- Ni-Catalyzed C(sp3)–O Arylation of α-Hydroxy Esters
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A Negishi cross-coupling of α-hydroxy ester derivatives and arylzinc reagents has been developed. This reaction tolerates both primary and secondary C(sp3)–O alcohol precursors and achieves efficient cross-coupling under Ni catalysis without the need for added external metal reductant, photocatalyst, or additives. The arylation of readily accessible C(sp3)–O electrophiles in this operationally simple, rapid, and mild reaction provides a complementary way of accessing desirable α-aryl ester products.
- Monteith, John J.,Rousseaux, Sophie A. L.
-
supporting information
p. 9485 - 9489
(2021/12/09)
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- Enhancing Effect of Residual Capping Agents in Heterogeneous Enantioselective Hydrogenation of α-keto Esters over Polymer-Capped Pt/Al2O3
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Heterogeneous enantioselective catalysis is considered a promising strategy for the large-scale production of enantiopure chemicals. In this work, polymer-capped Pt nanocatalysts having a uniform size were synthesized using poly(vinyl pyrrolidone) (PVP) and poly(vinyl alcohol) and supported on γ-Al2O3. After a facile heat treatment process, their catalytic performance for enantioselective hydrogenation of α-keto esters, a structure-sensitive reaction, was investigated. The presence of residual capping agents on the Pt surface often perturbs the adsorption of reacting species and reduces performance in structure-sensitive reactions. However, the 1 wt % PVP-Pt/Al2O3 catalyst exhibited an enhancement in both activity and enantioselectivity compared to a reference Pt/Al2O3 catalyst prepared by wet impregnation. Under optimized reaction conditions, the cinchonidine-modified PVP-Pt/Al2O3 gave an enantiomeric excess of 95% for the enantioselective hydrogenation of methyl pyruvate despite the low Pt loading. We demonstrate that depending on the type of polymers, the residual capping agents can lead to site-selective blockage of the Pt surface, that is, defects or terraces. Quantitative and qualitative analyses also show that the noticeable improvement in enantioselectivity is attributed to the stable adsorption of chiral modifiers on selectively exposed Pt terrace sites. The findings of this work provide a promising strategy to prepare metal nanoparticles having selectively exposed sites and offer insights into the enhancing effect of residual capping agents on the catalytic properties in structure-sensitive reactions.
- Chung, Iljun,Song, Byeongju,Kim, Jeongmyeong,Yun, Yongju
-
-
- Asymmetric Synthesis of N-Substituted α-Amino Esters from α-Ketoesters via Imine Reductase-Catalyzed Reductive Amination
-
N-Substituted α-amino esters are widely used as chiral intermediates in a range of pharmaceuticals. Here we report the enantioselective biocatalyic synthesis of N-substituted α-amino esters through the direct reductive coupling of α-ketoesters and amines employing sequence diverse metagenomic imine reductases (IREDs). Both enantiomers of N-substituted α-amino esters were obtained with high conversion and excellent enantioselectivity under mild reaction conditions. In addition >20 different preparative scale transformations were performed highlighting the scalability of this system.
- Yao, Peiyuan,Marshall, James R.,Xu, Zefei,Lim, Jesmine,Charnock, Simon J.,Zhu, Dunming,Turner, Nicholas J.
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supporting information
p. 8717 - 8721
(2021/03/16)
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- One-pot conversion of dihydroxyacetone into ethyl lactate by Zr-based catalysts
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Efficient strategies for producing bio-based reagents from sustainable biomass are highly attractive for cost-effective sustainable manufacturing. In this study, a series of eco-friendly Zr-based catalysts (basic zirconium carbonate, zirconium dioxide and zirconium hydroxide) were investigated for the efficient conversion of dihydroxyacetone to ethyl lactate in a one-pot system, in which basic zirconium carbonate exhibited the best performance with 100% dihydroxyacetone conversion and 85.3% EL (ethyl lactate) yield at 140 °C, 4.0 h and 1.0 MPa N2. The improved activity of basic zirconium carbonate could be attributed to the synergistic effect among acid and base active sites. Furthermore, this low-cost catalyst shows improved thermochemical stability and recyclability under optimal conditions, where no significant decrease in activity was observed after three runs. This catalytic process could be identified as a promising alternative to produce ethyl lactate from renewable biomass and its derivatives.
- Shi, Junjun,Li, Fukun,Zhang, Jie,Li, Ning,Wang, Xingmin,Zhang, Xianming,Liu, Yunqi
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p. 10935 - 10940
(2021/03/23)
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- Process method for producing ethyl lactate by using reactive distillation dividing wall tower technology
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The invention provides a process method for producing ethyl lactate by using a reactive distillation dividing wall tower technology. According to the process, the production of ethyl lactate is completed in a reactive distillation dividing wall tower, an esterification reaction of lactic acid and ethanol is completed in a middle section feeding side reaction section of the reactive distillation dividing wall tower to generate ethyl lactate and water, and the separation of ethanol and esterification product water is completed through a middle section extraction side rectification section, meanwhile, ethyl lactate purification is realized in a middle section feeding side stripping section and a middle section extracting side stripping section, and finally a food-grade ethyl lactate product is obtained at the bottom of the tower. Compared with the prior art, the process has the advantages of high ethyl lactate product yield, high equipment integration, short process flow, low one-time investment, low operation cost and the like.
- -
-
Paragraph 0039; 0040; 0046-0049
(2020/02/14)
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- Bi-Functional Magnesium Silicate Catalyzed Glucose and Furfural Transformations to Renewable Chemicals
-
Bio-refinery is attracting significant interest to produce a wide range of renewable chemicals and fuels from biomass that are alternative to fossil fuel derived petrochemicals. Similar to petrochemical industries, bio-refinery also depends on solid zeolite catalysts. Acid-base catalysis plays pivotal role in producing a wide range of chemicals from biomass. Herein, the Mg framework substituted MTW zeolite is synthesized and explored in the valorisation of glucose and furfural. Bi-functional (acidic and basic) characteristics are confirmed using pyridine adsorbed FT?IR analysis and NH3 and CO2 temperature-programmed desorption techniques. Textural properties and morphological information are retrieved from N2-sorption, X-ray photoelectron spectroscopy, and electron microscopy. The activity of the catalyst is demonstrated in the selective isomerisation of glucose to fructose in ethanol. Glucose is converted to methyl lactate in high yield using the same catalyst. Further, the bi-functional activity of this catalyst is demonstrated in the production of fuel precursor by the reaction of furfural and isopropanol. Mg?MTW zeolite exhibits excellent activity in the production of all these chemicals and fuel derivative. The catalyst exhibits no significant loss in the activity even after five recycles. One simple catalyst affording three renewable synthetic intermediates from glucose and furfural will attract significant attention to catalysis researchers and industrialists.
- Kumar, Abhinav,Srivastava, Rajendra
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p. 4807 - 4816
(2020/08/24)
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- A PROCESS FOR THE PREPARATION OF PLATFORM CHEMICALS FROM SUGAR USING ACID CATALYST
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The present invention relates to a process for the preparation of value added chemicals such as ethyl levulinate from a glucose or other sugars catalyzed by a mixture of a Lewis and a Bronsted acid catalyst.
