105-54-4Relevant articles and documents
Lipase-catalyzed synthesis of ethyl hexanoate in microemulsion system
Tan, Zhongqin,Han, Xiaoxiang,Hu, Xiaoli,Du, Huan,Bao, Xiuxiu
, p. 9675 - 9678 (2013)
This paper studied lipase-catalyzed synthesis of ethyl hexanoate in dodecylbenzenesulfonic acid/isooctane/water microemulsion system. The effect of several parameters, such as w0 ([H2O]/[surfactant]) value, reaction time, reaction temperature, oil phase solvent, buffer solution pH value of microemulsion system on the esterification have been investigated. The results showed that the best experimental conditions for catalytic synthesis ethyl hexanoate were as follows: w0 = 4, reaction time 4 h, reaction temperature 40 °C, buffer solution pH 7. Under these conditions, the conversion of ethyl hexanoate can reach 98.5 %. Lipase-catalyzed synthesis of ethyl hexanoate in dodecylbenzenesulfonic acid inverse microemulsion system has triple mechanism, namely acid catalyzes, microemulsion catalyzes and enzyme catalyzes.
The combined use of ultrasound and molecular sieves improves the synthesis of ethyl butyrate catalyzed by immobilized Thermomyces lanuginosus lipase
Paludo, Natalia,Alves, Joana S.,Altmann, Cintia,Ayub, Marco A.Z.,Fernandez-Lafuente, Roberto,Rodrigues, Rafael C.
, p. 89 - 94 (2015)
In this work, the combined use of ultrasound energy and molecular sieves was investigated for the synthesis of ethyl butyrate, ester with mango and banana notes, catalyzed by the immobilized lipase from Thermomyces lanuginosus (Lipozyme TL-IM). Initially, the best concentrations of biocatalysts (35%) and butyric acid (0.7 M) were tested using ultrasound as an alternative to mechanical agitation. The amount of acid in the reaction could be increased by 2-fold when compared to previous works where mechanical agitation was used. In the next step, substrate molar ratio and reaction temperature were optimized and the best conditions were at their lowest levels: 1:1 (acid:alcohol), and 30 °C, reaching 61% of conversion in 6 h. Molecular sieves (3 A?) were added to optimized reaction medium in order to remove the formed water and improve the maximum yield. The reaction yield increased 1.5 times, reaching 90% of conversion in 6 h, when 60 mg of molecular sieves per mmol of butyric acid was used. Finally, the reuse of Lipozyme TL-IM for the ultrasound-assisted synthesis of ethyl butyrate was verified for 10 batches, without any appreciable loss of activity, whereas in systems using mechanical agitation, the biocatalyst was completely inactivated after 5 batches. These results suggest that the combined use of ultrasound and molecular sieves greatly improve esterification reactions by stabilizing the enzyme and increasing yields.
New possibilities in the synthesis of fuel oxygenates from renewable sources
Varfolomeev,Vol’eva,Komissarova,Kurkovskaya,Malkova,Ovsyannikova,Gumerov,Usmanov
, p. 717 - 724 (2019)
A general problem in the production of the main types of liquid biofuel, bioethanol and biodiesel, is that renewable resources are not utilized completely. These are ballast polyols: hemicellulose or its structural units, pentaatomic monosaccharides (xylose and arabinose), and biodiesel glycerol. The problem of utilization of these compounds by transforming them into a hydrophobized fuel form by the conversion to cyclic ketals (CK) during condensation with lower carbonyl compounds is reviewed. The CK—ethanol pair significantly increases the octane number and provides phase stability of fuel compositions. The ability of CK to inhibit radical processes responsible for fuel characteristics was studied in model reactions with phenyl radicals and atomic chlorine. The carbon-centered radicals formed in protic media are transformed into more stable cyclic radical cations. Alternative methods of processing natural raw materials using biocatalysis and supercritical fluid technologies are analyzed.
