- Heteropolyacids as efficient catalysts for the synthesis of precursors to ethylene glycol by the liquid-phase carbonylation of dimethoxymethane
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Methyl methoxyacetate (MMAc), a precursor to ethylene glycol (EG), was synthesized successfully via the liquid-phase carbonylation of dimethoxymethane (DMM) catalyzed by heteropolyacids (HPAs). The experiment results showed that H3PW12O40 (PW12) exhibited the best catalytic performance for the carbonylation of DMM, and its high catalytic activity was attributed to the synergistic effect between its superior acidic strength and the high polarity of the solvent.
- Wang, Junpeng,Liu, Jianhua,Song, Heyuan,Chen, Jing
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Read Online
- Cobalt-catalyzed Hydroesterification of Formaldehyde Dialkyl Acetals
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Co2(CO)8-organic amine system was found to be an effective catalyst for the production of alkoxyacetic ester from formaldehyde dialkyl acetals and CO; this is the first example of homogeneous hydroesterification of acetals.
- Murata, Kazuhisa,Matsuda, Akio,Masuda, Takashi
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Read Online
- Activity enhancement of Nafion resin: Vapor-phase carbonylation of dimethoxymethane over Nafion-silica composite
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A kind of composite materials consisting of nano-sized Nafion resin homogeneously dispersed in a high-surface silica matrix was prepared by sol-gel method and used as catalysts in the vapor-phase carbonylation reaction of dimethoxymethane for production of methylmethoxy acetate. These composite catalysts showed much higher catalytic activity in comparison with the original pure Nafion resin catalyst. The remarkable improvement of catalytic performance was due to the increased accessibility of acid sites of Nafion resin in the composite catalysts. The contents of Nafion-H resin and silica precursors were found to have a great influence on the structure of the composite, resulting in different catalytic activity during DMM carbonylation reactions. Furthermore, the comparison of the composite catalysts with high-silica H-Y and H-Beta zeolite catalysts demonstrated that the excellent catalytic performance is closely related to the higher acid strength and larger pores of Nafion-silica composite materials.
- Liu, Shiping,Zhu, Wenliang,Shi, Lei,Liu, Hongchao,Liu, Yong,Ni, Youming,Li, Lina,Zhou, Hui,Xu, Shutao,He, Yanli,Liu, Zhongmin
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Read Online
- Excellent prospects in methyl methoxyacetate synthesis with a highly active and reusable sulfonic acid resin catalyst
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Methyl methoxyacetate (MMAc) is a significant chemical product and can be applied as a gasoline and diesel fuel additive. This study aimed to achieve the industrial production of MMAc via dimethoxymethane (DMM) carbonylation. The effects of industrial DMM sources, reaction temperature, water content, pretreatment temperature, reaction pressure and time, the ratio of CO to DMM and recycle times were systematically investigated without any solvent. The conversion of DMM was 99.98% with 50.66% selectivity of MMAc at 393 K, 6.0 MPa reaction pressure, with the ratio of CO to DMM of only 1.97/1. When water was extracted from the DMM reactant, the MMAc selectivity significantly rose to 68.83%. This resin catalyst was reused for more than nineteen times in a slurry phase reactor and continuously performed for 300 h without noticeable loss of activity in a fixed bed reactor, displaying excellent stability. The mixed products were successfully separated by distillation, and 99.18% purity of MMAc was obtained. Therefore, the reported DMM carbonylation to MMAc process has an excellent basis for industrial application.
- Chen, Fei,Shi, Lei,Bello, SuleimanSabo,Fan, Jiaqi,Wang, Yan,Zhang, Dongxi,Yao, Jie
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p. 1346 - 1353
(2020/02/04)
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- Preparation method of 4-alkoxyacetoacetate compound
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The invention discloses a preparation method of a 4-alkoxyacetoacetate compound, and the method comprises the following steps: reacting a compound I with a first alkali in a first solvent to obtain anintermediate II; reacting the intermediate II obtained in the step (1) with a second alkali in a second solvent to obtain an intermediate III; reacting the intermediate III obtained in the step (2) in an aqueous solution of acid to obtain a product IV, namely the 4-alkoxyacetoacetate compound, wherein X is chlorine, bromine or iodine; wherein R is a C1-C4 alkyl group and a derivative thereof. Thepreparation method provided by the invention has the advantages of simple steps, mild conditions, environmental friendliness, cheap and easily available raw materials, stable supply and low cost, andcreates favorable conditions for reducing the raw material cost of dolutegravir.
