01083nas a2200193 4500008004100000022001400041245016200055210006900217260011000286300001200396490000600408520025500414100002600669700001300695700001800708700001400726700001900740856013000759 2005 eng d a1463-926200aGreen process for chlorine-free benzaldehyde from the solvent-free oxidation of benzyl alcohol with molecular oxygen over a supported nano-size gold catalyst0 aGreen process for chlorinefree benzaldehyde from the solventfree aTHOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLANDbROYAL SOC CHEMISTRYcOCT a768-7700 v73 a

Benzyl alcohol is oxidized selectively to benzaldehyde with high yield, with a little formation of benzylbenzoate, by molecular oxygen over a reusable nano-size gold catalyst supported on U3O8, MgO, Al2O3 or ZrO2 in the absence of any solvent.

1 aChoudhary, Vasant, R.1 aDhar, A.1 aJana, Prabhas1 aJha, Rani1 aUphade, B., S. uhttps://library.ncl.res.in/content/green-process-chlorine-free-benzaldehyde-solvent-free-oxidation-benzyl-alcohol-molecular-002638nas a2200205 4500008004100000022001400041245017900055210006900234260007300303300001000376490000800386520175900394653002602153653003002179653002802209653002502237100002602262700001402288856013002302 2007 eng d a0926-860X00aGaClx- or GaAlClx-grafted Si-MCM-41: highly active and moisture insensitive/stable catalyst for the acylation and benzylation of benzene, naphthalene and substituted benzenes0 aGaClx or GaAlClxgrafted SiMCM41 highly active and moisture insen aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcDEC a42-480 v3333 a

GaClx- and GaAlClx-grafted Si-MCM-41 catalysts were prepared by reacting anhydrous GaCl3 and mixed anhydrous GaCl3 and AlCl3, respectively, with the terminal hydroxyl groups of Si-MCM-41 (pore size: 2.5 nm) in a dry non-aqueous reaction medium (CCl4) under reflux. The catalysts showed high activity for both the acylation and benzylation (with benzoyl chloride and benzyl chloride, respectively) of benzene, toluene, p-xylene, cumene, mesitylene, anisole and naphthalene. Both the catalysts are moisture insensitive or less moisture sensitive; the presence of moisture has a beneficial effect in the acylation over both the catalysts. The catalytically active sites of the GaClx-grafted Si-MCM-41 are (-O-)(2)GaCl (i.e. partially chlorided Ga anchored to Si through -O- linkage) species and the equivalent sites of the GaAlClx-grafted Si-MCM-41 are (-O-)(2)Ga(or Al)Cl and (-O-)(3)Ga(or Al) species. The high acylation/benzylation activities of both the catalysts even in the presence of moisture are attributed to their redox properties (Ga3+ -> Ga1+) rather than to their Lewis acid properties. After the grafting/chemical bonding, the grafted gallium chloride catalyst showed much higher acylation activity but lower benzylation activity than the physically deposited (on Si-MCM-41) or unsupported GaCl3. The GaAlClx-grafted Si-MCM-41 showed higher acylation activity than the GaClx-grafted Si-MCM-41, due to a synergetic effect of the Ga and Al species. However, the relative benzylation activity of the two catalysts showed strong dependence upon the presence or absence of electron donating group(s) and also upon the electron donating ability of the group(s) attached to the aromatic nucleus. (c) 2007 Elsevier B.V. All rights reserved.

10aacylation benzylation10aGaAlClx-grafted Si-MCM-4110aGaClx-grafted Si-MCM-4110amoisture insensitive1 aChoudhary, Vasant, R.1 aJha, Rani uhttps://library.ncl.res.in/content/gaclx-or-gaalclx-grafted-si-mcm-41-highly-active-and-moisture-insensitivestable-catalyst-002229nas a2200241 4500008004100000022001400041245017300055210006900228260007300297300001200370490000800382520125300390653003301643653002201676653002201698653002801720653002101748653002201769100002601791700001801817700002201835856013001857 2007 eng d a0926-860X00aGeneration of hydrogen peroxide via the selective reduction of oxygen by hydrazine sulfate over Br-promoted Pd/Al2O3 catalyst in an aqueous medium at ambient conditions0 aGeneration of hydrogen peroxide via the selective reduction of o aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAPR a202-2090 v3233 a

