- Improving carbon retention in biomass conversion by alkylation of phenolics with small oxygenates
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Alkylation of phenolics with alcohols is an efficient way to retain carbon from small oxygenates in the liquid products of pyrolysis bio-oil. In this contribution, we have investigated the alkylation of m-cresol with several alkylating agents over H-Beta zeolite. The alkylation activity follows the sequence 2-propanol > propylene > 1-propanol. In all cases, propylene is the actual alkylation agent since the alcohols dehydrate at a faster rate than the rate of alkylation. A two-stage process is proposed to convert fractions of bio-oil rich in small aldehydes and ketones together with phenolics. In the first stage, aldehydes and ketones are selectively hydrogenated to alcohols. In the second stage, the resulting alcohols alkylate the phenolic compounds and get incorporated into the upgraded liquid. To illustrate this concept, two consecutive catalyst beds have been used. The first bed contains a metal catalyst for the selective hydrogenation. Among several catalysts investigated, Cu/SiO2 and Pt-Fe/SiO2 were found to exhibit good selectivity to hydrogenate the aldehyde and ketone, respectively, while preserving the aromatic ring of the phenolic compound. The second bed contains an H-Beta zeolite for the alkylation stage.
- Nie, Lei,Resasco, Daniel E.
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- Low-temperature rhodium-catalyzed dehydration of primary alcohols promoted by tetralkylammonium and imidazolium halides
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Rhodium complexes, promoted by imidazolium or tetraalkylammonium halide salts, catalyze the dehydration of primary alcohols with good conversion and selectivity.
- Dowson, George R. M.,Shishkov, Igor V.,Wass, Duncan F.
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- Dehydration Pathways of 1-Propanol on HZSM-5 in the Presence and Absence of Water
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The Br?nsted acid-catalyzed gas-phase dehydration of 1-propanol (0.075-4 kPa) was studied on zeolite H-MFI (Si/Al = 26, containing minimal amounts of extra framework Al moieties) in the absence and presence of co-fed water (0-2.5 kPa) at 413-443 K. It is shown that propene can be formed from monomeric and dimeric adsorbed 1-propanol. The stronger adsorption of 1-propanol relative to water indicates that the reduced dehydration rates in the presence of water are not a consequence of the competitive adsorption between 1-propanol and water. Instead, the deleterious effect is related to the different extents of stabilization of adsorbed intermediates and the relevant elimination/substitution transition states by water. Water stabilizes the adsorbed 1-propanol monomer significantly more than the elimination transition state, leading to a higher activation barrier and a greater entropy gain for the rate-limiting step, which eventually leads to propene. In a similar manner, an excess of 1-propanol stabilizes the adsorbed state of 1-propanol more than the elimination transition state. In comparison with the monomer-mediated pathway, adsorbed dimer and the relevant transition states for propene and ether formation are similarly, while less effectively, stabilized by intrazeolite water molecules.
- Zhi, Yuchun,Shi, Hui,Mu, Linyu,Liu, Yue,Mei, Donghai,Camaioni, Donald M.,Lercher, Johannes A.
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- General Ether Synthesis under Mild Acid-Free Conditions. Trimethylsilyl Iodide Catalyzed Reductive Coupling of Carbonyl Compounds with Trialkylsilanes to Symmetrical Ethers and Reductive Condensation with Alkoxysilanes to Unsymmetrical Ethers
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Facile synthesis of symmetrical ethers is achieved by either trimethylsilyl triflate or trimethylsilyl iodide catalyzed reductive coupling of carbonyl compounds (aldehydes and ketones) with trialkylsilanes.The method was also extended to the trimethylsilyl iodide catalyzed preparation of unsymmetrical ethers by reductive condensation (of carbonyl compounds) with alkoxysilanes.The scope and limitations of the reactions are discussed with emphasis on diastereoselectivity.
- Sassaman, Mark B.,Kotian, Kirtivan D.,Prakash, G. K. Surya,Olah, George A.
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- Kinetics and site requirements of ether disproportionation on γ-Al2O3
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Abstract Measured rates of methyl propyl ether (MPE), an asymmetric ether, conversion on γ-alumina at 623 K verify that hydration rates are negligible compared to disproportionation rates below 2.0 kPa of water. Steady state kinetic measurements establish that diethyl ether (DEE) disproportionation rates possess reaction orders between 0 and 1. A mechanism for DEE disproportionation in which ethanol monomers and reactive ethoxy species are the primary surface species is consistent with measured pressure dependencies. The intrinsic rate constant of DEE disproportionation is nearly identical to that of unimolecular ethanol dehydration, revealing the similarity in the rate-limiting steps of these two reactions. In-situ pyridine titration studies verify that DEE disproportionation and unimolecular ethanol dehydration possess similar site requirements and densities (0.3 and 0.2 sites nm-2, respectively) while bimolecular ethanol dehydration occurs on a separate pool of catalytic sites.
