- Thermodynamic study of liquid phase synthesis of ethyl tert-butyl ether using tert-butyl alcohol and ethanol
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In this study, a detailed thermodynamic analysis of the ethyl tert-butyl ether (ETBE) synthesis reaction between tert-butyl alcohol (TBA) and ethanol is performed to determine a liquid phase equilibrium constant expression. The result is of practical sign
- Ozbay, Nalan,Oktar, Nuray
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Read Online
- Equilibrium constant for ethyl tert-butyl ether vapor-phase synthesis
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Equilibrium constants for the vapor-phase synthesis of ethyl tert-butyl ether (ETBE) were determined experimentally at temperatures from 319 to 373 K. Equilibrium was established in the addition of ethanol to isobutene for obtaining ETBE over Amberlyst-15 in a flow reactor maintained at atmospheric pressure. The equilibrium constants obtained in the present work were compared with estimates from thermochemical data. The values of ?H°, ?G°, ?S° at 298 K were obtained from the variation of equilibrium constant with temperature: ?H° = -14.87 ± 0.5 cal·mol-1, ?GΔR = -2.8 ± 0.8 kcal·mol-1, and ?S° =-40.5 ± 1.3 cal·mol-1·K-1. By use of published thermochemical data together with the experimental data, the enthalpy of formation, ?Hf°298, free energy of formation ?Gf°298, and absolute entropy, S°298, of ETBE were calculated to be -75.03 POM 0.5 kcal·mol-1, -29.14 ± 0.5 kcal·mol-1, and 97.1 ± 1 cal·mol-1·K-1, respectively.
- Iborra,Izquierdo,Tejero,Cunill
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Read Online
- Comparative vapor phase synthesis of ETBE from ethanol and isobutene over different acid zeolites
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Vapor phase synthesis of ETBE from ethanol and isobutene was studied over US-Y, Beta, and ZSM-5 zeolites with different Si/Al ratios, using Amberlyst-15 as a reference catalyst. The sequence of activity was Beta zeolite > US-Y> Mordenite > Omega ≥ ZSM-5. At maximum isobutene to ETBE conversion, the Beta zeolites yielded more ETBE than the commercial samples and acid resin. With external surface area of > 200 sq m/g, Beta zeolites were the most active among the zeolites. Amberlyst-15 and Beta zeolites were 100% selective below 55°C. Extra-framework Al species showed negative effect on the reaction, and their removal by a mild acid leaching was beneficial.
- Poncelet,Collignon
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Read Online
- Preparation of hybrid organo-inorganic catalysts based on msm-41 mesoporous molecular sieves and their properties in synthesis of ethyl tert-butyl ether
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A series of sulfoorganosilica (vinyl-containing) catalysts based on MSM-41 mesoporous molecular sieves were prepared by template synthesis. The structure and properties of these catalysts and their catalytic characteristics in synthesis of ethyl tert-buty
- Vlasenko,Kochkin, Yu. N.,Kovalenko
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Read Online
- Dehydrogenative ester synthesis from enol ethers and water with a ruthenium complex catalyzing two reactions in synergy
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We report the dehydrogenative synthesis of esters from enol ethers using water as the formal oxidant, catalyzed by a newly developed ruthenium acridine-based PNP(Ph)-type complex. Mechanistic experiments and density functional theory (DFT) studies suggest that an inner-sphere stepwise coupled reaction pathway is operational instead of a more intuitive outer-sphere tandem hydration-dehydrogenation pathway.
- Ben-David, Yehoshoa,Diskin-Posner, Yael,Kar, Sayan,Luo, Jie,Milstein, David,Rauch, Michael
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supporting information
p. 1481 - 1487
(2022/03/07)
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- Insight into the active site nature of zeolite H-BEA for liquid phase etherification of isobutylene with ethanol
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The nature of active acid sites of zeolite H-BEA with different Si/Al ratios (15-407) in liquid phase etherification of isobutylene with ethanol in a continuous flow reactor in the temperature range 80-180 °C has been explored. We describe and discuss data concerning the strength and concentration of acid sites of H-BEA obtained by techniques of stepwise (quasi-equilibrium) thermal desorption of ammonia, X-ray diffraction, low-Temperature adsorption of nitrogen, FTIR spectroscopy of adsorbed pyridine and solid-state 27Al MAS NMR. The average values of the adsorption energy of NH3 on H-BEA were experimentally determined as 63.7; 91.3 and 121.9 mmol g-1 (weak, medium, and strong, respectively). In agreement with this, a correlation between the rate of ethyl-Tert-butyl ether synthesis and the concentration of weak acid sites (ENH3 = 61.6-68.9 kJ mol-1) has been observed. It was concluded that the active sites of H-BEA for this reaction are Br?nsted hydroxyls representing internal silanol groups associated with octahedrally coordinated aluminum in the second coordination sphere.
- Vlasenko, Nina V.,Kochkin, Yuri N.,Telbiz, German M.,Shvets, Oleksiy V.,Strizhak, Peter E.
