- Combination of bio- and chemocatalysis for dynamic kinetic resolution: The assembly strategies for nanozeolite-modified flow microchannel reactors
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The combination of bio- and chemocatalysts in one-pot is regarded as a breakthrough both for development of new catalytic concepts and for preparation of high-value chemicals. Zeolite nanocrystals (nanozeolites) have been proved as the most used chemical catalysts and as promising supports for enzyme immobilization. These capabilities of nanozeolites endow them with new possibilities for constructing desired platforms for the combination of bio- and chemocatalysis. In this article, several strategies are proposed to develop a one-pot flow microchannel reactor (MCR) by combining enzyme and chemocatalysis via a nanozeolite assembly approach, and the compatibilities of different types of active centers in various assembly strategies are systematically discussed on the basis of the catalytic results of dynamic kinetic resolution (DKR) of sec-alcohol. By precisely controlling the spatial distribution and the ratio of acidic and enzymatic active sites, as well as the reaction conditions, nanozeolite-modified MCR can achieve fast and highly selective one-pot DKR of sec-alcohol within 30 min.
- Wang, Zhoujun,Li, Xiang,Wang, Wanlu,Tang, Yi,Zhang, Yahong
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- Enhanced activity and modified substrate-favoritism of Burkholderia cepacia lipase by the treatment with a pyridinium alkyl-PEG sulfate ionic liquid
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Three types of pyridinium salts, i.e., 1-ethylpyridin-1-ium cetyl-PEG10 sulfate (PYET), 1-butylpyridin-1-ium cetyl-PEG10 sulfate (PYBU), and 1-(3-methoxypropyl)pyridin-1-ium cetyl-PEG10 sulfate (PYMP), have been prepared and evaluated for their activation property of Burkholderia cepacia lipase by comparison to the control IL-coated enzymes, 1-butyl-2,3-dimethylimidazolium cetyl-PEG10 sulfate-coated lipase PS (IL1-PS). Among the tested pyridinium salt-coated lipases, the PYET-coated lipase PS (PYET-PS) exhibited the best results; the transesterification of 1-(pyridin-2-yl)ethanol, 1-(pyridin-3-yl)ethanol, 1-(pyridin-4-yl)ethanol, or 4-phenylbut-3-en-2-ol proceeded faster than those of the IL1-PS-catalyzed reaction while maintaining an excellent enantioselectivity (E > 200). This improved efficiency was found to be dependent on the increased Kcat value.
- Kadotani, Shiho,Nokami, Toshiki,Itoh, Toshiyuki
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p. 441 - 447
(2019/01/04)
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- Shell Cross-Linked Micelles as Nanoreactors for Enantioselective Three-Step Tandem Catalysis
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Functionalized amphiphilic poly(2-oxazoline)-based triblock copolymers that assemble into shell cross-linked micelles (SCMs) are described. These micelles permit the site isolation of three incompatible catalysts through compartmentalization, thereby enabling three-step non-orthogonal tandem processes in one pot. In particular, the acid-catalyzed ketal hydrolysis to prochiral ketones proceeded in the hydrophilic corona, followed by the Rh-catalyzed asymmetric transfer hydrogenation to enantio-enriched alcohols in the cross-linked shell, and nucleophilic base-catalyzed acylation in the hydrophobic core. The catalysts are positioned in close proximity on a single micelle support to take advantage of the intramicellar substrate diffusion, yet they are sufficiently spaced apart from each other in physically distinct microenvironments. These compartmentalized micelles are substrate selective and, on a basic level, mimic compartmentalized catalytic architectures found in nature.
- Kuepfert, Michael,Cohen, Aaron E.,Cullen, Olivia,Weck, Marcus
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supporting information
p. 18648 - 18652
(2018/11/23)
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- Easy and simple SiO2 immobilization of lipozyme CaLB-L: Its use as a catalyst in acylation reactions and comparison with other lipases
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In this study, lipase from Candida antarctica B (Lipozyme CaLB-L) was successfully immobilized on SiO2 through adsorption and used to obtain (R)-(+)-esters derived from (R,S)-1-phenylethanol. The new immobilized enzyme was compared with commercially immobilized lipases (Novozyme 435, Lipozyme 435 and Pseudomonas cepacia (PSC-II and PSD-I)). Lipozyme CaLB-L adsorbed onto SiO2 was found to be a good catalyst and, under optimal conditions, esters could be obtained with conversion 44percent, enantiomeric excess of product (eep) > 99percent, enantiomeric excess of substract (ees) 77percent and enantiomeric ratio (E) > 200. The lipase maintained enantioselectivity under adverse conditions, such as in organic solvents, with an excess of substrate and at different temperatures. The immobilized lipase could be reused five times with no significant loss of the activity.