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Paragraph 0044-0045; 0048-0049; 0052-0053; 0056-0057; 0060
(2020/04/22)
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- A boron-doped carbon aerogel-supported Cu catalyst for the selective hydrogenation of dimethyl oxalate
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Carbon aerogels (CA) were applied in the synthesis of Cu/CA catalysts by the impregnation method and the catalysts with boron-doped CA supports were systematically characterized and evaluated in the hydrogenation of dimethyl oxalate (DMO). The Cu/xB-CA catalyst with 25 wt% copper showed 100% DMO conversion and the highest ethylene glycol (EG) or methyl glycolate (MG) selectivity of 70% at 230 °C as well as a lifetime of over 150 h. The characterization results disclosed the reason the performance of the catalysts could be tuned facilely by changing the amount of boron doping, which effectively influenced the interrelation between copper and CA, acidity and alkalinity of catalysts and Cu dispersion. Both the original carbon aerogels and that promoted with little B could provide larger surface areas and high dispersion of the metal. The species, size of copper particles and the ratio of Cu+/(Cu+ + Cu0) could be regulated by boron doping, thus adjusting the type of hydrogenation products.
- Lu, Xiaodong,Lu, Xiaodong,Wang, Guofu,Yang, Yu,Kong, Xiangpeng,Chen, Jiangang
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p. 3232 - 3240
(2020/03/06)
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- METHOD FOR PREPARING ACETAL CARBONYL COMPOUND
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The present application provides a method for preparing acetal carbonyl compound used as a mediate for producing ethylene glycol, which comprises a step in which a raw material acetal and a raw gas carbon monoxide go through a reactor loaded with a catalyst containing an acidic microporous silicoaluminophosphate molecular sieve, for carrying out a carbonylation reaction. In the method of the present invention, the conversion rate of the raw material acetal is high, and the selectivity of acetal carbonylation is high, and the catalyst life is long, and no additional solvent is needed in the reaction process, and the reaction condition is relatively mild, and the process is continuous, showing the potential for industrial application. Moreover, the product of acetal carbonyl compound can be used for producing ethylene glycol by hydrogenation followed by hydrolysis.
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Paragraph 0065; 0066; 0067; 0068; 0069; 0070; 0071-0073
(2018/08/03)
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- Acetal carbonylation product preparation method
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The present invention provides a method for producing an ethylene glycol production intermediate acetal carbonylation product through an acetal carbonylation reaction, wherein the method comprises that a raw material acetal and raw material gas carbon monoxide are subjected to a carbonylation reaction with a catalyst supporting an acidic EMT and FAU eutectic structure molecular sieve through a reactor to obtain the product acetal carbonylation product. According to the present invention, the conversion rate of the raw material acetal is high, the selectivity of the acetal carbonylation product is high, the service life of the catalyst is long, the additional solvent is not required, the reaction conditions are mild, the continuous production can be achieved, the industrial application potential is provided, and ethylene glycol can be produced from the obtained acetal carbonylation product sequentially through hydrogenation and hydrolysis.
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Paragraph 0078-0087; 0092-0095
(2017/02/24)
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- Acetal carbonylation product preparation method
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The present invention provides a method for producing an ethylene glycol production intermediate acetal carbonylation product through an acetal carbonylation reaction, wherein the method comprises that a raw material acetal and raw material gas carbon monoxide are subjected to a carbonylation reaction with a catalyst supporting an acidic EMT molecular sieve through a reactor to obtain the product acetal carbonylation product. According to the present invention, the conversion rate of the raw material acetal is high, the selectivity of the acetal carbonylation product is high, the service life of the catalyst is long, the additional solvent is not required, the reaction conditions are mild, the continuous production can be achieved, the industrial application potential is provided, and ethylene glycol can be produced from the obtained acetal carbonylation product sequentially through hydrogenation and hydrolysis.
