02638nas 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<p>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+ -&gt; 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.</p>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-001310nas a2200217   4500008004100000022001400041245014200055210006900197260007300266300001200339490000800351520045600359653001400815653002100829653003000850653002800880653001700908100002600925700001400951856012700965       2009                        eng d  a1387-181100aAcylation of nitrobenzene and substituted nitrobenzenes by benzoyl chloride using GaClx- and GaAlClx-grafted meporous Si-MCM-41 catalysts0 aAcylation of nitrobenzene and substituted nitrobenzenes by benzo  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAR  a360-3620 v1193 a<p>A acylation of nitrobenzene and substituted nitrobenzene by benzoyl chloride can be accomplished with good yield in a short reaction period (&lt;= 3 h), even in the presence of moisture, using GaClx- and GaAlClx-grafted mesoporous silica (Si-MCM-41) catalyst. The catalyst is reusable/environmentally friendly. The presence of moisture in the catalyst has beneficial effect on the acylation reaction. (C) 2008 Elsevier Inc. All rights reserved.</p>10aAcylation10aBenzoyl chloride10aGaAlClx-grafted Si-MCM-4110aGaClx-grafted Si-MCM-4110anitrobenzene1 aChoudhary, Vasant, R.1 aJha, Rani  uhttps://library.ncl.res.in/content/acylation-nitrobenzene-and-substituted-nitrobenzenes-benzoyl-chloride-using-gaclx-and-0