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Shin-ichiroKeywords: Hydroformylation / Rhodium / Dialdehyde / Fluorinated ligand / Supercritical carbon dioxideRhodium-catalyzed hydroformylation of 1,5-hexadiene to dialdehydes was investigated in compressed CO 2 and in toluene using different fluorinated phosphane compounds as ligands at a temperature of 60°C. Product yields depend greatly on the ligand used and, of the ligands examined, tris[3,5-bis(trifluoromethyl)phenyl]phosphane is the most effective for the production of dialdehydes both in supercritical CO 2 (scCO 2 ) and in toluene. The total yield of the dialde- IntroductionSupercritical carbon dioxide (scCO 2 ) is gaining considerable interest as an ecologically benign and economically feasible new generation reaction medium that could replace conventional toxic, flammable organic solvents. [1,2] Various chemical substances are soluble in scCO 2 and they can be easily separated by depressurization; scCO 2 is also nonflammable, nontoxic and has no gas/liquid phase boundary. The physicochemical properties of scCO 2 can be tuned within a certain range by adjusting the pressure and temperature, these also being the parameters for optimization of reactions in this solvent.Organometallic complexes are effective catalysts for various chemical transformations in conventional solvents. [3] Although homogeneous organometallic catalysis in scCO 2 is attractive, the organometallic complexes must be soluble in scCO 2 . Phosphane ligands, such as triphenylphosphane (TPP), that are often used in these complexes are less sol- [a]

Hydroformylation of 1-hexene was carried out in supercritical CO 2 (scCO 2 ) and in organic solvents (toluene and ethyl acetate) using polymer-supported rhodium catalysts, which were prepared from polystyrene bound triphenylphosphine (TPP) and dicarbonylacetylecetonato rhodium. Preparation variables such as TPP/Rh ratio, time of rhodium precursor fixation on the support and time of syngas pretreatment do not indicate significant effects on the reaction. The product distribution slightly changes with CO 2 pressure. It increases appreciably as H pressure is raised in scCO but CO retards the reaction. The influence of H 2 2 2 pressure in scCO 2 is slightly different from that in toluene. Changes of the structure of rhodium complexes on the polymer during the catalyst preparation and the reaction were investigated by diffuse reflectance FT-IR. It should be noted that the catalyst is recyclable for the reaction in scCO 2 and the reaction rate and selectivity of the hydroformylation are much higher than those in the organic solvents.

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Aldehydes Aldehydes P 0170 Rhodium-Tris(3,5-bis(trifluoromethyl)phenyl)phosphine Catalyzed Hydroformylation of Dienes to Dialdehydes in Supercritical Carbon Dioxide with HighActivity. -The hydroformylation of α,ω-dienes such as (I) is investigated in highly compressed carbon dioxide as the solvent. The phosphine catalyst ligand exhibits remarkable influence on the product selectivity. -(FUJITA, S.-I.; FUJISAWA, S.; BHANAGE, B. M.; ARAI*, M.; Tetrahedron Lett. 45 (2004) 6, 1307-1310; Div. Mater. Sci. Eng., Grad. Sch. Eng., Hokkaido Univ., Sapporo 060, Japan; Eng.) -Mais 19-051