- Vapor-phase catalytic dehydration of 2,3-butanediol to 3-buten-2-ol over ZrO2 modified with alkaline earth metal oxides
-
Vapor-phase catalytic dehydration of 2,3-butanediol (2,3-BDO) to produce 3-buten-2-ol (3B2OL) was investigated over several monoclinic ZrO2 (m-ZrO2) catalysts modified with alkaline earth metal oxides (MOs), such as SrO, BaO, and MgO, to compare with the previously reported CaO/m-ZrO2. It was found that these modifiers enhanced the 3B2OL formation to the same level as CaO did by loading an appropriate MO content. Among all the tested catalysts, the BaO/m-ZrO2 calcined at 800?°C with a low BaO content (molar ratio of BaO/ZrO2?=?0.0452) shows the highest 2,3-BDO conversion (72.4%) and 3B2OL selectivity (74.4%) in the initial stage of 5?h at 350?°C. In order to characterize those catalysts, their catalytic activities, crystal structures, and basic properties were studied in detail. In X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) experiment, it was elucidated that highly dispersed M-O-Zr (M?=?Ca, Sr, and Ba) hetero-linkages were formed on the surface by loading these MOs onto m-ZrO2 with an appropriate content and then calcining at 800?°C. It can be concluded that the M-O-Zr hetero-linkages generate the proper base-acid balance for the efficient formation of 3B2OL from 2,3-BDO.
- Duan, Hailing,Yamada, Yasuhiro,Kubo, Shingo,Sato, Satoshi
-
-
Read Online
- Synthesis of quadruply carbon-13 labeled tetramethyltetrathiafulvalene
-
A short synthesis of tetramethyltetrathiafulvalene quadruply labeled with carbon-13 is described.
- Merlic, Craig A.,Baur, Andreas,Yamada, Ken,Brown, Stuart E.
-
-
Read Online
- Kinetics and Mechanisms of Oxidations by Metal Ions. V. Oxidation of 4-Oxopentanoic Acid by the Aquavanadium(V) Ion
-
The outer sphere oxidation of 4-oxopentanoic acid (4-OPA), studied at 50 deg C by aquavanadium (V) ion, is H(1+)-catalyzed reaction.The reaction has a first-order dependence on each of , , and .The H(1+) catalysis can not be ascribed to keto enol equilibrium because of the knowledge that a γ-keto acid is the least enolized amongst keto acids.Hence V(OH)3(2+)(aq) ion is the active oxidant.The proposed mechanism, assumed to involve the initial decarboxylation, is supported by the spot test characterization of acetoin as the intermediate oxidation product.Acetoin is further oxidized to two moles of acetic acid which is the final oxidation product.The overall energy of activation (ΔH1=26+/-3 kJ mol-1) is lower than the normal value (84 kJ mol-1) and therefore the highly negative value of the overall entropy of activation (ΔS1=-268+/-8 JK-1 mol-1) is considered to be responsible for the observed slowrate of oxidation.
- Mehrotra, Raj Narain
-
-
Read Online
- Influence of Br- Concentration on (Br)+-Mediated Indirect Electrooxidation of Alcohols to the Corresponding Carbonyl Compounds
-
Current efficiency for the (Br)+ (positive bromine species)-mediated indirect electrooxidation of alcohols to the corresponding carbonyl compounds decreased with increase in Br- concentration in dichloromethane and aqueous acidic solutions, while no concentration dependence was observed in an aqueous neutral solution.These facts suggested a general practical guideline for the indirect electrooxidation, i.e. low Br- concentration is favorable in an electrolytic solution of low nucleophilicity.It was also found that the kind of (Br)+ species formed anodically in the absence of the alcohols in dichloromethane celarly depended on charge(Q) passed as follows:Br3- at Q-1 (1F = 96480 C), Brn- (n>3) at 2/3-1, and Br2 at Q = 1F mol-1.Among these species, Br3- and Br2 seemed to be the weakest and strongest oxidizing agents, respectively.Lower efficiency for the direct electrooxidation in higher Br- concentration was rationalized as due to more predominant formation of Br3- and/or Brn- with smaller n values.
- Takiguchi, Tsuyoshi,Nonaka, Tsutomu
-
-
Read Online
- Influence of Calcium Ions on the Mechanism of Oxime Formation from Acetoin
-
The effect of calcium ions on the reaction of acetoin with hydroxylamine was studied. This reaction proceeds by a two-step mechanism: the attack of hydroxylamine on the carbonyl compound to give a tetrahedral addition intermediate, and the dehydration of this intermediate to form the oxime. The presence of calcium ions decreases the value of the equilibrium constant of the tetrahedral addition intermediate formation, but increases the overall rate constant of the reaction when dehydration is the rate-determining step. Evidence suggests that the effect of calcium ions is through the formation of a complex with the hydroxyl groups of the tetrahedral addition intermediate, facilitating the dehydration step of the reaction.
- Fett, Roseane,Brighente, Ines Maria Costa,Yunes, Rosendo Augusto
-
-
Read Online
- A highly efficient thiazolylidene catalyzed acetoin formation: Reaction, tolerance and catalyst recycling
-
An efficient formation of acetoin from acetaldehyde was achieved under thiazolylidene catalysis. High yields and TON were achieved. Its sufficient tolerance toward ethanol and moisture renders it a practical key step of the ethanol upgrading process. A new type of solid supported thiazolylidene catalyst was designed to make catalyst recycling achievable. This journal is
- Gu, Liuqun,Lu, Ting,Li, Xiukai,Zhang, Yugen
-
-
Read Online
- New Enantioselective Reactions catalysed by Cinchonidine-modified Platinum
-
The conjugated diketones butane-2,3-dione and hexane-3,4-dione can be hydrogenated enantioselectively over Pt/silica modified by cinchonidine giving enantiomeric excesses in favour of (R)-(-)-3-hydroxybutan-2-one of up to 38percent and of (R)-(-)-4-hydroxyhexan-3-one up to 33percent.
- Vermeer, Wilhelmus A. H.,Fulford, Anthony,Johnston, Peter,Wells, Peter B.
-
-
Read Online
- Practical tethering of vitamin B1 on a silica surface via its phosphate group and evaluation of its activity
-
A convenient immobilization of thiamine pyrophosphate molecules on a silica surface through the phosphate group is developed, leading to a very active heterogenised biocatalyst for pyruvate decarboxylation.
- Vartzouma,Louloudi,Butler,Hadjiliadis
-
-
Read Online
- Selective hydrogenation by novel composite supported Pd egg-shell catalysts
-
Two organic-inorganic mixed phase supports were prepared, comprising an alumina filler and polymers of different chemical nature. Four low loaded Pd catalysts were prepared. Good activities and selectivities were obtained during the hydrogenations of styrene, 1-heptyne and 2,3-butanedione. The catalysts were found to have excellent mechanical properties and could be used in applications needing high attrition resistance and crushing strength. In this sense, processes for fine chemicals using slurry reactors or processes for commodities using long packed beds could advantageously use them.
