- One-step synthesis of dimethyl carbonate from carbon dioxide, propylene oxide and methanol over alkali halides promoted by crown ethers
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Crown ethers (i.e. [2,4]-dibenzo-18-crown-6 (DBC), 18-crown-6, 15-crown-5 and 12-crown-4) show obvious co-catalytic effect for alkali halides catalyzing one-step synthesis of dimethyl carbonate (DMC) from CO2, propylene oxide and methanol. Especially, the DMC yield of KCl catalyst promoted by DBC can increase by more than five times and reach about 40% under mild reaction conditions (i.e., low mole ratio of methanol and epoxieds: 7:3, low initial pressure of CO2: 1.5 MPa, reaction temperature: 140 °C, time: 10 h). The optimized molar ratio of KCl to DBC is 2: 1. Due to the good complexing ability between DBC and K+, KCl and DBC formed an organometallic complex. Actually, DBC can not only promote the reaction rate and equilibrium of cycloaddition and transesterification reactions, but also prevent side reaction. Importantly, DBC can conveniently achieve high recovery ratio and show excellent reusability.
- Li, Lei,Shi, Shikai,Song, Li,Guo, Liping,Wang, Yifei,Ma, Hongxia,Hou, Jie,Wang, Haidong
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- Tunable synthesis of propylene glycol ether from methanol and propylene oxide under ambient pressure
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A series of basic and acidic ionic liquids, 1-butyl-3-methylimidazolium hydroxide (BMIMOH), 1-acetyl-3-methylimidazolium chloride (AcMIMCl) and AcMIMCl-FeCl3, or analogues of AcMIMCl, namely 1-potassium acetate-3-methylimidazolium chloride (KAcMIMCl), 1-potassium (sodium, ammonium) acetate-3-methylimidazolium hydroxides (KAcMIMOH, NaAcMIMOH and NH 4AcMIMOH), were prepared and used as catalysts for catalytic synthesis of propylene glycol ether via reaction of propylene oxide (PO) with methanol under mild reaction conditions. KAcMIMOH exhibited outstanding catalytic performance with 94.2% of conversion of PO and 99.1% of selectivity to 1-methoxy-2-propanol (MP-2) at 60°C and ambient pressure for 4 h. However, AcMIMCl-FeCl3 showed a good catalysis performance with high selectivity to 2-methoxy-1-propanol (MP-1). The tunable synthesis of MP-2 or MP-1 catalyzed by basic compound KAcMIMOH or acidic ionic liquid AcMIMCl-FeCl3 was realized.
- Bai, Yu,Cai, Qinghai,Wang, Xiaoguang,Lu, Bin
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- Ionic-Liquid-Based Heterogeneous Covalent Triazine Framework Cobalt Catalyst for the Direct Synthesis of Methyl 3-Hydroxybutyrate from Propylene Oxide
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β-Hydroxy esters are considered as potential building blocks for the production of fine chemicals and potential drug molecules in various industries. Developing an efficient and recyclable catalyst for the synthesis of β-hydroxy esters is challenging. Her
- Rajendiran, Senkuttuvan,Park, Kwangho,Lee, Kwangyeol,Yoon, Sungho
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- One-pot two-step process for direct propylene oxide production catalyzed by bi-functional Pd(Au)@TS-1 materials
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Different bi-functional materials (Pd(Au)@TS-1) based on metallic nanoparticles supported onto active nanocrystalline titanium silicalite (TS-1) zeolites were synthesized, characterized and used as recyclable heterogeneous catalysts for direct propylene oxide production from hydrogen, oxygen and propylene through one-pot two-step consecutive process. These catalysts allowed carrying out the combined reaction where metallic nanoparticles catalyzed the formation of in situ H2O2 that was the necessary intermediate for propylene epoxidation catalyzed by active TS-1 nanocrystalline support. Several variables were considered such as use of supercritical CO2 conditions, modifiable content of metallic species, and presence of additional co-solvents, surface acidity inhibitors and H2O2 stabilizers. Reusability and stability of the bi-functional catalyst was showed through consecutive catalytic cycles.
- Prieto, Alejandro,Palomino, Miguel,Díaz, Urbano,Corma, Avelino
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- Supported ionic liquids on solid materials as catalysts for the synthesis of propylene glycol methyl ether
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Ionic liquid 1,1,3,3-tetramethylguanidium lactate was immobilized on three solid supports, MCM-41, silica-gel and attapulgite (Atta), by different methods. The prepared materials were used to catalyze the reaction of propylene oxide and methanol to produce propylene glycol methyl ether. 1-Methoxy-2-propanol was the predominant product. The influence of the amount of the catalyst, molar ratio of the reactants, reaction temperature and time on the yield and selectivity was studied. The three catalysts proved to be efficient reusable catalysts for the reaction.
- Haa, Minh Ngoc,Whiting, Roger,Han, Sheng,Wang, Yuhong
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- Effect of propylene glycol monomethyl ether and rust impurities on TS-1 deactivation in propylene epoxidation
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The properties of TS-1 catalyst in continuous reaction of propylene epoxidation, as well as the effects of by-product propylene glycol monomethyl ether (PGME) on catalytic performance, was investigated in a low-pressure fixed bed reactor with chemical pure methanol as solvent. As the rust could be doped from the pipings and solvent containers, its impact on catalyst deactivation was then studied by using industrial-grade methanol. Finally the catalyst before and after deactivation was contrastively characterized by means of micro-structure analysis, TPD and TPR. The results showed that self-developed TS-1 catalyst performed well in the reaction, and the by-product propylene glycol monomethyl ether would not depress the catalytic activity in 80 h. The presence of rust could not only block active sites leading to partial loss of activity, but also increase the surface acidity, which would induce side reactions and decrease the selectivity of propylene oxide.