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p. 35957 - 35968
(2019/11/20)
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- METHOD FOR PRODUCING ASYMMETRIC ALKYL ETHER HAVING TERTIARY ALKYL GROUP
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PROBLEM TO BE SOLVED: To provide a method capable of obtaining an asymmetric alkyl ether having a tertiary alkyl group easily and industrially. SOLUTION: (1) There is provided a method for producing an asymmetric alkyl ether having a tertiary alkyl group by subjecting a tertiary alcohol and a primary alcohol or a secondary alcohol to a dehydration reaction using activated clay as a catalyst. (2) There is provided the method for producing an asymmetric alkyl ether having a tertiary alkyl group according to (1), where the tertiary alcohol is any one selected from the group consisting of tert-butanol, tert-amylalcohol and 1-adamantyl alcohol. SELECTED DRAWING: None COPYRIGHT: (C)2016,JPOandINPIT
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Paragraph 0019
(2017/01/31)
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- 1,2,3-Triazolylidene ruthenium(ii)-cyclometalated complexes and olefin selective hydrogenation catalysis
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Silver(i) 1,2,3-triazol-5-ylidenes [(RCH2C2N2(NMe)Ph)2Ag][AgCl2] (R = Ph 3a, C6H2iPr33b, C6H2Me33c) and [(PhCH2C2N2(NMe)R)2Ag][AgCl2] (R = C6H4Me 3d, C6H4CF33e) were synthesized and subsequently treated with RuHCl(PPh3)3 and RuHCl(H2)(PCy3)2. The reaction of 3a with RuHCl(PPh3)3 gave RuHCl(PPh3)2(PhCH2C2N2(NMe)Ph) (4a1) as the minor product and the cyclometalated complex RuCl(PPh3)2(PhCH2C2N2(NMe)C6H4) (4a2) as the major product. However, similar reaction with 3b selectively formed the cyclometalated complex RuCl(PPh3)2((C6H2iPr3)CH2C2N2(NMe)C6H4) (4b2). Similarly the silver(i) triazolylidenes 3a and 3b were reacted with RuHCl(H2)(PCy3)2; gave RuHCl(PCy3)2(PhCH2C2N2(NMe)Ph) (5a1), RuCl(PCy3)2(PhCH2C2N2(NMe)C6H4) (5a2) and RuCl(PCy3)2((C6H2iPr3)CH2C2N2(NMe)C6H4) (5b2), respectively. Species 3c, 3d and 3e resulted in the cyclometalated complexes (5c2, 5d2 and 5e2) as the major products as well as the ruthenium-hydride complexes (5c1, 5d1 and 5e1) as the minor products. The cyclometalated species are derived from the ruthenium-hydride complexes via C(sp2)-H activation. These Ru-complexes were shown to act as hydrogenation catalyst precursors for olefinic substrates including those containing a variety of functional groups. This journal is
- Bagh, Bidraha,McKinty, Adam M.,Lough, Alan J.,Stephan, Douglas W.
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p. 2712 - 2723
(2015/02/19)
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- Method for coproducing isobutene and ETBE from tert-Butanol mixture
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This invention describes a method for co-producing isobutene and ethyl tert-butyl ether from tert-butanol mixture in a catalytic distillation column, wherein catalyzing the tert-butanol mixture with the ethanol undergoes dehydration and etherification. The tert-butanol mixture contains absolute ethanol or aqueous ethanol as the antifreeze agent. The isobutene and the ethyl tert-butyl ether withdrawn from the column top are further separated, thus high purity isobutene and ethyl tert-butyl ether for fuel-additive are obtained.
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Page/Page column 6-12
(2015/11/09)
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- Half sandwich ruthenium(ii) hydrides: Hydrogenation of terminal, internal, cyclic and functionalized olefins
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Bis(1,2,3-triazolylidene) silver(i) complex 1a was reacted with [RuCl2(p-cymene)]2 to give the ruthenium complex [PhCH2N2(NMe)C2(C6H4CF3)]RuCl2(p-cymene) (2a) as major product in addition to the minor C(sp2)-H activated product [PhCH2N2(NMe)C2(C6H3CF3)]RuCl(p-cymene) (2a′). Similar ruthenium complexes 2b, 2c, 2d and 2e with general formula RuCl2(p-cymene)(NHC) (NHC = MesCH2N2(NMe)C2Ph 2b, PhCH2N2(NMe)C2Ph 2c, TripCH2N2(NMe)C2Ph 2d, IMes 2e) were also synthesized. Subsequent reaction of Me3SiOSO2CF3 with 2a and 2b resulted in cationic ruthenium species [(PhCH2N2(NMe)C2(C6H4CF3))RuCl(p-cymene)][OSO2CF3] (3a) and [(MesCH2N2(NMe)C2Ph)RuCl(p-cymene)][OSO2CF3] (3b), respectively. Complexes 3a and 3b dissolved in CD3CN to give [(PhCH2N2(NMe)C2(C6H4CF3))RuCl(CD3CN)(p-cymene)][OSO2CF3] (4a) and [(MesCH2N2(NMe)C2Ph)RuCl(CD3CN)(p-cymene)][OSO2CF3] (4b), respectively. Cationic ruthenium species 4a and 4b failed to show catalytic activity towards hydrogenation of olefins. Ruthenium(ii) complexes 2b-e with the general formula RuCl2(p-cymene)(NHC) were reacted with Et3SiH to generate a series of ruthenium(ii) hydrides 5b-e. These compounds 5b-e are effective catalysts for the hydrogenation of terminal, internal and cyclic and functionalized olefins.