- Carrara,Badano,Betti,Lederhos,Rintoul,Coloma-Pascual,Vera,Quiroga
-
-
Read Online
- Vapor-phase catalytic dehydration of 2,3-butanediol into 3-buten-2-ol over Sc2O3
-
Vapor-phase catalytic dehydration of 2,3-butanediol (2,3-BDO) was investigated over rare earth oxide (REO) catalysts as well as In2O3. In the dehydration of 2,3-BDO, 3-buten-2-ol (3B2OL) was produced together with 3-hydroxy-2-butanone (3H2BO), butanone (MEK), 2-methylpropanal (IBA), 2-methyl-1-propanol (IBO), etc. Sc2O3 and In2O3 showed hi gher 3B2OL select ivities than other REOs. In particular, Sc2O3 converted 2,3-BDO into 3B2OL with an excellent selectivity of 85.0% at 99.9% conversion.
- Duan, Hailing,Yamada, Yasuhiro,Sato, Satoshi
-
-
Read Online
- Oxidation of 2,3-butanediol by alkaline hexacyanoferrate(III) using Ru(III) or Ru(VI) as catalyst
-
The reactions of 2,3-butanediol by hexacyanoferrate(III) in alkaline medium using ruthenium compounds as catalysts have been studied spectrophotometrically. The effect on the reaction rate of concentration of substrate, oxidant, catalyst and basicity of the medium leads to similar experimental rate equations for both catalysts, Ru(III) and Ru(VI). The reaction mechanism involves the formation of a catalyst-substrate complex that yields a carbocation for Ru(VI) or a radical for Ru(III) oxidation. Hexacyanoferrate(III) 's role is the catalyst regeneration. The rate constants of complex decomposition and catalyst regeneration have been determined. Copyright
- Poblete,Mucientes,Villarreal,Santiago,Cabanas,Gabaldon
-
-
Read Online
- N-PEGylated Thiazolium Salt: A Green and Reusable Homogenous Organocatalyst for the Synthesis of Benzoins and Acyloins
-
N-PEGylated-thiazolium salt is used as efficient catalyst for the benzoin condensation. The catalyst was synthesized by reaction of activated polyethylene glycol 10,000 (PEG-10000) with 4-methyl-5-thiazoleethanol (sulfurol). Reaction mixture undergoes temperature-assisted phase transition and catalyst separated by simple filtration. After reaction course, catalyst can be recycled and reused without any apparent loss of activity which makes this process cost effective and hence ecofriendly. Synthesized benzoins and acyloins by this method have been characterized on the basis of melting point and 1H-NMR spectral studies. Graphic Abstract: [Figure not available: see fulltext.]
- Haghighi, Ali Javaheri,Mokhtari, Javad,Karimian, Khashayar
-
p. 1646 - 1652
(2020/10/19)
-
- carba Nicotinamide Adenine Dinucleotide Phosphate: Robust Cofactor for Redox Biocatalysis
-
Here we report a new robust nicotinamide dinucleotide phosphate cofactor analog (carba-NADP+) and its acceptance by many enzymes in the class of oxidoreductases. Replacing one ribose oxygen with a methylene group of the natural NADP+ was found to enhance stability dramatically. Decomposition experiments at moderate and high temperatures with the cofactors showed a drastic increase in half-life time at elevated temperatures since it significantly disfavors hydrolysis of the pyridinium-N?glycoside bond. Overall, more than 27 different oxidoreductases were successfully tested, and a thorough analytical characterization and comparison is given. The cofactor carba-NADP+ opens up the field of redox-biocatalysis under harsh conditions.
- D?ring, Manuel,Sieber, Volker,Simon, Robert C.,Tafertshofer, Georg,Zachos, Ioannis
-
supporting information
p. 14701 - 14706
(2021/05/13)
-
- Sol-gel synthesis of ceria-zirconia-based high-entropy oxides as high-promotion catalysts for the synthesis of 1,2-diketones from aldehyde
-
Efficient Lewis-acid-catalyzed direct conversion of aldehydes to 1,2-diketones in the liquid phase was enabled by using newly designed and developed ceria–zirconia-based high-entropy oxides (HEOs) as the actual catalysts. The synergistic effect of various cations incorporated in the same oxide structure (framework) was partially responsible for the efficiency of multicationic materials compared to the corresponding single-cation oxide forms. Furthermore, a clear, linear relationship between the Lewis acidity and the catalytic activity of the HEOs was observed. Due to the developed strategy, exclusively diketone-selective, recyclable, versatile heterogeneous catalytic transformation of aldehydes can be realized under mild reaction conditions.
- Dinjar, Kristijan,Djerdj, Igor,Koj?inovi?, Jelena,Kukovecz, ákos,Markovi?, Berislav,Mileti?, Aleksandar,Nagy, Sándor Balázs,Sapi, Andras,Stenzel, David,Széchenyi, Aleksandar,Szenti, Imre,Tang, Yushu,Tatar, Dalibor,Varga, Gábor,Ziegenheim, Szilveszter
-
-
- Selective Hydrogenation of Diketones on Supported Transition Metal Catalysts
-
Abstract: The hydrogenation of α-diketones yields α-hydroxyketones or vic-diols, both compounds of great interest in fine chemistry. The reaction tests were the liquid phase hydrogenation of 2,3-butanedione and 2,3-pentanedione at mild conditions. The objectives of this work were evaluating the effect over the activity and selectivity of: (a) different transition metallic phase based catalysts supported on activated carbon, (b) the symmetry of the reactants and (c) solvents. The physicochemical characterization of the catalysts was carried out by ICP, XRD, TEM, N2 adsorption and XPS. The keto-enol equilibrium of diketones was studied by 1H-NMR. All the catalysts were active in both reactions. In terms of activity, Pt and Rh were the best active phases. For both reactants the highest selectivity towards hydroxyketones were achieved with Pd, while Ru was the most selective towards the diol. Both the activity and selectivity followed similar patterns in the hydrogenation of both diketones. The greater activity of Pt was attributed to the high dispersion of the active metal phase in this catalyst and the high efficiency of Pt for C = O bond reduction. The high selectivity of the Pd catalysts towards the intermediate product was attributed to many effects: (i) a lower interaction of the hydroxyketone with the active site as compared to the diketone, (ii) the easy reducibility of the C = C double bond on Pd, provided by the keto-enol tautomerism of diketones.
