02106nas a2200253   4500008004100000022001400041245019400055210006900249260007300318300001200391490000800403520111100411653002601522653002201548653001701570653001401587100001601601700002501617700002101642700002401663700001901687700001801706856012801724       2009                        eng d  a1381-116900aCatalytic meerwein-ponndorf-verley reductions over mesoporous silica supports: rational design of hydrophobic mesoporous silica for enhanced stability of aluminum doped mesoporous catalysts0 aCatalytic meerweinponndorfverley reductions over mesoporous sili  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAR  a118-1260 v3013 a<p>A series of aluminum isopropoxide-grafted mesoporous organosilica having ethane (-CH(2)-CH(2)-) and ethene (-CH=CH-) groups in the frame wall positions (ethane-silica, ethene-silica) as well as mesoporous silicas (MCM-41, MCM-48. SBA-15) through siloxide linkages were fabricated. The samples were used as catalysts in the Meerwein-Ponndorf-Verley reduction of ketones and aldehydes of different nature and size using secondary alcohols as the hydrogen transfer agents. Aluminum isopropoxide supported mesoporous silica samples show higher catalytic conversion and among them, the one-dimensionally channel oriented Si-MCM-41 supported aluminum isopropoxide shows better results than the three-dimensional Si-MCM-48 and the large pore Si-SBA-15. Compared to aluminum isopropoxide-grafted mesoporous silica samples, aluminum alkoxide-grafted organosilica samples shows better catalytic activity even in the presence of 10% of water and the better stability is attributed to the presence of integrated hydrophobic organic groups in the frame wall positions. (C) 2008 Elsevier B.V. All rights reserved.</p>10aAluminum isopropoxide10aMesoporous silica10aOrganosilica10areduction1 aShylesh, S.1 aKapoor, Mahendra, P.1 aJuneja, Lekh, R.1 aSamuel, Prinson, R.1 aSrilakshmi, Ch1 aSingh, A., R.  uhttps://library.ncl.res.in/content/catalytic-meerwein-ponndorf-verley-reductions-over-mesoporous-silica-supports-rational-002068nas a2200241   4500008004100000022001400041245010400055210006900159260009200228300001200320490000600332520118900338653001401527653002501541653002701566653001801593100001601611700002501627700002101652700002001673700001801693856011501711       2011                        eng d  a1941-490000aSynthesis and characterization of bifunctional ethenylene bridged mesoporous organoaluminosilicates0 aSynthesis and characterization of bifunctional ethenylene bridge  a26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USAbAMER SCIENTIFIC PUBLISHERScAUG  a497-5020 v33 a<p>Bifunctional mesoporous organosilicas having -CH=CH- bridges and aluminium in tetrahedral coordination with tailorable pore sizes have been synthesized using a one-step templating method using cationic surfactants of different chain lengths. Unlike the conventional EtOH-HCl template extraction process, EtOH-NH(4)NO(3) was used as the surfactant-extracting medium and chemical analysis results suggest that through this procedure the mesoporous structure can be retained and dealumination can be minimized. The surfactant-extracted mesoporous solids display high surface area, pore volume and the pore size of the material varies in the range 2.6-3.6 nm, with respect to the alkyl chain length of the cationic surfactant. XRD and nitrogen physisorption studies further proved that the organosilicas are hydro thermally stable than the conventional Al-MCM-41 materials and their better stability is attributed to the thick pore walls as well as due to the presence of hydrophobic bridging ethenylene groups in the wall positions. The coupling of Al(4) with -CH=CH- bridges offer new prospects for the application of periodic mesoporous organosilicas in heterogeneous catalysis.</p>10aAluminium10aCationic Surfactants10aHydrothermal stability10aOrganosilicas1 aShylesh, S.1 aKapoor, Mahendra, P.1 aJuneja, Lekh, R.1 aSrilakshmi, Ch.1 aSingh, A., P.  uhttps://library.ncl.res.in/content/synthesis-and-characterization-bifunctional-ethenylene-bridged-mesoporous-0