- Li, Yi-Chuan,Shen, Ben-Xian,Zhao, Ji-Gang
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- Tuning Zr12O22 Node Defects as Catalytic Sites in the Metal-Organic Framework hcp UiO-66
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Defects in metal-organic frameworks (MOFs) play important roles in MOF reactivity and catalysis. Now, we report evidence of the reactivity and the quantitative characterization of the missing linker defects on the Zr12O22 nodes in the MOF hcp UiO-66 (these are paired Zr6O8 nodes bridged by OH groups) and those on the Zr6O8 nodes of the MOF UiO-66. The defect sites catalyze the ring-opening reactions of epoxides with alcohols, and new sites formed by removal of bridging OH groups on the Zr12O22 nodes also participate in the catalysis. The hcp UiO-66 was synthesized from UiO-66 and from molecular precursors, and, under various synthesis conditions, the nodes incorporated acetate ligands, where linkers were missing, and the number of these ligands was controlled by the synthesis conditions. These ligands are inhibitors of the catalytic reactions, and their removal by reaction with, for example, methanol (to form, for example, methyl acetate) preceded catalysis on the defect sites. The former MOF incorporated more defect sites than the latter, correspondingly being a more active catalyst. The defect sites on the Zr12O22 nodes are 2-6 times more active per site than those on the isolated Zr6O8 nodes, with the node-bridging OH groups increasing the catalytic activity of the neighboring node defect sites because new sites are formed by their removal. The results help point the way to the design and control of catalytic sites on metal oxide-like MOF nodes by tuning of the number and reactivity of the defect sites.
- Chen, Xi,Gates, Bruce C.,Lyu, Yinghui,Qiao, Xu,Wang, Zhengyan,Yang, Dong
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- Selectivity controlled transformation of carbon dioxide into a versatile bi-functional multi-carbon oxygenate using a physically mixed ruthenium-iridium catalyst
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To mitigate environmental concern and energy issues, the conversion of carbon dioxide (CO2) to valuable and useful carbon chemicals offers a promising strategy for the development of a carbon neutral economy. The utilization of inert CO2as a building block in the synthesis of multi-carbon (>2) oxygenated compounds, specifically propylene glycol methyl ether (PGME; C4H10O2), produced annually at a multi-million-ton scale from petroleum-based propylene oxide is of particular interest because of its multifaceted industrial and commercial applications. Herein, we present a simple and straightforward system that uses CO2in compressed form as the C1 feedstock for the synthesis of PGME by direct hydrogenation and subsequent C-C coupling without any other sacrificial reagents. In addition, we combine experimental results with DFT calculations to elucidate the synergistic contributions of two catalytic metals (Ru and Ir) to activation of CO2for hydrogenation and consequent mediation of the C-C bond formation leading to the generation of PGME. Taken together, our findings suggest that the strategy presented herewith may serve as a starting point for the development of a sustainable chemical synthesis platform for multi-carbon oxygenates by utilizing CO2as the starting material.
- Chatterjee, Abhijit,Chatterjee, Maya,Kawanami, Hajime,Kitta, Mitsunori
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- Ketone-alcohol hydrogen-transfer equilibria: Is the biooxidation of halohydrins blocked?
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To ensure the quasi-irreversibility of the oxidation of alcohols coupled with the reduction of ketones in a hydrogen-transfer (HT) fashion, stoichiometric amounts of a-halo carbonyl compounds have been employed as hydrogen acceptors. The reason that these substrates lead to quasi-quantitative conversions has been tacitly attributed to both thermodynamic and kinetic effects. To provide a clear rationale for this behavior, we investigate herein the redox equilibrium of a selected series of ketones and 2-propanol by undertaking a study that combines experimental and theoretical approaches. First, the activity of the (R)-specific alcohol dehydrogenase from Lactobacillus brevis (LBADH) with these substrates was studied. The docking of acetophenone/(R)-l-phenyethanol and a-chloroacetophenone/(S)-2-chloro- lphenylethanol in the active site of the enzyme confirms that there seems to be no structural reason for the lack of reactivity of halohydrins. This assumption is confirmed by the fact that the corresponding aluminum-catalyzed Meerwein-Ponndorf-Verley-Oppenauer (MPVO) reactions afford similar conversions to those obtained with LBADH, showing that the observed reactivity is independent of the catalyst employed. While the initial rates of the enzymatic reductions and the IR v(C=0) values contradict the general belief that electron-withdrawing groups increase the electrophilicity of the carbonyl group, the calculated βG values of the isodesmic redox transformations of these series of ketones/alcohols with 2-propanol/acetone support the thermodynamic control of the reaction. As a result, a general method to predict the degree of conversion obtained in the HT-reduction process of a given ketone based on the IR absorption band of the carbonyl group is proposed, and a strategy to achieve the HT oxidation of halohydrins is also shown.
- Bisogno, Fabricio R.,Garcia-Urdiales, Eduardo,Valdes, Haydee,Lavandera, Ivan,Kroutil, Wolfgang,Suarez, Dimas,Gotor, Vicente
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- A novel strategy for constructing mesoporous solid superbase catalysts: Bimetallic Al-La oxides supported on SBA-15 modified with KF
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Bimetallic Al-La oxides were conjointly precoated on SBA-15 prior to the introduction of potassium fluoride to achieve solid superbases at low temperature by a modified wetness impregnation method. This breaks the tradition of decomposition of KNO3 at high temperature and gives rise to a new approach to generating superbasic sites on SBA-15. The physico-chemical characteristics of the prepared KF/Al-La@SBA-15 materials were investigated using FT-IR, XRD, TG-DTG, N2 adsorption-desorption, TEM, SEM-EDS, acid-base titration, Hammett indicators and CO2-TPD measurements. The results demonstrated that the addition of Al species promoted the dispersion behavior of La species inside the channels, and the bimetallic species could synergistically protect the mesoporous structures of SBA-15 against KF corrosion. With increasing Al content, KF/Al-La@SBA-15 exhibited a long-range ordering of the pores with relatively narrow pore size distribution as well as high specific surface area. The research results showed that the KF/Al-La@SBA-15 (0.4) catalyst possessed a total basicity up to 0.79 mmol g-1 and superbasicity with a strength of 26.5. The catalytic activity of the prepared materials was evaluated in the ring-opening reaction of propylene oxide with methanol. Compared with the SBA-15 supported monometallic oxide (Al or La) catalysts, KF/Al-La@SBA-15 (0.4) exhibited the highest catalytic activity for the ring-opening reaction of propylene oxide with methanol. This is associated with the synergistic effects between Al and La species and the high dispersion of active components on the SBA-15 support.