- Bagh, Bidraha,Stephan, Douglas W.
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p. 15638 - 15645
(2015/01/08)
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- Kinetics of the reactions of tert-butanol with C2-C5 alcohols on sulfo cation exchangers
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The kinetics of etherification of tert-butanol with aliphatic alcohols on gel KU-2×8 and macroporous KU-23 sulfo cation exchangers was studied. The first order of reaction with respect to tert-butanol and the -SO3H groups of a catalyst was established. The activation energy of the process observed on KU-2×8 was 60-95 kJ/mol. It was shown that the etherification of tert-butanol on KU-2×8 occurred in a surface layer. The reactivity of primary alcohols introduced into the reaction with tert-butanol increased with their molecular weights (C2-C5). The rate of reaction with secondary alcohols was lower than that with primary alcohols.
- Golovanov,Pisareva,Levshenkov
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p. 179 - 183
(2013/05/22)
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- SNAAP sulfonimidate alkylating agent for acids, alcohols, and phenols 1
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Stable, crystalline ethyl N-tert-butyl-4-nitrobenzenesulfonimidate has been prepared in high yield by direct O-ethylation of N-tert-butyl-4- nitrobenzenesulfonamide with iodoethane and silver(I) oxide in dichloromethane. This sulfonimidate directly ethylates various acids to esters; the stronger the acid, the faster it alkylates and in higher yield. It readily ethylates alcohols and phenols to ethers at room temperature in the presence of tetrafluoroboric acid catalyst without molecular rearrangements or racemization. We have defined these reactions as SNAAP alkylations: [substitution, nucleophilic of acids, alcohols and phenols]. The hard sulfonimidate alkylating agent is chemoselective, preferring oxygen > nitrogen > sulfur. The sulfonamide byproduct of alkylation is readily recycled to the sulfonimidate. Georg Thieme Verlag Stuttgart . New York.
- Maricich, Tom J.,Allan, Matthew J.,Kislin, Brett S.,Chen, Andrea I-T.,Meng, Fan-Chun,Bradford, Christine,Kuan, Nai-Chia,Wood, Jeremy,Aisagbonhi, Omonigho,Poste, Alethea,Wride, Dustin,Kim, Sylvia,Santos, Therese,Fimbres, Michael,Choi, Dianne,Elia, Haydi,Kaladjian, Joseph,Abou-Zahr, Ali,Mejia, Arturo
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p. 3361 - 3368
(2014/01/06)
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- Byproducts formation in the ethyl tert-butyl ether (ETBE) synthesis reaction on macroreticular acid ion-exchange resins
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Ethyl tert-butyl ether (ETBE) production is one of the industrial processes of major importance today in Europe. However, the study of side reactions in this synthesis reaction appears scarcely in the open literature. Side reactions take place along with the etherification of C4 olefinic cuts with ethanol, catalyzed by acidic ion-exchange resins. In this work, byproducts formation is studied in a batch reactor. The presence of diethyl ether (DEE), ethyl sec-butyl ether (ESBE), dimers of isobutene (2,4,4-trimethyl-1-pentene (TMP-1) and 2,4,4-trimethyl-2-pentene (TMP-2)) and tert-butyl alcohol (TBA) has been studied in terms of production and selectivity. The effect of temperature, ranging from 323 to 383 K, and the influence of initial molar ratio ethanol/isobutene (R A/O), ranging from 0.5 to 2.0, on byproducts formation have been analyzed. All byproducts formation was favored by high temperatures. A low initial molar ratio ethanol/isobutene favored the formation of DEE, ESBE, TMP-1 and TMP-2, whereas high molar ratios favored TBA formation.
- Badia,Fité,Bringué,Ramírez,Cunill
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p. 384 - 394
(2013/10/22)
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- Direct synthesis of unsymmetrical ethers from alcohols catalyzed by titanium cation-exchanged montmorillonite
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Titanium-exchanged montmorillonite (Ti4+-mont) was found to act as an efficient heterogeneous catalyst for the etherification of a wide range of alcohols under mild reaction conditions. Ti4+-mont was reusable with retention of high efficiency and applicable to scale-up reaction conditions. The Royal Society of Chemistry 2012.
