- Absolute rates of the solution-phase addition of atomic hydrogen to a vinyl ether and a vinyl ester: Effect of oxygen substitution on hydrogen atom reactivity with olefins
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The reactions of vinyl butyl ether and vinyl butyrate with atomic hydrogen and deuterium lead to addition at the terminal position of the olefins. This observation is consistent with the reactions carried out earlier with other olefins. Both of the absolute rates of addition to vinylbutyl ether and vinyl butyrate, in acetone and hexane, were measured at several temperatures. The relative rates are consistent with only modest stabilization of the transition state of the radical adduct by the α-O substituent compared with that of hydrogen atom addition to 1-octene. The relative rates measured in acetone and hexane indicate no significant differential solvation of the ground state relative to the transition structures of the hydrogen atom addition. The kinetics reveal that the early transition states for hydrogen atom addition exhibit little selectivity (vinyl ether versus simple olefin) in either the abstraction of hydrogen a to the oxygen or by terminal addition to the olefinic ether and reflects the modest influence of the increased enthalpy of reaction associated with resonance stabilization by the oxygen substituent at the developing radical site.
- Tanner,Kandanarachchi,Das,Franz
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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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- Selective hydrogenolysis of 2-furancarboxylic acid to 5-hydroxyvaleric acid derivatives over supported platinum catalysts
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The conversion of 2-furancarboxylic acid (FCA), which is produced by oxidation of furfural, to 5-hydroxyvaleric acid (5-HVA) and its ester/lactone derivatives with H2 was investigated. Monometallic Pt catalysts were effective, and other noble metals were not effective due to the formation of ring-hydrogenation products. Supports and solvents had a small effect on the performance; however, Pt/Al2O3 was the best catalyst and short chain alcohols such as methanol were better solvents. The optimum reaction temperature was about 373 K, and at higher temperature the catalyst was drastically deactivated by deposition of organic materials on the catalyst. The highest yield of target products (5-HVA, δ-valerolactone (DVL), and methyl 5-hydroxyvalerate) was 62%, mainly obtained as methyl 5-hydroxyvalerate (55% yield). The byproducts were mainly ring-hydrogenation compounds (tetrahydrofuran-2-carboxylic acid and its ester) and undetected ones (loss of carbon balance). The catalyst was gradually deactivated during reuses even at a reaction temperature of 373 K; however, the catalytic activity was recovered by calcination at 573 K. The reactions of various related substrates were carried out, and it was found that the O-C bond in the O-CC structure (1,2,3-position of the furan ring) is dissociated before CC hydrogenation while the presence and position of the carboxyl group (or methoxy carbonyl group) much affect the reactivity.
- Asano, Takehiro,Takagi, Hiroshi,Nakagawa, Yoshinao,Tamura, Masazumi,Tomishige, Keiichi
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p. 6133 - 6145
(2019/11/20)
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- The Guanidine-Promoted Direct Synthesis of Open-Chained Carbonates
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In order to reduce CO2 accumulation in the atmosphere, chemical fixation methodologies were developed and proved to be promising. In general, CO2 was turned into cyclic carbonates by cycloaddition with epoxides. However, the cyclic carbonates need to be converted into open-chained carbonates by transesterification for industrial usage, which results in wasted energy and materials. Herein, we report a process catalyzed by tetramethylguanidine (TMG) to afford linear carbonates directly. This process is greener and shows potential for industrial applications.
- Shang, Yuhan,Zheng, Mai,Zhang, Haibo,Zhou, Xiaohai
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p. 933 - 938
(2019/09/30)
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- Ethanol to Butanol Conversion over Bifunctional Zeotype Catalysts Containing Palladium and Zirconium
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Abstract: A study of the kinetics of ethanol conversion in the presence of Zr-containing zeolites BEA doped with palladium particles has revealed the order of formation of the main reaction products. It has been shown that the primary processes are ethanol dehydrogenation to acetaldehyde on Pd sites and ethanol dehydration to diethyl ether on the acid sites of the catalyst. After that, acetaldehyde undergoes the aldol–croton condensation reaction to form crotonal, which is hydrogenated to butanol on the metal sites. Butanol, in turn, is dehydrated into butenes, which undergo hydrogenation to butane. The presence of hydrogen in the gas phase leads to the displacement of ethanol from the metal surface and prevents the formation of surface carbonates and acetates. It has been found that hydrogen significantly accelerates ethanol dehydration owing to a decrease in the activation energy, which can be attributed to hydrogen spillover to the zeolite. The addition of water inhibits all acid-catalyzed reactions owing to competitive adsorption on acid sites and thereby decreases the butanol yield and the ethanol conversion.
