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Continuous-flow rhodium-catalysed hydroformylation of long chain alkenes has been achieved with selectivities to the desired linear aldehyde of 92% and minimum rhodium loss, using a xantphos-derived ligand attached to an imidazolium salt in a supercritical fluid–ionic liquid system. The effect of oxygen in the system can be ameliorated to some extent by adding a simple sulfonated triphenylphosphine to the catalytic solution. [ABSTRACT FROM AUTHOR]

Depending on the amount of methanol present in solution, CO2 adducts of N-heterocyclic carbenes (NHCs) and N-heterocyclic olefins (NHOs) have been found to be in fully reversible equilibrium with the corresponding methyl carbonate salts [EMIm][OCO2Me] and [EMMIm][OCO2Me]. The reactivity pattern of representative 1-ethyl-3-methyl-NHO-CO2 adduct 4 has been investigated and compared with the corresponding NHC-CO2 zwitterion: The protonation of 4 with HX led to the imidazolium salts [NHO-CO2H][X], which underwent decarboxylation to [EMMIm][X] in the presence of nucleophilic catalysts. NHO-CO2 zwitterion 4 can act as an efficient carboxylating agent towards CH acids such as acetonitrile. The [EMMIm] cyanoacetate and [EMMIm]2 cyanomalonate salts formed exemplify the first C−C bond-forming carboxylation reactions with NHO-activated CO2. The reaction of the free NHO with dimethyl carbonate selectively led to methoxycarbonylated NHO, which is a perfect precursor for the synthesis of functionalized ILs [NHO-CO2Me][X]. The first NHO-SO2 adduct was synthesized and structurally characterized; it showed a similar reactivity pattern, which allowed the synthesis of imidazolium methyl sulfites upon reaction with methanol. [ABSTRACT FROM AUTHOR]

Continuous-flow rhodium-catalysed hydroformylation of long chain alkenes has been achieved with selectivities to the desired linear aldehyde of 92% and minimum rhodium loss, using a xantphos-derived ligand attached to an imidazolium salt in a supercritical fluid–ionic liquid system. The effect of oxygen in the system can be ameliorated to some extent by adding a simple sulfonated triphenylphosphine to the catalytic solution. [ABSTRACT FROM AUTHOR]

Two protic alkylimidazolium polyoxometalates, together with two corresponding aprotic N-methyl-alkylimidazolium polyoxometalates were synthesized and characterized by the methods of NMR, IR and TGA etc. Then, these salts were employed as catalysts for the epoxidation of cyclooctene in different media. The novel protic N-dodecylimidazolium peroxotungstate [HDIm]2[{WO(O2)2}2(μ–O)] was found to be a room temperature liquid molten salt (ionic liquid) and the most effective catalyst for the epoxidation of cyclooctene among these salts. The ionic liquid catalyst [HDIm]2[{WO(O2)2}2(μ–O)] can also be extended to the epoxidation of some other substrates. On the basis of this experimental observation, an efficient reaction-induced phase-separation catalyst system has been developed in this work. The reaction system can switch from tri-phase to emulsion and then to biphase and finally to all the catalyst self-precipitating at the end of the reaction, which made the recovery and reuse of the present catalyst very convenient. [ABSTRACT FROM AUTHOR]