- -
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Page/Page column 8
(2020/07/31)
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- Method for preparing lactate
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The invention relates to a method for preparing lactate. The method comprises the following steps of: contacting sugar and alcohol with a catalyst in a reactor, and reacting to obtain a lactate-containing product, wherein the molar ratio of the sugar to the alcohol is 1:(50-900), the reaction temperature is 150-250 DEG C, the reaction time is 10-50 hours, the catalyst contains a mixture of a titanium-silicon molecular sieve and a tin-silicon molecular sieve, and the weight ratio of the sugar to the mixture of the titanium-silicon molecular sieve and the tin-silicon molecular sieve based on drybasis weight is 1:(0.1-6). The method provided by the invention has high sugar conversion rate and high lactate yield.
- -
-
Paragraph 0084-0085
(2020/06/30)
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- Method for preparing lactate
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The invention relates to a method for preparing lactate. The method comprises the following steps: contacting pyruvic aldehyde and alcohol with a catalyst in a reactor, and reacting to obtain a lactate-containing product, wherein the molar ratio of the pyruvic aldehyde to the alcohol is 1:(20-225), the reaction temperature is 30-180 DEG C, the reaction time is 1-10 hours, the catalyst contains a mixture of a titanium-silicon molecular sieve and a tin-silicon molecular sieve, and the weight ratio of the pyruvic aldehyde to the mixture of the titanium-silicon molecular sieve and the tin-siliconmolecular sieve based on dry basis weight is 1:(0.1-6). The method provided by the invention has high pyruvic aldehyde conversion rate and high lactate yield.
- -
-
Paragraph 0084-0085
(2020/06/30)
-
- Method for preparing lactate by catalyzing pyruvic aldehyde
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The invention relates to a method for preparing lactate by catalyzing pyruvic aldehyde. The method comprises the following steps: contacting pyruvic aldehyde and alcohol with a catalyst in a reactor,and reacting to obtain a lactate-containing product, wherein the molar ratio of pyruvic aldehyde to alcohol is 1:(50-225), the reaction temperature is 30-180 DEG C, the reaction time is 1-10 h, the reaction pressure is 0.1-3 MPa, the catalyst contains a tin-titanium-silicon molecular sieve, and the weight ratio of pyruvic aldehyde to the tin-titanium-silicon molecular sieve based on dry basis weight is 1:(1-6). According to the method, the catalyst containing the binary tin-titanium-silicon molecular sieve is adopted, framework tin atoms and framework titanium atoms of the molecular sieve synergistically catalyze pyruvic aldehyde and alcohol to generate lactate, and the reaction efficiency is improved.
- -
-
Paragraph 0189; 0190; 0210
(2020/07/02)
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- NMR Spectroscopic Characterization of Flame-Made Amorphous Silica-Alumina for Cyclohexanol and Glyceraldehyde Conversion
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Amorphous silica-aluminas (ASAs), possessing both Br?nsted acid sites (BAS) and Lewis acid sites (LAS), are important bifunctional catalysts in various industrial applications. Solid-state NMR spectroscopy has been widely used for characterizing the local structure and the surface sites of ASAs with probe molecules. In this work, four-, five- and six-coordinated Al species have been observed on the flame-made ASAs by 27Al MQ MAS NMR experiment. 1H/27Al TRAPDOR MAS NMR experiments confirmed that surface Al species contribute to the formation of BAS and protonate ammonia probe molecules. The adsorption of ammonia on Lewis acidic Al sites (δ1H=3.0 ppm) was evidenced by various 1H MAS NMR experiments on samples dehydrated at different temperatures, allowing the distinction from ammonium ions (δ1H=6.7 ppm) formed at BAS. The signal of ammonia adsorbed on LAS increased with increasing Al content in the ASAs. These properties together with the absence of pore diffusional constraints render the flame-made ASAs excellent catalysts for cyclohexanol dehydration and the conversion of glyceraldehyde in ethanol to ethyl lactate, outperforming the performance of other ASAs or zeolites.
- Wang, Zichun,Jiang, Yijiao,Stampfl, Catherine,Baiker, Alfons,Hunger, Michael,Huang, Jun
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p. 287 - 293
(2019/12/12)
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- Novel SO3H-functionalized polyoxometalate-based ionic liquids as highly efficient catalysts for esterification reaction
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Three novel heteropolyanion-based Br?nsted acidic ionic liquids (BAILs), butane mono sulfoacid-functionalized 1,10-phenanthrolinum, butane mono and bis sulfoacid-functionalized 1,4-dimethylpiperazinium salts of phosphortungstate catalyst (PhBs1-PW, [PipBs1]3-PW and [PipBs2]3-(PW)2) were synthesized and well characterized with FTIR, 1H and 13C NMR, Electro-Spray Ionization Mass Spectrometry (ESI-MS), Elemental analysis (CHNS), EDX and TG analysis techniques. The esterification reactions of monocarboxylic acids with monohydric alcohols were carried out using these catalysts. The introduced catalysts present a self-separation performance after reaction, which can be easily recovered and quite steadily reused as confirmed by six-run recycling test. Moreover, bis sulfoacid-functionalized 1,4-dimethylpiperazinium salt of phosphortungstate showed the best catalytic performance among the prepared catalysts for the esterification reaction.
- Keshavarz, Mosadegh,Iravani, Nasir,Parhami, Abolfath
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p. 272 - 278
(2019/04/25)
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- Half-sandwich ruthenium-based versatile catalyst for both alcohol oxidation and catalytic hydrogenation of carbonyl compounds in aqueous media
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A series of half-sandwich ruthenium-based catalysts for both alcohol oxidation and carbonyl compounds hydrogenation have been synthesized through metal-induced C–H bond activation based on benzothiazole ligands. The neutral ruthenium complexes 1–4 were fully characterized by UV–vis, NMR, IR, and elemental analysis. Molecular structures of complexes 1 and 3 were further confirmed by X-ray diffraction analysis. All complexes exhibited high activity for the catalytic oxidation of a variety of alcohols with tBuOOH as oxidants to give carbonyl compounds with high yields in water. Moreover, these half-sandwich complexes also showed high efficiency for the catalytic hydrogenation of carbonyl compounds in a methanol–water mixture. The catalyst could be reused for at least five cycles without any loss of activity. The catalytic system also worked well for various kinds of substrates with either electron-donating or electron-withdrawing groups.
- Qiao, Xin-Chao,Qiu, Dan-Chen,Lin, Nan,Zhu, Jing-Wei,Deng, Wei,Yao, Zi-Jian
-
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- Biotechnological properties of sponges from northeast Brazil: Cliona varians as a Biocatalyst for Enantioselective Reduction of Carbonyl Compounds
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To research the potential ability of whole marine sponges to act as biocatalysts, this paper describes for the first time the employment of whole Cliona varians sponge in the stereoselective reduction of prochiral α-keto esters and isatin to the corresponding chiral alcohols. The addition of D-fructose, D-glucose or sucrose remarkably increased the conversion ratios and stereoselectivities by this marine sponge. Furthermore, in the presence of D-glucose and D-maltose, the reduction of isatin by C. varians afforded the corresponding 3-hydroxyindolin-2-one with high conversions (85-90percent) and good enantioselectivities (60-74percent). These results showed that the marine sponge presents great potential to be used as biocatalyst for stereoselective reduction of carbonyl compounds.