- Kots,Zabilska,Grigor’ev, Yu. V.,Ivanova
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p. 925 - 934
(2019/08/20)
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- Conversion of ethanol into linear primary alcohols on gold, nickel, and gold–nickel catalysts
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The direct conversion of ethanol into the linear primary alcohols CnH2n+1OH (n = 4, 6, and 8) in the presence of the original mono- and bimetallic catalysts Au/Al2O3, Ni/Al2O3, and Au–Ni/Al2O3 was studied. It was established that the rate and selectivity of the reaction performed under the conditions of a supercritical state of ethanol sharply increased in the presence of Au–Ni/Al2O3. The yield of target products on the bimetallic catalyst was higher by a factor of 2–3 than that reached on the monometallic analogs. Differences in the catalytic behaviors of the Au, Ni, and Au–Ni systems were discussed with consideration for their structure peculiarities and reaction mechanisms.
- Chistyakov,Zharova,Tsodikov,Nikolaev,Krotova,Ezzhelenko
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p. 803 - 811
(2016/12/07)
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- Conversion of ethanol and glycerol to olefins over the Re- and W-containing catalysts
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The catalytic conversion of a mixture of ethanol and glycerol over the Re - W/Al2O3 catalysts was studied. The Re - W binary system exhibits a non-additive cocatalytic effect in the conversion of ethanol and its mixture with glycerol into the fraction of olefins C4 - C9. The non-additive increase in the catalytic activity is associated with the specific structure of the binuclear metallocomplex precursors, due to which the supported metals are arranged in the immediate vicinity from each other on the support surface and intensively interact to form Re7+. The study of the combined conversion of ethanol and glycerol made it possible to find an optimum ratio of the reactants in the initial mixture. The yield of target hydrocarbons attains 50 wt.% based on the amount of carbon passed through the reactor.
- Zharova,Chistyakov,Zavelev,Kriventsov,Yakimchuk,Kryzhovets,Petrakova,Drobot,Tsodikov
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p. 337 - 345
(2015/11/02)
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- Ion exchange resins as catalysts for the liquid-phase dehydration of 1-butanol to di-n-butyl ether
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This work reports the production of di-n-butyl ether (DNBE) by means of 1-butanol dehydration in the liquid phase on acidic ion-exchange resins. Dehydration experiments were performed at 150 °C and 40 bar on 13 styrene-codivinylbenzene ion exchangers of different morphology. By comparing 1-butanol conversions to DNBE and initial reaction rates it is concluded that oversulfonated resins are the most active catalysts for 1-butanol dehydration reaction whereas gel-type resins that swell significantly in the reaction medium as well as the macroreticular thermostable resin Amberlyst 70 are the most selective to DNBE. The highest DNBE yield was achieved on Amberlyst 36. The influence of typical 1-butanol impurities on the dehydration reaction were also investigated showing that the presence of 2-methyl-1-propanol (isobutanol) enhances the formation of branched ethers such as 1-(1-methylpropoxy) butane and 1-(2-methylpropoxy) butane, whereas the presence of ethanol and acetone yields ethyl butyl ether and, to a much lesser extent, diethyl ether.