- Liu, Ning,Wu, Zhimin,Li, Meng,Li, Shanshan,Li, Yongfei,Yu, Rongdong,Pan, Langsheng,Liu, Yuejin
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- Fluorine-modified Mg-Al mixed oxides: A solid base with variable basic sites and tunable basicity
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The fluorine-modified Mg-Al mixed oxides were synthesized by thermal decomposition of the fluorine-containing Mg-Al hydrotalcites, and their physicochemical properties were characterized by ICP, TGA, XRD, FTIR, CO2-TPD and N2 adsorption/desorption techniques. It was found that weak basic sites were gradually transformed into moderate and strong basic sites during thermal decomposition, and thus weak basic sites (OH- groups), moderate basic sites (Mg-O, Mg-F and Al-O pairs) and strong basic sites (coordinatively unsaturated F- and O2- ions) were all produced in the as-prepared samples. Furthermore, the basicity of moderate basic sites could be controlled by the change of fluorine content, which caused the change in the amounts of Mg-F pairs. In the synthesis of propylene glycol methyl ether from methanol and propylene oxide, the base-catalytic performance of the obtained samples was shown to be closely associated with their moderate basic sites.
- Wu, Gongde,Wang, Xiaoli,Wei, Wei,Sun, Yuhan
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- Epoxidation of propylene over titanosilicate-1 in fixed-bed reactor: Experiments and kinetics
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The epoxidation of propylene with hydrogen peroxide over titanosilicate-1 is studied in a fixed-bed reactor with methanol/water as the solvent. The effects of methanol concentration (40-70 wt %), hydrogen peroxide concentration (5-20 wt %), pressure (1.8-3 MPa) and temperature (35-50 °C) on the reaction are investigated. The results show that the reaction rate decreases with increasing reaction pressure, which is opposite to that reported in the literature. The activation energy of the reaction is 57.4 kJ mol-1 and the orders with respects to hydrogen peroxide and propylene are 0.71 and 0.29, respectively. The intrinsic kinetic modeling results show that an Eley-Rideal (H2O2 adsorbed) kinetic model incorporating the effects of hydrogen peroxide, propylene, methanol and propylene oxide satisfactorily agrees with the experimental results.
- Wang, Lina,Wang, Yaquan,Wu, Guoqiang,Feng, Wenping,Zhang, Teng,Yang, Rumin,Jin, Xing,Shi, Hainan,Wang, Shuhai
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- Chemo- and Regioselective Reductions of Functionalized Epoxides by Bu3SnH/Bu3SnI-Phosphine Oxide
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A novel reagent, Bu3SnH/Bu3SnI-phosphine oxide, reduced functionalized epoxides to the corresponding alcohols in high chemo- and regioselectivities.
- Kawakami, Takayo,Tanizawa, Daisuke,Shibata, Ikuya,Baba, Akio
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- Enhanced Catalytic Performance of Titanium Silicalite-1 in Tuning the Crystal Size in the Range 1200-200nm in a Tetrapropylammonium Bromide System
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A facile method for the size-controllable synthesis of titanium silicalite-1 (TS-1) is presented. A tetrapropylammonium bromide hydrothermal system was used, and the amount of seeds (silicalite-1 suspension) and crystallization time were tuned to control the crystal size. The crystal size could be adjusted from 200 to 1200nm by varying the seed amount from 12 to 0.05wt%. Crystallization time plays a less important role than the seed amount on the crystal size. TS-1 samples with different crystal sizes were characterized and evaluated in propene epoxidation. The catalytic activity and selectivity of propene oxide are enhanced by decreasing the crystal size from 1200 to 200nm because the diffusion limitation is eliminated gradually. The seed is significant for this system, as a lack of seeds leads to poor crystallization and low catalytic activity. The mechanism of the seed function was studied by simulating the transformation process of the seed in the TS-1 synthesis system.
- Zuo, Yi,Liu, Min,Zhang, Ting,Meng, Changgong,Guo, Xinwen,Song, Chunshan
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- Selective decomposition of hydrogen peroxide in the epoxidation effluent of the HPPO process
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This work describes the selective H2O2 decomposition in the exit stream of the epoxidation reactor employed in the Hydrogen Peroxide-Propylene Oxide (HPPO) process. Pd/Al2O3 and Pt/Al2O3 catalysts were tested. The effects of the reaction temperature and the pH of the solution on catalyst performance were investigated. It was found that the Pt catalyst is much more active than its Pd counterpart. An increase in the temperature and the pH of the solution resulted in an increase in the H2O2 decomposition rate; however, a parallel increase of by-products from PO was also observed. Working with a Pt/Al2O3 catalyst under optimized reaction conditions (333 K, pH = 7), hydrogen peroxide can be completely decomposed at reaction times of 120 min with no by-products produced from propylene oxide.
- Blanco-Brieva, Gema,De Frutos-Escrig, M. Pilar,Martín, Hilario,Campos-Martin, Jose M.,Fierro, Jose L.G.
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- The tetramethylguanidine-based ionic liquid-catalyzed synthesis of propylene glycol methyl ether
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Tetramethylguanidine-based ionic liquids were used as effective catalysts for the synthesis of propylene glycol methyl ether from methanol and propylene oxide. 1-Methoxy-2-propanol was produced in nearly 90% yield under much milder conditions. The catalyst can be reused at least ten times without any considerable decrease in its activity and selectivity.
- Liang, Shuguang,Liu, Huizhen,Zhou, Yinxi,Jiang, Tao,Han, Buxing
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- Synthesis of propylene glycol methyl ether catalyzed by MCM-41
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In this work, we found that MCM-41 prepared using cetyltrimethyl ammonium bromide (CTAB) as the template could be used as a heterogeneous catalyst for the reaction of methanol with propylene oxide to produce propylene glycol methyl ether. 1-Methoxy-2-propanol was the predominant product. The influence of ratio of the reactants, reaction temperature, and time on the yield and selectivity was studied. The as-prepared MCM-41 proved to be an efficient and reusable catalyst, and the separation of the catalyst form the product was very easy.
- Liang, Shuguang,Zhou, Yinxi,Liu, Huizhen,Jiang, Tao,Han, Buxing
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- Generation of a solid Bronsted acid site in a chiral framework
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Protonation of chiral porous materials introduces a Bronsted acid centre, the structure of which is unique to the heterogeneous phase requiring pore wall confinement for stable isolation. The Royal Society of Chemistry.
- Ingleson, Michael J.,Barrio, Jorge Perez,Bacsa, John,Dickinson, Calum,Park, Hyunsoo,Rosseinsky, Matthew J.