- Carrara,Badano,Vailard,Vera,Quiroga
-
p. 461 - 470
(2019/11/13)
-
- Energy- And cost-effective non-sterilized fermentation of 2,3-butanediol by an engineered: Klebsiella pneumoniae OU7 with an anti-microbial contamination system
-
Microbial contamination is a serious challenge that needs to be overcome for the successful biosynthesis of 2,3-butanediol (2,3-BD). However, traditional strategies such as antibiotic administration or sterilization are costly, have high energy demands, and may increase the risk of antibiotic resistance. Here, we intend to develop a robust strategy to achieve non-sterilized fermentation of 2,3-BD. Briefly, the robust strain can metabolize unconventional chemicals as essential growth nutrients, and therefore, outcompete contaminant microbes that cannot use unconventional chemicals. To this end, Klebsiella pneumoniae OU7, a robust strain, was confirmed to rapidly exploit urea and phosphite (unconventional chemicals) as the primary sources of nitrogen (N) and phosphorus (P), and withstand deliberate contamination in the possibly contaminated systems. Secondly, metabolic engineering, pathogenicity elimination and adaptive laboratory evolution were successively performed, endowing the best strain with an excellent fermentation performance for safe 2,3-BD production. Finally, 84.53 g L-1 of 2,3-BD was synthesized with a productivity of 1.17 g L-1 h-1 and a yield of 0.38 g g-1 under the non-sterilized system. In summary, our technique reduces labor and energy costs and simplifies the fermentation process because sterilization does not need to be performed. Thus, our work will be beneficial for the sustainable synthesis of 2,3-BD. This journal is
- Guo, Ze-Wang,Ou, Xiao-Yang,Xu, Pei,Gao, Hui-Fang,Zhang, Liao-Yuan,Zong, Min-Hua,Lou, Wen-Yong
-
p. 8584 - 8593
(2020/12/31)
-
- Vapor-phase catalytic dehydration of butanediols to unsaturated alcohols over yttria-stabilized zirconia catalysts
-
Vapor-phase catalytic dehydration of butanediols (BDOs) such as 1,3-, 1,4-, and 2,3-butanediol was investigated over yttria-stabilized tetragonal zirconia (YSZ) catalysts as well as monoclinic zirconia (MZ). BDOs were converted to unsaturated alcohols with some by-products over YSZ and MZ. YSZ is superior to MZ for these reactions in a view point of selective formation of unsaturated alcohols. Calcination temperature of YSZ significantly affected the products selectivity as well as the conversion of BDOs: high selectivity to unsaturated alcohols was obtained over the YSZ calcined at high temperatures over 800 °C. In the conversion of 1,4-butanediol at 325 °C, the highest 3-buten-1-ol selectivity of 75.3% was obtained over the YSZ calcined at 1050 °C, whereas 2,3-butanediol was less reactive than the other BDOs. In the dehydration of 1,3-butanediol at 325 °C, in particular, it was found that a YSZ catalyst with a Y2O3 content of 3.2 wt.% exhibited an excellent stable catalytic activity: the highest selectivity to unsaturated alcohols such as 2-buten-1-ol and 3-buten-2-ol over 98% was obtained at a conversion of 66%. Structures of active sites for the dehydration of 1,3-butanediol were discussed using a crystal model of tetragonal ZrO2 and a probable model structure of active site was proposed. The well-crystalized YSZ inevitably has oxygen defect sites on the most stable surface of tetragonal ZrO2 (101). The defect site, which exposes three cations such as Zr4+ and Y3+, is surrounded by six O2? anions. The selective dehydration of 1,3-butanediol to produce 3-buten-2-ol over the YSZ could be explained by tridentate interactions followed by sequential dehydration: the position-2 hydrogen is firstly abstracted by a basic O2? anion and then the position-1 hydroxyl group is subsequently or simultaneously abstracted by an acidic Y3+ cation. Another OH group at position 3 plays an important role of anchoring 1,3-butanediol to the catalyst surface. Thus, the selective dehydration of 1,3-butanediol could proceed via the speculative base-acid-concerted mechanism.
- Ohtsuka, Shota,Nemoto, Takuma,Yotsumoto, Rikako,Yamada, Yasuhiro,Sato, Fumiya,Takahashi, Ryoji,Sato, Satoshi
-
-
- 2,3-Butanediol dehydration catalyzed by silica-supported alkali phosphates
-
Characterization of acid-base centers and catalytic dehydration of 2,3-butanediol (BDO) was performed over a wide range of silica-supported alkali phosphates (M_P/SiO2; M = Na, K, Cs; M:P = 0.5–3 mol:mol). Selectivity to 1,3-butadiene (BD) and 3-butene-2-ol (3B2OL) formed by elimination correlates with the densities of conjugated acid-base pairs and increases in the order Na ??M+ moieties. Isolated Br?nsted acid centers are probably silica grafted phosphoric acid molecules at low M/P and –PO(OH)2 end groups of oligophosphates at M/P > 1.5. Deactivation rate increases with the increase of M/P ratio in order Na K Cs. Deactivation patterns imply that sites responsible for elimination are active in dehydrative epoxidation. Dehydration of 3B2OL smoothly proceeds to BD, but the catalysts deactivate faster compared to BDO dehydration.
- Kim, Wooyoung,Shin, Wookyun,Lee, Kyoung Jun,Cho, YongSeok,Kim, Hyung Soon,Filimonov, Igor N.
-
p. 148 - 163
(2018/11/26)
-
- Preparation Method for 2,3-pentanedione
-
A preparation method for 2,3-pentanedione, including the steps of adding one or both of 3-hydroxy-2-pentanone and 2-hydroxy-3-pentanone into water and conducting mixing, and introducing ozone at the temperature of 3-20° C. for a reaction to obtain 2,3-pentanedione. The synthesis process of the present invention uses ozone for oxidizing a mixture containing 3-hydroxy-2-pentanone and 2-hydroxy-3-pentanone, acetic acid is used as a cocatalyst, reaction conditions are mild, the operation process is simple, the product yield is high, and the cost is low.
- -
-
Paragraph 0018; 0019; 0024; 0025; 0029
(2019/04/25)
-
- An artificial synthetic pathway for acetoin, 2,3-butanediol, and 2-butanol production from ethanol using cell free multi-enzyme catalysis
-
Upgrading ethanol to higher order alcohols is desired but difficult using current biotechnological methods. In this study, we designed a completely artificial reaction pathway for upgrading ethanol to acetoin, 2,3-butanediol, and 2-butanol in a cell-free bio-system composed of ethanol dehydrogenase, formolase, 2,3-butanediol dehydrogenase, diol dehydratase, and NADH oxidase. Under optimized conditions, acetoin, 2,3-butanediol, and 2-butanol were produced at 88.78%, 88.28%, and 27.25% of the theoretical yield from 100 mM ethanol, respectively. These results demonstrate that this artificial synthetic pathway is an environmentally-friendly novel approach for upgrading bio-ethanol to acetoin, 2,3-butanediol, and 2-butanol.
