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Noncovalent immobilization of chiral cyclopropanation catalysts on mesoporous TUD-1: Comparison of liquid-phase and gas-phase ion-exchange

Paper ID Volume ID Publish Year Pages File Format Full-Text
42296 45919 2010 7 PDF Available
Title
Noncovalent immobilization of chiral cyclopropanation catalysts on mesoporous TUD-1: Comparison of liquid-phase and gas-phase ion-exchange
Abstract

TUD-1 has been used as Brønsted acidic mesoporous support for the immobilization of a chiral cyclopropanation catalyst. Brønsted acid sites were introduced by supporting phosphotungstic acid on all alumina TUD-1 matrix (PW-TUD-Al2O3) or by substitution of Si by Al in all silica TUD-1 matrix (Al-TUD-1). The chiral cyclopropanation catalyst Cu(I)- 2,2′-methylenebis [(4R,5S)-4,5-diphenyl-4,5-dihydro-1,3-oxazole] was immobilized by different noncovalent immobilization techniques; ion-exchange in solution and solid–gas ion-exchange. The chiral cyclopropanation catalyst was adsorbed on PW-TUD-Al2O3 during ion-exchange in solution. This catalyst system displayed high leaching of copper reaching values of 21%. While using Al-TUD-1 as support copper was introduced as CuCl at temperatures from 550 to 850 °C subsequently followed by introduction of the ligand. Noncovalent immobilization by solid–gas ion-exchange of CuCl on Al-TUD-1 resulted in heterogenous catalyst with only 1% leaching of copper but also moderate results in the cyclopropanation of styrene in terms of yield (33%) and enantioselectivities.

Graphical abstractMesoporous, Brønsted acidic TUD-1 materials have been applied as supports for the electrostatic immobilization of a cyclopropanation catalyst. The chiral copper catalyst was immobilized using liquid-phase or gas-phase ion-exchange. While liquid-phase immobilization led to adsorption rather than ion-exchange, gas-phase ion-exchange gave the desired catalyst.Figure optionsDownload full-size imageDownload high-quality image (87 K)Download as PowerPoint slide

Keywords
Chiral catalysis; Heterogeneous catalysis; Mesoporous support; Electrostatic immobilization; Cyclopropanation
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Noncovalent immobilization of chiral cyclopropanation catalysts on mesoporous TUD-1: Comparison of liquid-phase and gas-phase ion-exchange
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Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis A: General - Volume 372, Issue 2, 15 January 2010, Pages 217–223
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us