02341nas 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-002395nas a2200169   4500008004100000022001400041245011900055210006900174260007100243300001400314490000700328520168200335100002302017700002502040700002902065856013102094       2009                        eng d  a0888-588500aHydroformylation of 1,4-diacetoxy-2-butene using HRh(CO)(PPh3)(3) tethered on alumina as a catalyst: kinetic study0 aHydroformylation of 14diacetoxy2butene using HRhCOPPh33 tethered  a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcNOV  a9479-94890 v483 a<p>Hydroformylation of 1,4-diacetoxy-2-butene (DAB) was studied using [HRh(CO)(PPh3)(3)] complex catalyst tethered on alumina using phosphotungstic acid (PTA) as an anchoring agent, with the aim to understand the product distribution, selectivity, and intrinsic kinetics. It was observed that with the tethered heterogeneous catalyst a simultaneous hydroformylation followed by deacetoxylation steps was possible, which is relevant for combining two steps in the sequence of synthesis of vitamin-A intermediate [2-formyl-4-acetoxy butene (FAB)]. P-31 cross-polarization magic angle spinning nuclear magnetic resonance (CP MAS NMR) and infrared (IR) instrumental techniques were found be the most effective techniques to establish the catalyst structure and true heterogeneity. On the basis of the spectroscopic evidence, we postulate the loss of a PPh3 group during tethering to give HRh(CO)(PPh3)(2)-PTA-Al2O3 as a heterogeneous complex catalyst. 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 loading were studied in a 50 mL stirred batch reactor over a temperature range of 338-358 K. The analysis of solid-liquid-gas mass transfer effects was investigated to ensure that the reaction was operating in the kinetic regime Various models were developed, and the best model was chosen by a model discrimination procedure. The agreement between the model prediction and the experimental data was found to be excellent. The activation energies for the hydroformylation and deacetoxylation steps were found to be 42.5 and 80.2 kJ/mol.</p>1 aChansarkar, Rashmi1 aKelkar, Ashutosh, A.1 aChaudhari, Raghunath, V.  uhttps://library.ncl.res.in/content/hydroformylation-14-diacetoxy-2-butene-using-hrhcopph33-tethered-alumina-catalyst-kinetic-0