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- Low-Temperature Preparation of a Mesoporous Silica Superbase by Employing the Multifunctionality of a La2O3 Interlayer
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A simple and effective approach for the preparation of the solid superbasic La2O3–SBA-15-supported KF (KF/La2O3–SBA-15) was developed by a low-temperature strategy. The KF/La2O3–SBA-15 with ordered mesostructure and a high base strength (H?=27.0) was realized at 350 °C in still air, which breaks the traditional method of thermally induced decomposition of basic metal nitrate derived species KNO3 under higher temperatures (>600 °C). The resultant mesoporous basic materials were adopted for the production of 1-methoxy-2-propanol from propylene oxide and methanol. It showed excellent catalytic performance exhibiting 93 % conversion of propylene oxide and 93 % selectivity to 1-methoxy-2-propanol. This performance is better than that over the catalysts without mesoporous silica despite having a higher KF content.
- Liu, Ning,Wu, Zhimin,Li, Meng,Li, Shanshan,Luo, Zhantao,Li, Yongfei,Pan, Langsheng,Liu, Yuejin
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- Sonocatalytic removal of naproxen by synthesized zinc oxide nanoparticles on montmorillonite
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ZnO/MMT nanocomposite as sonocatalyst was prepared by immobilizing synthesized ZnO on the montmorillonite surface. The characteristics of as-prepared nanocomposite were studied by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) techniques. The synthesized samples were used as a catalyst for sonocatalytic degradation of naproxen. ZnO/MMT catalyst in the presence of ultrasound irradiation was more effective compared to pure ZnO nanoparticles and MMT particles in the sonocatalysis of naproxen. The effect of different operational parameters on the sonocatalytic degradation of naproxen including initial drug concentration, sonocatalyst dosage, solution pH, ultrasonic power and the presence of organic and inorganic scavengers were evaluated. It was found that the presence of the scavengers suppressed the sonocatalytic degradation efficiency. The reusability of the nanocomposite was examined in several consecutive runs, and the degradation efficiency decreased only 2% after 5 repeated runs. The main intermediates of naproxen degradation were determined by gas chromatography-mass spectrometry (GC-Mass).
- Karaca, Melike,Kiran?an, Murat,Karaca, Semra,Khataee, Alireza,Karimi, Atefeh
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- 13C-N.M.R.-SPECTRAL AND RELATED STUDIES ON THE DISTRIBUTION OF SUBSTITUENTS IN O-(2-HYDROXYPROPYL)CELLULOSE
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Information about the degree of substitution at individual oxygen atoms of O-(2-hydroxypropyl)cellulose, and the total molar substitution, was obtained from 13C-n.m.r. spectra of the intact polymer and of its hydrolyzate.On the basis of their 13-CH3 chemical-shifts, O-(2-hydroxypropyl) (HOPr) substituents occurring singly, or as terminal units of substituent chains, were radily distinguished from inner HOPr units of chains.Differentiation between monomeric HOPr units and longer chains located at O-2 of D-glucosyl residues was effected by the transformation of appropriatly substituted sugars in the hydrolyzate into 1,2-cyclic acetals incorporating a 2-O-(2-hydroxypropyl) group.Similarly, the pattern of substitution at O-6 of D-glucosyl residues was determined, through selective degradation, from the identity of HOPr derivatives of ethylene glycol, representing C-5 and C-6 of the residues.Overall, it was found that, although O-2 and O-6 are more readily substituted than O-3, the rate at which each, initially introduced, HOPr substituent is converted into a dimeric structure is not materially affected by its location.Also described are the synthesis and the n.m.r. spectra of several HOPr derivatives of D-glucose, and of simple alkanols that served as model compounds.
- Lee, Dae-Sil,Perlin, Arthur S.
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- An atom-economic reaction for synthesis of 1-phenoxy-2-propanol over Al2O3/MgO
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Al2O3/MgO materials with various Mg/Al molar ratios were prepared and characterized by XRD, FT-IR, SEM and BET analysis. These materials were used as catalysts for synthesis of 1-phenoxy-2-propanol (1-PhP) from phenol and propylene oxide as compared with some oxides, i.e. MgO, CaO, ZnO and Al2O3, etc. Al2O3/MgO with Al/Mg molar ratio of 1.5% exhibited outstanding catalytic performance with 98.2% conversion and 99.3% selectivity to 1-PhP at 120 °C for 5 h. This catalyst can be easily recovered and reused due to its heterogeneous catalytic nature.
- Zhang, Yongbo,Lu, Bin,Wang, Xiaoguang,Zhao, Jingxiang,Cai, Qinghai
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- Ship-in-bottle preparation of multi-SO3H functionalized ionic liquid@MIL-100(Fe) for acid-catalyzed ring-opening of epoxides
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The fact that the homogeneous acid catalysts are usually separated difficulty than heterogeneous catalysts from the reaction media, the opportunity to combine the advantages of both homogeneous and heterogeneous catalytic systems by immobilizing ILs within the pores of a porous solid support host is an alternative method. In this research, a multi-SO3H functionalized ionic liquid derived from hexamethylenetetramine (HMTA) and 1,3-propane sultone was entrapped inside the pores of MIL-100(Fe) through the ship-in-bottle method and utilized for heterogeneous acid-catalyzed ring-opening of epoxides under solvent-free conditions. The physicochemical properties of prepared catalyst were fully elucidated by various methods. FT-IR spectroscopy and elemental analysis approved the successful incorporation of modified groups within the MIL-100(Fe) cavities. The concentration of acid sites was measured via the acid–base titration which exhibited the 0.9?mmol/g H+ in the catalyst structure. Also, thermogravimetric analysis (TGA) profile showed the loosing of modified groups at 300–600°C. Moreover, X-ray diffraction (XRD) analysis showed that the MIL-100(Fe) structure was retained after modification and nitrogen adsorption–desorption analysis (BET method) manifested the decrease in surface area caused by incorporation of ionic liquid. The fabricated catalyst exhibited high catalytic efficiency in methanolysis of styrene oxide (99% conversion in 3?h) under ambient conditions and used without a substantial drop in product yield in further rounds.
- Mortazavi, Saeideh-Sadat,Masteri-Farahani, Majid,Abbasi, Alireza
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- Synthetic and natural materials with the brucite-like layers as high active catalyst for synthesis of 1-methoxy-2-propanol from methanol and propylene oxide
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The aim of this study was to investigate the correlation between the basic and catalytic properties of brucite and Mg,Al-layered double hydroxides (Mg,Al-LDHs) in the reaction of propylene oxide with methanol. The basic properties of the solids were investigated by FT-IR spectroscopy using CDCl3 as probe molecule and Hammett acidity titration with n-butylamine and benzoic acid. Both the increase in the activation temperature and the decrease in Al content favored the increase in the basicity of Mg,Al-LDH. The nature of “Mn+[Formula presented]2? Lewis acid-base” pairs was a key factor to control the catalytic behavior of the solids. The length of the M-O bond, the basicity of the oxygen ion and the strength of the metal ion on the surface affected the catalytic activity of the solids and their isomer selectivity in the reaction between methanol and propylene oxide to form 1-methoxy-2-propanol. It was demonstrated that brucite(150) can be applied as catalyst for at least four successive cycles without loss of activity.