- Mitsudome, Takato,Matsuno, Tsuyoshi,Sueoka, Shoichiro,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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supporting information; experimental part
p. 610 - 613
(2012/04/23)
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- Oniumsilica-immobilized-Keggin acids: Acidity and catalytic activity for ethyl tert-butyl ether synthesis and acetic acid esterification with ethanol
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Keggin heteropolyacids were immobilized on functionalized silica as their onium (γ-propyl-N-pyridinium, γ-propyl-N-methyl and γ-propyl-N-butyl-imidazolium) salts. Interaction between HPA and the surface-grafted onium cations affords acid salts. In contrast to bare silica, impregnated with HPA, these materials have monoanionic dispersions of HPA on the surface and superior resistance to HPA leaching in polar media. The greatest stability of the Keggin structure and resistance to leaching were found for H4SiW12O40-(SiW)-, and the lowest for H3PMo12O40-(PMo)-based samples. In the two model reactions tested, the liquid-phase synthesis of ETBE and the esterification of AcOH with EtOH, these solids display good catalytic performance (activity per anion, up to 150 and 25 h-1, respectively) and relative high structural stability. Catalysts having a greater coverage of organic functions (revealed by comparing two pyridinium salts) and hydrophobic cations (by comparing two imidazolium salts) have the best performance. Amongst the heteropolyacids studied, H4SiW12O40 is the most active and promising for catalyst design.
- Kovalchuk,Kochkin,Sfihi,Zaitsev,Fraissard
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experimental part
p. 247 - 257
(2009/07/10)
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- Carbon-Based Solid Acid, Catalyst Comprising the Solid Acid, and Reaction Using the Solid Acid as Catalyst
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A carbon-based solid acid which has high activity and high thermal stability and is useful as an acid catalyst for various reactions such as hydration of olefins. The carbon-based solid acid for use as a catalyst is obtained by carbonization and sulfonation of an organic substance, which has a reduction rate of 10 mol % or less of acid content as measured by immersing the solid acid in hot water at 120° C. for 2 hours, is used as the acid catalyst. The organic substance to be used as the raw material for preparing the solid acid is preferably a saccharide having β1-4 glycosidic bond (e.g. cellulose) or lignin. Amylose is also suitable as the raw material. Examples of the reaction for which the solid catalyst can be used include hydration of olefins, etherification of olefins, and acid/alcohol esterification.
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Page/Page column 5
(2009/04/24)
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- Stereochemistry of 1,2-elimination reactions at the E2-E1cB interface - Tert-butyl 3-tosyloxybutanoate and its thioester
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Experimental data on the stereoselectivity of base-catalyzed 1,2-elimination reactions that produce conjugated carbonyl compounds are scarce in spite of the importance of these reactions in organic and biochemistry. As part of a comprehensive study in this area, we have synthesized stereospecifically-deuterated β-tosyloxybutanoate esters and thioesters and studied the stereoselectivity of their elimination reactions under non-ion pairing conditions. With the availability of both the (2R*,3R*) and (2R*,3S*) diastereomers the innate stereoselectivity could be determined unambiguously. 1H and 2H NMR data show that these substrates produce 5-6% syn elimination, the usual amount for acyclic substrates undergoing E2 reactions. Contrary to earlier suggestions, activation by a carbonyl group has virtually no influence upon the stereoselectivity. Elimination of the (2R*,3R*) diastereomer of the β-tosyloxyester and thioester produces 21-25% of the (Z)-alkene, much more than observed with a poorer β-nucleofuge. A relatively large amount of (Z)-alkene product seems to be a good marker for an E2 pathway, in which the transition state is E1cB-like, rather than an E1cBirrev mechanism. Syn KIE values were higher than those for anti elimination for the esters as well as the thioesters. Experimental challenges to the synthesis of stereospecifically-deuterated β-tosyloxyesters are discussed. The Royal Society of Chemistry 2008.
- Mohrig, Jerry R.,Alberg, David G.,Cartwright, Craig H.,Pflum, Mary Kay H.,Aldrich, Jeffrey S.,Anderson, J. Kyle,Anderson, Shelby R.,Fimmen, Ryan L.,Snover, Amy K.
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experimental part
p. 1641 - 1646
(2008/10/09)
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- On the miscibility of ethers and perfluorocarbons. An experimental and theoretical study
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Despite their significant polar character, some organic ethers such as diethyl ether were found to be miscible with perfluorocarbon solvents. Solubilities of various ethers in perfluorocarbons and miscibility temperatures were determined. These properties were found to be greatly dependent on the polarity but also size and shape of the ether molecule. Theoretical calculations of the miscibility temperatures of organic solvents and perfluorocarbons using COSMO-RS method were correlated with experimental data. Considering the difficulties in the accurate description of the macroscopic properties, such as miscibility temperatures, from the first principles, the agreement between experimental and theoretical data is reasonable.
