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.
Triethylborane-induced radical reactions with gallium- and indium hydrides
Takami, Kazuaki,Mikami, Satoshi,Yorimitsu, Hideki,Shinokubo, Hiroshi,Oshima, Koichiro
, p. 6627 - 6635 (2003)
A gallium hydride reagent, HGaCl2, was found to act as a radical mediator. Treatment of alkyl halides with the gallium hydride reagent, generated from gallium trichloride and sodium bis(2-methoxyethoxy)aluminum hydride, provided the corresponding reduced products in excellent yields. Radical cyclization of halo acetals was also successful with not only the stoichiometric gallium reagent but also a catalytic amount of gallium trichloride combined with stoichiometric aluminum hydride as a hydride source. An indium hydride reagent, HInCl2, prepared from indium trichloride and diisobutylaluminum hydride also worked as a radical mediator. HInCl2 could reduce aryl iodides and bromides in the presence of Et3B as a radical initiator.
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.
Poly(vinylsulfonic acid)-grafted solid catalysts: New materials for acid-catalysed organic synthetic reactions
Okayasu, Teruyuki,Saito, Kei,Nishide, Hiroyuki,Hearn, Milton T. W.
, p. 1981 - 1989 (2010)
The synthesis, characterisation and application of novel high-density poly(vinylsulfonic acid)-grafted solid acid catalysts are described. A graft, radical polymerization procedure was employed, allowing the immobilisation of the acid form of vinylsulfonic acid monomer onto various carrier materials, such as polystyrene, silica or polysaccharide-based gels. The highest acid-exchange capacity (as determined by acid-base titration methods) achieved with these new materials was 5.2 mmol H+ g-1. The properties of these PVS-grafted materials as solid state acid catalysts have been examined from several perspectives, including their fundamental properties as materials with extremely high acid dissociation characteristics, their structural features as revealed from IR and solid-state NMR measurements, their thermal stability properties, and their surface morphologies, humidity dependencies and functionality. Compared to many other types of acid catalysts, these high-density poly(vinylsulfonic acid)-grafted materials demonstrated superior catalytic performance in esterification, Friedel-Crafts acylation, and condensation reactions. Moreover, these novel materials show high stability, significant anticorrosion capability and can be easily recycled. The Royal Society of Chemistry 2010.
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.
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.
Ultrasound technology and molecular sieves improve the thermodynamically controlled esterification of butyric acid mediated by immobilized lipase from Rhizomucor miehei
Fallavena, Lucas P.,Antunes, Fabio H. F.,Alves, Joana S.,Paludo, Natalia,Ayub, Marco A. Z.,Fernandez-Lafuente, Roberto,Rodrigues, Rafael C.
, p. 8675 - 8681 (2014)
In this research, the effects of ultrasound stirring and the addition of molecular sieves on esterification reactions between butyric acid and several alcohols catalyzed by immobilized lipase from Rhizomucor miehei (Lipozyme RM-IM) were studied. Among the tested alcohols, 1-propanol and isobutanol allowed the highest activities, whereas Lipozyme RM-IM showed poor activities for esterification using secondary and tertiary alcohols. Different solvents were also tested and n-hexane was selected because of its reaction effects, besides being cheaper, available at low boiling point, and ease of recovery. Using the preselected alcohol and solvent, other reaction parameters (butyric acid concentration, temperature, substrate molar rate, and biocatalyst content) were studied to optimize the reaction conditions. Optimal conditions were acid concentration, 0.7 M; substrate molar ratio, 11 alcohol-acid; temperature 45 °C; biocatalyst content, 14% (by substrate mass). Under these conditions, it was possible to obtain a yield of 86% of butyl butyrate in 2.5 h. When molecular sieves (90 mg mmol-1 butytic acid) were added to the reaction, the observed yield increased to 96%. The biocatalyst was used in 5 successive reaction cycles keeping 100% of its initial activity. The overall process productivity was improved 2-fold when compared to the traditional mechanical agitation, showing that ultrasound is a promising technology for application in biocatalysis. The Royal Society of Chemistry.