- DeWilde, Joseph F.,Bhan, Aditya
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- Decarboxylation of dialkyl carbonates to dialkyl ethers over alkali metal-exchanged faujasites
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Non-toxic DAlCs, especially lighter dimethyl- and diethyl-carbonate, are regarded as very green alkylating reagents, particularly when coupled with metal-exchanged Y- and X-faujasites as catalysts. These reactions are selective, free from wastes or byproducts, and often require no additional solvent other than the carbonate. Nonetheless, this paper demonstrates that the operating temperature and the nature of the faujasite must be carefully chosen in order to avoid DAlC decomposition. In fact, at temperatures ranging from 150 to 240°C, faujasites can promote decarboxylation of light DAlCs to the corresponding ethers CH3OCH3 and CH3CH 2OCH2CH3 plus CO2. Heavier DAlCs (dipropyl- and dioctyl-carbonate) undergo a similar decomposition pathway, followed by further reactions to the corresponding alcohols (n-propanol and n-octanol) and alkenes [propylene and octene(s)]. These transformations not only consume DAlCs, but also give rise to dangerously flammable ethers, as well as undesirable alcohols, alkenes and CO2. The present work reports an original investigation of the decarboxylation of DAlCs on faujasites with the aim of providing operative boundaries to the experimental conditions to minimise unwanted decomposition. The reaction is strongly affected by the nature of the catalyst: the more basic zeolites, NaX and CsY, are by far more active systems than NaY and LiY. However, solid K2CO3 proves to be rather inefficient. The temperature also plays a crucial role: for example, the onset of the decarboxylation of DMC requires a temperature of ~30°C lower than that for DEC and DPrC. Overall, awareness that certain zeolites cause decomposition of DAlCs under conditions similar to the ones used for DAlC-promoted alkylations allows determination of the correct experimental boundaries for a safer and more productive use of DAlCs as alkylating agents. The Royal Society of Chemistry.
- Selva, Maurizio,Fabris, Massimo,Perosa, Alvise
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- INTRAMOLECULAR COORDINATION BETWEEN MAGNESIUM AND OXYGEN IN CYCLIC ORGANOMAGNESIUM COMPOUNDS
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Association measurements in THF solution reveal that cyclic organomagnesium compounds capable of intramolecular coordination between magnesium and a suitably located oxygen atom in the ring exist exclusively as monomers in THF solution, whereas their oxygen-free analogues have a high tendency to dimerize; 1-oxa-5-magnesacyclooctane (I), 1-oxa-6-magnesacyclodecane (II), its dibenzoanalogue III, and the corresponding di-Grignard reagents IIB and IIIB were investigated.A thermochemical investigation of I-III yielded more quantitative information; the intramolecular coordinative O-Mg bond has been found to be stronger than the intermolecular bond to THF.The ring strain in these compounds is discussed.
- Freijee, F. J. M.,Wal, G. Van Der,Schat, G.,Akkerman, O. S.,Bickelhaupt, F.
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- The adsorption and reaction of alcohols on TiO2 and Pd/TiO 2 catalysts
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The decomposition of alcohols (methanol, ethanol, n-propanol, i-propanol) on TiO2 and Pd/TiO2 catalysts has been studied using temperature programmed desorption. The alcohols mainly decompose via a dehydration pathway on TiO2 catalysts, with no evidence for reactions involving α CC scission or dehydrogenation. However, the reaction pathway was fundamentally altered by the presence of Pd nanoparticles, and products of α CC scission became dominant due to decarbonylation pathways. For the reaction with ethanol, there was no evidence of the dehydration product ethylene even though the surface is mainly composed of titania, indicating that diffusion of alkoxy species from the support to the Pd occurs efficiently during TPD. However, competing dehydration reactions did occur on Pd/TiO2 in the cases of n-propanol and i-propanol decomposition which is postulated to be due to more limited diffusivity of the bulkier alkoxides.
- Bahruji, Hasliza,Bowker, Michael,Brookes, Catherine,Davies, Philip R.,Wawata, Ibrahim
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- Reduction of Propanoic Acid over Pd-Promoted Supported WOx Catalysts
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Silica-, titania-, and zirconia-supported tungsten oxide catalysts were synthesized by wetness impregnation techniques. When promoted with Pd, these materials catalyzed the reduction of propanoic acid to 1-propanol at 433 K with a selectivity of up to 92 % (13.5 % conversion) in atmospheric pressure of H2. Over Pd-promoted WOx/TiO2, the observed orders of reaction were 0.2 in H2 and 0.7 in propanoic acid, and the apparent activation energy was 54 kJ mol?1. In situ X-ray absorption spectroscopy of Pd-promoted WOx/SiO2 revealed a slight reduction of the W from +6 to an average oxidation state of about +5 during H2 treatment above 473 K. In situ infrared spectroscopy indicated the catalyst surface was covered mostly by propanoate species during reaction. For comparison, supported phosphotungstic acid was also evaluated as a catalyst under identical conditions, but the resulting high acidity of the catalyst was deleterious to alcohol selectivity.
- Kammert, James D.,Brezicki, Gordon,Miyake, Naomi,Stavitski, Eli,Davis, Robert J.
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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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- Cobalt-catalyzed alkene hydrogenation by reductive turnover
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Earth abundant metal catalysts hold advantages in cost, environmental burden and chemoselectivity over precious metal catalysts. Differences in reactivity for a given metal center result from ligand field strength, which can promote reaction through either open- or closed-shell carbon intermediates. Herein we report a simple protocol for cobalt-catalyzed alkene reduction. Instead of using an oxidative turnover mechanism that requires stoichiometric hydride, we find a reductive turnover mechanism that requires stoichiometric proton. The reaction mechanism appears to involve coordination and hydrocobaltation of terminal alkenes.