- Babiak, Peter,Němcová, Adriana,Rulí?ek, Lubomír,Beier, Petr
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p. 397 - 401
(2008/12/21)
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- ACETONITRILE REMOVAL FROM THE OLEFINIC FEED OF ETHER PRODUCTION PROCESSES USING IONIC LIQUIDS
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An enhanced ether production process from an olefinic cut containing at least one iso-olefin and from an alcohol comprises a stage of removal of the acetonitrile present in the hydrocarbon feed by liquid-liquid extraction, the extraction solvent being a non-aqueous ionic liquid of general formula Q+A?, wherein Q+ is an ammonium, phosphonium and/or sulfonium cation, and A? an anion likely to form a liquid salt with said cation. Advantageously, the method according to the invention generally allows the amount of water at the etherification reactor inlet to be divided by at least two and thus the purity of the ether produced to be improved.
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Page/Page column 4
(2008/12/06)
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- Specifics of the synthesis of some alkyl tert-alkyl ethers and their thermodynamic properties
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The conditions of synthesis and isolation of pure (98-99%) and extra pure (>99.9%) alkyl tert-alkyl ethers containing six to eight carbon atoms in their molecule, which are used as high-octane additives to motor fuels, were studied. The key thermodynamic properties, including melting point, density, saturated vapor pressure, enthalpy of vaporization at 298.15 K, normal boiling point, and critical parameters, obtained by experimental and calculation methods, are given. Copyright
- Krasnykh,Levanova,Karaseva,Kirgizova,Varushchenko,Druzhinina,Pashchenko
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- The first non-acid catalytic synthesis of tert-butyl ether from tert-butyl alcohol using ionic liquid as dehydrator
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Methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and isopropyl tert-butyl ether (IPTBE) have been synthesized for the first time over a non-acid ionic liquid as catalyst and dehydrator with high conversion (> 90%) and selectivity (> 90%) under mild conditions.
- Shi, Feng,Xiong, Hai,Gu, Yanlong,Guo, Shu,Deng, Youquan
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p. 1054 - 1055
(2007/10/03)
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- Hydroesterification of tert-butyl alcohol in room temperature ionic liquids
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Hydroesterification of tert-butyl alcohol with ethanol catalyzed by transition metal triphenylphosphine complexes in the presence of p-toluenesulfonic acid was investigated using room temperature ionic liquids as the reaction medium at 373-413 K and 3-6 MPa of CO. In comparison with the organic solvents as reaction medium, higher conversion was achieved and ethyl tert-valerate could be directly formed in the ionic liquid medium. The products could be separated from the ionic liquids easily due to their immiscibility in this medium.
- Qiao, Kun,Deng, Youquan
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p. 667 - 670
(2007/10/03)
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- Kinetics of liquid phase synthesis of ethyl tert-butyl ether from tert-butyl alcohol and ethanol catalyzed by β-zeolite supported on monolith
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This paper compared the performance of β-zeolite and Amberlyst-15 catalysts on a liquid phase synthesis of ethyl tert-butyl ether (ETBE) from ethanol (EtOH) and tert-butyl alcohol (TBA) β-Zeolite was synthesized and deposited on monolith support. Its structure was confirmed by an XRD measurement and its composition was analyzed by an XRF measurement. It was found that even though the catalytic activity of β-zeolite was lower than that of Amberlyst-15, the selectivity of ETBE was much higher than that of Amberlyst-15, resulting in almost the same level of ETBE yield. The dehydration of TBA to isobutene (IB) was the major side reaction. The kinetic study of the reaction catalyzed by β-zeolite supported on monolith was carried out by using a semibatch reactor. The effect of external mass transfer was investigated by varying stirring speeds. The activity-based rate expressions were developed taking into account of water inhibition. Three temperature levels of 323, 333, and 343 K were performed in the study to obtain the parameters in the Arrhenius's equation and the Van't Hoff's equation.
