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7636697 
Journal Article 
Immobilization of Cinchona Quaternary Ammonium Salts as the Chiral Phase Transfer Catalysts on Multi-walled Carbon Nanotubes and Their Application in Enantioselective Alkylation 
Liu Jian; Liu Yan; Shi Xin; Yang Qihua; , 
2012 
1 
Chinese Journal of Catalysis
ISSN: 1872-2067 
SCIENCE PRESS 
BEIJING 
33 
5 
891-897 
Chinese 
WOS:000304019200022 
The pyrene-tagged cinchona quaternary ammonium salt, the chiral phase transfer catalysts (PTC-1), was synthesized and immobilized on multi-walled carbon nanotubes (MWCNTs). The new catalysts (PTC-1/MWCNTs) were employed in enantioselective alkylation of N-(diphenylmethyene)glycine tert-butyl ester. UV-Vis absorption spectra show the effect of different organic solvents on the adsorption and desorption of PTC-1 onto and from MWCNTs, respectively. The results show that 5.3 mg PTC-1 can be loaded on 10 mg MWCNTs in toluene, and 0.02025 mg PTC-1 was desorbed from 12.7 mg PTC-1/MWCNTs when washed by CHCl3. In the enantioselective alkylation of different halohydrocarbons with N-(diphenylmethyene)glycine tert-butyl ester using PTC-1/MWCNTs as a catalyst, the alkylating products were obtained with high yield and ee value. Furthermore, PTC-1/MWCNTs catalyst can be recovered and used repeatedly. PTC-1/MWCNTs as a new catalyst is effective in enantioselective alkylation of multiple halohydrocarbon. 
Adsorption; Chiral phase transfer catalyst; Cinchona alkaloid; Enantioselective alkylation; Multi-walled carbon nanotube