- Zhang, Liaoyuan,Singh, Raushan,Sivakumar,Guo, Zewang,Li, Jiahuan,Chen, Fanbing,He, Yuanzhi,Guan, Xiong,Kang, Yun Chan,Lee, Jung-Kul
-
p. 230 - 242
(2018/01/12)
-
- Effects of different techniques of malolactic fermentation induction on diacetyl metabolism and biosynthesis of selected aromatic esters in cool- climate grape wines
-
Thr effects of different malolactic bacteria fermentation techniques on the bioconversion of aromatic compounds in cool-climate grape wines were examined. During three wine seasons, red and white grape wines were produced using various malolactic fermentation induction techniques: Coinoculation, sequential inoculation, and spontaneous process. Volatile compounds (diacetyl and the products of its metabolism, and selected ethyl fatty acid esters) were extracted by solid phase microextraction. Compounds were identified with a multidimensional gas chromatograph-GC × GC-ToFMS with ZOEX cryogenic (N2) modulator. Sensory evaluation of the wines was also performed. It was found that the fermentation-derived metabolites studied were affected by the malolactic bacteria inoculation regime. Quantitatively, ethyl lactate, diethyl succinate, and ethyl acetate dominated as esters with the largest increase in content. The total concentration of ethyl esters was highest for the coinoculation technique, while the highest concentration of diacetyl was noted for the spontaneous technique. Controlled malolactic fermentation, especially using the coinoculation technique, can be proposed as a safe and efficient enological practice for producing quality cool-climate grape wines enriched with fruity, fresh, and floral aromas.
- Lasik-Kurdys, Ma?gorzata,Majcher, Ma?gorzata,Nowak, Jacek
-
-
- Preparation method of 2,3-pentanedione
-
The invention discloses a preparation method of 2,3-pentanedione. The preparation method comprises the following steps: one or two of 3-hydroxy-2-pentanone and 2-hydroxy-3-pentanone is/are added to water and uniformly mixed with water, ozone is introduced at the temperature of 3-20 DEG C for a reaction, and 2,3-pentanedione is obtained. According to the synthesis process, ozone is adopted to oxidize the mixture containing 3-hydroxy-2-pentanone and 2-hydroxy-3-pentanone, acetic acid is adopted as a cocatalyst, reaction conditions are mild, and operation process is simple; product yield is high;cost is low; the method has the advantages of being safe and environmentally friendly, and no wastewater is produced.
- -
-
Paragraph 0004; 0017-0019; 0024-0026; 0031-0033
(2018/09/08)
-
- Aqueous phase reforming of glycerol using doped graphenes as metal-free catalysts
-
Boron-doped graphene obtained by pyrolysis at 900°C of the boric acid ester of alginate was found to be the most active graphene among a series of doped and co-doped graphenes to promote the aqueous phase reforming of glycerol at 250°C. This reaction is of interest in the context of valorization of the aqueous wastes of carbohydrate syrups. Control experiments adding to undoped graphene 1 wt% of triphenylborane, tris(pentafluorophenyl)borane or bis(pinacolyl)diborane as models of possible boron atom types present in B-doped graphene, and boric acid that could be present in a residual amount after pyrolysis, show in all cases an increase in the catalytic activity of graphene. B-doped graphene has also activity for glucose aqueous phase reforming. B-doped graphene undergoes deactivation upon reuse, probably due to B leaching. The results show that graphenes are promising metal-free catalysts for aqueous phase reforming and are alternatives to those containing platinum.
- Esteve-Adell, Iván,Crapart, Bertrand,Primo, Ana,Serp, Philippe,Garcia, Hermenegildo
-
p. 3061 - 3068
(2017/07/15)
-
- Electrochemistry for the Generation of Renewable Chemicals: One-Pot Electrochemical Deoxygenation of Xylose to Δ-Valerolactone
-
In this study, the electrochemical conversion of xylose to δ-valerolactone via carbonyl intermediates is demonstrated. The conversion was achieved in aqueous media and at ambient conditions. This study also demonstrates that the feedstock for production of renewable chemicals and biofuels through electrochemistry can be extended to primary carbohydrate molecules. This is the first report on a one-pot electrochemical deoxygenation of xylose to δ-valerolactone.
- James, Olusola O.,Sauter, Waldemer,Schr?der, Uwe
-
p. 2015 - 2022
(2017/05/16)
-
- Preparation method of acyloin compounds
-
The invention relates to a preparation method of acyloin compounds, and belongs to the field of fine chemical industry. A new catalyst 1-n butyl benzimidazole hydrochloride is provided for synthesis of the acyloin compounds, and the products have the advantages of good quality and less side reactions; deficiencies existed in the prior art are overcome.
- -
-
Paragraph 0018; 0019; 0020
(2017/08/27)
-
- Green synthesizing method for 2,3-butanedione
-
The invention discloses a green synthesizing method for 2,3-butanedione. The green synthesizing method comprises the following process steps: taking acetaldehyde (I) as a raw material and thiazolium salt as a catalyst, regulating the PH value of reaction liquid to be 9-10 by sodium bicarbonate, heating in a pressure reaction kettle to carry out condensation reaction, if the pressure of the reaction kettle is reduced to 0Mpa after reacting for 3-4 hours, showing that reaction is finished basically, and cooling and distilling under reduced pressure to obtain acetoin (II); and adding water and a cocatalyst in the prepared acetoin (II), keeping low temperature, feeding ozone to carry out oxidizing reaction, tracking a reaction process by using a gas chromatography, removing a peroxide value after reaction is finished, carrying out distilling and separating under reduced pressure to obtain the 2,3-butanedione (III). The invention aims to overcome shortcomings in the prior art. The green synthesizing method for the 2,3 butanedione is simple in process and is pollution-free.
- -
-
Paragraph 0016-0018
(2017/09/01)
-
- Hydrogenation of diacetyl over composite-supported egg-shell noble metal catalysts
-
Two composite supports with a mixed inorganic-organic structure were synthesized: BTAl and UTAl. Hydrophilic-hydrophobic dual properties of the supports were suitable for preparing egg-shell-supported metal catalysts for selective hydrogenation reactions. The catalysts were characterized by ICP, XRD, OM, TEM, EPMA, XPS and TGA. Their mechanical resistance was assessed. Activity and selectivity were tested with the hydrogenation of 2,3-butanedione (diacetyl) to 3-hydroxy-2-butanoneacetoin (acetoin). The same order of increasing metal particle size was found for the two tested supports: Pt +). It was rationalized that the hydrogen bond cleavage was performed on the Me° active sites, while reactant adsorption occurred on the Me+ sites. The differences in activity and selectivity between the composite catalysts were attributed to electronic effects on the different metals and to different adsorptive properties of the different polymers. The high selectivity to acetoin was attributed to the preferential adsorption of diacetyl as compared to the adsorption of acetoin. The BTAl catalysts were slightly more active and selective than the UTAl ones. This was attributed to electronic effects caused by remnant organic groups on the composite supports (urethane or biphenyl on UTAl or BTAl, respectively). Pd-BTAl was the most active and selective catalyst, a fact related to electronic effects of both palladium and the support.