- van der Puyl, Vincent,McCourt, Ruairi O.,Shenvi, Ryan A.
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supporting information
(2021/04/19)
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- Metal-organic frameworks containing nitrogen-donor ligands for efficient catalytic organic transformations
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Metal-organic framework (MOFs) compositions based on nitrogen donor-based organic bridging ligands, including ligands based on 1,3-diketimine (NacNac), bipyridines and salicylaldimine, were synthesized and then post-synthetically metalated with metal precursors, such as complexes of first row transition metals. Metal complexes of the organic bridging ligands could also be directly incorporated into the MOFs. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
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Page/Page column 41-43
(2020/06/03)
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- STABILIZATION OF ACTIVE METAL CATALYSTS AT METAL-ORGANIC FRAMEWORK NODES FOR HIGHLY EFFICIENT ORGANIC TRANSFORMATIONS
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Metal-organic framework (MOFs) compositions based on post?synthetic metalation of secondary building unit (SBU) terminal or bridging OH or OH2 groups with metal precursors or other post-synthetic manipulations are described. The MOFs provide a versatile family of recyclable and reusable single-site solid catalysts for catalyzing a variety of asymmetric organic transformations, including the regioselective boryiation and siiylation of benzyiic C—H bonds, the hydrogenation of aikenes, imines, carbonyls, nitroarenes, and heterocycles, hydroboration, hydrophosphination, and cyclization reactions. The solid catalysts can also be integrated into a flow reactor or a supercritical fluid reactor.
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Paragraph 0247; 0257; 0338
(2019/01/07)
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- Synthesis of Benzyl Alkyl Ethers by Intermolecular Dehydration of Benzyl Alcohol with Aliphatic Alcohols under the Effect of Copper Containing Catalysts
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Synthesis of benzyl alkyl ethers was performed in high yields by intermolecular dehydration of benzyl and primary, secondary, tertiary alcohols under the effect of copper containing catalysts. The formation of benzyl alkyl ethers occurs with participation of benzyl cation.
- Bayguzina,Gimaletdinova,Khusnutdinov
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p. 1148 - 1155
(2018/10/24)
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- Iron-Catalyzed Ring-Closing C?O/C?O Metathesis of Aliphatic Ethers
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Among all metathesis reactions known to date in organic chemistry, the metathesis of multiple bonds such as alkenes and alkynes has evolved into one of the most powerful methods to construct molecular complexity. In contrast, metathesis reactions involving single bonds are scarce and far less developed, particularly in the context of synthetically valuable ring-closing reactions. Herein, we report an iron-catalyzed ring-closing metathesis of aliphatic ethers for the synthesis of substituted tetrahydropyrans and tetrahydrofurans, as well as morpholines and polycyclic ethers. This transformation is enabled by a simple iron catalyst and likely proceeds via cyclic oxonium intermediates.
- Biberger, Tobias,Makai, Szabolcs,Lian, Zhong,Morandi, Bill
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supporting information
p. 6940 - 6944
(2018/05/14)
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- Single-Site Cobalt Catalysts at New Zr8(μ2-O)8(μ2-OH)4 Metal-Organic Framework Nodes for Highly Active Hydrogenation of Alkenes, Imines, Carbonyls, and Heterocycles
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We report here the synthesis of robust and porous metal-organic frameworks (MOFs), M-MTBC (M = Zr or Hf), constructed from the tetrahedral linker methane-tetrakis(p-biphenylcarboxylate) (MTBC) and two types of secondary building units (SBUs): cubic M8(μ2-O)8(μ2-OH)4 and octahedral M6(μ3-O)4(μ3-OH)4. While the M6-SBU is isostructural with the 12-connected octahedral SBUs of UiO-type MOFs, the M8-SBU is composed of eight MIV ions in a cubic fashion linked by eight μ2-oxo and four μ2-OH groups. The metalation of Zr-MTBC SBUs with CoCl2, followed by treatment with NaBEt3H, afforded highly active and reusable solid Zr-MTBC-CoH catalysts for the hydrogenation of alkenes, imines, carbonyls, and heterocycles. Zr-MTBC-CoH was impressively tolerant of a range of functional groups and displayed high activity in the hydrogenation of tri- and tetra-substituted alkenes with TON > 8000 for the hydrogenation of 2,3-dimethyl-2-butene. Our structural and spectroscopic studies show that site isolation of and open environments around the cobalt-hydride catalytic species at Zr8-SBUs are responsible for high catalytic activity in the hydrogenation of a wide range of challenging substrates. MOFs thus provide a novel platform for discovering and studying new single-site base-metal solid catalysts with enormous potential for sustainable chemical synthesis.
