Carbon dioxide, supercritical carbonylation

Keywords Asymmetric Hydrogenation m Carbon Dioxide m Carbonylation m Dimethylformamide Enantioselectivity m Formic Acid m Homogeneous Hydrogenation n Palladium Catalysts Radical Reactions m Ruthenium Catalysts m Supercritical Fluids m Solvent Replacement... 

Trimethylsilyl derivatives of ten hydroxy- and methoxyhydroxyflavonoids have been studied by the GC-FTIR technique." " The correlation found between retention and gas-phase IR data was used in structural identification of compounds having very similar chromatographic behavior. The shift of the carbonyl frequency gave information on the presence of substitution. Some hydroxy- and methoxy-substituted flavones have been studied following carbon dioxide supercritical fluid chromatography on polymethylsiloxane capillary columns using flame ionization and FTIR detection." " " ... 

Y. Kayaki, Y. Noguchi, S. Iwasa, T. Ikariya, R. Noyori, An Effitient Carbonylation of Aryl Halides Catalysed by Palladium Complexes with Phosphite Ligands in Supercritical Carbon Dioxide , Chem Commun. 1999, 1235-1236. 

This chapter covers the recent advances in amidocarbonylations, cyclohydrocarbonylations, aminocarbonylations, cascade carbonylative cyclizations, carbonylative ring-expansion reactions, thiocarbonylations, and related reactions from 1993 to early 2005. In addition, technical development in carbonylation processes with the use of microwave irradiation as well as new reaction media such as supercritical carbon dioxide and ionic liquids are also discussed. These carbonylation reactions provide efficient and powerful methods for the syntheses of a variety of carbonyl compounds, amino acids, heterocycles, and carbocycles. 

The use of supercritical fluids as reaction media for organometallic species is also investigated. Reactions include photochemical replacement of carbon monoxide with N2 and H2 in metal carbonyls, where the reaction medium is supercritical xenon. Also, photochemical activation of C-H bonds by organometallic complexes in supercritical carbon dioxide is investigated. More recent studies on photochemical reactions also include laser flash photolysis of metal carbonyls in supercritical carbon dioxide and ethane and laser flash photolysis of hydrogen abstraction reaction of triplet benzophenone in supercritical ethane and... 

Palladium(II) acetate micro-encapsulated in polyurea is an economical and versatile heterogeneous catalyst for a range of phosphine-free cross-coupling reactions in both conventional solvents and supercritical carbon dioxide. The catalyst can be recovered by simple filtration and recycled up to four times [93]. The potential of these materials has been demonstrated by their efficacy in Suzuld-type couplings. Investigations have centered upon carbonylation reactions to prepare aryl esters from commercially available aryl iodides. Treatment of iodo-methyl benzene tvith 3 mol% of catalyst in butanol and triethylamine at 90 °C under an atmosphere of carbon monoxide afforded butyl-methyl benzoate in an excellent yield of 89% in 16 h. 

Rathke JW, Klingler RJ. Cobalt carbonyl catalyzed olefin hydroformylation in supercritical carbon dioxide. U.S.A. US 5,198,589, 1993 8. 

In a further variation, the PVP-supported rhodium catalyst was used for methanol carbonylation in supercritical carbon dioxide [100]. This reaction medium has complete miscibility with CO and dissolves high concentrations of methanol and methyl iodide, while being a poor solvent for ionic metal complexes. Catalytic reaction rates up to half of those obtained in conventional liquid-phase catalysis were achieved with minimal catalyst leaching. 

It is interesting to note that Ikariya and Kishimoto recently investigated (TMS)3SiH-mediated radical carbonylation using supercritical carbon dioxide as a... 

Reaction medium. By virtue of its attributes supercritical carbon dioxide deserves its increasing applications as a reaction medium in synthesis. These include epoxidation" with oxygen and PhCHO, rhodium-catalyzed hydroboration, Pd(0)-catalyzed 1,4-hydroarylation of enones" and Heck reaction in the presence of Pd-C," carbonylation of aryl halides, Glaser coupling of 1-alkynes (mediated by CuCy using a solid ba.se (NaOAc)," as well as seandium(III) perfluorooctanesulfonate-catalyzed Diels-Alder and hetero-Diels-Alder reaetions. ... 

In a related process, formation of benzofuranone from carbonylation of 2-iodobenzyl alcohol in supercritical carbon dioxide was recently reported by Kayaki et al. The rate of reaction in supercritical CO2, using palladium chloride in combination with trialkyl or triaryl phosphites as ligands, was reported to be higher than that in typical organic solvents. 

I Wender, P Pino. Organic Syntheses via Metal Carbonyls. New York Wiley, 1977. S Kainz, D Koch, W Baumann, W Leitner. Perfluoroalkyl-substituted arylphos-phanes as ligands for homogeneous catalysis in supercritical carbon dioxide. Angew Chem Int Ed Engl 36 1628-1630, 1997. 

I Ojima, M Tzamarioudaki, C-Y Chuang, DM lula, Z Li. Catalytic carbonylations in supercritical carbon dioxide. In FE Herkes, ed. Catalysis of Organic Reactions. New York Marcel Dekker, 1998, pp 333-343. 

US 5,198,589 Rafiike, Jerome W. Klingler, Robert J. Cobalt Carbonyl Catalyzed Olefin Hydroformylation in Supercritical Carbon Dioxide U.S. Dept, of Energy (US) 30 March 1993... 

Y Kayaki, Y Noguchi, S Iwasa, T Ikariya, R Noyori. An efficient carbonylation of aryl halides catalysed by paUadimn complexes with phosphite ligands in supercritical carbon dioxide. Chem Commun 1235-1236, 1999. 

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