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Paragraph 0076; 0077
(2017/04/11)
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- The MOF-driven synthesis of supported palladium clusters with catalytic activity for carbene-mediated chemistry
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The development of catalysts able to assist industrially important chemical processes is a topic of high importance. In view of the catalytic capabilities of small metal clusters, research efforts are being focused on the synthesis of novel catalysts bearing such active sites. Here we report a heterogeneous catalyst consisting of Pd4 clusters with mixed-valence 0/+1 oxidation states, stabilized and homogeneously organized within the walls of a metal-organic framework (MOF). The resulting solid catalyst outperforms state-of-the-art metal catalysts in carbene-mediated reactions of diazoacetates, with high yields (>90%) and turnover numbers (up to 100,000). In addition, the MOF-supported Pd4 clusters retain their catalytic activity in repeated batch and flow reactions (>20 cycles). Our findings demonstrate how this synthetic approach may now instruct the future design of heterogeneous catalysts with advantageous reaction capabilities for other important processes.
- Fortea-Pérez, Francisco R.,Mon, Marta,Ferrando-Soria, Jesús,Boronat, Mercedes,Leyva-Pérez, Antonio,Corma, Avelino,Herrera, Juan Manuel,Osadchii, Dmitrii,Gascon, Jorge,Armentano, Donatella,Pardo, Emilio
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p. 760 - 766
(2017/07/04)
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- On the incompatibility of lithium-O2 battery technology with CO2
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When solubilized in a hexacarboxamide cryptand anion receptor, the peroxide dianion reacts rapidly with CO2 in polar aprotic organic media to produce hydroperoxycarbonate (HOOCO2-) and peroxydicarbonate (-O2COOCO2-). Peroxydicarbonate is subject to thermal fragmentation into two equivalents of the highly reactive carbonate radical anion, which promotes hydrogen atom abstraction reactions responsible for the oxidative degradation of organic solvents. The activation and conversion of the peroxide dianion by CO2 is general. Exposure of solid lithium peroxide (Li2O2) to CO2 in polar aprotic organic media results in aggressive oxidation. These findings indicate that CO2 must not be introduced in conditions relevant to typical lithium-O2 cell configurations, as production of HOOCO2- and -O2COOCO2- during lithium-O2 cell cycling will lead to cell degradation via oxidation of organic electrolytes and other vulnerable cell components.
- Zhang, Shiyu,Nava, Matthew J.,Chow, Gary K.,Lopez, Nazario,Wu, Gang,Britt, David R.,Nocera, Daniel G.,Cummins, Christopher C.
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p. 6117 - 6122
(2017/08/29)
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- Synergistic Effect of a Boron-Doped Carbon-Nanotube-Supported Cu Catalyst for Selective Hydrogenation of Dimethyl Oxalate to Ethanol
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Heteroatom doping is a promising approach to improve the properties of carbon materials for customized applications. Herein, a series of Cu catalysts supported on boron-doped carbon nanotubes (Cu/xB-CNTs) were prepared for the hydrogenation of dimethyl oxalate (DMO) to ethanol. The structure and chemical properties of boron-doped catalysts were characterized by XRD, TEM, N2O pulse adsorption, CO chemisorption, H2 temperature-programmed reduction, and NH3 temperature-programmed desorption, which revealed that doping boron into CNT supports improved the Cu dispersion, strengthened the interaction of Cu species with the CNT support, introduced more surface acid sites, and increased the surface area of Cu0 and especially Cu+ sites. Consequently, the catalytic activity and stability of the catalysts were greatly enhanced by boron doping. 100 % DMO conversion and 78.1 % ethanol selectivity could be achieved over the Cu/1B-CNTs catalyst, the ethanol selectivity of which was almost 1.7 times higher than that of the catalyst without boron doping. These results suggest that doping CNTs with boron is an efficient approach to improve the catalytic performance of CNT-based catalysts for hydrogenation of DMO. The boron-doped CNT-based catalyst with improved ethanol selectivity and catalytic stability will be helpful in the development of efficient Cu catalysts supported on non-silica materials for selective hydrogenation of DMO to ethanol.
