<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Srivastava, R</style></author><author><style face="normal" font="default" size="100%">Srinivas, D</style></author><author><style face="normal" font="default" size="100%">Ratnasamy, P</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">CO2 activation and synthesis of cyclic carbonates and alkyl/aryl carbamates over adenine-modified Ti-SBA-15 solid catalysts</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of Catalysis</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">activation of CO2</style></keyword><keyword><style  face="normal" font="default" size="100%">CO2 fixation</style></keyword><keyword><style  face="normal" font="default" size="100%">DRIFTIR spectroscopy of adsorbed pyridine and CO2</style></keyword><keyword><style  face="normal" font="default" size="100%">organo-functionalized mesoporous silica</style></keyword><keyword><style  face="normal" font="default" size="100%">phosgene-free synthesis</style></keyword><keyword><style  face="normal" font="default" size="100%">synthesis of carbamates</style></keyword><keyword><style  face="normal" font="default" size="100%">synthesis of cyclic carbonates</style></keyword><keyword><style  face="normal" font="default" size="100%">temperature-programmed desorption of NH3 and CO2 titanosilicates</style></keyword><keyword><style  face="normal" font="default" size="100%">Ti-SBA-15</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2005</style></year><pub-dates><date><style  face="normal" font="default" size="100%">JUL</style></date></pub-dates></dates><number><style face="normal" font="default" size="100%">1</style></number><publisher><style face="normal" font="default" size="100%">ACADEMIC PRESS INC ELSEVIER SCIENCE</style></publisher><pub-location><style face="normal" font="default" size="100%">525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA</style></pub-location><volume><style face="normal" font="default" size="100%">233</style></volume><pages><style face="normal" font="default" size="100%">1-15</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Cyclic carbonates were synthesized by the cycloaddition Of CO2 to epoxides (epichlorohydrin, propene oxide, and styrene oxide), and carbamates were synthesized by reaction of alkyl or aryl amines, CO2, and n-butyl bromide. Solvents and cocatalysts/promoters, like N,N-dimethylaminopyridine (DMAP) and quaternary ammonium salts, which are usually essential with conventional catalyst systems, could be avoided with the use of adenine-modi lied Ti-SBA-15 catalysts. The catalysts were reused in several recycle experiments. The structural and textural properties of the catalysts were determined by X-ray diffraction (XRD), transmission electron microscopy (TEM), N-2 adsorption, and Fourier transform infrared (FTIR) and diffuse reflectance ultraviolet-visible (UV-vis DRS) techniques. Acid-base properties of the solid catalysts were investigated by temperature-programmed desorption (TPD) of NH3 and CO2 and DRIFTIR spectroscopy of adsorbed pyridine and CO2 techniques. The studies reveal that the Ti4+ ions increase catalytic activity by enhancing the adsorption of the epoxide and alkyl or aryl amine substrates. CO2 molecules are activated at the basic nitrogen groups of adenine. Increasing the surface concentrations of either CO2 (by anchoring basic molecules like adenine or increasing the partial pressure of CO2) or epoxides and alkyl or aryl amines (by increasing the concentration of Lewis acidic Ti4+ ions) enhances the catalytic activity. CO2 molecules activated at the covalently anchored adenine sites react with epoxide/amines adsorbed on the silica surface to form carbonates/carbamates. (c) 2005 Elsevier Inc. All rights reserved.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">1</style></issue><work-type><style face="normal" font="default" size="100%">Article</style></work-type><custom3><style face="normal" font="default" size="100%">&lt;p&gt;Foreign&lt;/p&gt;</style></custom3><custom4><style face="normal" font="default" size="100%">7.354</style></custom4></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Ratnasamy, P</style></author><author><style face="normal" font="default" size="100%">Raja, R</style></author><author><style face="normal" font="default" size="100%">Srinivasi, D</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Novel, benign, solid catalysts for the oxidation of hydrocarbons</style></title><secondary-title><style face="normal" font="default" size="100%">Philosophical Transactions of the Royal Society A - Mathematical, Physical and Engineering Sciences</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">benign catalytic