01884nas a2200253   4500008004100000022001400041245011800055210006900173260007300242300001200315490000800327520094000335653002301275653002301298653002701321653002301348653002101371653002401392100001501416700001901431700002401450700002801474856012801502       2006                        eng d  a0926-860X00aTransesterification of cyclic carbonates with methanol at ambient conditions over tungstate-based solid catalysts0 aTransesterification of cyclic carbonates with methanol at ambien  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcSEP  a108-1140 v3123 a<p>Dimethyl carbonate synthesis with 80 mol% yield is achieved through transesterification of ethylene carbonate with methanol at ambient conditions (RT and atmospheric pressure) using alkali and alkaline-earth tungstates as solid catalysts. The catalysts are efficient even at the sub-ambient temperatures. Reactions under CO2 pressure indicate that CO2 atmosphere retards the transesterification reaction completely below 100 degrees C. Experimental conditions of 150 degrees C and 3.4 MPa CO2 pressure are required to obtain maximum DMC yield of 71 mol%. Synthesis of DMC by one-pot synthesis using epoxide, CO2 and methanol is not as effective as that by two-step method with the present catalyst system. Raman and IR spectra of methanol-interacting tungstates indicate the formation of a methoxide ion species adsorbed at the catalyst surface as one possible reaction intermediates. (C) 2006 Elsevier B.V. All rights reserved.</p>10aDimethyl carbonate10aethylene carbonate10aheterogeneous catalyst10aRaman spectroscopy10asodium tungstate10atransesterification1 aSankar, M.1 aNair, Madhavan1 aMurty, K., V. G. K.1 aManikandan, Palanichamy  uhttps://library.ncl.res.in/content/transesterification-cyclic-carbonates-methanol-ambient-conditions-over-tungstate-based-001897nas a2200241   4500008004100000022001400041245011900055210006900174260009200243300001000335490000600345520098600351653002501337653002301362653002401385653001501409653001201424100002201436700002101458700002501479700002101504856013001525       2012                        eng d  a1751-825300aEnvironmentally benign synthesis of beta-hydroxy sulfides using cyclic carbonates catalyzed by large-pore zeolites0 aEnvironmentally benign synthesis of betahydroxy sulfides using c  a4 PARK SQUARE, MILTON PARK, ABINGDON OX14 4RN, OXON, ENGLANDbTAYLOR & FRANCIS LTDcAUG  a19-260 v53 a<p>An efficient one-pot synthesis of beta-hydroxy sulfides from thiophenol and cyclic carbonates catalyzed by large-pore zeolites has been reported. Reaction of thiophenol with ethylene carbonate in the presence of the Na-X zeolite catalyst gave the highest yield of 2-(phenylthio)ethanol (100%), while reaction with propylene carbonate a highest yield of regioselective product 1-(phenylthio)propan-2-ol was obtained (97%). Enantiomerically pure 1,2-propylene carbonate gave highly regioselective and stereospecific phenylthiopropanol, demonstrating that original chirality of propylene carbonate is retained. A plausible mechanism has been proposed for zeolite-catalyzed transformation involving a chemoselective nucleophilic attack of thiophenoloxide ion onto the less-substituted carbon of cyclic carbonate. The Na-X zeolite catalyst is recyclable and provides advantages of green chemistry approach to the synthesis of beta-hydroxy sulfides without the use of any solvent.</p>10abeta-hydroxy sulfide10aethylene carbonate10apropylene carbonate10athiophenol10azeolite1 aUpare, Pravin, P.1 aKinage, Anil, K.1 aShingote, Savita, K.1 aGupte, Sunil, P.  uhttps://library.ncl.res.in/content/environmentally-benign-synthesis-beta-hydroxy-sulfides-using-cyclic-carbonates-catalyzed-001999nas a2200205   4500008004100000245016600041210006900207260000800276300001500284490000800299520118800307653002301495653002301518653003801541653002401579100002201603700001901625700001901644856013001663       2017                        eng d00aMgFeCe ternary layered double hydroxide as highly efficient and recyclable heterogeneous base catalyst for synthesis of dimethyl carbonate by transesterification0 aMgFeCe ternary layered double hydroxide as highly efficient and   cOCT  a 2558-25690 v1473 aA series of Mg3:Fex + Ce1−x LDHs (3:1) were synthesized by co-precipitation method by varying molar ratio of Fe:Ce between 1:0 to 0:1 (LDH-1 to LDH-6). All synthesized LDHs were characterized by XRD, FT-IR, TEM, N2 sorption, benzoic acid titration and XPS in detail and evaluated for selective synthesis of dimethyl carbonate by transesterification of ethylene carbonate with methanol. It was demonstrated that the structural and basic properties of synthesized LDHs were strongly dependent on the Fe:Ce molar ratio (Ce concentration). The correlation between their physicochemical properties and catalytic performance was studied in detail. Among all synthesized LDHs the best result was obtained with LDH-3 (Fe:Ce = 0.85:0.15) where LDH structure remained intact, and showed high number of strong basic sites on LDH surface. LDH-3 was recycled 7 times while maintaining high catalyst activity and selectivity towards DMC. The obtained results elucidate the important role of Ce in modifying the basic properties of LDH in enhancing the catalytic activity for DMC synthesis. Graphical Abstract: [Figure not available: see fulltext.]. © 2017, Springer Science+Business Media, LLC.10aDimethyl carbonate10aethylene carbonate10aMg–Fe–Ce Ternary Hydrotalcite10atransesterification1 aNivangune, N., T.1 aRanade, V., V.1 aKelkar, A., A.  uhttps://library.ncl.res.in/content/mgfece-ternary-layered-double-hydroxide-highly-efficient-and-recyclable-heterogeneous-base