- Timofeeva, Maria N.,Kapustin, Aleksey E.,Panchenko, Valentina N.,Butenko, Eleonora O.,Krupskaya, Victoria V.,Gil, Antonio,Vicente, Miguel A.
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- Methylammonium-FAU zeolite: Investigation of the basic sites in base catalyzed reactions and its performance
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The basicity of methylammonium-faujasite zeolites (FAU) was evaluated in the Knoevenagel and Claisen-Schmidt condensation reactions and in the alcoholysis of propylene oxide with methanol. The basic character of FAU zeolites (Y zeolite with Si/Al = 2.5 and X zeolite with Si/Al = 1.4) was systematically altered by incorporating cesium and methylammonium cations, which were located in charge compensation sites. In all three reactions, methylammonium-FAU zeolites showed higher specific activity in comparison to cesium-FAU, indicating that these catalysts encompass stronger basic sites. Characterization of the zeolites has shown that ion exchange of sodium by methylammonium cations reduces their micropore volume, however enhances the strength of their basic sites. TPD-CO2 experiments demonstrated that aluminum rich zeolites possess higher basicity due to higher number of sites. Additionally, XPS (O1s) measurements illustrated that when monomethylammonium cation is present in ion exchange sites, structural zeolite oxygen anions have a higher basic character in comparison to cesium-FAU. This unique result opens news perspectives for application of these highly basic and low-cost methylammonium molecular sieves in base-catalyzed reactions such as Knoevenagel, Claisen-Schmidt condensation and nucleophilic cleavage of propylene oxide with methanol.
- Martins, Leandro,Hoelderich, Wolfgang,Cardoso, Dilson
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- An improved one-pot synthesis of dimethyl carbonate from propylene oxide, CO2 and methanol
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The direct synthesis of dimethyl carbonate (DMC) and propylene glycol from propylene oxide, CO2 and methanol has been studied with potassium carbonate as catalyst. This is the first time that K2CO3 which is readily available has been used as a catalyst. It is quite simple and cheap to use. This route may be an effective way of producing DMC on the large-scale. DMC is used in polycarbonate synthesis, polyurethane synthesis, carbonylating reagents, alkylating reagents, polar solvents, octane boosters in gasoline, carbon-particle reducing agents for diesel engines It is a safe and environmentally benign alternative for phosgene in some reactions.
- Fan, Bin,Qu, Bo,Cai, Liang,Chen, Qingchuan,Wen, Yicun,Zhang, Rui
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- Immobilized 1,1,3,3-tetramethylguanidine ionic liquids as the catalyst for synthesizing propylene glycol methyl ether
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In this work, we immobilized ionic liquid 1,1,3,3-tetramethylguanidium lactate on two solid supports, bentonite and SBA-15, by different methods. The prepared materials were used to catalyze the reaction of propylene oxide and methanol to produce propylene glycol methyl ether. 1-Methoxy-2-propanol was the predominant product. The influence of the amount of the catalyst, molar ratio of the reactants, reaction temperature and time on the yield and selectivity was studied. The two catalysts were proved to be efficient and reusable catalysts for the reaction. Graphical Abstract: 1,1,3,3-Tetramethylguanidium lactate was supported on bentonite and SBA-15, which were effective and recyclable catalysts for the synthesis of propylene glycol methyl ether from methanol and propylene oxide.[Figure not available: see fulltext.]
- Liang, Shuguang,Zhou, Yinxi,Liu, Huizhen,Jiang, Tao,Han, Buxing
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- Kinetics of propylene epoxidation with hydrogen peroxide catalyzed by extruded titanium silicalite in methanol
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The kinetics of propylene oxidation into propylene oxide in the presence of extruded titanium silicalite was studied. Based on the experimental data, a kinetic model of the process was designed and the activation energies of the target and side reactions, the rate constants, and the adsorption equilibrium constants were determined. The adequacy of the proposed kinetic model was verified on a continuously-operated test bench laboratory unit.
- Sulimov,Danov,Ovcharova,Ovcharov,Flid
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- Nano metal oxides as efficient catalysts for selective synthesis of 1-methoxy-2-propanol from methanol and propylene oxide
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Nano metal oxides such as Fe2O3, Fe3O4, CuO, NiO, ZnO and SnO2 were prepared and characterized using XRD, SEM and TEM analysis. These as-prepared metal oxide materials were used as catalysts for the etherification of methanol with propylene oxide (PO). The results showed that α-Fe2O3 exhibited outstanding catalytic performance with 97.7% conversion and 83.0% selectivity to MP-2 at 160 °C for 8 h. Furthermore, the relationship between the catalytic activity or selectivity and surface basicity or energy gap was investigated. This catalyst could be easily recovered and reused due to its heterogeneous catalytic nature.
- Zhang, Jiawei,Cai, Qinghai,Zhao, Jingxiang,Zang, Shuying
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- Synthesis of cyclic carbonates and dimethyl carbonate using CO2 as a building block catalyzed by MOF-5/KI and MOF-5/KI/K2CO 3
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The synthesis of cyclic carbonates or dimethyl carbonate (DMC) using CO2 as a building block is a very interesting topic. In this work, we found that the metalorganic framework-5 (MOF-5)/KI was an active and a selective catalytic system for the synthesis of cyclic carbonates from CO 2 and epoxides, and MOF-5/KI/K2CO3 was efficient for the preparation of DMC from CO2, propylene, and methanol by a sequential route. The impacts of temperature, pressure, and reaction time length on the reactions were investigated, and the mechanism of the reactions is proposed on the basis of the experimental results.