- Ai, Peipei,Tan, Minghui,Yamane, Noriyuki,Liu, Guoguo,Fan, Ronggang,Yang, Guohui,Yoneyama, Yoshiharu,Yang, Ruiqin,Tsubaki, Noritatsu
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supporting information
p. 8252 - 8261
(2017/06/23)
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- METHOD FOR PREPARING POLYOXYMETHYLENE DIMETHYL ETHER CARBONYL COMPOUND AND METHYL METHOXYACETATE
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A method for preparing a polyoxymethylene dimethyl ether carbonyl compound and/or methyl methoxyacetate as intermediates for producing ethylene glycol, which comprises passing a raw material: polyoxymethylene dimethyl ether or methylal together with carbon monoxide and hydrogen gas through a reactor carrying an acidic molecular sieve catalyst, and performing a reaction to prepare a corresponding product under an appropriate condition where no other solvent is added, in which the process of the reaction is a gas-liquid-solid three-phase reaction, the raw material of polyoxymethylene dimethyl ether or methylal has a high conversion rate, each product has a high selectivity, the catalyst has a long service life, additional solvents are not required to be used, and reaction conditions are relatively mild.
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Paragraph 0051; 0053
(2017/01/23)
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- A methoxy acetic acid method for catalytic synthesis of methyl
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The invention relates to a catalytic synthesis method for methyl methoxyacetate with the formula (I) shown in the specification. The catalytic synthesis method comprises the steps that a compound with the formula (II) shown in the specification reacts with methyl alcohol under normal pressure in the presence of a solid carrier load catalyst and a bi-component accelerant, and therefore methyl methoxyacetate is obtained. According to the catalytic synthesis method, by means of the unique catalyst and accelerant, and particular load component selected and specific preparation method used in the catalyst preparing process, a target product can be obtained with the high yield, and the research value and application potential are high.
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Paragraph 0059; 0060; 0061
(2016/11/24)
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- SPIROCYCLIC HETEROCYCLE COMPOUNDS USEFUL AS HIV INTEGRASE INHIBITORS
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The present invention relates to Spirocyclic Heterocycle Compounds of Formula (I): and pharmaceutically acceptable salts thereof, wherein A, B, X, Y, R1, R2 and R11 are as defined herein. The present invention also relates to compositions comprising at least one Spirocyclic Heterocycle Compound, and methods of using the Spirocyclic Heterocycle Compounds for treating or preventing HIV infection in a subject.
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Page/Page column 60
(2015/07/07)
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- SPIROCYCLIC HETEROCYCLE COMPOUNDS USEFUL AS HIV INTEGRASE INHIBITORS
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Disclosed are Spirocyclic Heterocycle Compounds of Formula (I) and pharmaceutically acceptable salts thereof, where A, B, X, Y, R1, R2 and R11 are as defined herein. Composition comprising at least one Spirocyclic Heterocycle Compound, and methods of using the Spirocyclic Heterocycle Compounds for treating or preventing HIV infection in a subject are also disclosed.
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Page/Page column 38
(2015/07/07)
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- A highly efficient Nafion-H catalyst for vapour phase carbonylation of dimethoxymethane
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A highly active Nafion-H catalyst is developed for vapour phase carbonylation of dimethoxymethane (DMM) to methyl methoxyacetate (MMAc) with a significant MMAc selectivity as high as 90%. The excellently catalytic performance is because of the unique structure and high acid strength of the Nafion-H catalyst.
- Liu, Shiping,Zhu, Wenliang,Shi, Lei,Liu, Hongchao,Liu, Yong,Ni, Youming,Li, Lina,Zhou, Hui,Xu, Shutao,Liu, Zhongmin
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p. 40999 - 41002
(2015/02/18)
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- 4-PYRIDINONETRIAZINE DERIVATIVES AS HIV INTEGRASE INHIBITORS
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The present invention relates to 4-Pyridinonetriazine Derivatives of Formula (I); and pharmaceutically acceptable salts thereof, wherein A, X, Y, R1, R2, R3 and R5 are as defined herein. The present invention also relates to compositions comprising at least one 4-Pyridinonetriazine Derivative, and methods of using the 4-Pyridinonetriazine Derivatives for treating or preventing HIV infection in a subject.