- Riatto, Valéria B.,Victor, Mauricio M.,Sousa, Jaqueline F.,Menegola, Carla
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p. 149 - 157
(2018/12/13)
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- Enantioselective hydrogenation of α-ketoesters catalyzed by cinchona alkaloid stabilized Rh nanoparticles in ionic liquid
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The heterogeneous enantioselective hydrogenation of α-ketoesters catalyzed by rhodium nanoparticles (Rh NPs) in ionic liquid was studied with the stabilization and modification of cinchona alkaloids. TEM characterization showed that well-dispersed Rh NPs of about 1.96?nm were obtained in ionic liquid. The results showed that cinchona alkaloids not only had good enantiodifferentiating ability but also accelerated the catalytic reaction. Under the optimum reaction conditions, the enantiomeric excess in ethyl benzoylformate hydrogenation could reach as high as 60.9%.
- Jiang, He-yan,Xu, Jie,Sun, Bin
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p. 818 - 823
(2019/08/07)
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- A sustainable catalytic enantioselective synthesis of norstatine derivatives
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Norstatine derivatives are of important value in pharmaceutical science. However, their catalytic asymmetric synthesis is rare. We developed a sustainable method via chiral phosphoric acid (CPA)-[Rh(OAc)2]2 co-catalyzed multi-component reactions (MCR) of diazoacetates with alcohol/water and imines. This method allows us to synthesize a library of 45 norstatines with excellent enanotioselectivites and broad substrate scope which includes anti-α-aryl-norstatines 11-1, anti-α-alkyl-norstatines 11-2, syn-α-hydro-norstatines 11-3 and syn-α-aryl-norstatines 11-4. The sustainability of this method lies in the reliable scalability, improved safety, and reusable [Rh(OAc)2]2 catalyst. The synthetic value of norstatine derivatives was demonstrated by preparing oxazolinone 14, ezetimibe analogue 15, and Taxol C-13 chain 16. Mechanistic study reveals that the synergetic catalysis of CPA and [Rh(OAc)2]2 is essential to maintain chemo- and enantioselectivity. Control experiments support the mechanism where the reactions proceed through the trapping of hyper-reactive oxonium ylides with imines. Shortly, we report herein the sustainable catalytic enantioselective synthesis of both syn- and anti-norstatine derivatives. We believe that this method might shed light on the sustainable synthesis of norstatine derivative-based drug candidates.
- Shi, Taoda,Jing, Changcheng,Qian, Yu,Xu, Xinfang,Alavala, Gopi Krishna Reddy,Lv, Xinxin,Hu, Wenhao
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supporting information
p. 9792 - 9798
(2019/12/02)
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- Method for directly preparing lactate from 1,2-propanediol and short-chain alkyl alcohols
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The invention belongs to the technical field of organic matter synthesis, and particularly relates to a method for directly preparing lactate from 1,2-propanediol and short-chain alkyl alcohols, and the method comprises the following steps: using a sodium stannate loaded rare noble metal as a catalyst, adding C1-C4 alkyl alcohols and the 1,2-propanediol into a high-pressure reaction kettle, usingnitrogen for purging air in the kettle, heating and stirring while the temperature is maintained to promote esterification of the 1,2-propanediol with the C1-C4 alkyl alcohols after oxidation of the 1,2-propanediol to produce the lactate. The method has mild reaction conditions and simple reaction steps, the 1,2-propanediol is completely converted, and the highest selectivity of the lactate can reach 78%. Meanwhile, the synthesized sodium stannate loaded rare noble metal has high catalytic activity and reusability.
- -
-
Paragraph 0046; 0049
(2019/10/15)
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- The cooperative effect of Lewis and Br?nsted acid sites on Sn-MCM-41 catalysts for the conversion of 1,3-dihydroxyacetone to ethyl lactate
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Lactic acid and alkyl lactates are widely applied in the production of food, cosmetics, pharmaceuticals, organic synthesis and biodegradable polymers. They can be prepared via one-pot synthesis from renewable trioses, such as dihydroxyacetone (DHA). Br?nsted-Lewis bifunctional solid acids (BAS & LAS) can promote the reaction via a two-step cascade reaction mechanism. BAS catalyses the dehydration of DHA, resulting in the formation of pyruvaldehyde (PA) via the rearrangement of the enol form. Upon alcohol addition, PA can be converted to the desired alkyl lactates at LAS or to pyruvaldehyde hemiacetal (PAHA) at strong BAS. The density and strength control of Br?nsted acid sites (BAS) and Lewis acid sites (LAS) and the optimization of their cooperation are essential for the efficient conversion of trioses to the target products. Here, we prepared a series of Sn-containing mesoporous MCM-41 catalysts with various BAS/LAS ratios by room temperature techniques. Sn-doped [Si]MCM-41 having a lower BAS/LAS ratio in this research shows a high initial selectivity to ethyl lactate (EL) and similar EL yield in 6 hours as the reported best Sn catalyst Sn-grafted [Si]MCM-41/carbon network materials in DHA conversion. A relatively large density of LAS in Sn-doped [Si]MCM-41 causes a fast conversion of PA to EL, while the overall yield has been limited by the BAS density for the DHA conversion. New H-form [Sn]MCM-41, having a suitable density of LAS and weak BAS and an optimized BAS/LAS ratio, provides a 100% yield of ethyl lactate in the catalytic conversion of DHA in ethanol within 30 min, showing a superior performance hitherto.
- Kim, Kyung Duk,Wang, Zichun,Jiang, Yijiao,Hunger, Michael,Huang, Jun
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supporting information
p. 3383 - 3393
(2019/06/24)
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- Production of lactic acid derivatives from sugars over post-synthesized Sn-Beta zeolite promoted by WO3
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Various metal oxides were used as co-catalysts to improve the production of alkyl lactate over Sn-Beta-P. WO3 exhibited the best promotion effect. The yield of MLA increased from 25% (6.5 g L?1) over Sn-Beta-P (0.2 g) to 52% (13.4 g L?1) over WO3 (0.1 g) and Sn-Beta-P (0.1 g) at 160 °C for 5 h and 3.1 wt% of glucose concentration. MLA yield of 38% was attained even at glucose concentration of 10 wt% and the space-time yield reached 7.1 g L?1 h?1. The action mechanism of WO3 was investigated. Fine WO3 particles adsorbed on surface of Sn-Beta-P in reaction media and decreased the silanol defects of Sn-Beta-P. This promotes retro-aldol of fructose, the rate-determining step of whole reaction, thus facilitated the formation of MLA. Kinetic studies indicate that the presence of WO3 decreased the activation energy of the retro-aldol of fructose. The binary solid WO3 and Sn-Beta-P is recyclable.
