01672nas a2200229   4500008004100000022001400041245013600055210006900191260007300260300001200333490000600345520074600351653003001097653003601127653005001163653001701213653001701230100001901247700001701266700002901283856013001312       2007                        eng d  a1566-736700aBimetallic Pt-Sn/gamma-alumina catalyst for highly selective liquid phase hydrogenation of diethyl succinate to gamma-butyrolactone0 aBimetallic PtSngammaalumina catalyst for highly selective liquid  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAR  a340-3440 v83 a<p>Platinum-tin bimetallic catalyst on gamma-alumina support was prepared by impregnation method and was reduced by sodium borohydride at room temperature. XRD and XPS characterization revealed that platinum was reduced to Pt-0 while, tin was probably partially reduced to Sn2+ due to the low temperature reduction method and Sn-0 was completely absent, avoiding the formation of P-Sn alloy. Pt-Sn/gamma-alumina (Pt 1%, Sn 9%) thus prepared was found to give almost complete selectivity to gamma-butyrolactone in liquid phase hydrogenation of diethyl succinate. A plausible reaction pathway is proposed involving Pt-O-Sn state and high selectivity to GBL is due to the Lewis acidity of Sn2+/4+ (c) 2006 Elsevier B.V. All rights reserved.</p>10abimetallic Pt-Sn catalyst10agamma-butyrolactone selectivity10aliquid phase hydrogenation of diethyl maleate10aXPS of Pt-Sn10aXRD of Pt-Sn1 aVaidya, S., H.1 aRode, C., V.1 aChaudhari, Raghunath, V.  uhttps://library.ncl.res.in/content/bimetallic-pt-sngamma-alumina-catalyst-highly-selective-liquid-phase-hydrogenation-diethyl02341nas a2200169   4500008004100000022001400041245007300055210006800128260007100196300001400267490000700281520170300288100002301991700002502014700002902039856010302068       2007                        eng d  a0888-588500aBiphasic hydroformylation of 1,4-diacetoxy-2-butene: a kinetic study0 aBiphasic hydroformylation of 14diacetoxy2butene a kinetic study  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcDEC  a8629-86370 v463 a<p>Hydroformylation of 1,4-diacetoxy-2-butene was studied using a water-soluble Rh complex catalyst prepared in situ from [Rh(COD)Cl](2) complex and trisodium salt of tri-(m-sulfophenyl)phosphine (TPPTS) in a biphasic system. The sequence of addition of catalyst precursor, ligand, and reactant/solvent showed a significant effect on leaching of Rh from aqueous to organic phase, and hence, the procedure was optimized to develop a nonleaching and stable biphasic catalyst system. The only hydroformylation product (1,4-diacetoxy-2-formyl butane, DAFB) formed was found to deacetoxylate completely to 2-formyl-4-acetoxybutene (FAB), thus allowing a one-pot synthesis of FAB, an important intermediate for Vitamin A. Experimental data on the concentration-time and CO/H-2 consumption-time profiles were obtained, and the effects of DAB concentration, CO partial pressure, H-2 partial pressure, and catalyst concentration were studied in a stirred batch reactor over a temperature range of 338-358 K. The effect of aqueous phase holdup on the initial rate of hydroformylation and analysis of gas-liquid and liquid-liquid mass transfer effects were also investigated to identify the reaction rate data operating in a kinetic regime. A rate equation based on the known hydroformylation reaction mechanism was used to fit the experimental rate data and to evaluate kinetic parameters. The agreement between the model prediction and the experimental data was found to be excellent. The activation energy was calculated as 30.1 kJ/mol. The biphasic catalyst system reported here is not only efficient for catalyst-product separation but also provides a tandem synthesis of Vitamin A intermediate, FAB.</p>1 aChansarkar, Rashmi1 aKelkar, Ashutosh, A.1 aChaudhari, Raghunath, V.  uhttps://library.ncl.res.in/content/biphasic-hydroformylation-14-diacetoxy-2-butene-kinetic-study-0