Immobilised catalysts for continuous reactions in supercritical carbon dioxide
This Thesis investigates immobilised metal- and biocatalysts for continuous reactions in scC02. Chemical transformations with high atom economy and low E-factor (amount of waste per kg of product) are highly desired in the green chemical viewpoint. One of the approaches to decrease the production of...
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| Format: | Thesis |
| Language: | English |
| Published: |
2010
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| Online Access: | http://eprints.nottingham.ac.uk/27830/ https://eprints.nottingham.ac.uk/27830/1/523704.pdf |
| Summary: | This Thesis investigates immobilised metal- and biocatalysts for continuous reactions in scC02. Chemical transformations with high atom economy and low E-factor (amount of waste per kg of product) are highly desired in the green chemical viewpoint. One of the approaches to decrease the production of waste is the use of catalysis (possibly highly selective). Another approach is the use of a 'green' reaction medium as a substitute for traditional solvents that can reduce the production of harmful solvent waste. How this Thesis encompasses by these topics is discussed in Chapter 1. The details of the apparatus, experimental and analytical equipment and procedures are reported in Chapter 2. The field of asymmetric catalytic hydrogenation is a currently important and expanding field of research. In Chapters 3 and 4, the continuous asymmetric hydrogenation of dimethyl itaconate is covered. High enantioselectivity (ees up to 83 %) was obtained in the continuous asymmetric hydrogenation of dimethyl itaconate catalysed by supported homogeneous chiral Rh catalysts on alumina in SCC02 (Chapter 3). This is one of the first examples of the use of chiral catalyst in a continuous flow system without the need for the addition of the chiral modifier. The continuous asymmetric hydrogenation of dimethyl itaconate was also examined with chiral Rh catalysts immobilised in ionic liquids in a biphasic system ionic liquid/scC02 (Chapter 4). High enantioselectivity was achieved in the continuous flow system: ees up to 76 %. Chapter 5 describes the kinetic resolution of secondary alcohols catalysed by immobilised Candida antarctica lipase B (Cal B) in a continuous flow scC02 system. The continuous kinetic resolution of a-tetralol with Cal B immobilised in the form of Cross-Linked Enzyme Aggregate (CLEA) gave excellent enantioselectivity (eeR to 99 %). Different acyl donors (vinyl acetate, phenyl acetate and p-nitrophenyl acetate) were investigated, and were shown to influence the enantioselectivity of the reaction. In Chapter 6, a two ... |
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