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Page/Page column 32
(2014/07/08)
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- Larvicidal activity and click synthesis of 2-alkoxyl-2-(1,2,3-triazole-1- yl)acetamide library
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Heterogeneous copper-in-charcoal-catalyzed click synthesis in 96-well polypropylene filter plates is an efficient method for the rapid generation of sufficient pure 2-alkoxyl-2-(1,2,3-triazole-1-yl) acetamide derivatives library by simple filtration, which directly assay the products for larvicidal activity against mosquitoes. In this procedure, copper nanoparticles on charcoal were arrayed into each well on a 96-well plate, reagents were delivered using a pipette gun, and a constant temperature shaker bath was used to complete the click reaction in 24-72 hours under temperature-controlled conditions. The results of bioassays indicated that the target compounds possessed excellent larvacidal activities against mosquitoes. In particular, the larvacidal activities against mosquitoes of compounds 8[2,3] and 8[7,1] at 2g.mL-1 were 100% and 73%, respectively.
- Su, Na-Na,Xiong, Li-Xia,Yu, Shu-Jing,Zhang, Xiao,Cui, Can,Li, Zheng-Ming,Zhao, Wei-Guang
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p. 484 - 493
(2013/07/28)
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- Efficient and catalyst-free condensation of acid chlorides and alcohols using continuous flow
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An efficient, catalyst-free continuous flow procedure for the condensation of acid chlorides and alcohols was developed. Different esters could be obtained using this protocol with excellent conversions starting from the corresponding acid chlorides and alcohols in very short reaction times (5-7 min). The reaction was performed solventless for liquid reagents but requires a solvent for solid reagents in order to prevent clogging of the microreactor. Since no catalyst is needed, the purification of the reaction mixture is very straightforward. Scale-up of the reaction to a microreactor with an internal volume of 13.8 ml makes it possible to produce 2.2 g min-1 of ester with an isolated yield of 98% and recuperation of the formed HCl.
- Van Waes, Frederik E. A.,Cukalovic, A.,Stevens, Christian V.,Drabowicz, J.
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p. 2776 - 2779,4
(2020/09/14)
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- Broensted acidic ionic liquids as efficient and recyclable catalysts for the carbonylation of formaldehyde
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Methyl glycolate (MG), as a precursor to ethylene glycol (EG), was synthesized by an efficient and eco-friendly procedure of one-pot, two-step, sequential reaction, including carbonylation and esterification from HCHO with Broensted acidic ionic liquids (BAILs) as catalysts. MG was obtained in high yield under mild conditions. In addition, the catalyst could be recycled eight times after separating the unreacted materials and products from the reaction system by distillation under vacuum and no significant decrease in catalytic activity was observed.
- Song, Heyuan,Li, Zhen,Chen, Jing,Xia, Chungu
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experimental part
p. 81 - 86
(2012/04/10)
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- PROCESS FOR THE PRODUCTION OF ALKYL ALKOXYACETATES
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A process for the production of lower alkyl alkoxyacetates, preferably methyl methoxyacetate, by reaction of a di-(lower alkoxy)methane, preferably dimethoxymethane, with the acid form of a medium-pore or large-pore zeolite catalyst, preferably the acid form of faujasite, ZSM-5, mordenite, or beta, in the gas phase at atmospheric or near-atmospheric pressures.
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Page/Page column 1; 2
(2010/05/13)
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- Bulky diarylammonium arenesulfonates as mild and extremely active dehydrative ester condensation catalysts
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More environmentally benign alternatives to current chemical processes, especially large-scale, fundamental reactions like ester condensations, are highly desirable for many reactions. Bulky diarylammonium pentafluorobenzenesulfonates and tosylates serve as extremely active dehydration catalysts for the ester condensation reaction of carboxylic acids with equimolar amounts of sterically demanding alcohols and acid-sensitive alcohols. Typically, the esterification reaction is performed in heptane by heating at 80°C in the presence of 1 mol% of the catalyst without removing water. Esterification with primary alcohols proceeds without solvents even at room temperature. Furthermore, 4-(N-mesitylamino)polystyrene resin-bound pentafluorobenzenesulfonate can be recycled more than 10 times without a loss of activity.
