Polymeric catalysts for chemo- and enantioselective epoxidation of olefins: new crosslinked chiral transition metal complexing polymers

De, Binod B. ; Lohray, Braj B. ; Sivaram, Swaminathan ; Dhal, Pradeep K. (1997) Polymeric catalysts for chemo- and enantioselective epoxidation of olefins: new crosslinked chiral transition metal complexing polymers Journal of Polymer Science Part A: Polymer Chemistry, 35 (9). pp. 1809-1818. ISSN 0887-624X

Full text not available from this repository.

Official URL: http://onlinelibrary.wiley.com/doi/10.1002/(SICI)1...

Related URL: http://dx.doi.org/10.1002/(SICI)1099-0518(19970715)35:9<1809::AID-POLA21>3.0.CO;2-8

Abstract

Polymeric analogs of well-known chiral Mn(III)-salen complexes were synthesized and were used as recyclable catalysts for asymmetric epoxidation of olefins. For this purpose two different monomers, 2 and 3, bearing chiral Mn(III)-salen moieties were synthesized. The monomer 3 carries a bulky substituent closer to the Schiff base moiety, while monomer 2 lacks such a substituent. These metal complexed chiral monomers were subsequently copolymerized with ethylene glycol dimethacrylate producing insoluble crosslinked functional matrices that possess macroporous morphology. Chemo- and enantioselective catalytic activities of these two polymers were evaluated for epoxidation of olefins. Both polymers catalyzed the epoxidation of a variety of olefins at room temperature in the presence of iodosylbenzene (PhIO) as the terminal oxidant with yields comparable to the homogenous system. In terms of their enantioselective catalytic activity, polymer P-2 (obtained from 3) performed better than polymer P-1 (obtained from 2). Unfortunately, while the homogeneous systems are reported to offer over 80% enantioselectivity, with the present polymeric catalysts, enantioselectivity to a maximum of 30% were observed. Unlike the homogeneous system, use of an external nitrogenous donor played a very insignificant role in influencing enantioselectivity.

Item Type:Article
Source:Copyright of this article belongs to John Wiley and Sons.
Keywords:Polymeric Catalyst; Asymmetric Synthesis; Polymer-metal Complex; Chiral Polymer
ID Code:51631
Deposited On:29 Jul 2011 03:59
Last Modified:29 Jul 2011 03:59

Repository Staff Only: item control page