- Assabumrungrat,Kiatkittipong,Sevitoon,Praserthdam,Goto
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p. 292 - 299
(2007/10/03)
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- The carbonylation of allylic halides and prop-2-en-1-ol catalysed by triethylphosphine complexes of rhodium
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In ethanol, [RhX(CO)(PEt3)2] added directly or formed in situ from [Rh2(OAc)4]·2MeOH (OAc = O2CMe) and PEt3 or [Rh(OAc)(CO)(PEt3)2] catalysed the carbonylation of CH2=CHCH2X (X = Cl, Br or I) to ethyl but-3-enoate with CH2=CHCH2OEt as a side product. Small amounts of the isomerisation product, ethyl but-2-enoate were produced but no base was required for the reaction. The selectivity of the reaction is in the order Cl > Br > I and prop-2-en-1-ol can be successfully carbonylated to prop-2-enyl but-3-enoate by the same system using 3-chloroprop-1-ene as a promoter. 3-Fluoropropene was not carbonylated, but in the presence of H2 underwent hydroformylation to produce acetals. 3-Chlorobut-1-ene and 1-chlorobut-2-ene both produced ethyl pent-3-enoate and 3-ethoxybut-1-ene. In situ and ex situ NMR and IR spectroscopic studies have been used to show that the first step of the reaction is oxidative addition to give [Rh(CH2CH=CH2)Cl2(CO)(PEt3) 2] for which thermodynamic parameters have been obtained. Both 3-chlorobut-1-ene and 1-chlorobut-2-ene give [Rh(CH2CH=CHMe)Cl2-(CO)(PEt3)2] but with different E:Z ratios. The detailed mechanism of the oxidative addition is discussed. The CO inserts into the Rh-C bond to give [Rh(COCH2CH=CH2)Cl2(CO)(PEt3) 2], from which but-3-enoyl chloride reductively eliminates to react with ethanol to give the observed products. High-pressure IR and high-pressure NMR studies reveal that [RhX(CO)(PEt3)2] (X = Cl or Br) reacts with CO to give [RhX(CO)2(PEt3)2], which exists as two isomeric forms. The compound [Rh(OAc)(CO)(PEt3)2] catalyses the formation of prop-2-enyl ethanoate from 1-chloroprop-2-ene and sodium ethanoate. A mechanism is proposed.
- Payne, Marc J.,Cole-Hamilton, David J.
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p. 3167 - 3175
(2007/10/03)
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- Kinetics of Liquid-Phase Synthesis of Ethyl tert-Butyl Ether from tert-Butyl Alcohol and Ethanol Catalyzed by Ion Exchange Resin and Heteropoly Acid
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Synthesis of ethyl tert-butyl ether (ETBE) from ethanol (EtOH) and tert-butyl alcohol (TBA) in the liquid phase was studied by using ion exchange resin, Amberlyst 15 (A15) in the H+ form and heteropoly acid, H0.5Cs3.5SiW12O40(HPA).Experiments were carried out in a stirred batch reactor with different temperatures under atmospheric pressure.It was found that water will inhibit the reaction rates greatly and the dehydration of TBA could not be neglected in this study.A kinetics model which considered the inhibition of water and the decrease of volume was proposed.The experimental results agreed well with the model.
- Yin, Xiaodong,Yang, Bolun,Goto, Shigeo
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p. 1065 - 1074
(2007/10/02)
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- Enthalpies of formation of 2-methyl-2-ethoxypropane and 2-ethyl-2-ethoxypropane from equilibrium measurements
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The equilibria for the synthesis of C2H5OC(CH3)3 (A) and C2H5OC(CH3)2(C2H5) (B) from C2H5OH (C) and CH2:C(CH3)2 (D) or CH3CH:C(CH3)2 (E) in the liquid phase were investigated at temperatures from 313 K to 412 K.On the basis of experimental equilibrium constants found for n(C)/n(D) or n(C)/n(E) >/= 4, the following values were obtained for ΔrH0m/(kJ * mol-1) and ΔrS0m/(J * K-1 * mol-1): (C + D = A), -(35.45 +/- 1.94) and -(82.37 +/- 5.99); (C + A = B), -(34.13 +/- 0.81) and -(87.82 +/- 2.18).The following values of ΔfH0m(298.15 K)/(kJ * mol-1) have been derived: C2H5OC(CH3)3(l), -(350.8 +/- 2.6); C2H5OC(CH3)2(C2H5)(l), -(379.8 +/- 1.4).
- Sharanov, K. G.,Rozhnov, A. M.,Korol'kov, A. V.,Karaseva, S. Y.,Miroshnichenko, E. A.,Korchatova, L. I.
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p. 751 - 754
(2007/10/02)
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- Carbonylation of Organic Halides catalysed by Rhodium Triethylphosphine Complexes
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Allyl and benzyl halides but not phenyl or propyl halides have been carbonylated in ethanol in the presence of rhodium triethylphosphine complexes to their respective butenoic or benzylic esters; no added base was required.
- Simpson, Michael C.,Payne, Marc J.,Cole-Hamilton, David J.
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p. 2899 - 2900
(2007/10/02)
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- Unimolecular Reactions of Ionised Ethers
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The 12.1 eV 75 deg C electron ionisation mass spectra of 25 saturated dialkyl ethers containing between six and eight carbon atoms are reported and discussed in energetic terms.Dissociation by α-cleavage of M+. typically gives rise to intense peaks in these spectra.However, rearrangement processes, leading to eventual 1,3-O-alkyl shifts and subsequent ethyl radical loss, are also important for ionised ethers in which both alkyl groups have primary structures.Other significant ions in the spectra of n-CnH2n+1OR ethers include those formed by loss of ROH or CnH2n-1. from M+..Ionised ethers containing one secondary alkyl group tend to dissociate by α-cleavage of this group, or to a lesser extent by loss of the corresponding alkane, without undergoing such extensive rearrangements.Distonic ions and ion-molecule complexes play key roles in the isomerisation and dissociation steps involved in these fragmentations.Simple cleavages dominate the spectra of ethers containing a tertiary alkyl group.These ethers show very small or negligible M+. peaks.Ions corresponding to rupture of the C-O ?-bond, with charge retention by the hydrocarbon fragment, appear in the spectra of some ethers.There is evidence, however, that these ions may originate, at least in part, by secondary dissociations of the primary daughter ions, rather than by direct decomposition of M+..