- Mittersteiner, Mateus,Machado, Tayani M.,De Jesus, Paulo Cesar,Brondani, Patrícia B.,Scharf, Dilamara R.,Wendhausen, Renato
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p. 1185 - 1192
(2017/06/07)
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- Core-Shell Composite as the Racemization Catalyst in the Dynamic Kinetic Resolution of Secondary Alcohols
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Beta-Silicalite-1 core-shell microcomposites with controllable shell thickness were synthesized and used as racemization catalysts in the one-pot dynamic kinetic resolution (DKR) of secondary alcohols by using lipase-catalyzed transesterification. The inert Silicalite-1 shell covered the external acidic sites of the Beta zeolite core, suppressing dehydration and non-enantioselective transesterification of the alcohol. The alcohols could penetrate the Silicalite-1 shell to access the acidic sites at the core Beta for racemization, however, the enzymatically formed (R)-esters were excluded owing to their larger size. As a result, the high ee of the (R)-ester products was conserved and dehydration side products were minimized. Owing to the shape selective nature of the composite racemization catalyst, small and readily available acyl donors could be used in the enzyme-catalyzed transesterification to obtain the esters with high enantiopurity. The DKR of 1-phenylethanol with isopropenyl acetate using an optimized core-shell catalyst, CS-60, gave 92% selectivity to ester formation and the desired (R)-1-phenylethyl acetate was formed with 94% ee.
- Wang, Jie,Do, Dong-Minh,Chuah, Gaik-Khuan,Jaenicke, Stephan
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p. 247 - 254
(2013/03/13)
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- Catalytic performance of H-β nanozeolite microspheres in one-pot dynamic kinetic resolution of aromatic sec-alcohols
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In this paper, uniform H-β nanozeolite microsphere (β-ZMS) prepared by polymerization-induced colloid aggregation, combined with an immobilized lipase B from Candida antarctica (commercially available Novozym 435), is applied as a racemization catalyst to the one-pot dynamic kinetic resolution (DKR) of aromatic sec-alcohols. The DKRs of various aromatic sec-alcohols can be carried out with high selectivity and conversion under optimum conditions. Importantly, it is found that, compared to commercial zeolites β (C-β), β-ZMSs display high selectivity for small sec-alcohol molecules because their shorter microporous channels reduce the diffusion time of substrate/product in the three-dimensional framework, and thereby decrease the possibility of secondary reactions. However, the β-ZMSs show a high racemization rate in the DKR of large sec-alcohol molecules, such as racemic 1-(1-naphthyl)-ethanol, thanks to their abundant accessible active sites. This observation will not only benefit the performance of acidic zeolite catalysts in one-pot DKR systems but also provide a new perspective on the application of nanozeolites in catalysis.
- Li, Xiang,Shi, Yi,Wang, Zhoujun,Zhang, Yahong,Tang, Yi
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scheme or table
p. 24 - 32
(2012/04/23)
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- Immobilization of lipase on aminopropyl-grafted mesoporous silica nanotubes for the resolution of (R, S)-1-phenylethanol
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Mesoporous silica nanotubes and aminopropyl-grafted mesoporous silica nanotubes were prepared as supports to immobilize lipase from Candida sp. 99-125(ClLip) by physical adsorption. The immobilization conditions were investigated. Moreover, immobilized lipases on both kinds of supports were employed to catalyze olive oil hydrolization and resolution of 1-phenylethanol by esterification. The results showed that the hydrolization activity of the lipase immobilized on aminopropyl-grafted mesoporous silica nanotubes was almost twice of that on mesoporous silica nanotubes. In addition, the resolution of 1-phenylethanol catalyzed by the former catalyst also increased 22%. Circular dichroism spectra revealed a reduction of α-helix and an increase of β-sheet when lipase was adsorbed on aminopropyl-grafted mesoporous silica nanotubes, which suggested that parts of α-helix were extended and reformed to be β-sheet.