- Carrara,Badano,Coloma-Pascual,Vera,Quiroga
-
p. 1669 - 1683
(2017/09/02)
-
- Acetoin synthesis method
-
The invention provides an acetoin synthesis method. The method comprises 1, catalyst preparation: mixing 4-methyl-5-beta-hydroxyethyl thiazole (I) and bromoethane according to a mole ratio of 1: 1, carrying out heating reflux in an acetoin solvent in an oil bath for a reaction, then carrying out stirring cooling to the room temperature, carrying out rotary evaporation, recovering the solvent, standing the white precipitates, carrying out suction filtration and washing, carrying out acetoin recrystallization and carrying out drying to obtain a catalyst 3-ethyl-4-methyl-5-hydroxyethyl thiazole bromide (II) and 2, carrying out acetaldehyde condensation to obtain acetoin, adding the catalyst 3-ethyl-4-methyl-5-hydroxyethyl thiazole bromide (II) into an acetaldehyde solution, adjusting pH to 9-10, carrying out heating stirring for a condensation reaction in a pressure reactor until the pressure in the pressure reactor is 0 MPa, mixing the reaction solution, the recovered solvent and solutions collected in standing, suction filtration and washing processes, and carrying out reduced pressure distillation to obtain acetoin (III).
- -
-
Paragraph 0024; 0025; 0028; 0029; 0032; 0033
(2017/10/09)
-
- Hydrogen-Free Gas-Phase Deoxydehydration of 2,3-Butanediol to Butene on Silica-Supported Vanadium Catalysts
-
The gas-phase deoxydehydration of 2,3-butanediol to butene was investigated in a plug flow reactor over SiO2-supported vanadium oxide, γ-alumina, P/ZSM-5, and MgO catalysts with acid/base sites of varying strengths. 5 wt % vanadium on SiO2 (i.e., 5V/SiO2) showed the best performance with 100 % conversion and up to 45.2 % butene selectivity. The combination of weak acid sites and polymeric VOx surface species provided the 5V/SiO2 catalyst with bifunctional capabilities to achieve both dehydration and transfer hydrogenation, which allowed it to catalyze the deoxydehydration of 2,3-butanediol to butene even in the absence of H2. As 2,3-butanediol is a common yet underutilized biomass product, this reaction may provide a viable route for a biomass-to-chemicals application for 2,3-butanediol.
- Kwok, Kelvin Mingyao,Choong, Catherine Kai Shin,Ong, Daniel Sze Wei,Ng, Joy Chun Qi,Gwie, Chuandayani Gunawan,Chen, Luwei,Borgna, Armando
-
p. 2443 - 2447
(2017/07/12)
-
- Iron complexes with nitrogen bidentate ligands as green catalysts for alcohol oxidation
-
The iron(II) complexes [Fe(N-N)3](OTf)2 (N-N = 2,2′- bipyridine, 1,10-phenanthroline and substituted derivatives) were employed as catalyst precursors for the oxidation of primary and secondary alcohols, including glycerol. The single-crystal structure of [Fe(bipy)3](OTf)2 was determined by X-ray crystallography.The catalytic reactions were performed using either H2O2 or tert-butilhydroperoxide (TBHP) as oxidating agent, in mild experimental conditions: with all catalysts employed, secondary alcohols were oxidized to the corresponding ketones with up to 100% yields, whereas other substrates gave lower conversions. Indications on the nature of the catalytically active species, which is probably formed via dissociation of a nitrogen ligand from the iron center, were obtained from NMR and ESI-MS spectra.
- Chàvez, Jennifer E.,Crotti, Corrado,Zangrando, Ennio,Farnetti, Erica
-
p. 189 - 195
(2016/07/06)
-
- METHOD FOR PRODUCING ACETOIN
-
The présent invention relates to a recombinant yeast having a reduced pyruvate dccarboxylase activity, in thc génome of which has been inserted: - one or more nucleic acids encoding an acetolactate synthasc or ALS, - one or more nucleic acids encoding an acetolactate decarboxylasc or ALD, and - one or more copies of a nucleic acids encoding a NADH oxidase or NOXE.
- -
-
Page/Page column 56
(2016/02/26)
-
- Zeolite-supported iron catalysts for allyl alcohol synthesis from glycerol
-
Under most reaction conditions studied, acrolein is reported as the primary product in the conversion of glycerol over zeolites. In such processes, acrolein forms at relatively high yields, with negligible allyl alcohol selectivity. In this contribution, we report the development of ZSM5-supported iron catalysts, modified by rubidium deposition, as stable materials for production of allyl alcohol from glycerol. Our results demonstrate a reduced rate of formation of acrolein over modified catalysts. Both unmodified and modified catalysts were analysed by inductively coupled plasma optical emission spectrometry, nitrogen adsorption, scanning electron microscope, X-ray diffraction, ammonia temperature programmed desorption, X-ray photoelectron spectroscopy and ultraviolet-visible spectroscopy. These techniques revealed that differences in product distribution and catalyst performance are due to the combined effects of iron loading, catalyst acidity and changes in the porosity of the catalyst.
- Sánchez,Dlugogorski,Kennedy,Stockenhuber
-
p. 130 - 142
(2015/11/24)
-
- An environmentally benign hydration of alkynes catalyzed by gallic acid/tannic acid in water
-
A gallic acid catalyzed hydration strategy from alkynes under mild conditions has been developed. The catalyst system exhibits excellent activity, thus avoiding the use of any transition metal, strong acids or other toxic reagent as cocatalysts. Recycling experiments were conducted, and this procedure can be scaled up. Other tannins such as tannic acid can also be applied in this reaction which shows the potential utilization of natural feedstocks.