- Song, Jinliang,Zhang, Binbin,Jiang, Tao,Yang, Guanying,Han, Buxing
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Read Online
- Synthesis of propylene glycol monomethyl ether over Mg/Al hydrotalcite catalyst
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Mg-Al hydrotalcites with different Mg/Al molar ratios were prepared and characterized by XRD, FT-IR, SEM and BET analyses. The calcined hydrotalcite with Mg/Al molar ratio of 4.0 (LDO Mg/Al 4.0) exhibited the highest catalytic activity in the synthesis of propylene glycol methyl ether (PM). The catalytic activity relating to the amount of the basic sites and crystallinity depended on the Mg/Al molar ratio. The optimal equilibrium of acid-base property and high crystallinity made the LDO Mg/Al 4.0 an excellent catalyst in the reaction. Etherification of propylene oxide (PO) with methanol over the LDO Mg/Al 4.0 was researched. The optimized reaction conditions were as follows: 140 °C, catalyst amount 0.9 wt%, methanol/PO molar ratio 4.0 and 6 h. The PO conversion and PM selectivity were 93.2 and 97.4%, respectively. Above all, almost all the PM was 1-methoxy-2-propanol, for no 2-methoxy-1-propanol was detected by GC analysis in the reaction products, and the catalyst could be reused for five times.
- Zeng, Hong-Yan,Wang, Ya-Ju,Feng, Zhen,You, Kui-Yi,Zhao, Ce,Sun, Jin-Wei,Liu, Ping-Le
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Read Online
- Nanotitania catalyzes the chemoselective hydration and alkoxylation of epoxides
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Glycols and ethoxy– and propoxy–alcohols are fundamental chemicals in industry, with annual productions of millions of tons, still manufactured in many cases with corrosive and unrecoverable catalysts such as KOH, amines and BF3?OEt2. Here we show that commercially available, inexpensive, non–toxic, solid and recyclable nanotitania catalyzes the hydration and alkoxylation of epoxides, with water and primary and secondary alcohols but not with phenols, carboxylic acids and tertiary alcohols. In this way, the chemoselective synthesis of different glycols and 1,4–dioxanones, and the implementation of nanotitania for the production in–flow of glycols and alkoxylated alcohols, has been achieved. Mechanistic studies support the key role of vacancies in the nano–oxide catalyst.
- Ballesteros–Soberanas, Jordi,Leyva–Pérez, Antonio,Martínez–Castelló, Aarón,Oliver–Meseguer, Judit,Tejeda–Serrano, María
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- Hydrogen bonding-catalysed alcoholysis of propylene oxide at room temperature
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Alcoholysis of propylene oxide (PO) is achieved over azolate ionic liquids (IL,e.g., 1-hydroxyethyl-3-methyl imidazolium imidazolate) at room temperature, accessing glycol ethers in high yields with excellent selectivity (e.g., >99%). Mechanism investigation indicates that cooperation of hydrogen-bonding of the anion with methanol and that of the cation with PO catalyses the reaction.
- Li, Ruipeng,Liu, Zhimin,Wang, Yuepeng,Xiang, Junfeng,Xu, Yueting,Zhang, Fengtao,Zhao, Yanfei
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supporting information
p. 8734 - 8737
(2021/09/08)
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- Method for preparing propylene glycol monomethyl ether (by machine translation)
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The method comprises, under the alcoholysis reaction condition, contacting: the propylene oxide, methanol and the catalyst in the reaction zone of the moving bed reactor, the selectivity, of, methoxy - 1 1-propanol. in the fixed bed reactor can be effectively avoided, and the service life, of the catalyst can be prolonged simultaneously. 2 - The catalyst containing titanium silicoaluminophosphate molecular sieve (MME - 2) can effectively avoid the catalyst bed temperature scheduling problem . The catalyst containing the propylene glycol monomethyl ether can be, regenerated . (by machine translation)
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Paragraph 0092-0109
(2020/05/08)
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- Propylene oxidation process
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The invention relates to a propylene oxidation method, which comprises: S1, carrying out a first reaction on propylene, an oxidizing agent and methanol in the presence of a first catalyst to obtain afirst reaction mixture, wherein the first catalyst contains a titanium silicalite molecular sieve; S2, mixing the first reaction mixture with a second catalyst to carry out a second reaction, whereinthe second catalyst contains a titanium-silicon-aluminum molecular sieve; the molar ratio of the propylene to the oxidizing agent to the methanol is 1: (0.1-10): (10.5-100); and the ratio of the reaction time of the first reaction to the reaction time of the second reaction is 1: (0.1-50). The method can be used for producing propylene glycol monomethyl ether under mild conditions.
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Paragraph 0118-0135; 0147
(2020/05/14)
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- Method for preparing methoxyacetone by using micro reaction device
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The invention discloses a method for preparing methoxyacetone by using a microreaction device. The method comprises the following steps: mixing methanol with a basic catalyst to obtain a methanol solution; then pumping the methanol solution and epoxypropane into a micromixer in the microreaction device; sufficiently mixing and then introducing a mixed solution into a first microreactor in the microreaction device for reacting; after the reaction is ended, carrying out neutralizing and flash evaporation and concentration on a reaction solution to obtain 1-methoxy-2-propanol; pumping the 1-methoxy-2-propanol and an aqueous solution of sodium hypochlorite into a second microreactor in the microreaction device for reacting to obtain the methoxyacetone. According to the preparation method of the methoxyacetone, disclosed by the invention, the problems in the existing production can be overcome, the use of a complex catalyst is avoided, and the content of a byproduct is reduced; the production cost is low, the continuation degree of the process is high; the safety of the production process can be substantially improved; the quality of a product is improved.
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Paragraph 0028-0048
(2020/09/09)
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- PROCESS FOR MAKING FORMIC ACID UTILIZING LOWER-BOILING FORMATE ESTERS
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Disclosed is a process for recovering formic acid from a formate ester of a C3 to C4 alcohol. Disclosed is also a process for producing formic acid by carbonylating a C3 to C4 alcohol, hydrolyzing the formate ester of the alcohol, and recovering a formic acid product. The alcohol may be dried and returned to the reactor. The process enables a more energy efficient production of formic acid than the carbonylation of methanol to produce methyl formate.
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Paragraph 00177; 00178
(2019/02/15)
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- Method for preparing propylene glycol monomethyl ether from propylene
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The present invention relates to the field of fine chemical industry, and specifically provides a method for preparing propylene glycol monomethyl ether from propylene. The method comprises that propylene, methanol and a hydrogen peroxide source contact a catalyst under an oxidation reaction condition, wherein the catalyst contains a modified titanium-silicon molecular sieve and a multi-metal oxyacid and/or a multi-metal oxysalt, and the modified titanium-silicon molecular sieve preparation steps comprise: making a titanium-silicon molecular sieve contact a modification liquid containing nitric acid and at least a peroxide, and carrying out modification treatment. With the method of the present invention, the propylene conversion rate is high, and the selectivity of the target product propylene glycol monomethyl ether is high.