- Bowen, Richard D.,Maccoll, Allan
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p. 147 - 155
(2007/10/02)
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- Empirical Correlations of Partial Molar Volumes at Infinite Dilution of Organic Solutes and Transition States for SN1 and SN2 Ethanolysis of Alkyl Halides
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Activation volumes are measured to be -21 to -29 cm3 mol-1 for the ethanolysis of t-butyl chloride and bromide and methyl bromide in ethanol at 318.15 K.Partial molar volumes at infinite dilution are measured for 34 organic solutes.Partial molar volumes of the transition states can be treated in the same way as those of common solutes, in which the partial molar volume of each solute is compared with that of an alkane having the same van der Waals volume.The volume changes caused by the molecularity of reaction and the intermolecular interaction during the activation process are discussed.
- Itsuki, Hidenori,Yamamoto, Hisashi,Okazaki, Haruo,Terasawa, Seiji
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p. 1545 - 1550
(2007/10/02)
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- IODINE MEDIATED SYNTHESIS OF ALKYL TERTIO-ALKYL ETHERS
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Mixed alkyl t-alkyl ethers have been prepared by the selective coupling of the alcohol precursors.Dehydration was promoted by iodine under hydrogen pressure at 100 deg C.
- Jenner G.
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p. 2445 - 2448
(2007/10/02)
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- SYNTHETIC APPLICATION OF MICELLAR CATALYSIS. WILLIAMSON'S SYNTHESIS OF ETHERS
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A simple, rapid and efficient procedure for the preparation of di-alkyl, simple phenyl-alkyl and hindered phenyl-alkyl ethers has been developed.Based on the principle of micellar catalysis the method involves alkylation of the alkoxide or the phenoxide ion with an alkyl chloride at 80 deg C in the presence of cationic micelles.For the preparation of phenyl-alkyl ethers normal micelles were used, while for the di-alkyl ethers reverse micelles were more effective.By increasing the ionic strength of the solution the rate of formation of phenyl-alkyl ethers could be increased.
- Jursic, Branko
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p. 6677 - 6680
(2007/10/02)
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- Deamination Reactions, 41. Reactions of Aliphatic Diazonium Ions and Carbocations with Ethers
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Aliphatic diazonium ions and carbocations were generated by deacylation of appropriate nitrosoureas (1, 5, 9) in alcohol-ether mixtures or in 2-alkoxyethanols.Ethers were generally inferior to alcohols in capturing cationic intermediates.Formation of trialkyloxonium ions led to alkyl exchange or ring opening.The observed reactivity orders were n-butyl > isobutyl for the diazonium ions, allyl > sec-butyl > tert-butyl for the carbocations, methoxy > ethoxy and oxirane > oxetane > tetrahydrofuran for the ethers, indicating the predominance of steric effects.Neighboring group participation in 4-methoxy-1-butanediazonium ions (58) and 4,5-epoxy-1-pentanediazonium ions (74) was detectable but inefficient ( 20percent of cyclic oxonium ions).
- Kirmse, Wolfgang,Jansen, Ulrich
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p. 2607 - 2625
(2007/10/02)
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- Relative Reactivity of Bridgehead Adamantyl and Homoadamantyl Substrates from Solvolyses with Heptafluorobutyrate as a Highly Reactive Carboxylate Leaving Group. Absence of SN2 Character of Solvolysis of tert-Butyl Derivatives
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Heptafluorobutyrates, conveniently prepared from alcohols, possess a reactivity similar to that of halides in solvolysis reactions.A product and isotope distribution study for the reaction of 1-adamantyl heptafluorobutyrate (1a) in 80:20 ethanol-H2(18)O demonstrated exclusive alkyl-oxygen cleavage.The reactivities of 1a, 1-(2a), and 3-homoadamantyl heptafluorobutyrate (3a) increase with the flexibility of the hydrocarbon skeleton.The rate constants are linearly correlated with the strain increase upon ionization.No acceleration attributable to nucleophilic solvent assistance was evidenced for the tert-butyl ester, 4a.A literature proposal for such assistance in solvolyses of 4 is examined.The existing data are explained better by an SN1 process with electrophilic assistance of the leaving group in the solvents that can form very strong hydrogen bonds.