- Sakakura, Akira,Nakagawa, Shoko,Ishihara, Kazuaki
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p. 422 - 433
(2007/10/03)
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- METHOD FOR PRODUCING ESTER AND ESTERIFICATION CATALYST
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A process for producing an ester includes the step of allowing a carboxylic acid to react with an alcohol, wherein an ammonium sulfonate is used as an esterification catalyst, the ammonium sulfonate being composed of an ammonium cation having a basic skeleton represented by formula (1) (wherein n represents 1 or 2) in which hydrogen atoms in the benzene rings and hydrogen atoms bonded to bridge carbon may be substituted), and a sulfonic acid anion represented by RSO 3 - (wherein R represents an arene, a perfluoroalkane having 1 to 8 carbon atoms, or a bulky alkane).
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Page/Page column 22
(2008/06/13)
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- Bulky diarylammonium arenesulfonates as selective esterification catalysts
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More environmentally benign alternatives to current chemical processes, especially large-scale, fundamental reactions such as ester condensations, are highly desirable for many reactions. Bulky diarylammonium pentafluorobenzenesulfonates and tosylates serve as extremely active dehydration catalysts for the ester condensation reaction of carboxylic acids with equimolar amounts of sterically demanding alcohols and acid-sensitive alcohols. Typically, the esterification reaction is performed in heptane by heating at 80 °C in the presence of 1 mol % of the catalyst without removing water. Esterification with primary alcohols proceeds without solvents even at room temperature. Furthermore, 4-(N-mesitylamino)polystyrene resin-bound pentafluorobenzenesulfonate can be recycled more than 10 times without activity loss. Copyright
- Ishihara, Kazuaki,Nakagawa, Shoko,Sakakura, Akira
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p. 4168 - 4169
(2007/10/03)
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- Studies on the mechanism of action of 2-formyl-4-pyrrolidinopyridine: Isolation and characterization of a reactive intermediate
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This paper describes the mechanism of action of 2-formyl-4- pyrrolidinopyridine (FPP, 1a) which is a catalyst for the hydroxyl-directed methanolysis of α-hydroxy esters. This species was initially designed to act as a nucleophilic catalyst; however, we have ruled out a nucleophilic mechanism by examining the activity of 6-substituted-FPP derivatives. These compounds are more hindered in the vicinity of the pyridine nitrogen than FPP itself but are also more active catalysts. Furthermore, the presence of p- nitrophenol, a mild acid, was found to accelerate the catalytic reaction. These results are inconsistent with a nucleophilic catalysis mechanism. We provide evidence that the reaction instead proceeds via dioxolanone intermediate 10. Dioxolanone 10 can be obtained by treating either the p- nitrophenyl ester or the pentafluorophenyl ester of glycolic acid with FPP in chloroform in the absence of methanol. It has been isolated, characterized, and shown to be kinetically competent when subjected to the conditions of the catalytic reaction.
- Sammakia, Tarek,Hurley, T. Brian
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p. 4652 - 4664
(2007/10/03)
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- Efficient Dimethyl Malonate Synthesis by Methoxycarbonylation of Dichloromethane catalysed by Electrogenerated - Species
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Electrochemistry is used for the synthesis of - complex in a methanol-methyl formate medium, which catalyses the alkoxycarbonylation of dichloromethane to dimethyl malonate in up to 75percent yield.
- Suisse, P.,Pellegrini, S.,Castanet, Y.,Mortreux, A.,Lecolier, S.
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p. 847 - 848
(2007/10/02)
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- Chain carbonylation of methoxymethyl chloride by using AgSbF6 catalyst under high pressure of CO
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The chain carbonylation of methoxymethyl chloride (1) by the use of AgSbF6 catalyst smoothly proceeded under high pressure of carbon monoxide to give methyl methoxyacetate after treatment with methanol. The reaction was highly dependent on the CO pressure and the reaction temperature, indicating the presence of equilibrium processes. From the temperature dependence of the equilibrium constant, the enthalpy change of the reaction was calculated to be -25.4 kJ mol-1.
