Xi:Irritant;84921-89-1Relevant articles and documents
Use of 'small but smart' libraries to enhance the enantioselectivity of an esterase from Bacillus stearothermophilus towards tetrahydrofuran-3-yl acetate
Nobili, Alberto,Gall, Markus G.,Pavlidis, Ioannis V.,Thompson, Mark L.,Schmidt, Marlen,Bornscheuer, Uwe T.
, p. 3084 - 3093 (2013)
Two libraries of simultaneous double mutations in the active site region of an esterase from Bacillus stearothermophilus were constructed to improve the enantioselectivity in the hydrolysis of tetrahydrofuran-3-yl acetate. As screening of large mutant libraries is hampered by the necessity for GC/MS analysis, mutant libraries were designed according to a 'small but smart' concept. The design of focused libraries was based on data derived from a structural alignment of 3317 amino acid sequences of α/β-hydrolase fold enzymes with the bioinformatic tool 3dm. In this way, the number of mutants to be screened was substantially reduced as compared with a standard site-saturation mutagenesis approach. Whereas the wild-type esterase showed only poor enantioselectivity (E = 4.3) in the hydrolysis of (S)-tetrahydrofuran-3-yl acetate, the best variants obtained with this approach showed increased E-values of up to 10.4. Furthermore, some variants with inverted enantiopreference were found. A semi-rational approach was applied for the enhancement of the enantioselectivity of an esterase from Bacillus stearothermophilus towards the industrially interesting substrate tetrahydrofuran-3-yl acetate, based on data derived from structural alignment. The design of 'small but smart' libraries led to a 2.4-fold increase of (S)-selectivity compared to wild type enzyme, while some mutants with marginal (R)-selectivity were found.
Preparation method of hydroxyl oxacycloalkane derivative
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Paragraph 0049-0070, (2021/08/14)
The invention relates to a preparation method of a hydroxyl oxacycloalkane derivative, which comprises the following steps: 1) preparing an initial reaction raw material compound and a catalyst into a raw material solution by using a solvent, and respectively pumping the raw material solution and an oxide material into a continuous flow reactor preheating module from different material conveying equipment for preheating; 2) feeding the material passing through the preheating module into a mixing module, feeding the mixed material into a reaction module, and continuously reacting in the reaction module to obtain a reaction mixture; (3) after the reaction, enabling a reaction mixture to enter a product separation module, and carrying out organic-inorganic separation or solvent removal on reaction liquid at cooling or reaction temperature or raised temperature to obtain a crude product; and refining the crude product to obtain a pure product. According to the method disclosed by the invention, the reaction process can be simplified, the reaction time can be shortened, and the hydroxyl oxacycloalkane derivative can be more efficiently synthesized.
Preparation method of (s)-3-hydroxytetrahydrofuran
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Paragraph 0032; 0037-0039; 0044-0046; 0051-0053; 0058-0060, (2019/11/13)
The invention provides a preparation method of (s)-3-hydroxytetrahydrofuran. According to the preparation method, ethyl 4-chloroacetoacetate is taken as an initial raw material, (s)-4-chloro-3 hydroxyl-1-butanol is prepared, wherein a substrate is dissolved in a first solvent, an alkali is added, under the catalytic effect of a first catalyst and a second catalyst, asymmetric hydrogenation reaction with hydrogen gas is carried out to produce (s)-4-chloro-3 hydroxyl-1-butanol; chiral 3-hydroxytetrahydrofuran is prepared, wherein prepared chiral 4-chloro-3 hydroxyl-1-butanol is dissolved in a second solvent, an acid is added as a catalyst, and reaction is carried out to obtain (s)-3-hydroxytetrahydrofuran; wherein the first catalyst is a complex generated through reaction of [Ir(COD)Cl]2 with phosphine-pyridine ligand, and the second catalyst is Ru-MACHO complex. The reaction route is short; technology is simple; raw materials are cheap and easily available; production cost is low; reaction process environment pollution is low; product optical purity is high; and the preparation method is suitable for industrialized production.
Preparation of Highly Active Monometallic Rhenium Catalysts for Selective Synthesis of 1,4-Butanediol from 1,4-Anhydroerythritol
Wang, Tianmiao,Tamura, Masazumi,Nakagawa, Yoshinao,Tomishige, Keiichi
, p. 3615 - 3626 (2019/07/15)
1,4-Butanediol can be produced from 1,4-anhydroerythritol through the co-catalysis of monometallic mixed catalysts (ReOx/CeO2+ReOx/C) in the one-pot reduction with H2. The highest yield of 1,4-butanediol was over 80 %, which is similar to the value obtained over ReOx–Au/CeO2+ReOx/C catalysts. Mixed catalysts of CeO2+ReOx/C showed almost the same performance, giving 89 % yield of 1,4-butanediol. The reactivity trends of possible intermediates suggest that the reaction mechanism over ReOx/CeO2+ReOx/C is similar to that over ReOx–Au/CeO2+ReOx/C: deoxydehydration (DODH) of 1,4-anhydroerythritol to 2,5-dihydrofuran over ReOx species on the CeO2 support with the promotion of H2 activation by ReOx/C, isomerization of 2,5-dihydrofuran to 2,3-dihydrofuran catalyzed by ReOx on the C support, hydration of 2,3-dihydrofuran catalyzed by C, and hydrogenation to 1,4-butanediol catalyzed by ReOx/C. The reaction order of conversion of 1,4-anhydroerythritol with respect to H2 pressure is almost zero and this indicates that the rate-determining step is the formation of 2,5-dihydrofuran from the coordinated substrate with reduced Re in the DODH step. The activity of ReOx/CeO2+ReOx/C is higher than that of ReOx–Au/CeO2+ReOx/C, which is probably related to the reducibility of ReOx/C and the mobility of the Re species between the supports. High-valent Re species such as Re7+ on the CeO2 and C supports are mobile in the solvent; however, low-valent Re species, including metallic Re species, have much lower mobility. Metallic Re and cationic low-valent Re species with high reducibility and low mobility can be present on the carbon support as a trigger for H2 activation and promoter of the reduction of Re species on CeO2. The presence of noble metals such as Au can enhance the reducibility through the activation of H2 molecules on the noble metal and the formation of spilt-over hydrogen over noble metal/CeO2, as indicated by H2 temperature-programmed reduction. The higher reducibility of ReOx–Au/CeO2 lowers the DODH activity of ReOx–Au/CeO2+ReOx/C in comparison with ReOx/CeO2+ReOx/C by restricting the movement of Re species from C to CeO2.