oxidations</style></keyword><keyword><style  face="normal" font="default" size="100%">encapsulated metal complexes</style></keyword><keyword><style  face="normal" font="default" size="100%">Solid catalysts</style></keyword><keyword><style  face="normal" font="default" size="100%">titanosilicate molecular sieves</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2005</style></year><pub-dates><date><style  face="normal" font="default" size="100%">APR</style></date></pub-dates></dates><number><style face="normal" font="default" size="100%">1829</style></number><publisher><style face="normal" font="default" size="100%">ROYAL SOCIETY</style></publisher><pub-location><style face="normal" font="default" size="100%">6-9 CARLTON HOUSE TERRACE, LONDON SW1Y 5AG, ENGLAND</style></pub-location><volume><style face="normal" font="default" size="100%">363</style></volume><pages><style face="normal" font="default" size="100%">1001-1012</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;The catalytic properties of two classes of solid catalysts for the oxidation of hydrocarbons in the liquid phase are discussed: (i) microporous solids, encapsulating transition metal complexes in their cavities and (ii) titanosilicate molecular sieves. Copper acetate dimers encapsulated in molecular sieves Y, AICM-22 and VPI-5 use dioxygen to regioselectively ortho-hydroxylate L-tyrosine to L-dopa, phenol to catechol and cresols to the corresponding o-dihydroxy and o-quinone compounds. Monomeric copper phthalocyanine and salen complexes entrapped in zeolite-Y oxidize methane to methanol, toluene to cresols, naphthalene to naphthols, xylene to xylenols and phenol to diphenols. Trimeric mu(3)-oxo-bridged Co/Mn cluster complexes, encapsulated inside Y-zeolite, oxidize para-xylene, almost quantitatively, to terephthalic acid. In almost all cases, the intrinsic catalytic activity (turnover frequency) of the metal complex is enhanced very significantly, upon encapsulation in the porous solids. Spectroscopic and electrochemical studies suggest that the geometric distortions of the complex on encapsulation change the electron density at the metal ion site and its redox behaviour, thereby influencing its catalytic activity and selectivity in oxidation reactions. Titanosilieate molecular sieves can oxidize hydrocarbons using dioxygen when loaded with transition metals like Pd, An or Ag. The structure of surface Ti ions and the type of oxo-Ti species generated on contact with oxidants depend on several factors including the method of zeolite synthesis, zeolite structure, solvent, temperature and oxidant. Although, similar oxo-Ti species are present on all the titanosilicates, their relative concentrations vary among different structures and determine the product selectivity.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">1829</style></issue><work-type><style face="normal" font="default" size="100%">Article</style></work-type><custom3><style face="normal" font="default" size="100%">&lt;p&gt;Foreign&lt;/p&gt;</style></custom3><custom4><style face="normal" font="default" size="100%">2.441</style></custom4></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Shetti, VN</style></author><author><style face="normal" font="default" size="100%">Srinivas, D</style></author><author><style face="normal" font="default" size="100%">Ratnasamy, P</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Ti-oxo radicals and product selectivity in olefin oxidations over titanosilicate molecular sieves</style></title><secondary-title><style face="normal" font="default" size="100%">Zeitschrift für Physikalische Chemie International Journal of Research in Physical Chemistry and Chemical Physics</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">cyclic voltammetry of titanosilicates</style></keyword><keyword><style  face="normal" font="default" size="100%">EPR-spin trap experiments</style></keyword><keyword><style  face="normal" font="default" size="100%">Molecular sieves</style></keyword><keyword><style  face="normal" font="default" size="100%">oxidations</style></keyword><keyword><style  face="normal" font="default" size="100%">product selectivity</style></keyword><keyword><style  face="normal" font="default" size="100%">reactive oxygen species</style></keyword><keyword><style  face="normal" font="default" size="100%">titaniunz-oxo radicals</style></keyword><keyword><style  face="normal" font="default" size="100%">Titanosilicates</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2005</style></year><pub-dates><date><style  face="normal" font="default" size="100%">JUL</style></date></pub-dates></dates><number><style face="normal" font="default" size="100%">7</style></number><publisher><style