- Ji, Pengfei,Manna, Kuntal,Lin, Zekai,Urban, Ania,Greene, Francis X.,Lan, Guangxu,Lin, Wenbin
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supporting information
p. 12234 - 12242
(2016/09/28)
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- Salicylaldimine-based metal - Organic framework enabling highly active olefin hydrogenation with iron and cobalt catalysts
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A robust and porous Zr metal - organic framework, sal-MOF, of UiO topology was synthesized using a salicylaldimine (sal)-derived dicarboxylate bridging ligand. Postsynthetic metalation of sal-MOF with iron(II) or cobalt(II) chloride followed by treatment with NaBEt3H in THF resulted in Fe- and Co-functionalized MOFs (sal-M-MOF, M = Fe, Co) which are highly active solid catalysts for alkene hydrogenation. Impressively, sal-Fe-MOF displayed very high turnover numbers of up to 145000 and was recycled and reused more than 15 times. This work highlights the unique opportunity of developing MOF-based earth-abundant catalysts for sustainable chemical synthesis.
- Manna, Kuntal,Zhang, Teng,Carboni, Micha?l,Abney, Carter W.,Lin, Wenbin
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supporting information
p. 13182 - 13185
(2015/03/30)
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- Propylene from renewable resources: Catalytic conversion of glycerol into propylene
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Propylene, one of the most demanded commodity chemicals, is obtained overwhelmingly from fossil resources. In view of the diminishing fossil resources and the ongoing climate change, the identification of new efficient and alternative routes for the large-scale production of propylene from biorenewable resources has become essential. Herein, a new selective route for the synthesis of propylene from bio-derived glycerol is demonstrated. The route consists of the formation of 1-propanol (a versatile bulk chemical) as intermediate through hydrogenolysis of glycerol at a high selectivity. A subsequent dehydration produces propylene. Renewable propylene: Glycerol, which is abundantly available as by-product of biodiesel production, can be efficiently and selectively converted into propylene by using an integrated process involving the formation of 1-propanol as intermediate (see Scheme), thus offering a promising opportunity to meet the growing worldwide propylene demand and supply shortage.
- Yu, Lei,Yuan, Jing,Zhang, Qi,Liu, Yong-Mei,He, He-Yong,Fan, Kang-Nian,Cao, Yong
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p. 743 - 747
(2014/03/21)
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- METHODS OF CONVERTING POLYOLS
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Methods for converting polyols are provided. The methods provided can include using a metal pincer catalyst (e.g., an iridium pincer catalyst) to remove at least one alcohol group from a polyol. The methods provided can include converting glycerol to 1,3-propanediol.
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Paragraph 0088-0090; sheet 1
(2015/01/06)
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- Conversion of fructose into 5-hydroxymethylfurfural and alkyl levulinates catalyzed by sulfonic acid-functionalized carbon materials
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A series of sulfonic acid-functionalized carbon materials (C-SO 3H), including poly(p-styrenesulfonic acid)-grafted carbon nanotubes (CNT-PSSA), poly(p-styrenesulfonic acid)-grafted carbon nanofibers (CNF-PSSA), benzenesulfonic acid-grafted CMK-5 (CMK-5-BSA), and benzenesulfonic acid-grafted carbon nanotubes (CNT-BSA), have been studied for fructose dehydration to 5-hydroxymethylfurfural (HMF) and fructose alcoholysis to alkyl levulinate. A study for optimizing the reaction conditions such as the catalyst loading, the reaction time, and the temperature has been performed. Under the optimal conditions, high HMF and ethyl levulinate yields of up to 89% and 86%, respectively, are obtained. The catalytic activities of C-SO3H for the conversions of fructose into both HMF and ethyl levulinate follow the order of their acid strength. The relationship between the catalytic activity and acid density of C-SO3H shows a linear correspondence in the fructose dehydration to HMF. The facile separation, ease of recovery, and high thermal stability make the developed C-SO3H efficient and environment-friendly catalytic materials for transforming biomass carbohydrate into fine chemicals.
- Liu, Ruliang,Chen, Jinzhu,Huang, Xing,Chen, Limin,Ma, Longlong,Li, Xinjun
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supporting information
p. 2895 - 2903
(2013/10/08)
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- Reversible O -ylide formation in carbene/ether reactions
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p-Nitrophenylchlorocarbene reacted reversibly with diethyl ether, di-n-propyl ether, or tetrahydrofuran (THF) to form O-ylides, which were visualized by their UV-visible spectroscopic signatures. Equilibrium constants (Keq) were determined spectroscopically and ranged from 0.10 M -1 (di-n-propyl ether) to 7.5 M-1 (THF) at 295 K. Studies of Keq as a function of temperature afforded δHo, δSo, and δGo for the di-n-propyl ether and THF/O-ylide equilibria. δHo was favorable for ylide formation, but δSo was quite negative, so that δGos for the equilibria were small. Electronic structure calculations based on density functional theory provided structures, spectroscopic signatures, and energetics for the carbene/ether O-ylides.
- Hoijemberg, Pablo A.,Moss, Robert A.,Krogh-Jespersen, Karsten
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experimental part
p. 358 - 363
(2012/03/12)
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- Rhodium-catalyzed, efficient deutero- and tritiosilylation of carbonyl compounds from hydrosilanes and deuterium or tritium
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A cationic rhodium compound which is an active catalyst for both the hydrogen isotope exchange in hydrosilanes and the hydrosilylation of carbonyl compounds permits, in a one-flask, two-step procedure, efficient deutero- and tritiosilylations using SiEt3H under D2 (0.5 bar) or T2, at low catalyst loadings (0.1-0.5 mol %).
