- Chiral ammonium-capped rhodium(0) nanocatalysts: Synthesis, characterization, and advances in asymmetric hydrogenation in neat water
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Optically active amphiphilic compounds derived from N-methylephedrine, N-methylprolinol, or cinchona derivatives possessing bromide or chiral lactate counterions were efficiently used as protective agents for rhodium(0) nanoparticles. The full characterization of these surfactants and the obtained nanocatalysts was performed by means of different techniques. These spherical nanoparticles, with sizes between 0.8-2.5 nm depending on the stabilizer, were evaluated in the hydrogenation of model substrates in neat water as a green solvent. The rhodium catalysts showed relevant kinetic properties, but modest enantiomeric excess values of up to 13 % in the hydrogenation of ethyl pyruvate. They were also investigated in the hydrogenation of disubstituted arenes, such as m-methylanisole, providing interesting catalytic activities and a preferential cis selectivity of around 80 %; however, no asymmetric induction was observed. Green nanocatalysts: Optically active compounds derived from N-methylephedrine, N-methylprolinol, or cinchona derivatives with bromide or chiral lactate counterions are used as protective agents for rhodium(0) nanoparticles in asymmetric catalysis of the hydrogenation of ethyl pyruvate and m-methylanisole in water as a green solvent. Copyright
- Guyonnet Bilé, Elodie,Cortelazzo-Polisini, Elodie,Denicourt-Nowicki, Audrey,Sassine, Rita,Launay, Franck,Roucoux, Alain
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- N-Methylephedrium salts as chiral surfactants for asymmetric hydrogenation in neat water with rhodium(0) nanocatalysts
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A new family of chiral surfactants derived from N-methylephedrine possessing different counter-ions (Br-, ${{{rm {rm HCO}}{{- hfill atop 3hfill}}}}$, (S)-(-)-lactate-) is easily prepared and used as efficient protective agents of rhodium(0) nanoparticles. The resulting, well-characterized materials prove to be active catalysts in the hydrogenation of ethylpyruvate in neat water, with modest enantiomeric excesses.
- Guyonnet-Bilé, Elodie,Denicourt-Nowicki, Audrey,Sassine, Rita,Beaunier, Patricia,Launay, Franck,Roucoux, Alain
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p. 1276 - 1279
(2011/12/02)
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