- Yang, Xiaomei,Zhang, Yali,Zhou, Lipeng,Gao, Beibei,Lu, Tianliang,Su, Yunlai,Xu, Jie
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p. 285 - 291
(2019/03/21)
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- Application of tungsten-based solid acid in lactic acid and lactate preparation using biomass and saccharides
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The invention relates to the technical field of chemical catalyzing, in particular to application of tungsten-based solid acid in lactic acid and lactate preparation using biomass and saccharides. Tungsten-containing salt is allowed to have hydro-thermal synthesis reaction with the chlorine salt, sulfate, nitrate, phosphate and oxalate of barium, calcium, lead, aluminum, chromium, erbium, tin, germanium, niobium and tantalum to prepare a multiple-component tungsten-based solid acid catalyst. The multiple-component tungsten-based solid acid catalyst is simple to prepare, cheap, good in hydrothermal stability, easy to recycle, capable of catalyzing monosaccharides such as fructose and glucose to convert into the lactic acid or lactate, capable of catalyzing polysaccharides such as sucrose, maltose, starch and cellulose even biomass such as wood and corn straw containing cellulose to have hydrolysis reaction so as to prepare the lactic acid or lactate, promising in application prospect and the like, multi-step reaction catalyzing by one single catalyst is achieved, and the range of the biomass and the saccharides which can be converted by the catalyst is wide.
- -
-
Paragraph 0041; 0043
(2018/11/03)
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- Rapid room temperature synthesis of tin-based mesoporous solids: Influence of the particle size on the production of ethyl lactate
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A series of tin-based mesoporous catalysts was prepared via a novel straightforward sol-gel procedure leading to an extremely short synthesis time decreased up to 5 min at room temperature. This synthesis, together with the precise control of the selected particle size, represents an advancement compared to the state of the art and can be easily applied to large scale production. Characterization of the materials revealed the presence of MCM-41 like architecture with a high specific surface area, narrow pore size distribution, insertion of tin in tetrahedral coordination and a good balance of Lewis/Br?nsted acidity. Moreover, all these characteristics were almost identical for the entire series thus making these solids an ideal case study to investigate the influence of the particle size on the catalytic behavior. The Sn-containing materials were tested as catalysts in the conversion of dihydroxyacetone into ethyl lactate. The excellent correlation between particle size and catalytic performances proves the importance of size control. In addition, the absence of leaching was proved via hot filtration experiments and the materials preserved their activity in multiple catalytic cycles.
- Godard, Nicolas,Collard, Xavier,Vivian, Alvise,Bivona, Lucia Anna,Fiorilli, Sonia,Fusaro, Luca,Aprile, Carmela
-
-
- Synthetic and Catalytic Potential of Amorphous Mesoporous Aluminosilicates Prepared by Postsynthetic Aluminations of Silica in Aqueous Media
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Amorphous aluminosilicate catalysts have been used industrially on a large scale for almost a century. However, the influence of the pH on the alumination of silica in aqueous solutions has remained largely unclear. Herein, room temperature aluminations of different mesoporous amorphous silicas (fumed silica, dried silica gel, SBA-15, MCM-41, and COK-12) with aqueous solutions of various pH (3–13) are explored. The aqueous solutions are prepared using different aluminum sources (Al(NO3)3 or NaAlO2) and alkaline additives (NaOH or NH4OH). The decoupling of pH and Al source using alkaline additives results in a vast experimental potential to prepare unique aluminosilicates, whereby an important role is played by the pH development during the treatment. The bulk and surface composition, acidity, aluminum coordination, morphology, hydrothermal stability, and porosity of the obtained materials are characterized. Optimal samples possess large surface areas and superior acidities (up to 50 % higher) and outstanding stabilities compared to aluminosilicates prepared with state-of-the-art methods. The obtained materials are evaluated in a series of acid-catalyzed model reactions involving substrates of various chemical reactivity and size, enabling insight in the catalytic functionality of the introduced Br?nsted and Lewis sites. The potential of the obtained materials is emphasized by the similar or superior acidity and catalytic performance compared to several benchmark industrial silica–alumina-based catalysts.
- Locus, Roel,Verboekend, Danny,d'Halluin, Martin,Dusselier, Michiel,Liao, Yuhe,Nuttens, Nicolas,Jaumann, Tony,Oswald, Steffen,Mafra, Luís,Giebeler, Lars,Sels, Bert
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p. 1385 - 1397
(2018/02/21)
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- Investigation of synthetic pathways of carboxylic acid phthalocyanines from glycolic and lactic acids
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We present the study of synthetic pathways to prepare carboxylic acid substituted phthalocyanines from glycolic and lactic acids. Hydroquinone was used as an alternative catalyst for cyclotetramerization reaction of metal free and zinc phthalocyanines, which were characterized by 1H MR spectroscopy, infrared absorption and mass analysis. The photophysical and photochemical properties in dimethyl sulfoxide (DMSO) were analyzed. We verified that the presence of the methyl radical group, that distinguish both structures, diminish the macrocycle aggregation in solution and promote higher quantum yields of fluorescence and for singlet oxygen generation.
- do Nascimento, Francisco B.,Ribeiro, Anderson O.
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p. 106 - 116
(2017/08/07)
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- High-Yield Synthesis of Ethyl Lactate with Mesoporous Tin Silicate Catalysts Prepared by an Aerosol-Assisted Sol–Gel Process
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An aerosol-assisted sol–gel method is used to prepare mesoporous tin silicate catalysts that exhibit a record activity in the synthesis of ethyl lactate from dihydroxyacetone and ethanol. The method is based on the formation of an aerosol from a solution of precursors and surfactant. During the fast drying of the droplets, the surfactant self-assembles and the Sn-silica matrix is formed by polycondensation reactions. After calcination, the resulting material is composed of a true tin-silicon mixed oxide in the form of spherical microparticles with calibrated mesopores of 5–6 nm. Sn species are incorporated in the silica network, mainly in the form of single sites. This makes these catalysts highly active for the targeted reaction, as shown by record turnover numbers. The catalyst is recyclable and truly heterogeneous as it can be reused for several cycles and it does not leach.
- Godard, Nicolas,Vivian, Alvise,Fusaro, Luca,Cannavicci, Lorenzo,Aprile, Carmela,Debecker, Damien P.
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p. 2211 - 2218
(2017/06/27)
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- Zwitterionic amidinates as effective ligands for platinum nanoparticle hydrogenation catalysts
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Ligand control of metal nanoparticles (MNPs) is rapidly gaining importance as ligands can stabilize the MNPs and regulate their catalytic properties. Herein we report the first example of Pt NPs ligated by imidazolium-amidinate ligands that bind strongly through the amidinate anion to the platinum surface atoms. The binding was established by15N NMR spectroscopy, a precedent for nitrogen ligands on MNPs, and XPS. Both monodentate and bidentate coordination modes were found. DFT showed a high bonding energy of up to -48 kcal mol-1 for bidentate bonding to two adjacent metal atoms, which decreased to -28 ± 4 kcal mol-1 for monodentate bonding in the absence of impediments by other ligands. While the surface is densely covered with ligands, both IR and13C MAS NMR spectra proved the adsorption of CO on the surface and thus the availability of sites for catalysis. A particle size dependent Knight shift was observed in the13C MAS NMR spectra for the atoms that coordinate to the surface, but for small particles, ~1.2 nm, it almost vanished, as theory for MNPs predicts; this had not been experimentally verified before. The Pt NPs were found to be catalysts for the hydrogenation of ketones and a notable ligand effect was observed in the hydrogenation of electron-poor carbonyl groups. The catalytic activity is influenced by remote electron donor/acceptor groups introduced in the aryl-N-substituents of the amidinates; p-anisyl groups on the ligand gave catalysts several times faster the ligand containing p-chlorophenyl groups.