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Paragraph 0117; 0118; 0119; 0120; 0121; 0122; 0123-0130
(2018/06/16)
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- Synthesis of propylene glycol ethers from propylene oxide catalyzed by environmentally friendly ionic liquids
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A series of acetate ionic liquids were synthesized using a typical two-step method. The ionic liquids were used as environmentally benign catalysts in the production of propylene glycol ethers from propylene oxide and alcohols under mild conditions. The basic strengths of the ionic liquids were evaluated by determination of their Hammett functions, obtained using ultraviolet-visible spectroscopy, and the relationship between their catalytic activities and basicities was established. The catalytic efficiencies of the ionic liquids were higher than that of the traditional basic catalyst NaOH. This can be attributed to the involvement of a novel reaction mechanism when these ionic liquids are used. A possible electrophilic-nucleophilic dual activation mechanism was proposed and confirmed using electrospray ionization quadrupole time-of-flight mass spectrometry. In addition, the effects of significant reaction parameters such as concentration of catalyst, molar ratio of alcohol to propylene oxide, reaction temperature, and steric hindrance of the alcohol were investigated in detail.
- Zhao, Cong,Chen, Shengxin,Zhang, Ruirui,Li, Zihang,Liu, Ruixia,Ren, Baozeng,Zhang, Suojiang
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p. 879 - 888
(2017/05/24)
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- A method for the preparation of propylene glycol monomethyl ether
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The invention provides a method for preparing propylene glycol monomethyl ether. According to the method for preparing the propylene glycol monomethyl ether, propylene epoxide and methanol come into contact with a catalyst under the alcoholysis reaction condition, wherein the catalyst is a titanium silicalite molecular sieve containing a template agent. The method for preparing propylene glycol monomethyl ether has the advantages that the titanium silicalite molecular sieve containing the template agent is taken as the catalyst for preparing propylene glycol monomethyl ether from propylene epoxide, and high propylene epoxide conversion rate and high propylene glycol monomethyl ether selectivity can be obtained; meanwhile, the method provided by the invention is simple and easy, and the molecular sieve can be separated from liquid-phase mixture containing propylene glycol monomethyl ether only by adopting a solid-liquid separation method like filtering.
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Paragraph 0057-0061; 0065; 0066; 0071; 0072; 0077; 0078
(2017/04/25)
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- Application of ionic liquid in synthesis of propylene glycol ether and synthetic method of propylene glycol ether
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The invention relates to the technical field of chemical engineering catalysis and provides application of ionic liquid in synthesis of propylene glycol ether and a synthetic method of propylene glycol ether. The ionic liquid is methyl carbonate ionic liquid and is taken as a catalyst for catalyzed synthesis of propylene glycol ether. The synthetic method of propylene glycol ether comprises the steps of adding epoxy propane and alcohol into a reactor to be in contact with the catalyst, and heating to 50-200 DEG C in a closed environment, so as to obtain propylene glycol ether, wherein the catalyst is the methyl carbonate ionic liquid. The synthetic method of propylene glycol ether is an environment-friendly synthetic process, has no special requirements on production equipment and is beneficial to industrial production and application, and the process is simple and easy to control.
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Paragraph 0027; 0030-0062; 0085; 0086; 0090-0095
(2018/03/01)
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- Actinic ray-sensitive or radiation-sensitive resin composition, and, actinic ray-sensitive or radiation-sensitive film and pattern forming method, each using the same
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An actinic ray-sensitive or radiation-sensitive resin composition in the present invention contains a nitrogen-containing compound (N) which is represented by the following general formula (N1): wherein, in the general formula (N1), X represents a group including a hetero atom; L represents a single bond or an alkylene group; R2 represents a substituent, in the case where a plurality of R2's are present, they may be the same as or different from each other and a plurality of R2's may be bonded to each other to form a ring; R3 represents a hydrogen atom or a substituent; and n represents an integer of 0 to 4.
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- Epoxide hydrolysis and alcoholysis reactions over crystalline Mo-V-O oxide
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Crystalline Mo-V-O oxides have been used as a catalyst for the hydrolysis and alcoholysis of propylene oxide to diols and ethers, respectively. Relationships between the active crystal facet, the acidity of Mo-V-O catalysts and the activity have been established. Our results indicate that the a-b plane is the active facet for the hydrolysis reaction.
- Zhang, Xiaochen,Wang, Min,Zhang, Chaofeng,Lu, Jianmin,Wang, Yehong,Wang, Feng
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p. 70842 - 70847
(2016/08/05)
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- Synthetic method for methoxyacetone
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The invention belongs to the technical field of organic synthesis, and specifically relates to a synthetic method for methoxyacetone. The method comprises the following steps: subjecting propylene oxide and methanol to continuous reaction through a fixed-bed catalyst so as to obtain propylene glycol methyl ether; and mixing propylene glycol methyl ether with water, and carrying out continuous dehydrogenation reaction through the fixed-bed catalyst so as to obtain methoxyacetone. The synthetic method for methoxyacetone provided by the invention is scientific and reasonable, has simple process, is free of byproducts and contains less impurities.
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Paragraph 0040; 0041
(2016/10/24)
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- A method for the preparation of propylene glycol monomethyl ether (by machine translation)
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The present invention relates to the field of fine chemicals, in particular provides a process for the preparation of propylene glycol monomethyl ether of the method, the method comprising: under the condition in the alcoholysis reaction, the epoxy propane and methanol to contact with the catalyst, wherein the catalyst comprises a silicoaluminophosphate molecular sieve, the molecular sieve comprises: aluminum element, silicon element and oxygen element, wherein the silicon-aluminum molecular sieve pore volume in the 0.3 cm3 /G or more, the total specific surface area in the 200m2 /G or more, in the outer surface area of 30m2 /G or more, and the total specific surface area of the outer surface area of the proportion of 10 - 55%; silicon molecular sieve on the 25 °C, P/P0 =0.10 and adsorption time is 1h benzene adsorptive capacity measured under the condition of at least one of 65 mg/g molecular sieve, N2 The static adsorption test has a 0.9 - 2.0 nm range of micropore size distribution. The method of the invention, conversion of propylene oxide and propylene glycol monomethyl ether high selectivity. (by machine translation)
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Paragraph 0164; 0165
(2016/12/22)
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- Propylene glycol monomethyl ether preparation method
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The present invention provides a propylene glycol monomethyl ether preparation method, which comprises that: (1) propylene is oxidized to prepare propylene oxide; and (2) under an alcoholysis reaction condition, the propylene oxide obtained in the step (1) and methanol contact a catalyst, wherein the catalyst is a titanium silicon molecular sieve containing a templating agent. According to the present invention, the titanium silicon molecular sieve containing the templating agent is used for the alcoholysis of the propylene oxide obtained through the propylene oxidizing so as to prepare the catalyst for the propylene glycol monomethyl ether, such that the high propylene oxide conversion rate and the high propylene glycol monomethyl ether selectivity can be obtained; and the new uses of the titanium silicon molecular sieve containing the templating agent are developed, and the production cost is reduced.