- Farcasiu, Dan,Jaehme, Joachim,Ruechardt, Christoph
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p. 5717 - 5722
(2007/10/02)
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- THE INFLUENCE OF INTERLAYER WATER ON CLAY CATALYSTS. INTERLAMELLAR CONVERSION OF 2-METHYLPROPENE
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Evidence is provided for two alternative pathways for the reactions undergone by 2-methylpropene between the layers of a sheet silicate catalyst (Al3+-exchanged montmorillonite).This clay, when it initially contains ca. 12percent interlayer water, catalyses the addition of either water or methanol to 2-methylpropene to yield, respectively, t-butanol or 2-methoxy-2-methyl propane (methyl tertiary butyl ether, MTBE), whereas the same clay following deliberate dehydration acts as an effective catalyst for the oligomerisation of 2-methylpropene.Similar results are obtained with an Al3+-exchanged synthetic hectorite.
- Ballantine, James A.,Jones, William,Purnell, J. Howard,Tennakoon, Dayananda T. B.,Thomas, John M.
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p. 763 - 766
(2007/10/02)
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- Catalysis by Iodine in the Solvolysis of Tertiary Alkyl Halides
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Solvolysis of t-butyl and t-amyl iodides in aqueous ethanol and aqueous hexafluoropropan-2-ol is catalysed by iodine.The same effect, but to a smaller extent, is also found for t-butyl bromide in aqueous ethanol; the strongest catalysis by iodine was found for the aqueous ethanolysis of 1-adamantyl iodide.The catalytic constants for aqueous ethanolysis of t-butyl iodide decrease less steeply than the rate constants of the uncatalysed reactions as the proportion of ethanol in the medium is increased.The results are accomodated by a mechanism involving pre-association of iodine with the alkyl halide superimposed upon a general mechanism for solvolysis the rate-determining step of which may be ionization, ion-pair separation, or reaction of reversibly formed intimate ion-pairs with the solvent according to the nature of the alkyl halide and the solvolytic medium.
- Cox, Brian G.,Maskill, H.
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p. 1901 - 1906
(2007/10/02)
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- HETEROGENOUS CATALYSIS IN SOLUTION
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The SN1 solvolysis of 2-bromo-2-methylpropane (t-butyl bromide) in 80 volpercent (55.2 molpercent) EtOH + H2O at 25 degC was found to be catalysed by silver and several insoluble silver and mercury salts but not by BaSO4, SiO2 or platinium.The relative catalytic effectiveness of these solids could be largely explained by Pearson's SHAB concept.The kinetics of the AgBr-catalysed process were studied in detail by a pH-stat technique.The results fitted in which t-BuBr molecules and product Br(1-) ions competitively adsorbed on the surface according to Langmuir isotherms.Calculations showed the surface reaction to be ca. 105 times faster than the homogeneous solvolysis and to possess a much lower activation energy.The heterogeneous reaction was found to be selective, forming no alkene product and a higher ratio t-BuOEt:t-BuOH than in the bulk solution.These findings have been discussed in terms of the structure of the interfacial region.
- Barbosa, Ester F. G.,Mortimer, Roger J.,Spiro, Michael
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p. 111 - 121
(2007/10/02)
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- Model Studies on the Mechanism of Biotin-Dependent Carboxylations. 2. Site of Protonation vs. CO2 Transfer
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Three irreversibly acidified model compounds (6-8) of N'-carboxybiotin (2) have been prepared to access the importance of proir protonation of the biotin ring system of the CO2-transfer potential of the N'-carboxy group.Substrates 6 and 7 can be considered model compounds of N'-carboxybiotin (2) in which protonation has occurred at the ureido carbonyl oxygen atom.Conversely, compound 8 was synthesized to evaluate the CO2-transfer potential of the N'-carboxy group, if protonation occurred at the N'-nitrogen atom.The reactivity of each substrate with nucleophiles has been evaluated.Of these three compounds, only 8 led to efficient transfer to the carbomethoxy group upon treatment with nitrogen-containing nucleophiles (morpholine, cyclohexylamine, and diisopropylamine).With smaller nucleophiles (i.e, water, methanol) reaction was centered at the ring C-2 position.Correspondingly, treatment of compound 6 with nucleophiles (i.e, alcohols, amines) led to products which can be explained in terms of two competing reactions.One pathway involves initial attack of the nucleophile at the C-2 position of the imidazolinium cation (an AAC2 process) to give a tetrahedral intermediate which then undergoes bond cleavage in either of two directions.The competing pathway observed was an irreversible SN2 displacement reactions (an AAL2 process) at the methylene position of the O-alkyl side chain.Factors are presented which account for the overall product distribution obtained from these reactions.Finally, the products obtained from the treatment of compound 7 with nucleophiles (i.e., alcohols, amines) could be accounted for solely by reactions which occurred at the C-2 position of the ring (an AAC2 process).The corresponding SN2 pathway is not a viably route for this substrate.The significance of these results to the mechanism of action of biotin is discussed.
- Cravey, Melanie J.,Kohn, Harold
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p. 3928 - 3939
(2007/10/02)
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- Preparation and recovery of ethers
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Methyl t-butyl ether may be recovered from etherification reaction effluent by extractive distillation in the presence of n-butanol.
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