- Deng, Tao,Wang, Cheng-Zhang
-
p. 7029 - 7032
(2016/10/07)
-
- Regio- and Stereoselective Aliphatic–Aromatic Cross-Benzoin Reaction: Enzymatic Divergent Catalysis
-
The catalytic asymmetric synthesis of chiral 2-hydroxy ketones by using different thiamine diphosphate dependent enzymes, namely benzaldehyde lyase from Pseudomonas fluorescens (PfBAL), a variant of benzoylformate decarboxylase from?Pseudomonas putida (PpBFD-L461A), branched-chain 2-keto acid decarboxylase from Lactococcus lactis (LlKdcA) and a variant of pyruvate decarboxylase from Acetobacter pasteurianus (ApPDC-E469G), was studied. Starting with the same set of substrates, substituted benzaldehydes in combination with different aliphatic aldehydes, PfBAL and PpBFD-L461A selectively deliver the (R)- and (S)-2-hydroxy-propiophenone derivatives, respectively. The (R)- and (S)-phenylacetylcarbinol (1-hydroxy-1-phenylacetone) derivatives are accessible in a similar way using LlKdcA and ApPDC-E469G, respectively. In many cases excellent stereochemical purities (>98 % enantiomeric excess) could be achieved. Hence, the regio- and stereochemistry of the product in the asymmetric aliphatic–aromatic cross-benzoin reaction can be controlled solely by choice of the appropriate enzyme or enzyme variant.
- Beigi, Maryam,Gauchenova, Ekaterina,Walter, Lydia,Waltzer, Simon,Bonina, Fabrizio,Stillger, Thomas,Rother, D?rte,Pohl, Martina,Müller, Michael
-
supporting information
p. 13999 - 14005
(2016/09/21)
-
- RECOMBINANT STRAIN FOR PRODUCING 2,3-BUTANEDIOL, COMPRISING (A) INACTIVATED LACTATE DEHYDROGENASE AND (B) INACTIVATED SUCROSE REGULATOR
-
The present invention relates to a recombinant strain for producing 2,3-butanediol, comprising (a) an inactivated lactate dehydrogenase and (b) an inactivated sucrose regulator. According to the present invention, it is possible to economically produce 2,3-butanediol using a cheap carbon source, and the efficiency and productivity of 2,3-butanediol is remarkable compared with a wild type.
- -
-
Paragraph 0050-0072
(2016/08/03)
-
- RECOMBINANT MICROORGANISM WITH INCREASED PRODUCTIVITY OF 2,3-BUTANEDIOL, AND METHOD FOR PRODUCING 2,3-BUTANEDIOL USING SAME
-
Disclosed herein is a recombinant microorganism having enhanced 2,3-butanediol producing ability, wherein a pathway for converting pyruvate to acetyl-CoA, a pathway for converting pyruvate to formic acid, or a pathway for converting pyruvate to lactate is inhibited in a microorganism having acetyl-CoA and lactate biosynthetic pathways.
- -
-
Paragraph 0057; 0058
(2016/03/19)
-
- 1H-pyrrole-2,4-dicarbonyl-derivatives and their use as flavoring agents
-
The present invention primarily relates to 1H-pyrrole-2,4-dicarbonyl-derivatives of Formula (I) wherein R1, R2, R3, Z. Z' and J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) or of a mixture of compounds of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
- -
-
-
- Imidazo[1,2-a]pyridine-ylmethyl-derivatives and their use as flavoring agents
-
The present invention primarily relates to imidazo[1,2-a]pyridine-ylmethyl-derivatives of Formula (I) wherein R1, R2, X, W e J are as defined in the description, to mixtures thereof and to the use thereof as flavoring agents. The compounds in accordance with the present invention are suitable for producing, imparting, or intensifying an umami flavor. The invention further relates to flavoring mixtures, compositions for oral consumption as well as ready-to-eat, ready-to-use and semifinished products, comprising an effective amount of the compound of Formula (I) and to specific methods for producing, imparting, modifying and/or intensifying specific flavor impressions.
- -
-
-
- CONDENSATION OF ALDEHYDE
-
The present disclosure relates to a process for producing hydroxyketone by condensation of one or more 5 aldehydes in the presence of a thiazolium salt of Formula I as defined herein, and a base.
- -
-
Page/Page column 38; 42
(2015/08/06)
-
- Water-Soluble Gold-N-Heterocyclic Carbene Complexes for the Catalytic Homogeneous Acid- and Silver-Free Hydration of Hydrophilic Alkynes
-
Water-soluble gold(III/I) N-heterocylic carbene complexes behave as efficient catalysts for the hydration of terminal alkynes in neat water. The transformation proceeds in the absence of Bronsted acids or halide scavengers and is suitable for sensitive substrates. Kinetic profiles and DFT studies provide a clear picture of intermediates present during catalysis.
- Ibrahim, Houssein,Defrmont, Pierre,Braunstein, Pierre,Thry, Vincent,Nauton, Lionel,Cisnetti, Federico,Gautier, Arnaud
-
p. 3893 - 3900
(2016/01/25)
-
- Conversion of 2,3-butanediol to butenes over bifunctional catalysts in a single reactor
-
Abstract In this study, Cu/ZSM-5 catalysts were used to catalyze the hydrodeoxygenation of 2,3-butanediol to butenes in a single reactor in the presence of hydrogen. The carbon selectivity of butenes increased with increasing SiO2/Al2O3 ratio (lowering acidity of zeolite) and H2/2,3-butanediol ratio. Cu/ZSM-5 with a SiO2/Al2O3 ratio of 280 showed the best activity toward the production of butenes; however, Cu/ZSM-5 with SiO2/Al2O3 of 23 was favorable for the dehydrogenation reaction of 2,3-butanediol even in the excess of hydrogen. On zeolite ZSM-5(280), the carbon selectivity of butenes increased with increasing copper loading and 19.2 wt% of CuO showed the highest selectivity of butenes (maximum 71%). The optimal reaction temperature is around 250 °C. Experiments demonstrated that methyl ethyl ketone (MEK) and 2-methylpropanal are the intermediates in the conversion of 2,3-butanediol to butenes. The optimal performance toward the production of butene is the result of a balance between copper and acid catalytic functions.
- Zheng, Quanxing,Wales, Michael D.,Heidlage, Michael G.,Rezac, Mary,Wang, Hongwang,Bossmann, Stefan H.,Hohn, Keith L.
-
p. 222 - 237
(2015/08/18)
-
- Heterogeneously catalyzed oxidation of butanediols in base free aqueous media
-
The oxidation of four butanediols under base-free conditions has been investigated using a set of Au, Pd and Pt catalysts prepared using sol-immobilization. The supported nanoparticles are found to be active with bimetallic alloys having much higher activity when compared with the monometallic counterparts. In general the AuPt catalysts are the most active and in all cases the corresponding C4 oxidation products were observed with high selectivity; sequential reaction of these products leads to the formation of acetic acid as an undesired by-product.
- Ryabenkova, Yulia,Miedziak, Peter J.,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.