- Rubio, Miguel,Campos, Jesuus,Carmona, Ernesto
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supporting information; experimental part
p. 5236 - 5239
(2011/12/15)
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- Alcohol Dehydration
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Catalyst compositions are disclosed exhibiting activity for dehydrating an alcohol, the composition comprising a source of a Group VIII transition metal, an organic salt, an acid and/or a compound consisting of a conjugate base of an acid bonded to a radical of the alcohol to be dehydrated and, optionally, a ligand. Also disclosed are methods of converting an alcohol into a product using the catalyst composition. The product of the methods may be predominately alkene or ether depending on the method. In some embodiments of the method a second catalyst for converting a product into a further product may be present.
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Page/Page column 5
(2010/11/03)
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- Etherification of aldehydes, alcohols and their mixtures on Pd/SiO2 catalysts
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Dialkyl ethers have been selectively produced from etherification of aldehydes and alcohols on supported Pd catalysts. A yield of 79% ether with a selectivity of 90% was observed when feeding 2-methylpentanal with 2-methylpentanol at a molar ratio 1:1 at 125 °C. Cross etherification of n-butanol with 2-methylpentanal shows a much higher rate than that observed when the alcohol or aldehyde is fed alone. This enhanced activity is in line with the catalyst requirement for large ensembles that allow surface alkoxide species next to η2 adsorbed aldehydes. Etherification when only aldehyde or alcohol is fed arises predominantly due to aldehyde-alcohol inter-conversion to produce the necessary co-reactant. The ether yield at the same reaction conditions decreases with metal loading in the order 16 > 10 > 3 wt.% Pd. Increasing reduction temperature also increases ether yield. It is apparent that etherification is highly sensitive to metal particle morphology, consistent with needing ensembles that accommodate the two adjacent adsorption sites.
- Pham, Trung T.,Crossley, Steven. P.,Sooknoi, Tawan,Lobban, Lance L.,Resasco, Daniel E.,Mallinson, Richard G.
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experimental part
p. 135 - 140
(2010/09/05)
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- Catalytic deoxygenation of 1,2-propanediol to give n-propanol
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Deoxygenation of 1,2-propanediol (1.0M in sulfolane) catalyzed by bis(dicarbonyl)(μhydrido)(pentamethylcyclopentadiene)ruthenium trifluoromethanesulfonate ({[Cp*Ru(CO)2]2(μ.-H)} +OTf-) (0.5 mol%) at 110°C under hydrogen (750 psi) in the presence of trifluoromethanesulfonic acid (HOTf) (60 mM) gives n-propanol as the major product, indicating high selectivity for deoxygenation of the internal hydroxy group over the terminal hydroxy group of the diol. The deoxygenation of 1,2-propanediol is strongly influenced by the concentration of acid, giving faster rates and proceeding to higher conversions as the concentration of HOTf is increased. Propionaldehyde was observed as an intermediate, being formed through acid-catalyzed dehydration of 1,2-propanediol. This aldehyde is hydrogenated to n-propanol through an ionic pathway involving protonation of the aldehyde, followed by hydride transfer from the neutral hydride, dicarbonyl(pentamethylcyclopentadiene)ruthenium hydride [Cp*Ru(CO)2H]. The proposed mechanism for the deoxygenation/hydrogenation reaction involves formation of a highly acidic dihydrogen complex [Cp*Ru(CO)2(η2-H 2)]+ OTf-.
- Schlaf, Marcel,Ghosh, Prasenjit,Fagan, Paul J.,Hauptman, Elisabeth,Morris Bullock
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body text
p. 789 - 800
(2009/12/03)
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- CATALYSTS, SYSTEMS AND METHODS FOR ETHER SYNTHESIS
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The present invention relates to methods and catalysts for synthesizing ethers. In an embodiment, the invention includes a process for synthesizing ethers from an alcohol feedstock including heating the alcohol feedstock to a temperature greater than about 100 degrees Celsius; and contacting the alcohol feedstock with a catalyst comprising a metal oxide selected from the group consisting of titania and alumina. Other embodiments are also described herein.
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Page/Page column 7-8
(2009/01/24)
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- METHOD FOR PRODUCING BIO-FUEL THAT INTEGRATES HEAT FROM CARBON-CARBON BOND-FORMING REACTIONS TO DRIVE BIOMASS GASIFICATION REACTIONS
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A low-temperature catalytic process for converting biomass (preferably glycerol recovered from the fabrication of bio-diesel) to synthesis gas (i.e., H2/CO gas mixture) in an endothermic gasification reaction is described. The synthesis gas is used in exothermic carbon-carbon bond-forming reactions, such as Fischer-Tropsch, methanol, or dimethylether syntheses. The heat from the exothermic carbon-carbon bond-forming reaction is integrated with the endothermic gasification reaction, thus providing an energy-efficient route for producing fuels and chemicals from renewable biomass resources.