The in situ generation of H2O2 via the selective reduction of OZ by hydrazine sulfate (in an aqueous medium) has been thoroughly investigated over the Br-promoted Pd(or PdO)/Al2O3 catalyst. The influence of the following factors have been addressed in this study: (a) Br concentration (in the reaction medium or incorporated in the catalyst); (b) reaction conditions (viz. reaction time, temperature); (c) concentrations of reducing agent and phosphoric acid in the reaction medium. Decomposition of N2H4 (from NH4-H2SO4) and its reaction with H2O2 under similar reaction conditions (in the absence of O-2) have also been studied. H2O2, which is an intermediate product of the O-2 reduction, is involved in further consecutive reactions. It can be converted to water via its decomposition and/or reaction with the unconverted NZH(4). In the presence of Br promoter, the later (reaction with unconverted N2H4) is more dominant. Both the consecutive reactions are drastically retarded in the presence of protons and Br promoter. A plausible reaction mechanism has been proposed for illustrating the role of the protons and Br promoter in the selective formation of H2O2 in the O-2 reduction process. (C) 2007 Elsevier B.V. All rights reserved.

10abrominated Pd/Al2O3 catalyst10ahydrazine sulfate10aHydrogen peroxide10ain situ H2O2 generation10aoxygen reduction10aPd/Al2O3 catalyst1 aChoudhary, Vasant, R.1 aJana, Prabhas1 aSamanta, Chanchal uhttps://library.ncl.res.in/content/generation-hydrogen-peroxide-selective-reduction-oxygen-hydrazine-sulfate-over-br-promoted01616nas a2200193 4500008004100000022001400041245014200055210006900197260007300266300001400339490000600353520080100359653003001160653002901190653003201219100002601251700001401277856013101291 2008 eng d a1566-736700aGaAlCl(x)-grafted Mont.K-10 clay: highly active and stable solid catalyst for the friedel-crafts type benzylation and acylation reactions0 aGaAlClxgrafted MontK10 clay highly active and stable solid catal aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAR a1101-11050 v93 a

A liquid phase reaction of anhydrous GaCl(3) and AlCl(3) with the surface hydroxyl groups (with HCl evolution) of Mont. K-10 clay in dry CCL(4) under reflux resulted in a novel GaAlCl(x),-grafted Mont.K-10 catalyst [with Cl/(Ga + Al) = 1]. The catalyst showed high activity and stability in the Freidel-Crafts type benzylation and benzoylation (by benzyl chloride and benzoyl chloride, respectively) of benzene, naphthalene and substituted benzenes, even in the presence of moisture. It also showed good activity for the benzoylation of nitrobenzene (i.e. even in the presence of strong electron withdrawing group, like nitro group, attached to the benzene ring). The catalytically active surface species in the catalyst are -(O)(2)-Ga(or Al)Cl. (c) 2007 Elsevier B.V. All rights reserved.

10abenzoylation of aromatics10abenzylation of aromatics10aGaAlCl(x)-grafted Mont.K-101 aChoudhary, Vasant, R.1 aJha, Rani uhttps://library.ncl.res.in/content/gaalclx-grafted-montk-10-clay-highly-active-and-stable-solid-catalyst-friedel-crafts-type-001218nas a2200229 4500008004100000022001400041245010400055210006900159260008600228300001800314490000700332520037500339653001700714653001200731653000700743653003000750653000900780100002200789700002700811700002600838856012400864 2011 eng d a0039-791100aGreener ullmann-type coupling of aryl halides for preparing biaryls using reusable Pd/ZrO2 catalyst0 aGreener ullmanntype coupling of aryl halides for preparing biary a325 CHESTNUT ST, SUITE 800, PHILADELPHIA, PA 19106 USAbTAYLOR & FRANCIS INCcJAN aPII 9312497960 v413 a

Biaryls with excellent yields can be prepared by the Ullmann-type coupling of aryl halides in the presence of potassium carbonate (as a base) and dimethylformamide (as a solvent), at 140 degrees C, using a reusable Pd (2.5wt%)/ZrO2 catalyst. The product yield of 4-iodoanisole coupling is strongly influenced by the catalyst preparation method, solvent, and base.

10aAryl halides10aBiaryls10aPd10aUllmann coupling reaction10aZrO21 aDumbre, Deepa, K.1 aWakharkar, Radhika, D.1 aChoudhary, Vasant, R. uhttps://library.ncl.res.in/content/greener-ullmann-type-coupling-aryl-halides-preparing-biaryls-using-reusable-pdzro2-0