Fluorescent microplate assay method for high-throughput detection of lipase transesterification activity
Zheng, Jianyong,Wei, Wei,Lan, Xing,Zhang, Yinjun,Wang, Zhao
, p. 26 - 28 (2018)
This study describes a sensitive and fluorescent microplate assay method to detect lipase transesterification activity. Lipase-catalyzed transesterification between butyryl 4-methyl umbelliferone (Bu-4-Mu) and methanol in tert-butanol was selected as the model reaction. The release of 4-methylumbelliferone (4-Mu) in the reaction was determined by detecting the fluorescence intensity at λex 330 nm and λem 390 nm. Several lipases were used to investigate the accuracy and efficiency of the proposed method. Apparent Michaelis constant (Km) was calculated for transesterification between Bu-4-Mu and methanol by the lipases. The main advantages of the assay method include high sensitivity, inexpensive reagents, and simple detection process.
Zinc Complexes with Cyanoxime: Structural, Spectroscopic, and Catalysis Studies in the Pivaloylcyanoxime-Zn System
Opalade, Adedamola A.,Karmakar, Anirban,Rúbio,Pombeiro, Armando J. L.,Gerasimchuk, Nikolay
, p. 13962 - 13974 (2017)
Reaction of 2-hydroxyimino-4,4-dimethyl-3-oxo-pentanenitrile (common abbreviation HPiCO, pivaloyl-cyanoxime) with zinc sulfate in an aqueous solution results in the formation of the two new complexes: [Zn(PiCO){H(PiCO)2}(H2O)] (I) and tetranuclear Zn complex [Zn4(μ3-OH)2(PiCO)6 (H2O)4] (II). Both complexes were characterized by elemental analysis, IR- and UV-visible spectra, DSC/TGA studies, and X-ray analysis. In complex II, the PiCO- cyanoxime anion adopts three bidentate binding modes: O-monodentate, chelating (κ2), and bridging (2) coordinations. Also, the ligand represents the mixture of two diasteromers (cis-anti and cis-syn) that form five- and six-membered chelate rings with Zn atoms and cocrystallize in one unit cell at population of 0.57-0.43. There are two crystallographically different Zn-centers in the ASU, and two μ3-bridging hydroxo-groups arrange via inversion center the formation of an elegant tetranuclear complex. Each Zn atom has a molecule of coordinated water and is in the distorted octahedral environment. Because of the structural flexibility and multidentate propensity of the pivaloyl-cyanoxime, complex II may act as a structural model of naturally occurring Zn-containing enzymes. Indeed, compound I exhibits an efficient catalytic performance for transesterification reaction of various esters in ethanol under mild reaction conditions. Therefore, obtained results allow assignment of observed activity as green catalysis.
Selective reduction of α,β-unsaturated esters with NaBH4-BiCl3 system
Ren,Pan,Dong,Wu
, p. 3395 - 3399 (1995)
Sodium borohydride-bismuth chloride system was applied for the selective reduction of carbon-carbon double bond of α,β-unsaturated esters with high selectivity.
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Sumrell,Ham
, p. 5573 (1956)
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Efficient and catalyst-free condensation of acid chlorides and alcohols using continuous flow
Van Waes, Frederik E. A.,Cukalovic, A.,Stevens, Christian V.,Drabowicz, J.
, p. 2776 - 2779,4 (2012)
An efficient, catalyst-free continuous flow procedure for the condensation of acid chlorides and alcohols was developed. Different esters could be obtained using this protocol with excellent conversions starting from the corresponding acid chlorides and alcohols in very short reaction times (5-7 min). The reaction was performed solventless for liquid reagents but requires a solvent for solid reagents in order to prevent clogging of the microreactor. Since no catalyst is needed, the purification of the reaction mixture is very straightforward. Scale-up of the reaction to a microreactor with an internal volume of 13.8 ml makes it possible to produce 2.2 g min-1 of ester with an isolated yield of 98% and recuperation of the formed HCl.