- Ohga, Yasushi,Netsu, Fuminori,Mori, Sadayuki,Kudo, Kiyoshi,Komatsu, Koichi,Sugita, Nobuyuki
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p. 11119 - 11124
(2007/10/02)
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- Vapor Phase Carbonylation of Organic Halo Compounds
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RCH2X, s-C4H9X and C6H5X were methoxy-carbonylated with carbon monoxide and methanol into methyl carboxylates in the presence of rhodium trichloride/potassium iodide supported on activated charcoal.The reactivity decreased in the order: X=I above Br above Cl.
- Yasuda, Kensei,Shinoda, Kiyonori
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p. 289 - 291
(2007/10/02)
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- Liquid Phase Carbonylation with Solid Catalyst. Carboxy Methylation of Dihalo Methane with Group VIII Metals Supported on Active Carbon
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It was found that cobalt supported on active carbon showed an excellent catalytic activity for the carbonylation of dibromo methane in the liquid phase.For example, when the reaction was conducted under the conditions of 140 deg C, P (CO) = 31 atm, the yields of dimethyl malonate and bromomethyl acetate were 34.4percent and 22.2percent, respectively.Pd and Rh also showed catalytic activities.
- Yagita, Hiroshi,Kuwahara, Hiroyuki,Omata, Kohji,Fujimoto, Kaoru
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p. 335 - 338
(2007/10/02)
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- Protected nucleosides which permit more efficient oligonucleotide syntheses
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The invention relates to derivatives of nucleosides and their use for the synthesis of oligonucleotides. These derivatives are in accordance with the formula: STR1 in which B represents a radical derived from guanine, cytosine or adenine, whose exocylic NH group is protected by the group STR2 with R1 representing a hydrogen atom or an alkyl radical and R2 a hydrogen atom, and alkyl radical, an alkoxy radical and optionally substituted aryloxy radical, R3 represents a hydrogen atom, the dimethoxytrityl radical or the radical STR3 R4 represents a hydrogen atom, the radical of formula: STR4 or a radical suitable for the synthesis of polynucleotides and R5 represents a hydrogen atom or the protected or unprotected hydroxyl OH radical.
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- Alkylcobalt carbonyls. 9. Alkoxy-, silyloxy-, and hydroxy-substituted methyl- and acetylcobalt carbonyls. Reduction of formaldehyde to methanol by hydridocobalt tetracarbonyl
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(Alkoxymethyl)-, ((silyloxy)methyl)-, and (hydroxymethyl)cobalt and (alkoxyacetyl)-, ((silyloxy)acetyl)-, and (hydroxyacetyl)cobalt tetracarbonyls and phosphine-substituted derivatives were prepared. The interconversions of these compounds by carbonylatio
- Sisak, Attila,Sámpár-Szerencsés, Ella,Galamb, Vilmos,Németh, László,Ungváry, Ferenc,Pályi, Gyula
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p. 1096 - 1100
(2008/10/08)
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- Synthesis of Alkyl(alkoxycarbonyl)tetracarbonyliron Complexes : the First Evidence of their Relevance to the Catalytic Cycle in the Carbonylation of Organic Halides induced by Pentacarbonyliron
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Reaction of (1-) (1) (R = Me or But) with BrCH2CO2Me produces stable complexes (3) which thermally decompose to yield Fe(CO)5 and malonic esters under a CO atmosphere; these reactions provide the first demonstration of possible key steps in the catalytic cycle of the carbonylation of reactive halides into esters with Fe(CO)5 and an alkoxide anion.
- Laurent, Pascale,Sabo-Etienne, Sylviane,Larsonneur, Anne-Marie,Abbayes, Herve des
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p. 929 - 930
(2007/10/02)
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- OXYGEN YLIDES-I. REACTIONS OF CARBENES WITH OXETANE
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The ylides generated from carbenes (:CH2, :CHCO2Et, :CHPh) and oxetane in the presence of methanol undergo Stevens rearrangement and protonation competitively, yielding tetrahydrofurans and 1,3-dialkoxycyclopropanes as major products.
- Friedrich, Klaus,Jansen, Ulrich,Kirmse, Wolfgang
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p. 193 - 196
(2007/10/02)
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- Process for preparation of methyl methoxyacetate
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A process for the preparation of methyl methoxyacetate by the oxycarbonylation of methanol which comprises reacting methanol with carbon monoxide in the presence of a hydrogen fluoride catalyst and an oxidizing agent containing a metal salt.
