期刊
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
卷 18, 期 4, 页码 1332-1338出版社
ELSEVIER SCIENCE INC
DOI: 10.1016/j.jiec.2012.01.034
关键词
Bifunctional aluminum-salen complex; Carbon dioxide; Propylene oxide; Propylene carbonate; Cycloaddition
资金
- National Natural Science Foundation of China [50973026]
- Korean Ministry of Knowledge and Economy through Wide Economy Region Cooperative Program
- NRF-NSFC cooperative program [51011140349, D00020]
Four novel bifunctional aluminum-salen complexes (2a, 2b, 2c, and 2d) containing both Lewis acidic metal center and Lewis base quaternary phosphonium salt sites within one molecule and an aluminum-salen complex with a neutral tert-butyl group (2f) for comparison were synthesized and characterized by UV-vis, IR, H-1, C-13, Al-27 NMR spectroscopy and Elemental analysis (EA). Their catalytic efficiencies as single-component catalysts toward the coupling reaction of carbon dioxide and propylene oxide were evaluated. These complexes exhibit catalytic activity in the order 2d > 2a > 2b > 2c >> 2f. Al-27 NMR spectra reveal the existence of five- and six-coordinated metal centers in the aluminum-salen complexes bearing a quaternary phosphonium salt group, whereas only five-coordinate aluminum species were found in the aluminum-salen complex with a neutral tert-butyl group. This indicates the importance of the six-coordinate aluminum center in enhancing the catalytic activity as well as an intramolecular cooperative effect in bifunctional aluminum-salen complexes 2a-d. The effects of reaction variables on the catalytic performance were investigated in detail. These new catalysts are highly stable to moisture and air and robust to impurities in the coupling reaction. (c) 2012 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.
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