- Bai, Wei,Yang, Yun-Jie,Tao, Xia,Chen, Jian-Feng,Tan, Tian-Wei
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experimental part
p. 82 - 88
(2012/04/11)
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- Dynamic kinetic resolution of secondary alcohols combining enzyme-catalyzed iransesterification and zeolite-catalyzed racemization
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Hydrophobic zeolite beta containing low concentrations of Zr or Al was found to be a good catalyst for the racemization of 1-phenylethanol. The formation of styrene as a side product could be minimized by reducing the metal concentration in the zeolite be
- Zhu, Yongzhong,Fow, Kam-Loon,Chuah, Gaik-Khuan,Jaenicke, Stephan
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p. 541 - 547
(2007/10/03)
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- (S)-Selective kinetic resolution and chemoenzymatic dynamic kinetic resolution of secondary alcohols
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(S)-Selective kinetic resolution was achieved through the use of a commercially available protease, which was activated with a combination of two different surfactants. The kinetic resolution (KR) process was optimized with respect to activation of the protease and to the acyl donor. The KR proved to be compatible with a range of functionalized sec-alcohols, giving good to high enantiomeric ratio values (up to >200). The enzymatic resolution was combined with a ruthenium-catalyzed racemization to give an (S)-selective dynamic kinetic resolution (DKR) of sec-alcohols. The DKR process works under very mild reaction conditions to give the corresponding esters in high yields and with excellent enantioselectivities.
- Boren, Linnea,Martin-Matute, Belen,Xu, Yongmei,Cordova, Armando,Baeckvall, Jan-E.
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p. 225 - 232
(2007/10/03)
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- Acid zeolites as alcohol racemization catalysts: Screening and application in biphasic dynamic kinetic resolution
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Acid zeolites were screened as heterogeneous catalysts for racemization of benzylic alcohols. The most promising zeolites appeared to be H-Beta zeolites, for which the optimal reaction conditions were studied in further detail. The zeolite performance was
- Wuyts,De Temmerman,De Vos,Jacobs
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p. 386 - 397
(2007/10/03)
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- A zeolite-enzyme combination for biphasic dynamic kinetic resolution of benzylic alcohols.
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Acid zeolites like H-Beta are efficient heterogeneous catalysts for racemization of benzylic alcohols in water; by combination of the racemization with an enzymatic kinetic resolution in a two-phase system, enantiomerically pure esters were obtained in hi
- Wuyts, Stijn,De Temmerman, Karolien,De Vos, Dirk,Jacobs, Pierre
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p. 1928 - 1929
(2007/10/03)
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- Microwave-promoted lipase-catalyzed reactions. Resolution of (±)-1-phenylethanol
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Microwave irradiation increased enzymatic affinity and selectivity of supported lipases in esterification and transesterification reactions carried out in dry media and at temperature near 100°C.
- Carrillo-Munoz, Jose-Ramon,Bouvet, Denis,Guibe-Jampel, Eryka,Loupy, Andre,Petit, Alain
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p. 7746 - 7749
(2007/10/03)
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- S-ethyl thiooctanoate as acyl donor in lipase catalysed resolution of secondary alcohols
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The use of S-ethyl thiooctanoate as acyl donor in resolution of secondary alcohols by lipase catalysed transesterification, resulted in an efficient displacement of the equilibrium towards esterification of the alcohol. A lipase (component B) from Candida antarctica was used as the catalyst. On a semi-preparative scale, 0.5 g of 2-octanol was resolved in less than one hour, affording an enantiomeric excess of >98% of the remaining alcohol and >97% of the produced ester. Three other alcohols, 1-phenyl ethanol, 1-cyclohexyl ethanol and trans-2-methyl cyclohexanol were also resolved with good optical yields. After 50% conversion on a preparative scale, 15 g of alcohol, the (S)-enantiomer of 2-octanol could be obtained with an enantiomeric excess of 96%. The (R)-enantiomer was isolated with an enantiomeric excess of 97% after hydrolysis of the produced ester.
- Frykman,Ohrner,Norin,Hult
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p. 1367 - 1370
(2007/10/02)
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- Enantioselectivity of some lipases, control and prediction
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Different strategies for the resolution of racemates in lipase catalyzed hydrolyses, esterifications, and transesterifications are presented.The importance of the equilibrium conversion for the optimization of the enantiomeric excess is emphasized.Investigations have been carried out on esters of 1-phenylethanol and 2-methylalkanoic acids.Results are presented, which provide general information about important parameters for the enhancement of the enantiomeric excess and the reaction rates.The application of a "matched strategy" stereochemical control for increasingthe enantiomeric excess is presented, i.e. the use of a chiral acid for the resolution of chiral alcohols.Molecular modelling of lipase from Rhizomucor miehei as well as the use of a simple active site model of lipase from Candida cylindracea to obtain information for the prediction and modification of enzyme specificity is presented.
- Hult, Karl,Norin, Torbjoern
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p. 123 - 126
(2007/10/02)
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