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Page/Page column 14-15; 17
(2008/06/13)
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- Reaction network of aldehyde hydrogenation over sulfided Ni-Mo/Al 2O3 catalysts
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A reaction network of aldehyde hydrogenation over NiMoS/Al 2O3 catalysts was studied with aldehydes with straight and branched carbon chains and different chain lengths as feed materials. The reactions in the gas phase and the liquid phase were compared. The main reaction in the aldehyde hydrogenation process is the hydrogenation of the CO double bond, which takes place over the coordinatively unsaturated sites. The major side reactions are self-condensation of aldehydes and condensation of aldehydes with alcohols. Both reactions involve α-hydrogen and are primarily catalyzed by acid-base bifunctional sites over the exposed Al2O 3 surfaces.
- Wang, Xueqin,Saleh, Ramzi Y.,Ozkan, Umit S.
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- Catalytic dehydroxylation of diols and polyols
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Secondary alcohols, specifically diols and polyols, are dehydroxylated to the corresponding primary alcohols using a homogeneous organometallic ruthenium complex catalyst.
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- Generation of alkyl hypochlorites in oxidation of alcohols with carbon tetrachloride catalyzed by vanadium and manganese compounds
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Primary alcohols and diols with various structures were subjected to transformations into esters, aldehydes, ketones, and lactones under the action of carbon tetrachloride in the presence of manganese compounds (MnCl 2, MnO2, Mn(OAc)2, Mn(acac)3) and vanadium compounds (VCl5, V2O5, VO(acac) 2) as catalysts. These transformation proceeded with the involvement of alkyl hypochlorites, which were generated in the course of oxidation of alcohols with carbon tetrachloride catalyzed by manganese or vanadium compounds. The optimum molar ratios between the catalyst and reagents were determined, and the reaction conditions for the highly selective synthesis of esters, aldehydes, ketones, and lactones from alcohols were found.
- Khusnutdinov,Shchadneva,Baiguzina,Lavrentieva,Dzhemilev
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p. 2074 - 2079
(2007/10/03)
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- Metal-catalyzed selective deoxygenation of diols to alcohols
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The internal OH group of 1,2-propanediol is selectively removed in the deoxygenation catalyzed by [{Cp*Ru(CO)2}2(μ-H)]+OTf - (1, Cp=C3Me5, OTf=trifluoromethanesulfonate; see scheme). This reaction provides a model for deoxygenation of polyols derived from carbohydrates, for use in alternative, biomass-based feedstock applications. An ionic mechanism is proposed that involves the dihydrogen complex [Cp*Ru(CO)2(η2-H2)]+.
- Schlaf, Marcel,Ghosh, Prasenjit,Fagan, Paul J.,Hauptman, Elisabeth,Morris Bullock
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p. 3887 - 3890
(2007/10/03)
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- The continuous acid-catalyzed dehydration of alcohols in supercritical fluids: A new approach to the cleaner synthesis of acetals, ketals, and ethers with high selectivity
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We report a new continuous method for forming ethers, acetals and ketals using solid acid catalysts, DELOXAN ASP or AMBERLYST 15, and supercritical fluid solvents. In the case of ether formation, we observe a high selectivity for linear alkyl ethers with little rearrangement to give branched ethers. Such rearrangement is common in conventional syntheses. Our approach is effective for a range of n-alcohols up to n-octanol and also for the secondary alcohol 2-propanol. In the reaction of phenol with an alkylating agent, the continuous reaction can be tuned to give preferential O- or C- alkylation with up to 49% O-alkylation with supercritical propene. We also investigate the synthesis of a range of cyclic ethers and show an improved method for the synthesis of THF from 1,4-butandiol under very mild conditions.
- Gray, William K.,Smail, Fiona R.,Hitzler, Martin G.,Ross, Stephen K.,Poliakoff, Martyn
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p. 10711 - 10718
(2007/10/03)
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- Hydrogen bonding Part 44 1Thermodynamics of complexation of 3,5-dichlorophenol with ketones and ethers in cyclohexane: The badger-Bauer relationship
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Equilibrium constants for 1 : 1 hydrogen bond complexation between 3,5-dichioropheno' (DCP) and 17 ketones and 12 ethers in cyclohexane solution have been obtained by an FTIR method that takes into account both diiaerization of the acid and formation of 2 :1 complexes. Enthalpies of complexation for the same ketones and ethers have been determined by a calorimeiric method, leading to values of log K, AG, AH and AS0 for 1 :1 complexation in the 29 systems, as well as log K2 for the 2 :1 complexation between 2 mol of acid and 1 mol of base. For the ketone systems there is very little variation in the three thermodynamic parameters with alkyl substitution, but for the ethers there are systematic variations depending on the alkyl substituent or if the ethers are cyclic. Values of the OH stretching frequency in the DCP complexes with the ketones and ethers in cyclohexane have been obtained. The band shapes for the DCP-ketone complexes are very asymmetric, possibly due to the presence of stereoisomeric complexes, but the VOH band for DCP-ether complexes is symmetric and very suitable for the evaluation of any relationship between v()H and A/f. It is found that for the complexation of DCP with the 12 aliphatic ethers in cyclohexane, there is almost no connection between the calorimetrically determined AH° values and values of AvOH.
- Abraham, Michael H.,Prior, David V.,Schulz, Ronald A.,Morris, Jeffrey J.,Taylor, Peter J.