- Martínez-Prieto,Cano,Márquez,Baquero,Tricard,Cusinato,Del Rosal,Poteau,Coppel,Philippot,Chaudret,Cámpora,Van Leeuwen
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p. 2931 - 2941
(2017/04/04)
-
- Correlation between Chiral Modifier Adsorption and Enantioselectivity in Hydrogenation Catalysis
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Infrared absorption spectroscopy performed in situ at the solid–liquid interface revealed that the adsorption on platinum supported catalysts of 1-(1-naphthyl)-ethylamine, which is used as a chiral modifier in hydrogenation catalysis, occurs through the amine group, not the aromatic ring as is widely believed. Comparisons were performed against a set of related modifier compounds with targeted substitutions to help identify the key moiety involved in the adsorption. It was determined that neither naphthalene-based modifiers without amine groups nor those with tertiary amine moieties are capable of adsorbing on the metal surface to any significant extent. A direct correlation was also found between the ability of the amines to adsorb on the platinum surface and their performance as chiral modifiers that impart enantioselectivity to the hydrogenation of α-keto esters such as ethyl pyruvate.
- Ni, Yufei,Gordon, Alexander D.,Tanicala, Florisa,Zaera, Francisco
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p. 7963 - 7966
(2017/06/27)
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- Kinetic study of the ethyl lactate synthesis from triose sugars on Sn/Al2O3 catalysts
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The reaction kinetics of the liquid-phase synthesis of ethyl lactate from dihydroxyacetone and ethanol was studied on Sn-promoted alumina catalysts. Yields of ≈70% were obtained at 353?K after 7?h of reaction. The effect of the catalyst Sn loading (1–8?wt.%) and reaction temperature (343–373?K) on the reaction kinetics was investigated. The reaction is promoted by Lewis acid sites provided by surface Sn species. A kinetic model based on a pseudohomogeneous mechanism was postulated to describe the reaction network comprising a sequence of consecutive and parallel reaction steps. The kinetic rate constant associated to ethyl lactate formation increases with the number of Lewis acid sites confirming that surface Sn species participate in the kinetically relevant reaction steps. Catalysts were prepared by impregnation and characterized by N2 physisorption, X-ray diffraction, UV-vis-DRS, FTIR of pyridine and TPD of NH3.
- Pighin,Díez,Di Cosimo
-
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- Quantitative NMR Approach to Optimize the Formation of Chemical Building Blocks from Abundant Carbohydrates
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The future role of biomass-derived chemicals relies on the formation of diverse functional monomers in high yields from carbohydrates. Recently, it has become clear that a series of α-hydroxy acids, esters, and lactones can be formed from carbohydrates in alcohol and water solvents using tin-containing catalysts such as Sn-Beta. These compounds are potential building blocks for polyesters bearing additional olefin and alcohol functionalities. An NMR approach was used to identify, quantify, and optimize the formation of these building blocks in the Sn-Beta-catalyzed transformation of abundant carbohydrates. Record yields of the target molecules can be achieved by obstructing competing reactions through solvent selection.
- Elliot, Samuel G.,Tolborg, S?ren,Sádaba, Irantzu,Taarning, Esben,Meier, Sebastian
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p. 2990 - 2996
(2017/07/25)
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- PRODUCTION OF ALPHA-HYDROXY CARBOXYLIC AIDS AND ESTERS FROM HIGHER SUGARS USING TANDEM CATALYST SYSTEMS
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The present disclosure is directed to methods and composition used in the preparation of alpha-hydroxy carboxylic acids and esters from higher sugars using a tandem catalyst system comprising retro-aldol catalysts and Lewis acid catalysts. In some embodiments, these alpha-hydroxy carboxylic acids may be prepared from pentoses and hexoses. The retro-aldol and Lewis catalysts may be characterized by their respective ability to catalyze a 1,2-carbon shift reaction and a 1,2-hydride shift reaction on an aldose or ketose substrate.
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Page/Page column 13-14
(2017/02/09)
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- Synthesis of ethyl lactate from triose sugars on Sn/Al2O3 catalysts
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Sn-promoted alumina catalysts with different Sn loadings (1-8 wt.%) were prepared by impregnation and characterized by N2 physisorption, X-ray diffraction, UV-vis-DRS, FTIR of pyridine and TPD of NH3. Surface Sn species present Lewis acid properties different from those of the alumina support; the number and strength of the surface Lewis centers increase with the Sn loading. These materials exhibit good catalytic performance for conversion of triose sugars, such as dihydroxyacetone, toward ethyl lactates at mild conditions. The catalyst preparation conditions, Sn content and reaction conditions affect the final ethyl lactate yield. Yields of ≈70% were obtained at 353 K after 7 h of reaction. Surface Sn species participate in the kinetically relevant reaction steps.
- Pighin,Díez,Di Cosimo
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p. 151 - 160
(2016/03/22)
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- Ruthenium Nanoparticles in High-Throughput Studies of Chemoselective Carbonyl Hydrogenation Reactions
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Small (≤1.4 nm) and very active Ru nanoparticles, stabilized in a polysiloxane matrix, were prepared and studied in hydrogenation reactions by the integration of catalysis and analysis. We used our strategy to combine catalytic activity and separation selectivity in a capillary microreactor, installed in a GC-MS instrument, to develop a fast and reliable screening tool for catalysis over Ru nanoparticles. A high conversion using a low catalyst loading of 0.3 mol % and temperature and long-term stability of the catalytically active column were observed for the hydrogenation of various carbonyl compounds, which included aldehydes, ketones, and pyruvates. Additionally, we observed a high chemoselectivity for aromatic carbonyl systems. Comprehensive measurements were performed in this high-throughput experimental setup to gain important insights into the kinetics of hydrogenation reactions at the interface between heterogeneous and homogeneous catalysis.
- Gmeiner, Julia,Behrens, Silke,Spliethoff, Bernd,Trapp, Oliver
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p. 571 - 576
(2016/02/20)
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- Active hydrogenation Rh nanocatalysts protected by new self-assembled supramolecular complexes of cyclodextrins and surfactants in water
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The stability of inclusion complexes between randomly methylated β-cyclodextrin (RaMeCD) or its leucine-grafted analogue (RaMeCDLeu) with two hydroxylated ammonium surfactants was investigated. The binding isotherms and complexation constants were measured using the Isothermal Titration Calorimetry (ITC) technique. These host-guest inclusion complexes were used as protective agents during the formation of rhodium(0) nanoparticles by chemical reduction of rhodium trichloride in water. The amount of protective agent was adjusted in order to ensure both stability and reactivity of the rhodium nanocatalysts under the catalytic conditions. The size and dispersion of air-stable and water-soluble rhodium suspensions were determined by Transmission Electron Microscopy (TEM) analyses. These spherical nanoparticles, with sizes between 1.20 to 1.50 nm according to the nature of inclusion complexes, were evaluated in the biphasic hydrogenation of various reducible compounds (olefins, linear or aromatic ketones), showing promising results in terms of activity and selectivity.
