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CO Pressure (co + pressure)
Selected AbstractsChemInform Abstract: Control over [2 + 2 + 2] and Carbonylative [4 + 2] Cycloaddition by CO Pressure in Co-Catalyzed Cycloaddition Between Internal Diynes and Cyclopentadiene.CHEMINFORM, Issue 43 2008Do Han Kim Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Co-Catalyzed Tandem Pauson,Khand Type Reaction/Dimerization of Terminal Diynes in the Presence of Cyclopentadiene under CO Pressure.CHEMINFORM, Issue 50 2007Do Han Kim Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Synthesis of N -Acetyl-,-aminobutyric Acid via Amidocarbonylation: A Case StudyADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 4 2003Dirk Gördes Abstract The synthesis of N -acetyl-,-aminobutyric acid by amidocarbonylation of propionaldehyde with acetamide in the presence of palladium catalysts is studied in detail. The influence of various reaction conditions and compositions (e.g., the co-catalysts acid and bromide) on the yield of N -acetyl-,-aminobutyric acid is shown. For the first time it is demonstrated that the palladium-catalyzed amidocarbonylations of aldehydes can be run with significantly lower halide concentrations (<30 mol,%) without a major yield decrease. While phosphine-free catalyst systems give best yields at low CO pressure, phosphine-ligated palladium catalysts lead to better yields at higher CO pressure. At low palladium loadings (<0.1 mol,%), unwanted condensation reactions of propionaldehyde become increasingly competitive. [source] The reaction of mixtures of [Rh4(CO)12] and triphenylphosphite with carbon monoxide or syngas as studied by high-resolution, high-pressure NMR spectroscopy,MAGNETIC RESONANCE IN CHEMISTRY, Issue S1 2008Gillian Overend Abstract The fragmentation and redistribution reactions of [Rh4(CO)12,x{P(OPh)3}x] (x = 1,4) with carbon monoxide have been studied using high-resolution, high-pressure NMR spectroscopy. Under the conditions of efficient gas mixing in a high-pressure NMR bubble column, [Rh4(CO)9{P(OPh)3}3] fragments to give mainly [Rh2(CO)6{P(OPh)3}2]; [Rh4(CO)11{P(OPh)3}] is also observed, implying redistribution of the phosphite ligand and/or recombination of the dimers to tetrameric clusters. Fragmentation of [Rh4(CO)10{P(OPh)3}2] is found to be pressure-dependent giving predominantly [Rh2(CO)6{P(OPh)3}2] at low CO pressure (1,40 bar), and increasing amounts of [Rh2(CO)7{P(OPh)3}] at higher (40,80 bar) pressure. Using Syngas (CO : H2 (1:1)) instead of CO in the above fragmentations, homolytic addition of H2 to the dimer [Rh2(CO)6{P(OPh)3}2] to give [RhH(CO)3{P(OPh3}] and [RhH(CO)2{P(OPh)3}2] is observed. The distribution of tetrameric species obtained is similar to that obtained under the same partial pressure of CO. On depressurisation/out-gassing of the sample, the original mixture of tetrameric clusters is obtained. Copyright © 2008 John Wiley & Sons, Ltd. [source] Palladium,dppb,borate-catalyzed regioselective synthesis of cinnamate esters by alkoxycarbonylation of phenylacetyleneAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 10 2008Jimoh Tijani Abstract The regioselective alkoxycarbonylation of phenylacetylene into various cinnamate esters was achieved with a catalyst system formed from palladium (II), 1,4-bis(diphenylphosphino) butane (dppb) and salicylborate complex in acetonitrile as a solvent. The influence of various parameters on the overall conversion of phenylacetylene and the selectivity of the reaction were studied systematically by varying the type of palladium complex, acids promoter, CO pressure, temperature and the reaction time. This investigation allowed us to obtain the predominant formation of cinnamate esters with excellent selectivity (90,96%). Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||