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p. 879 - 885
(2007/10/03)
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- Cholesterol lowering compounds
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Disclosed herein are compounds of structural formula (I) STR1 which are useful as cholesterol lowering agents. These compounds are also useful as inhibitors of squalene synthetase, inhibitors of fungal growth, inhibitors of farnesyl-protein transferase and farnesylation of the oncogene protein Ras. These compounds are also useful in the treatment of cancer.
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- Hydrolysis and Alcoholysis of Esters of o-Nitrobenzenesulfonic Acid
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The rate of solvolysis of esters of o-nitrobenzenesulfonic acid with water and C1-C4 alcohols is satisfactorily described by two-parametric Hammett-Taft equation with predominating effect of the electronic factor σ*. The effect of the structure of the hydrocarbon rest in the sulfonic ester group does not fit to this relationship.
- Sendega,Makitra,Pirig
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p. 1438 - 1446
(2007/10/03)
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- Anionic ruthenium iodocarbonyl complexes as selective dehydroxylation catalysts in aqueous solution
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The selective dehydroxylation in aqueous solution of C3-C5 polyols and C6 sugars in the presence of homogeneous ruthenium iodocarbonyl catalysts, - species, has been studied.Glycerol, pure or in dilute aqueous solution, is dehydroxylated to give n-propanol and its ethers with selectivities of up to 90percent.Xylitol and C6 sugars, glucose and fructose, are dehydrated and hydrogenated through initial formation of levulinic acid to give γ-valerolactone with high yields.The dehydroxylation of these polyhydroxylic substrates is made possible in water solution bythe bifunctional nature (acidity and hydrogenating ability) of the ruthenium catalystic system.The requirements necessary for the catalytic system to be active and stable in water have been studied, and the mechanism of the reaction discussed.
- Braca, Giuseppe,Galletti, Anna Maria Raspolli,Sbrana, Glauco
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- Reactivities of Carbonyl Compounds in Acid-Catalyzed Hydride Transfer vs. Electron Transfer
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Rate constants for acid-catalyzed hydride-transfer reactions from triethylsilane to a series of carbonyl compounds are compared with those for acid-catalyzed electron transfer from the excited state of 2+ to the same series of carbonyl compounds in the presence of HClO4 in acetonitrile at 298 K.
- Fukuzumi, Shunichi,Fujita, Morifumi
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p. 2059 - 2062
(2007/10/02)
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- Synthesis and Crystal Structure of . Hydrogenation-Dehydrogenation Reactions of Dienes and Alcohols with Heterogeneous Catalysts derived from
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The complex 2(μ-Cu(PPh3))(CO)9> has been synthesized in tetrahydrofuran (thf) by reaction of the anion 2(CO)9>-, generated in situ from 3(CO)9> and NaH, with 4>.Its structure has been determined by X-ray methods.Crystals are triclinic, space group P(*) with Z = 2 in a unit cell of dimensions a = 13.643(7), b = 14.120(6), c = 9.504(4) Angstroem, α = 94.88(3), β = 105.77(4), and γ = 102.15(3) deg.The structure has been solved from diffractometer data by direct and Fourier methods and refined by full-matrix least squares to R = 0.0462 for 2 191 observed reflections.The metal cluster can be described as a NiOs3 tetrahedron with an Os-Os edge bridged by the Cu atom from the Cu(PPh3) group.This complex, supported on Chromosorb and thermally activated under H2, forms a heterogeneous catalyst for the hydrogenation-dehydrogenation of several substrates, in particular alcohols.The behaviour of this catalyst is significantly different from that of systems derived from the parent cluster or from .In particular, it shows high dehydrogenation ability.
- Castagno, Fabrizio,Castiglioni, Mario,Sappa, Enrico,Tiripicchio, Antonio,Camellini, Marisa Tiripicchio,et al.
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p. 1477 - 1482
(2007/10/02)
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- Hydrocarbonylation of linear and branched aliphatic C2-C4 alcohols catalyzed by cobalt-ruthenium systems. A comparative study.
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In an extension of studies of the hydrocarbonylation of C2-C4 alcohols in the presence of a bimetallic catalyst system at high Syngas pressures to yield the next higher homologue, the effect of the catalytic system based on cobalt and ruthenium compounds promoted by iodine or iodides has been examined.For the optimal Co/Ru ratio the selectivity for the higher alcohol is highest because of a large decrease in the extent of hydrocarbon and ether formation.Neither this ratio nor the optimal pressure depends on the structure of the alcohol.It is suggested that the synergism observed in Co-Ru-catalyzed hydrocarbonylation of alcohols is due to a cocatalytic effect of the Ru catalyst involving reaction of ruthenium hydrides with acyl-cobalt complexes.The mechanism is consistent with the suggestion that there is an intermediate olefin that undergoes hydroformylation in a subsequent step.