- Thanh Chau, Nguyet Trang,Menuel, Stéphane,Colombel-Rouen, Sophie,Guerrero, Miguel,Monflier, Eric,Philippot, Karine,Denicourt-Nowicki, Audrey,Roucoux, Alain
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p. 108125 - 108131
(2016/11/29)
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- Synthesis of Itaconic Acid Ester Analogues via Self-Aldol Condensation of Ethyl Pyruvate Catalyzed by Hafnium BEA Zeolites
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Lewis acidic zeolites are used to synthesize unsaturated dicarboxylic acid esters via aldol condensation of keto esters. Hafnium-containing BEA (Hf-BEA) zeolites catalyze the condensation of ethyl pyruvate into diethyl 2-methyl-4-oxopent-2-enedioate and diethyl 2-methylene-4-oxopentanedioate (an itaconic acid ester analogue) with a selectivity of ca. 80% at ca. 60% conversion in a packed-bed reactor. The catalyst is stable for 132 h on stream, reaching a turnover number of 5110 molEP molHf-1. Analysis of the dynamic behavior of Hf-BEA under flow conditions and studies with Na-exchanged zeolites suggest that Hf(IV) open sites possess dual functionality for Lewis and Br?nsted acid catalysis.
- Wang, Yuran,Lewis, Jennifer D.,Román-Leshkov, Yuriy
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p. 2739 - 2744
(2016/07/06)
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- Direct Conversion of Cellulose into Ethyl Lactate in Supercritical Ethanol-Water Solutions
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Biomass-derived ethyl lactate is a green solvent with a growing market as the replacement for petroleum-derived toxic organic solvents. Here we report, for the first time, the production of ethyl lactate directly from cellulose with the mesoporous Zr-SBA-15 silicate catalyst in a supercritical mixture of ethanol and water. The relatively strong Lewis and weak Br?nsted acid sites on the catalyst, as well as the surface hydrophobicity, were beneficial to the reaction and led to synergy during consecutive reactions, such as depolymerization, retro-aldol condensation, and esterification. Under the optimum reaction conditions, μ33 % yield of ethyl lactate was produced from cellulose with the Zr-SBA-15 catalyst at 260 C in supercritical 95:5 (w/w) ethanol/water.
- Yang, Lisha,Yang, Xiaokun,Tian, Elli,Lin, Hongfei
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- Tandem catalytic conversion of glycerol using solid catalysts followed by transesterification to produce alkyl lactate
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This study investigated alkyl lactate production from glycerol by tandem processes which included glycerol conversion to calcium lactate using solid catalysts and subsequent transesterification of calcium lactate to alkyl lactate using methanol/ethanol and carbon dioxide. The effect of reaction conditions on alkyl lactate production was systematically investigated. A central composite design (CCD) and response surface methodology were used to design the experiments and evaluate the optimum process conditions. At the optimum conditions, the methyl lactate yield reached 57 mol% with a glycerol conversion of 94 mol% using refined glycerol. A yield of approximately 42 mol% for ethyl lactate was obtained using refined glycerol at the optimum conditions. Similar glycerol conversion and alkyl lactate yields were obtained using crude glycerol, indicating that the impurities in the crude glycerol had no significant effects on alkyl lactate production. The examination of regenerated catalysts that had been reused twice showed no negative effects on glycerol conversion and methyl lactate production. Compared to the traditional lactic acid and alkyl lactate production, this two-step process for alkyl lactate production from glycerol is both economical and environmentally benign since no gypsum was produced and the solid catalysts can be regenerated and reused.
- Ren, Shoujie,Ye, X. Philip,Ayers, Paul D.
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p. 53230 - 53239
(2015/06/30)
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- METHODS FOR PRODUCING ALKYL HYDROXYALKANOATES
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Methods and systems for producing alkyl hydroxyalkanoate from hydroxy carboxylic acid recovery bottoms. The methods generally comprise the steps of obtaining a hydroxy carboxylic acid recovery bottom, adding a mono-alcohol to the hydroxy carboxylic acid recovery bottom to obtain a first mixture, heating the first mixture in the presence of a catalyst to form a reaction product, distilling the reaction product, and recovering an alkyl hydroxyalkanoate fraction.
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Paragraph 00073
(2015/05/05)
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- Tandem catalysis for the production of alkyl lactates from ketohexoses at moderate temperatures
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Retro-aldol reactions have been implicated as the limiting steps in catalytic routes to convert biomass-derived hexoses and pentoses into valuable C2, C3, and C4 products such as glycolic acid, lactic acid, 2-hydroxy-3-butenoic acid, 2,4-dihydroxybutanoic acid, and alkyl esters thereof. Due to a lack of efficient retro-aldol catalysts, most previous investigations of catalytic pathways involving these reactions were conducted at high temperatures (≥160 °C). Here, we report moderate-temperature (around 100 °C) retro-aldol reactions of various hexoses in aqueous and alcoholic media with catalysts traditionally known for their capacity to catalyze 1,2-intramolecular carbon shift (1,2-CS) reactions of aldoses, i.e., various molybdenum oxide and molybdate species, nickel(II) diamine complexes, alkali-exchanged stannosilicate molecular sieves, and amorphous TiO2-SiO2 coprecipitates. Solid Lewis acid cocatalysts that are known to catalyze 1,2-intramolecular hydride shift (1,2-HS) reactions that enable the formation of α-hydroxy carboxylic acids from tetroses, trioses, and glycolaldehyde, but cannot readily catalyze retro-aldol reactions of hexoses and pentoses at these moderate temperatures, are shown to be compatible with the aforementioned retro-aldol catalysts. The combination of a distinct retroaldol catalyst with a 1,2-HS catalyst enables lactic acid and alkyl lactate formation from ketohexoses at moderate temperatures (around 100 °C), with yields comparable to best-reported chemocatalytic examples at high temperature conditions (≥160 °C). The use of moderate temperatures enables numerous desirable features such as lower pressure and significantly less catalyst deactivation.
- Orazov, Marat,Davis, Mark E.
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p. 11777 - 11782
(2015/10/12)
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- Method of synthesizing acid ester
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PROBLEM TO BE SOLVED: To provide a method for manufacturing lactate without the corrosion of a reactor nor trouble of waste liquid processing, using glycerol separated and generated from various oil-and-fats, including glycerol by-produced in the manufacture of a biodiesel fuel.SOLUTION: In the method, the lactate is synthesized from the glycerol in the presence of a solid basic catalyst, using alcohol in a high-temperature and high-pressure state as a reaction medium.