face="normal" font="default" size="100%">OLDENBOURG VERLAG</style></publisher><pub-location><style face="normal" font="default" size="100%">LEKTORAT MINT, POSTFACH 80 13 60, D-81613 MUNICH, GERMANY</style></pub-location><volume><style face="normal" font="default" size="100%">219</style></volume><pages><style face="normal" font="default" size="100%">905-920</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;The O-O bond of Ti-oxo species (Ti-peroxo, Ti-hydroperoxo or Ti-superoxo) generated on titanosilicate molecular sieves contacted with H2O2 cleaves either heterolytically or homolytically. While the former type of O-O cleavage (generating non-radical reactive oxygen intermediates) leads to selective epoxide products, the latter (generating reactive oxygen radical intermediates, O-2(-center dot) and HOOcenter dot) results in non-sclective, allylic oxidation products in cyclohexene oxidation. These radicals were detected using EPR spin trapping techniques 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was used as the spin trap. Radical quenchers like hydroquinone suppressed their concentration and enhanced epoxide selectivity.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">7</style></issue><work-type><style face="normal" font="default" size="100%">Article</style></work-type><custom3><style face="normal" font="default" size="100%">&lt;p&gt;Foreign&lt;/p&gt;</style></custom3><custom4><style face="normal" font="default" size="100%">1.133</style></custom4></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Srivastava, R</style></author><author><style face="normal" font="default" size="100%">Srinivas, D</style></author><author><style face="normal" font="default" size="100%">Ratnasamy, P</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Zeolite-based organic-inorganic hybrid catalysts for phosgene-free and solvent-free synthesis of cyclic carbonates and carbamates at mild conditions utilizing CO2</style></title><secondary-title><style face="normal" font="default" size="100%">Applied Catalysis A - General</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">alkyl and aryl carbamates</style></keyword><keyword><style  face="normal" font="default" size="100%">carbon dioxide utilization</style></keyword><keyword><style  face="normal" font="default" size="100%">cyclic carbonate</style></keyword><keyword><style  face="normal" font="default" size="100%">phosgene-free synthetic route</style></keyword><keyword><style  face="normal" font="default" size="100%">Polycarbonate</style></keyword><keyword><style  face="normal" font="default" size="100%">zeolite-beta</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2005</style></year><pub-dates><date><style  face="normal" font="default" size="100%">AUG</style></date></pub-dates></dates><number><style face="normal" font="default" size="100%">2</style></number><publisher><style face="normal" font="default" size="100%">ELSEVIER SCIENCE BV</style></publisher><pub-location><style face="normal" font="default" size="100%">PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS</style></pub-location><volume><style face="normal" font="default" size="100%">289</style></volume><pages><style face="normal" font="default" size="100%">128-134</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;As-synthesized zeolite-beta exhibits high catalytic activity for the synthesis of cyclic carbonates and alkyl and aryl carbarnates by a phosgene-free route, utilizing the greenhouse effect gas CO2. The reaction occurs with high yields of the desired products at mild conditions and without using any solvent or cocatalyst. Cyclic carbonates are synthesized by cycloaddition reaction Of CO2 with oxiranes (epichlorohydrin, propene oxide, styrene oxide and n-butene oxide) at 393 K and 6.9 bar. Alkyl and aryl carbarnates are synthesized by the reaction of the corresponding amines, CO2 and n-butyl bromide at 353 K and 3.4 bar. The as-synthesized zeolite-beta containing the encapsulated quaternary ammonium ions is not only reusable in several recycling experiments, but also shows superior activity to that of the corresponding homogeneous, quaternary ammonium halide salt generally used in the commercial synthetic practice. The microporous silica (inorganic) acting in concert with the encapsulated organic component constitutes an efficient, recyclable catalyst for this reaction. (c) 2005 Elsevier B.V. All rights reserved.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">2</style></issue><custom3><style face="normal" font="default" size="100%">&lt;p&gt;Foreign&lt;/p&gt;</style></custom3><custom4><style face="normal" font="default" size="100%">4.012</style></custom4></record></records></xml>