- Pérez,Bringué,Iborra,Tejero,Cunill
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- Catalytic alkylation of alcohols to liquid ethers and organic compounds to alkylated products
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A catalytic process is taught for non-oxidative alkylation of organic compounds, comprising alcohols, alkanes, glycols, ethers, aldehydes, ketones, carboxylic acids, esters, amines, thiols or phosphines, by alkyl groups produced from alcohols or glycols, forming products comprising ethers and other higher molecular weight alkylated compounds. The process is conducted at a reflux temperature below 200° C. in the presence of an acid, alkali or neutral salt dehydrating agent comprising sulfuric acid, phosphoric acid or their salts, lime or anhydrous calcium sulfate in the absence of zero valent metals and air. Specifically, this catalytic process converts ethanol to ethyl butyl ethers, ethyl hexyl ethers and dibutyl ethers or oxygenated gasoline as well as amines comprising n-butyl amine plus butanol to dibutyl amine and butyl hexyl amines at ambient pressure. This same catalytic alkylation chemistry, which does not constitute a condensation reaction, alkylates 4-hydroxybenzoic acid using ethanol to 4-ethoxyethylbenzoic acid products.
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Paragraph 0026
(2013/08/15)
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- Deuterium kinetic isotopic study for hydrogenolysis of ethyl butyrate
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The hydrogenation of ethyl butyrate, n-butyric acid, and n-butyraldehyde to their corresponding alcohol(s) has been studied over a γ-Al 2O3-supported cobalt catalyst using a high-pressure fixed-bed reactor in the temperature range of 473-493 K. H2-D 2-H2 switching experiments show that ethyl butyrate and n-butyric acid follow an inverse kinetic isotope effect (KIE) (i.e. r H/rD = 0.50-0.54), whereas n-butyraldehyde did not display any KIE (i.e. rH/rD = 0.98). DRIFTS experiments were performed over the support and catalyst to monitor the surface species formed during the adsorption of ethyl butyrate and n-butyric acid at atmospheric pressure and the desired temperature. Butanoate and butanoyl species are the stable surface intermediates formed during hydrogenation of ethyl butyrate. Hydrogenation of butanoate to a partially hydrogenated intermediate is likely involved in the rate-determining step of ethyl butyrate and butyric acid hydrogenation.
- Gnanamani, Muthu Kumaran,Jacobs, Gary,Keogh, Robert A.,Davis, Burtron H.
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experimental part
p. 27 - 35
(2011/02/28)
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- Empirical Correlations of Partial Molar Volumes at Infinite Dilution of Organic Solutes and Transition State for SN2 Hydrolysis and Ethanolysis of n-Alkyl Bromides
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Pseudo-first-order rate constants under pressures 3 mol-1) were ca. -11 for the hydrolysis and about -25 for the ethanolysis.Partial molar volumes at infinite dilution were measured for n-butyl bromide in water at 298.15 K and for 66 organic solutes in ethanol at 333.15 K.Partial molar volumes of the transition states are shown to be adaptable to volumetric behaviour for common solutes, in which the partial molar volume of each solute is compared with that of the n-alkane having the same van der Waals volume.
- Itsuki, Hidenori,Kuwabara, Mikizo,Hayase, Kouji,Terasawa, Seiji
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p. 563 - 572
(2007/10/02)
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- Chemistry of Carbenes: Part III - Reaction of Methylene with Ethyl n-Propyl Ether
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The bond reactivities for ethyl n-propyl ether, based on unity for the primary bonds of ethyl group, again prove the discriminate attack of methylene.All secondary bonds are attacked faster than the primary bonds of ethyl, the 2 C-H of ethyl itself being attacked 1.83 times, which is higher than the attack on secondary αC-H (1.74) and βC-H (1.29) bonds.The descending order of reactivities of C-H bonds in propyl is α > β > γ.Additional evidence of the electrophilic effect of ethereal oxygen on the insertion reactions as also on the displacement reaction where methylene gives a methyl alkyl ether and displaces an olefin has been obtained.Similarly, the predicted formation of aldehydes resulting from the abstraction reactions of methylene has been observed.These results obtained in gas phase contrasted with the liquid phase work of Doering et al who found the attack to be indiscriminate.This work further confirms the difference between the two phases.
- Mehta, R. K. S.