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Paragraph 0052; 0053
(2017/02/23)
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- Metal-containing TUD-1 mesoporous silicates as versatile solid acid catalysts for the conversion of bio-based compounds into valuable chemicals
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Three-dimensional mesoporous silicates of the TUD-1 family were synthesised with different metals (Zr, Hf and Sn) incorporated in the framework of the material. The mesoporosity of the prepared TUD-1s was confirmed by X-ray diffraction (XRD), nitrogen physisorption and TEM. The incorporation of the metals in the silicate structure was investigated by FT-IR and UV-Vis spectroscopy. All three TUD-1 materials present a combination of Lewis and mild Br?nsted acid sites, as determined by TPD-FT-IR of pyridine adsorption. The metal-containing TUD-1 materials were tested as solid acid catalysts for the conversion of three bio-based compounds into valuable chemical products. In the conversion of dihydroxyacetone into ethyl lactate, complete selectivity towards the desired lactate product was achieved with Zr-, Hf- and Sn-TUD-1. The three heterogeneous catalysts displayed similar activity, with Hf-TUD-1 reaching the highest conversion and metal-based turnover number. Sn-TUD-1 also displayed high activity and selectivity in two acetalisation reactions, i.e. the synthesis of solketal from acetone and glycerol and the reaction of vanillin with propylene glycol. The catalytic performance of these TUD-1 materials is ascribed to the high accessibility of their active sites and to the suitable combination of acid sites. The catalysts were successfully reused in consecutive runs and did not suffer from leaching.
- Li, Li,Cani, Damiano,Pescarmona, Paolo P.
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p. 289 - 296
(2015/06/02)
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- Post-synthesis Snβ: An exploration of synthesis parameters and catalysis
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Snβ is probably one of the best water tolerating heterogeneous Lewis acids for liquid phase catalysis. Instead of applying the usual lengthy hydrothermal synthesis to prepare Snβ, this contribution uses a more hands-on two-step synthesis method, involving the grafting of Sn precursors in isopropanol under reflux conditions on a commercial β zeolite that was dealuminated in acid. Among several reference synthesis procedures, this Sn introduction method resulted in active Sn catalytic sites. Taking advantage of this practical method, several synthesis parameters were explored and their impact on the catalytic activity in four different Lewis acid catalyzed reactions is discussed. The adsorption isotherm of SnIV in isopropanol over a broad range of Sn salt concentrations at reflux temperature is presented and discussed in relation with FTIR spectroscopy, UV-vis absorption characteristics and the porosity of the materials. The study reveals a selective Sn uptake, up to 2 wt% Sn loading, into silanol nests of the dealuminated precursor, forming a diversity of mononuclear SnIV. Higher Sn loadings result in less active Sn (hydrous) extraframework oxide phases, which also cause partial blockage of the zeolite micropores. Depending on the reaction type under study, space time yield may increase with increasing Sn loading, but the activity per Sn is always lower. Therefore it is concluded that a preferred synthesis should form high contents of isolated Sn active sites, especially for sugar isomerization and intermolecular Meerwein-Ponndorf-Verley, while the other reaction types like Baeyer-Villiger is also sufficiently catalyzed by the small Sn oxide clusters, albeit less actively.
- Dijkmans, Jan,Demol, Jan,Houthoofd, Kristof,Huang, Shuigen,Pontikes, Yiannis,Sels, Bert
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p. 545 - 557
(2015/10/05)
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- Pattern forming method, chemical amplification resist composition and resist film
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Provided is a negative type pattern forming method that satisfies high sensitivity, high resolution, good roughness and good dry etching resistance at the same time, and further, has a good development time dependency, the method including (i) forming a film by a chemical amplification resist composition containing (A) a fullerene derivative having an acid-decomposable group, (B) a compound generating an acid upon irradiation with an actinic ray or radiation, and (C) a solvent, (ii) exposing the film, and (iii) developing the exposed film by using an organic solvent-containing developer.
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- Actinic-ray-sensitive or radiation-sensitive resin composition, and resist film using the same, pattern forming method, electronic device manufacturing method, and electronic device, each using the same
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Provided are an actinic-ray-sensitive or a radiation-sensitive resin composition with greater residual film ratio and capable of suppressing pattern collapse and an occurrence of bridge defects after development, and a resist film, a pattern forming method, an electronic device manufacturing method, and an electronic device, each using the same. An actinic-ray-sensitive or radiation-sensitive resin composition includes a resin (P) having a repeating unit (a) represented by following General Formula (I), a compound (B) represented by any of following General Formulae (B-1) to (B-3), and a solvent, in General Formula (I), R0 represents a hydrogen atom or a methyl group, and R1, R2 and R3 each independently represent a straight chain or branched alkyl group.
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- Development of lactic ester as bifunctional additive of methanol-gasoline
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In this paper, lactic esters were synthesized and used as phase stabilizer and saturation vapor pressure depressor of methanol-gasoline. The results show that the stabilities of the methanol-gasoline depend on the length of the lactic esters' alkoxy group. Several lactic esters were found to be effective in various gasoline-methanol blends, and the lactic esters display high capacity to depress the saturation vapor pressure of methanol-gasoline. According to the results, it can be concluded that the lactic esters have the great potential to be bifunctional gasoline-methanol additives.
- Zhang, Jie,Yang, Changchun,Tang, Ying,Xu, Lianghong,Wang, Xiaoting
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p. 4827 - 4829
(2014/12/10)
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- Extra-small porous Sn-silicate nanoparticles as catalysts for the synthesis of lactates
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A series of Sn-MCM-41 nanoparticles (XS-Sn-MCM-41) with a diameter ranging from 20 to 140 nm and very high specific surface area were successfully prepared and tested as heterogeneous catalysts for the conversion of the triose sugar dihydroxyacetone to ethyl lactate. Characterization of the materials indicated that the physicochemical properties of the nanoparticles can be significantly affected by different synthesis parameters, including the metal loading, the sequence of adding the Si and Sn precursors into the synthesis mixture, the preparation time and temperature. Most of the XS-Sn-MCM-41 catalysts displayed higher activity compared to conventional Sn-MCM-41 with large particle size in the conversion of dihydroxyacetone into ethyl lactate. The superiority of the best XS-Sn-MCM-41 catalyst in terms of conversion and turnover number is correlated to its high amount of accessible acid sites, which in turn is ascribed to a combination of different physicochemical features such as high surface area, particles morphology and coordination of the tin atoms in tetrahedral framework sites. The best catalyst can be reused in consecutive runs without loss of activity.