-
p. 6055 - 6058
(2014/12/10)
-
- Heterogeneously catalyzed oxidation of butanediols in base free aqueous media
-
The oxidation of four butanediols under base-free conditions has been investigated using a set of Au, Pd and Pt catalysts prepared using sol-immobilization. The supported nanoparticles are found to be active with bimetallic alloys having much higher activity when compared with the monometallic counterparts. In general the AuPt catalysts are the most active and in all cases the corresponding C4 oxidation products were observed with high selectivity; sequential reaction of these products leads to the formation of acetic acid as an undesired by-product.
- Ryabenkova, Yulia,Miedziak, Peter J.,Knight, David W.,Taylor, Stuart H.,Hutchings, Graham J.
-
p. 6055 - 6058
(2015/03/30)
-
- Vitamin B1-Catalyzed Acetoin Formation from Acetaldehyde: A Key Step for Upgrading Bioethanol to Bulk C4Chemicals
-
The production of bulk chemicals and fuels from renewable biobased feedstocks is of significant importance for the sustainability of human society. The production of ethanol from biomass has dramatically increased and bioethanol also holds considerable potential as a versatile building block for the chemical industry. Herein, we report a highly selective process for the conversion of ethanol to C4bulk chemicals, such as 2,3-butanediol and butene, via a vitamin B1 (thiamine)-derived N-heterocyclic carbene (NHC)-catalyzed acetoin condensation as the key step to assemble two C2acetaldehydes into a C4product. The environmentally benign and cheap natural catalyst vitamin B1 demonstrates high selectivity (99 %), high efficiency (97 % yield), and high tolerance toward ethanol and water impurities in the acetoin reaction. The results enable a novel and efficient process for ethanol upgrading.
- Lu, Ting,Li, Xiukai,Gu, Liuqun,Zhang, Yugen
-
p. 2423 - 2426
(2016/12/23)
-
- N-Heterocyclic carbene-catalyzed double acylation of enones with benzils
-
Thiazolium carbene-catalyzed reaction of aromatic 1,2-diketones with enones in aprotic solvents gave double acylation products in good yields, whereas hydroacylation products formed by Stetter reaction were not detected at all. These results suggested the generation of aroyloxyenamine species from the 1,2-diketones instead of hydroxyenamines (Breslow intermediates). This journal is
- Takaki, Ken,Ohno, Akira,Hino, Makoto,Shitaoka, Takashi,Komeyama, Kimihiro,Yoshida, Hiroto
-
supporting information
p. 12285 - 12288
(2014/12/11)
-
- Synthesis of α-hydroxy ketones from vicinal diols by selective dehydrogenation over Ir-ReOx/SiO2 catalyst
-
Rhenium oxide-modified Ir/SiO2 (Ir-ReOx/SiO 2) catalyst shows high activity and selectivity for the dehydrogenation of trans-1,2-cyclohexanediol to 2-hydroxycyclohexanone in water solvent under Ar. Linear vicinal diols bearing two secondary hydroxy groups or both a primary hydroxy group and a secondary hydroxy group can also be transformed to the corresponding α-hydroxy ketones in high selectivities. Ir-ReOx/SiO2 can be reused at least four times without loss of activity and selectivity.
- Sato, Hiraku,Tamura, Masazumi,Nakagawa, Yoshinao,Tomishige, Keiichi
-
supporting information
p. 334 - 336
(2014/03/21)
-
- METHOD FOR PRODUCING ALPHA - HYDROXY KETONE COMPOUND
-
The present invention relates to a specific thiazolium salt used for producing an ∝-hydroxy ketone compound, and a method for producing an ∝-hydroxy ketone compound by carrying out a coupling reaction of an aldehyde compound in the presence of a base compound and the specific thiazolium salt.
- -
-
Paragraph 0186
(2013/03/26)
-
- Escherichia coli/ADH-A: An all-inclusive catalyst for the selective biooxidation and deracemisation of secondary alcohols
-
The nicotinamide adenine dinucleotide regeneration system present in Escherichia coli cells was exploited for the oxidation and deracemisation of secondary alcohols with the overexpressed alcohol dehydrogenase from Rhodococcus ruber DSM 44541 (E. coli/ADH-A). Thus, various racemic alcohols were selectively oxidised with lyophilised or resting E. coli/ADH-A cells without need for an external cofactor or co-substrate. The addition of these substrates to the E. coli/ADH-A cells in buffer afforded the corresponding ketones and the remaining enantioenriched (R)-alcohols. This methodology was used for the desymmetrisation of a meso-diol and for the synthesis of the highly valuable raspberry ketone. Moreover, a biocatalytic concurrent process was developed with the resting cells of E. coli/ADH-A, ADH from Lactobacillus brevis, and glucose dehydrogenase for the deracemisation of various secondary alcohols, which afforded the desired enantiopure alcohols in more than 99 % ee starting from the racemic mixture. The reaction time of deracemisation of 1-phenylethanol was estimated to be less than 30 min. The stereoinversion of (S)-1-phenylethanol to its pure (R)-enantiomer was also achieved, which provided a biocatalytic alternative to the chemical Mitsunobu inversion reaction. An integrated recycling system: A nicotinamide adenine dinucleotide regeneration system present in Escherichia coli cells is exploited for the oxidation of secondary alcohols with E. coli/alcohol dehydrogenase (ADH-A). Racemic alcohols are oxidized selectively without need for an external cofactor or cosubstrate, which affords the remaining enantioenriched (R)-alcohols. Deracemization, desymmetrization, and stereoinversion processes are developed, which leads to optically pure high value-added compounds. Copyright
- Paul, Caroline E.,Lavandera, Ivan,Gotor-Fernandez, Vicente,Kroutil, Wolfgang,Gotor, Vicente
-
p. 3875 - 3881
(2014/01/06)
-
- One-pot synthesis of polysubstituted imidazoles from arylaldehydes in water catalyzed by nhc using microwave irradiation
-
A simple, high yielding synthesis of tri (3a-i) and tetrasubstituted (4a-g) imidazols from aldehydes is described. The cornerstone of this methodology involves the condensation of NH4OAc, substituted aldehydes, and benzoin, which is synthesized in situ from aldehydes catalyzed by N-heterocyclic carbine (NHC), under microwave irradiation in water to afford trisubstituted imidazoles (3a-i). If arylamine is added in the solution, tetrasubstituted imidazoles (4a-g) can be obtained. Lepidilines B and trifenagrel are also synthesized in high yield using this procedure. All the experiment deta are in agreement with the literature.
- Wu, Lei,Jing, Xiaobi,Zhu, Hongxiang,Liu, Yinlin,Yan, Chaoguo
-
p. 1204 - 1207
(2013/03/28)
-
- Preparation of α-oxygenated ketones by the dioxygenation of alkenyl boronic acids
-
Two in two: Dioxygenation of alkenyl boronic acids has been achieved with N-hydroxyphthalimide. The two-step process involves etherification of an alkenyl boronic acid with N-hydroxyphthalimide followed by a [3,3] rearrangement. The dioxygenated product can then be hydrolyzed to form either the corresponding α-hydroxy ketone or the α-benzoyloxy ketone. Copyright
- Patil, Aditi S.,Mo, Dong-Liang,Wang, Heng-Yen,Mueller, Daniel S.,Anderson, Laura L.