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- Organomagnesium Inner Complexes, Part I. Bis(dialkylaminoalkyl)- and Bis(alkoxybutyl)magnesium Compounds
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A series of magnesium inner complexes has been prepared by reacting MgH2 (prepared by homogeneous catalysis) with dialkylallyl- and -3-butenylamines and -3-butenylethers in the presence of catalytic amounts of ZrCl4.The monomeric nature of bis(4-methoxybutyl)magnesium has been confirmed by X-ray diffraction.The analogous syntheses of bis(3-alkoxypropyl)magnesium compounds failed: cleavage of the allyl ether with elimination of propene occurred.This cleavage reaction is accelerated by catalytic amounts of NiCl2 or ZrCl4. - Keywords: Magnesium, Inner Complexes, Crystal Structure, X-Ray
- Angermund, Klaus,Bogdanovic, Borislav,Koppetsch, Gudrun,Krueger, Carl,Mynott, Richard,et al.
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p. 455 - 466
(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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- A HIGHLY ACTIVE SUPPORTED CATALYST FOR OLEFIN HYDROGENATION FROM COLLOIDAL NICKEL BORIDE
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Supported catalysts, which were prepared from colloidal nickel boride by immobilizing on inorganic substances such as Mg(OH)2, exhibited higher activity for olefin hydrogenation than a sol-type catalyst of colloidal nickel boride protected by polyvinylpyrrolidone.
- Nakao, Yukimichi
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p. 997 - 998
(2007/10/02)
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- KINETIC RELATIONSHIPS AND MECHANISM OF THE DECOMPOSITION OF 1,1-DIBUTOXYETHANE HYDROPEROXIDE
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The decomposition of 1,1-dibutoxyethane hydroperoxide at 70-95 deg C in oxidized 1,1-dibutoxyethane occurs by a unimolecular mechanism.The rate constants were determined: Overall thermal decomposition, kd= (6.3 +/- 0.6)E7.exp(-20,200 +/- 2000/RT), sec-1; unimolecular decomposition to free radicals, ki= (1.2 +/- 0.1)E10 exp(-25,000 +/- 1500/RT), sec-1.The fractions of induced, molecular, and radical dissociation of the hydroperoxide amount to 15-20, 60-65, and 16-20percent, respectively (90 deg.C, = 0.1-0.25 M).
- Estrina, G. Ya.,Kuramshin, E. M.,Imashev, U. B.,Zlotskii, S. S.,Rakhmankulov, D. L.
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p. 1355 - 1359
(2007/10/02)
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- Antiperspirants
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Compounds represented by the formula wherein m and n each are 1 or 2 and the sum of m and n is 3; R1 is alkyl; R2 is substituted and unsubstituted alkyl, cycloalkyl, alkenyl, cycloalkenyl, aryl, alkanoyl, alkenoyl or aroyl; wherein the substituents on R2 when R2 is alkyl, alkenyl, alkanoyl and alkenoyl are one or more of cycloalkyl, cycloalkenyl, alkyl substituted cycloalkenyl, or aryl, alkoxy, cycloalkoxy, cycloalkenyloxy, aryloxy or alkyl and/or alkoxy substituted aryl, alkoxy, cycloalkoxy, cycloalkenyloxy or aryloxy; and wherein the substituents on R2 when R2 is cycloalkyl, cycloalkenyl, aryl and aroyl are one or more of alkyl, alkoxy or aryl; and when R2 is phenyl two adjacent alkyl and/or alkoxy substituents on the phenyl can be joined to form a 5 or 6-membered saturated ring; when m is 2 and n is 1, R2 can be wherein R1 has the significance above and each R1 can be the same or different, R3 is a straight chain alkylene of 2 to 4 carbons and p is 0, 1 or 2; when m is 1 and n is 2, R2 has the significance above and each R2 can be the same or different or when one R2 is alkyl the other R2 can be STR1 WHEREIN R1 has the significance above and R4 is alkyl; are disclosed as having activity as antiperspirants. Antiperspirant/deodorant compositions containing one or more of the compounds as active ingredients and methods for preparing the compounds are also disclosed.
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