- Li, Li,Collard, Xavier,Bertrand, Arnaud,Sels, Bert F.,Pescarmona, Paolo P.,Aprile, Carmela
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- Ga-MCM-41 nanoparticles: Synthesis and application of versatile heterogeneous catalysts
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Ga-MCM-41 materials with nanosized particles (2-physisorption, TEM, SEM and EDX, while 71Ga MAS-NMR was employed to monitor the coordination of the gallium atoms. The two materials were tested as heterogeneous catalysts in three relevant reactions in the context of green production of valuable chemicals: (1) the reaction of glycerol with acetone to produce solketal; (2) the conversion of the triose sugar dihydroxyacetone to ethyl lactate; (3) the epoxidation of cyclooctene with aqueous hydrogen peroxide. The two nanosized Ga-MCM-41 materials show different catalytic behaviour in the various reactions, with the material prepared with lower Si/Ga displaying a higher versatility. This catalyst reaches higher turnover numbers compared to conventional Ga-MCM-41 reported in the literature. This result is ascribed to the higher specific surface area and to the shorter channels of the nanoparticles, which enhance the accessibility of the active sites.
- Collard, Xavier,Li, Li,Lueangchaichaweng, Warunee,Bertrand, Arnaud,Aprile, Carmela,Pescarmona, Paolo P.
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p. 184 - 192
(2014/08/18)
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- Cyclodextrin-based systems for the stabilization of metallic(0) nanoparticles and their versatile applications in catalysis
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In order to better respond to environmental standards, the development of metal nanoparticles using green approaches has exponentially grown for the last decade. Cyclodextrins, which are cyclic oligosaccharides composed of 6(α), 7(β) or 8(γ) glucopyranose units, have appeared to be interesting candidates for the synthesis of metal nanoparticles. Indeed, through the ability to form inclusion complexes or supramolecular adducts with organic molecules or metal precursors, cyclodextrins can be successfully employed to stabilize size-controlled zerovalent metallic nanoparticles active for hydrogenation reactions carried out in aqueous or gas-phase media. In this summary of our works, we report that cyclodextrins could be used in various forms and environments: (i) in free form, (ii) in complexed form with appropriate guests molecules, (iii) in combination with polymer matrices, (iv) in thermosensitive hydrogels and (v) immobilized onto porous carbons supports. All these studies highlight the fact that cyclodextrins can be seen as multi-task agents for nanocatalysis.
- No?l, Sébastien,Léger, Bastien,Ponchel, Anne,Philippot, Karine,Denicourt-Nowicki, Audrey,Roucoux, Alain,Monflier, Eric
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- Enantioselective hydrogenation of ethyl pyruvate catalyzed by 1,2-diphenyl-ethylenediamine-modified iridium complex: Effect of solvent
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The enantioselective hydrogenation of ethyl pyruvate was explored by a readily available homogeneous iridium catalysis system. It was found that (1R,2R)-(+)-1,2-diphenyl-ethylenediamine [(1R,2R)-DPEN] modified [Ir(COD)Cl]2 (COD = cis,cis-1,5-cyclooctadiene) was highly active for the enantioselective hydrogenation of ethyl pyruvate, and the moderate enantioselectivity of 29 % was obtained (the best value reported by iridium catalysts was 39 %). NMR spectroscopy proved that hydrogen bond between the solvent and the a-carbonyl of ethyl pyruvate would be favor to the enantioselective hydrogenation.
- Du, You,Li, Chun,Tan, Xiaoyun,Fu, Haiyan,Zheng, Xueli,Li, Ruixiang,Chen, Hua
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p. 319 - 322
(2014/06/09)
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- Versatile iridicycle catalysts for highly efficient and chemoselective transfer hydrogenation of carbonyl compounds in water
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Cyclometalated iridium complexes are shown to be highly efficient and chemoselective catalysts for the transfer hydrogenation of a wide range of carbonyl groups with formic acid in water. Examples include α-substituted ketones (α-ether, α-halo, α-hydroxy, α-amino, α-nitrile or α-ester), α-keto esters, β-keto esters and α,β-unsaturated aldehydes. The reduction was carried out at substrate/catalyst ratios of up to 50000 at pH 4.5 and required no organic solvent. The protocol provides a practical, easy and efficient way for the synthesis of β-functionalised secondary alcohols, such as β-hydroxyethers, β-hydroxyamines and β-hydroxyhalo compounds, which are valuable intermediates in pharmaceutical, fine chemical, perfume and agrochemical synthesis. Water wonder: Iridicycle catalysts are versatile and allow the highly efficient and chemoselective transfer hydrogenation of a variety of carbonyl compounds, including problematic and challenging ones, with formate in neat water (see scheme).
- Talwar, Dinesh,Wu, Xiaofeng,Saidi, Ourida,Salguero, Noemí Poyatos,Xiao, Jianliang
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supporting information
p. 12835 - 12842
(2015/03/30)
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- Selective conversion of dihydroxyacetone-ethanol mixture into ethyl lactate over amphoteric ZrO2-TiO2 catalyst
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The conversion of dihydroxyacetone in ethanol solution into ethyl lactate over several acidic and amphoteric oxides at 100-160 C was studied. The formation of ethyl lactate with 80-90% selectivity was observed on amphoteric ZrO2-TiO2
- Mylin, Artur M.,Levytska, Svitlana. I.,Sharanda, Mykhailo E.,Brei, Volodymyr V.
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- Esterification of Lactic Acid by Catalytic Extractive Reaction: An Efficient Way to Produce a Biosolvent Composition
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A biosolvent composition containing ethyl lactate and biodiesel was directly obtained by catalytic extractive esterification of lactic acid. Since the esterification of organic acids with alcohols is a thermodynamically limited reaction, the methodology consists in conducting the esterification and the ester extraction simultaneously thereby shifting the equilibrium towards more esters. The acid catalyzed esterification was performed in a biphasic solvent system composed of (i) a reactive polar phase which contains the esterification constituents, lactic acid, ethanol and an acid catalyst (ii) an extractive solvent selective of the ester, fatty acid methyl ester (biodiesel). This solvents system increases the ethyl lactate yield of more than 30 %. During the reaction progress, the selective solvent, fatty acid methyl ester, is progressively blended with ethyl lactate providing a mixture of esters, which can be directly used as an efficient composition of biosolvents without further purification. The solid acidic potassium salt of 12-phosphotungstic acid, K 2.5H0.5PW12O40, was shown to be more efficient than the conventional esterification catalysts, H2SO 4 or Amberlyst 15. K2.5H0.5PW 12O40 gives a yield in ethyl lactate higher than 80 mol% after 2 h of reaction in the biphasic solvent system, using a molar ratio ethanol/lactic acid of 3.3 only. Moreover, K2.5H0.5PW 12O40 shows a remarkable higher activity per protonic sites (factor 30) and is recyclable at least two times without apparent loss of activity. These excellent properties were ascribed to its low density of strong Bronsted acid sites and its adequate hydrophobicity which would make this acid more water tolerant than the conventional esterification catalysts, H 2SO4 or Amberlyst 15. Graphical Abstract: Acid catalyzed esterification of lactic acid with ethanol was performed in a biphasic system where biodiesel acts as an extractive solvent of ethyl lactate. This extractive reaction produces directly a composition of biosolvent: biodiesel blended with ethyl lactate.[Figure not available: see fulltext.]
- Vu, Thu Ha Thi,Au, Hang Thi,Nguyen, Thuy Ha Thi,Nguyen, Thu Trang Thi,Do, Manh Hung,Bui, Ngoc Quynh,Essayem, Nadine
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p. 950 - 956
(2013/10/08)
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