Biocatalytic production of ethyl butyrate from butyric acid with immobilized Candida rugosa lipase on cotton cloth
Shu, Chengliang,Cai, Jin,Huang, Lei,Zhu, Xiangcheng,Xu, Zhinan
, p. 139 - 144 (2011)
A novel method involving polyethylenimine (PEI) coating and glutaraldehyde cross-linking processes was developed to immobilize Candida rugosa lipase onto cotton cloth. After the systematic investigation, the optimal lipase immobilization was achieved when 0.1 g lipase was loaded on 1.5 g support, which was pretreated with 10 ml of 1.0 mg/ml PEI solution at pH 8.0. Subsequent catalytic analysis of immobilized lipase for ethyl butyrate synthesis was also carried out in the Erlenmeyer flasks. The results indicated that when optimal 0.25 M ethanol and 0.6 M butyric acid were catalyzed by the immobilized lipase at 25 °C, the highest conversion yield of 91.2% and 1.27 mmol h-1 g-1 productivity of ethyl butyrate were obtained. Furthermore, a kinetic model of Ping Pong Bi-Bi mode with inhibition of both substrates was proposed and validated by experimental data. To explore the practical potential of immobilized lipase, its operational stability was evaluated and the residual activity was remained about 50% after 12 repeated recycles, with a half-life time of about 300 h for the immobilized lipase. Finally, a recycle batch reactor using immobilized lipase was developed for ethyl butyrate production. The achieved result of 0.85 M final ethyl butyrate concentration, with the conversion of 70.6% and the productivity of 1.45 mmol h-1 g -1, had revealed the promising potential of this immobilized lipase in practical applications.
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Kutz,Adkins
, p. 4391,4397 (1930)
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The preparation of homogeneous triglycerides of eicosapentaenoic acid and docosahexaenoic acid by lipase
Haraldsson, Gudmundur G.,Gudmundsson, Birgir Oe.,Almarsson, Oern
, p. 5791 - 5794 (1993)
The highly efficient generation of homogeneous triglycerides of either pure eicosapentaenoic acid, 1, or docosahexaenoic acid, 2, by an immobilized nonregiospecific yeast lipase from Candida antarctica is described.
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Feuer,H. et al.
, p. 3622 - 3625 (1968)
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COMPETITIVE TYPE II ELIMINATIONS IN ALIPHATIC IMIDES
Mazzocchi, Paul H.,Jameson, William,Nishiyama, Tomikiro,DeCamp, Ann
, p. 989 - 992 (1980)
Aliphatic imides have been shown to undergo type II eliminations across the imide moiety in addition to those on the C-alkyl chain and α cleavage reactions.
Stability improvement of immobilized Candida antarctica lipase B in an organic medium under microwave radiation
Rejasse, Barbara,Lamare, Sylvain,Legoy, Marie-Dominique,Besson, Thierry
, p. 1086 - 1089 (2004)
The influence of microwave heating on the stability of immobilized Candida antarctica lipase B was studied at 100°C in an organic medium. The microwave radiation was carried out before enzymatic reaction (storage conditions) or during the enzymatic catalysis (use conditions). In both cases, enzymatic stability was higher under microwave heating than under conventional thermal heating, in strictly identical operating conditions. Furthermore, the gain of enzymatic stability under microwave heating appears to be higher in a more polar solvent, which interacts strongly with the microwave field. Our results suggest that microwave radiation has an effect, not related to temperature, on the process of enzymatic inactivation.
Cavity-promotion by pillar[5]arenes expedites organic photoredox-catalysed reductive dehalogenations
Esser, Birgit,Schmidt, Maximilian
supporting information, p. 9582 - 9585 (2021/09/28)
The efficiency of the photo-induced electron transfer in photoredox catalysis is limited by the diffusional collision of the excited catalyst and the substrate. We herein present cavity-bound photoredox catalysts, which preassociate the substrates, leading to significantly shortened reaction times. A pillar[5]arene serves as the cavity and phenothiazine as a catalyst in the reductive dehalogenation of aliphatic bromides as a proof of concept reaction.
Chromium-Catalyzed Production of Diols From Olefins
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Paragraph 0111, (2021/03/19)
Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.
Selective C-C Bond Scission of Ketones via Visible-Light-Mediated Cerium Catalysis
Chen, Yilin,Du, Jianbo,Zuo, Zhiwei
supporting information, p. 266 - 279 (2020/01/08)
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