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Paragraph 0110-0112
(2017/02/24)
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- CO2-MEDIATED ETHERIFICATION OF BIO-BASED DIOLS
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A method of etherifying glycols or other diols by employing renewable reagents is disclosed. In particular, the method involves contacting a diol with an alkylating agent in an alcoholic solvent, catalyzed with a catalyst (carbonic acid) generated in situ (from CO2). The mono- and di-ether products can serve as valued precursors to an array of renewable surfactants, dispersants, and lubricants, among others.
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Paragraph 0057; 0058; 0059; 0060
(2016/07/05)
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- Method for simultaneously preparing propylene glycol monomethyl ether and propylene carbonate
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The invention provides a method for preparing propylene glycol monomethyl ether and propylene carbonate. The method is characterized in that epoxypropane, methanol and CO2 are in contact with a catalyst, wherein the catalyst comprises a template-containing titanium silicalite molecular sieve. The method adopts template-containing titanium silicalite molecular sieve as the catalyst in preparation of propylene glycol monomethyl ether and propylene carbonate from epoxypropane, methanol and CO2, so a high epoxypropane conversion rate and high glycol monomethyl ether and propylene carbonate selectivity are obtained through a reaction at a low reaction temperature (being not higher than 160DEG C and even not higher than 120DEG C).
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Paragraph 0144; 0145; 0157; 0158
(2016/10/09)
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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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- Propylene epoxidation with in situ generated H2O2 in supercritical conditions
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Several bi-functional materials based on palladium nanoparticles supported onto nanocrystalline titanium silicalite zeolite (Pd@TS-1) were prepared and used as active and reusable catalysts to direct PO production from hydrogen, oxygen and propylene throu
- Prieto, Alejandro,Palomino, Miguel,Díaz, Urbano,Corma, Avelino
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- Quaternary ammonium ionic liquids as Bi-functional catalysts for one-step synthesis of dimethyl carbonate from ethylene oxide, carbon dioxide and methanol
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One kind of novel ionic liquids (ILs) with a tertiary amino moiety and a quaternary ammonium group were synthesized and identified by FT-IR, 1H and 13C NMR. The elemental chemical state and basicity of ILs were determined by XPS and Hammett indicator method, respectively. Then the catalytic performance of these bi-functional catalysts was investigated in one-step synthesis of dimethyl carbonate (DMC) from ethylene oxide (EO), carbon dioxide and methanol. The best catalytic performance with 99% EO conversion and a maximum of 74% DMC selectivity was obtained using [N111,6N11]I as catalyst under optimized reaction conditions. And the catalyst could be reused for several times. Normally, stronger basicity could be obtained by altering the anions with different nucleophilicity in ILs and a better catalytic activity could be achieved correspondingly. A mechanism that both the ring opening of epoxide through nucleophilic attacks and the transesterification play an important role in the reaction was proposed based on experimental results.
- Li, Jian,Wang, Liguo,Shi, Feng,Liu, Shimin,He, Yude,Lu, Liujin,Ma, Xiangyuan,Deng, Youquan
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experimental part
p. 339 - 346
(2011/12/22)
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- A systematic study on the activation of simple polyethers by MoCl 5 and WCl6
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MoCl5, 1a, and WCl6, 1b, activate 1,3-dioxolane at room temperature in chlorinated solvents: the compound [MoOCl 3{OC(H)OCH2CH2Cl}]2, 2, has been isolated from MoCl5/dioxolane. The mixed oxo-chloro species WOCl 4, 1c, reacts with 1,3-dioxolane, selectively giving the coordination adduct WOCl4(κ1-C3H6O 2), 3. Dimethoxymethane, CH2(OMe)2, undergoes activation including C-H bond cleavage when reacted with 1a to give the molybdenum complexes [MoOCl3{OC(H)OMe}]2, 4, and Mo 2Cl5(OMe)5, 5. The reactions of 1b with CH 2(OR)2 (R = Me, Et) proceed via O-abstraction with formation of the oxo-derivatives WOCl4[O(R)CH2Cl] (R = Me, 6a; R = Et, 6b) in admixture with equimolar amounts of RCl. The reactions of 1a,b with CMe2(OMe)2 lead to mesityl oxide, MeC(O)CHC(Me)2. A series of simple diethers of general formula ROCH2(CHR′)OR′′ are activated by 1a,b in CDCl 3, usually via cleavage of C-O bonds at high temperature. The complex WCl5(OCH2CH2OMe), 7, has been detected in solution as an intermediate species in the course of the degradation of 1,2-dimethoxyethane (dme) by 1b. The activation of CH(OMe)3 by 1 is limited to C-O bonds and selectively gives methyl chloride and methylformate, which has been found coordinated in WOCl4[OC(H)OMe], 8. The organic fragments produced in the reactions have been detected by GC-MS and NMR analyses, upon hydrolysis of the reaction mixtures. Compounds 2 and 5, which have had their molecular structures ascertained by X-ray diffraction, represent rare examples of crystallographically-characterized dinuclear Mo(v) species containing both halides and oxygen ligands.
- Dolci, Sara,Marchetti, Fabio,Pampaloni, Guido,Zacchini, Stefano
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experimental part
p. 5367 - 5376
(2010/08/04)
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- Ferric perchlorate as an efficient and useful catalyst for the selective benzylation and methylation of alcohols with benzyl chloride and methyl iodide
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A mild and efficient method was developed for selective benzylation and methylation of hydroxyl compounds in the presence of a catalytic amount of ferric perchlorate. We showed that ferric perchlorate was very effective in selectively promoting the benzylation and methylation of primary aliphatic and benzylic alcohols versus secondary aliphatic alcohols and phenolic hydroxy groups. Graphical abstract: [Figure not available: see fulltext.]
- Behbahani, Farahnaz K.,Heravi, Majid M.,Oskooie, Hossien A.
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experimental part
p. 181 - 184
(2010/03/26)
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