-
supporting information; experimental part
p. 7799 - 7803
(2012/09/08)
-
- Kinetics and mechanism of the oxidation of diols by butyltriphenylphosphonium dichromate
-
The oxidation of four vicinal, four non-vicinal diols and one of their monoethers by butyltriphenylphosphonium dichromate (BTPPD), in dimethylsulfoxide (DMSO), resulted in the formation of corresponding hydroxyaldehyde as a main product of the oxidation. The reactions are of first order with respect to BTPPD, however, second order dependence is obtained with respect to each the diol and hydrogen ion. The oxidation of [1,1,2,2-2H 4]ethanediol exhibited primary kinetic isotope effect (k H/kD = 6.61 at 298 K). The temperature dependence of the kinetic isotope effect suggested the symmetrical transition state in the rate-determining step. The rate constants of oxidation of four vicinal diols show excellent correlation with Taft's ∑ σ* values with negative reaction constant, ρz.ast;. The rate of oxidation of ethanediol has been determined in nineteen different solvents. An analysis of the solvent effect indicates the importance of the cation-solvating power of the solvents. A suitable mechanism has been postulated involving the formation of chromate ester in a pre-equilibrium.
- Panday, Dinesh,Kothari, Seema
-
experimental part
p. 918 - 925
(2011/09/19)
-
- Oxidation of some vicinal and non-vicinal diols by tetrakis(pyridine)silver dichromate: A kinetic and mechanistic study
-
The kinetics of oxidation of four vicinal, four non-vicinal diols and two of their monoethers by tetrakis(pyridine)-silver dichromate (TPSD) have been studied in dimethylsulphoxide (DMSO). The main product of oxidation is the corresponding hydroxycarbonyl compound. The reaction is first order in TPSD. Michaelis-Menten type of kinetics is observed with respect to the diols. The reaction is catalysed by hydrogen ions. The hydrogen ion dependence has the form : kobs = a + b (H+]. The oxidation of [1,1,2,2- 2H4] ethanediol exhibits a substantial primary kinetic isotope effect (kH/kD = 5.91 at 298 K). The reaction has been studied in nineteen different organic solvents and the solvent effect has been analysed using Taft's and Swain's multiparametric equations. The temperature dependence of the kinetic isotope effect indicates the presence of a symmetrical transition state in the rate-determining step. A suitable mechanism has been proposed.
- Meena,Daiya,Sharma,Banerji,Kotai,Sharma, Vinita
-
experimental part
p. 1887 - 1893
(2012/04/04)
-
- Oxidation of some vicinal and non-vicinal diols by morpholinium chlorochromate: A kinetic and mechanistic study
-
The kinetics of oxidation of four vicinal, four non-vicinal diols and two of their monoethers by morpholinium chlorochromate (MCC) have been studied in dimethylsulphoxide (DMSO). The main product of oxidation is the corresponding hydroxycarbonyl compound. The reaction is first order in MCC and the diols. The reaction is catalysed by hydrogen ions. The hydrogen ion dependence is taking the form : kobs = a + b [H+]. The oxidation of [1,1,2,2-2H4]ethanediol exhibits a substantial primary kinetic isotope effect (kH/kD = 5.82 at 298 K). The reaction has been studied in nineteen different organic solvents and the solvent effect has been analysed using Taft's and Swain's multiparametric equations. The temperature dependence of the kinetic isotope effect indicates the presence of a symmetrical transition state in the rate-determining step. A suitable mechanism has been proposed.
- Barthora,Baghmar,Agarwal,Sharma, Vinita
-
experimental part
p. 677 - 683
(2012/04/10)
-
- Efficient production of acetoin by the newly isolated Bacillus licheniformis strain MEL09
-
In this study, a new bacterial strain MEL09, which produces acetoin at high concentrations, was isolated from solid cultures of traditional Chinese vinegar. Based on physiological and biochemical characteristics as well as the 16S rDNA gene sequence, strain MEL09 was identified as Bacillus licheniformis. To improve acetoin production by B. licheniformis MEL09, medium composition and culture conditions were optimized by varying one factor at a time and using orthogonal array tests. Under these optimized conditions, the maximum acetoin concentration achieved was 41.26 g l-1, with 41.26% glucose conversion efficiency (84.39% of theoretical glucose conversion efficiency). This increase is 84.86% over the initial condition and is, to our knowledge, the highest acetoin level ever reported using fermentation methods.
- Liu, Yongfeng,Zhang, Shuling,Yong, Yang-Chun,Ji, Zhixia,Ma, Xin,Xu, Zhenghong,Chen, Shouwen
-
experimental part
p. 390 - 394
(2011/08/09)
-
- Chemoselective aerobic oxidation of unprotected diols catalyzed by Pd-(NHC) (NHC = N-heterocyclic carbene) complexes
-
Neutral Pd(X)(η3-allyl) (X = Cl, OAc (acetate)) complexes bearing mono-coordinating NHC ligands have been synthesized, characterized and employed to catalyze the aerobic oxidation of unprotected 1,2- and 1,3-diols selectively to hydroxy ketones. A comparison of the catalytic performance of these precursors with a reference system has shown that the precursor with the ligands N,N′-bis(adamantyl)imidazol-2-ylidene and chloride is the most efficient for the chemoselective oxidation of 1,2-diols is concerned. High-pressure 1H NMR (HPNMR) experiments in combination with catalytic batch reactions have provided valuable information on the activation of the precursor as well as on the stability of the catalysts.
- Bettucci, Lorenzo,Bianchini, Claudio,Oberhauser, Werner,Hsiao, Tsun-Hung,Lee, Hon Man
-
experimental part
p. 63 - 72
(2010/07/08)
-
- METHODS FOR THE ECONOMICAL PRODUCTION OF BIOFUEL FROM BIOMASS
-
Methods for producing a biofuel are provided. Also provided are biocatalysts that convert a feedstock to a biofuel.
- -
-
-
- BIOFUEL PRODUCTION
-
Methods, enzymes, recombinant microorganism, and microbial systems are provided for converting polysaccharides, such as those derived from biomass, into suitable monosaccharides or oligosaccharides, as well as for converting suitable monosaccharides or oligosaccharides into commodity chemicals, such as biofuels. Commodity chemicals produced by the methods described herein are also provided. Commodity chemical enriched, refinery-produced petroleum products are also provided, as well as methods for producing the same.
- -
-
-