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- 163. Reactions of Alkenediazonium Salts. Part 1. 2,2-Diethoxyethenediazonium Hexachloroantimonate: A Diazonium, a Carbenium or an Oxonium Salt?
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Reactions of the title compound 1 with various nucleophiles have been studied.The salt behaves like an alkylating agent towards ethers, alcohols and water forming ethyl diazoacetate (2), which reacts further with excess of the nucleophile.A solvent cage mechanism accounting for the observed products is proposed.Thermal decomposition in inert solvents leads to the alkylation of the counter-ion, i.e. formation of chloroethane, and in anisole, alkylation and chlorination of the solvent are also observed.With a standard coupling component, 2-naphtholate ion, no azo coupling reaction of 1 is observed, but instead 14-methyl-14H-dibenzoxanthene (17) is formed.The products of the reaction with diethylamine are diethylcyanoformamide (18) and ethyl diethylcarbamate (19).None of the chemistry of salt 1 is explained by the intervention of vinyl cations expected to be formed in a heterolytic dediazoniation.The predominant pathways seems to involve reactions of an oxonium salt (alkylating properties) or, in the case of diethylamine, a carbenium salt (primary nucleophilic attack on the β-C-atom of 1).The free energy barrier to C=C rotation in 1 is estimated to be 75 to 77 kJ/mol (18.0 to 18.5 kcal/mol), a value which falls between those expected for a double and a single bond.
- Szele, Ivanka,Tencer, Michal,Zollinger, Heinrich
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p. 1691 - 1703
(2007/10/02)
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- Absolute Rates for Dimerization of Capto-dative Substituted Methyl Radicals in Solution: Absence of Kinetic Stabilization
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For three capto-dative substituted methyl radicals, t-butoxy(cyano)methyl radical (1), t-butylthio(cyano)methyl radical (2), and methoxy(methoxycarbonyl)methyl radical (3), absolute rates for dimerization have been measured by e.s.r. spectroscopy and substantiated by product analysis.Values for the rate constants of 1.0E8 - 1.5E9 l mol-1s-1 in the temperature range -60 to +60 deg C support the diffusion-controlled nature of the dimerization.The comparison of Arrhenius activation parameters for dimerization with those for the bulk viscosity of the solutions does not provide evidence for noticeable intrinsic barriers to recombination, indicating the absence of kinetic stabilization for capto-dative substituted methyl radicals.
- Korth, Hans-Gert,Sustmann, Reiner,Merenyi, Robert,Viehe, Heinz Guenther
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- ELECTROCHEMICAL OXIDATION OF ALKYL-SUBSTITUTED ALLENES IN METHANOL
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Mono-, di- and tri-alkyl-substituted allenes were potentiostatically oxidized in methanol at graphite and Pt anodes.At the former electrode, α-methoxylated ketones (due to 4F/mole electricity consumption) and esters (6F/mole) were the major products.At a Pt anode, intermediate products such as vinyl-ether derivatives (2F/mole) were characterised too.Unlike the anodic oxidation of alkenes and alkynes previously reported in the literature, dimerisation is not a typical process in the allenes' oxidation, since of all the products obtained only a sole dimer has been observed.The mechanism for the formation of most products is discussed.
- Becker, James Y.,Zinger, Baruch
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p. 1677 - 1682
(2007/10/02)
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- The mechanism of oxidation of acetals by ozone. I. Stoichiometry, order of reaction, solvent effects, and substituent effects
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A systematic investigation of the reaction between ozone and acetals to form acetal hydrotrioxides A has been undertaken.The stoichiometry of the reaction has been shown to be 1:1 in each reactant and the order of the reaction was also one in each reactant.Substituent effects measured in a variety of systems and under several conditions of temperature and solvent were found to be small (ρ=-1.10 to -1.58).Solvent polarity was also found to have little effect on the rate of the reaction.Mechanistically, these facts are interpreted in terms of a 1,3-dipolar insertion of ozone into the C-H bond of the acetal function.
- Taillefer, Roland J.,Thomas, Shirley E.,Nadeau, Yves,Fliszar, S.,Henry, Herve
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p. 1138 - 1143
(2007/10/02)
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