevated…”

mentioning

confidence: 99%

Mesoporous materials: versatile supports in heterogeneous catalysis for liquid phase catalytic transformations

2015

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This review article provides an overview of the literature reported for several important liquid phase heterogeneous catalytic transformations performed over a wide range of mesoporous materials along with a brief outline of their surfactant-assisted synthesis and its pivotal role in the environment-friendly green catalysis.ABSTRACT: Due to their unprecedented intrinsic structural features, like tunable pore diameter of nanoscale dimensions, huge BET surface areas, good flexibility to recognize/accommodate various functional groups and metals onto the surface an inevitable linkage between nanoporous materials and catalysis has been built-up over past few decades. As a result of which a huge numbers of communications and articles dealing with these materials with nanoscale porosity have came to light. In this review, our objective is to provide a comprehensive overview on mesoporous solids, most remarkable member of nanoporous family of materials, the general strategy for their syntheses and application of those functionalized porous materials in the liquid phase catalytic reactions. In the latter part, role of catalytic centres in various organic transformations over these functionalized mesoporous materials and their economical, environmental and industrial aspects are described in detail.

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“…In 2007, the same group develops a new supported Pd catalyst using the mesophorous Ph-Al-MCM-41 as the support, which exhibit high activity and selectivity, as well as strong durability during a water-medium iodobenzene Ullmann reaction [28].…”

Section: Green Technologiesmentioning

confidence: 99%

Recent advancement of Ullmann-type coupling reactions in the formation of C–C bond

Mondal¹

2016

ChemTexts

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The present text discussed about the recent developments and applications of the Ullmann reaction in respect of the C-C bond formation. The major drawback of the Ullmann reaction, i.e., harsh reaction condition has recently been overcome with the development of various synthetic methodologies. Green synthetic methodologies such as metal-, ligand-, and additive free conditions, recyclable heterogenous catalysts, microwave-and ultrasoundassisted synthesis, etc. have got special importance in this field. This text lucidly describes all these recently developed synthetic methodologies which make the century old Ullmann reaction much efficient, effective, economical and attractive in the field of synthetic organic chemistry. Onsurface Ullmann coupling for the C-C bond formation, i.e., invoking C-C coupling reactions on a reactive surface has been discussed. All such developments of the Ullmann C-C coupling facilitate its application in the synthesis of bioactive heterocycles, drug-like molecules and natural products which has also been discussed in this text.

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Aqueous medium Ullmann reaction over a novel Pd/Ph–Al-MCM-41 as a new route of clean organic synthesis

Cited by 46 publications

References 29 publications

Hydrogenation of Phenol in Supercritical Carbon Dioxide Catalyzed by Palladium Supported on Al‐MCM‐41: A Facile Route for One‐Pot Cyclohexanone Formation

Hydrogenation of Phenol in Supercritical Carbon Dioxide Catalyzed by Palladium Supported on Al‐MCM‐41: A Facile Route for One‐Pot Cyclohexanone Formation

Mesoporous materials: versatile supports in heterogeneous catalysis for liquid phase catalytic transformations

Recent advancement of Ullmann-type coupling reactions in the formation of C–C bond

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