- Jenner, Gerard
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p. 237 - 252
(2007/10/02)
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- Continuous Conversion of Alcohols into Alkyl Halides by Gas-Liquid Phase-Transfer Catalysis (G.L.-P.T.C)
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A solution of a primary alcohol (propan-1-ol, butan-1-ol, and pentan-1-ol) in an aqueous halogen acid (hydrochloric or hydrobromic acid) when passed in the gaseous state over a solid porous bed (silica gel) supporting a catalyst, affords the corresponding alkyl halide.The reagent mixture is introduced continuously into a column maintained at 170 deg C and the product is collected at the outlet.Since the process is catalytic, the bed is not consumed during the reaction.The reaction by-products depend on the type of catalyst used: Lewis acids (ZnCl2, AlCl3) lead to large quantities of alkenes and isomeric halides, while under typical g.l.- p.t.c. conditions, with a phosphonium salt as the catalyst, only the corresponding dialkyl ether, in addition to the primary alkyl halide, is obtained.The yield of the ether can be reduced progessively to zero by increasing the contact time between the reaction mixture and the catalytic bed.
- Tundo, Pietro,Venturello, Paolo,Angeletti, Enrico
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p. 2157 - 2158
(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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- RING SIZE EFFECTS ON THE GAS PHASE PROTONATION OF CYCLIC KETONES
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Experimental proton affinities of cyclic ketones are determined showing evidence for a larger strain energy in protonated vs. neutral cyclic ketones.
- Bouchoux, G.,Houriet, R.
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p. 5755 - 5758
(2007/10/02)
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- Carbon-Hydrogen Bond Dissociation Energies in Alkylbenzenes. Proton Affinities of the Radicals and the Absolute Proton Affinity Scale
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Rate constants (k) were measured for proton-transfer reactions from alkylbenzene ions RH+ to a series of reference bases B, i.e., RH+ + B -> BH+ + R*.For exothermic reactions (ΔH -1.For example, the reaction C6H5CH3+ + B -> BH+ + C6H5CH2* is fast (reaction efficiency = k/kcol >/= 0.5) when B = MeO-t-Bu or stronger bases, but k/kcol is significantly smaller when B is n-Pr2O or weaker bases.From the falloff curve of reaction efficiency vs.PA(B), we find PA(n-Pr2O) = PA(C6H5CH2*) + 0.8 kcal mol-1 = 200.0 kcal mol-1.Since PA(C6H5CH2*) is obtained from known thermochemical data, this relation defines the absolute PA of n-Pr2O.Through a ladder of known PA, we then obtain PA(i-C4H8) = 186.8 kcal mol-1; we also obtain the absolute PAs of other oxygen bases.Falloff curves of reaction efficiencies of 3-FC6H4CH3+, C6H5C2H5+, C6H5-n-C3H7+, and C6H5-i-C3H7+ with these reference bases give then the following PAs of R* and R-H bond dissociation energies (Do) (all in kcal mol-1) as R*, PA(R*), Do(R-H): 3-FC6H4CH2*, 197.2, 89.4; , 197.9, 86.2; , 199.1, 86.1; , 199.6, 86.1.In similar manner, rate constants for H+ transfer from C6H5NH2+ to reference pyridines and amines yield PA(C6H5NH*) = 221.5 and Do(C6H5NH-H) = 85.1 kcal mol-1 (1 kcal mol-1 = 4.18 kJ mol-1).
- Meot-Ner (Mautner), Michael
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- Oxonium Ions. Solvation by Single Acetonitrile Molecules in the Gas Phase and by Bulk Solvents
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The standard free energy of formation of gaseous complexes between monoprotonic oxonium ions and acetonitrile have been obtained by using the ion cyclotron resonance equilibrium constant method for exchange of acetonitrile between the ions.The results show that the "solvation" by a single molecule of acetonitrile in the gas phase reproduces the important diverse effects of molecular structure on oxonium ion solvation by bulk water.It is estimated from the present results that the effects of solvation by bulk water are only about three times as great as the corresponding effects of "solvation" by a single water molecule in the gas phase.Internal charge delocalization from the protonic site of the oxonium ions may be reversed by differential solvation, both with single H-bonding molecules in the gas phase and with bulk solvent.Further evidence for the site of preffered protonation of esters and amides is provided.
- Bromilow, J.,Abboud, J. L. M.,Lebrilla, C. B.,Taft, R. W.,Scorrano, G.,Lucchini V.
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p. 5448 - 5453
(2007/10/02)
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- Chemical Conversions using Sheet Silicates: Novel Intermolecular Dehydrations of Alcohols to Ethers and Polymers
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Aliphatic primary alcohols, when intercalated in certain ion-exchanged montmorillonites, react preferentially via an intermolecular nucleophilic displacement of water to give high yields of di-(alk-1-yl) ethers, rather than the competitive intramolecular dehydration to alkenes; an essentially similar process yields polymeric material, poly(phenylenemethylene), from benzyl alcohol, but aliphatic secondary and tertiary alcohols, in contrast, yield alkenes almost exclusively.
- Ballantine, James A.,Davies, Mary,Purnell, Howard,Rayanakorn, Mongkon,Thomas, John M.,Williams, Kevin J.
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p. 427 - 428
(2007/10/02)
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- THE EFFECT OF PARTIAL EXCHANGE OF SULPHONATED MACROPOROUS STYRENE-DIVINYLBENZENE COPOLYMERS FOR DIFFERENT IONS ON THEIR CATALYTIC ACTIVITY
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The catalytic activity of sulphonated macroporous styrene-divinylbenzene copolymers, the exchange capacity of which was neutralized from 30, 50 and 80percent by Fe(III) ions and from 30percent by Na ions and that of Wofatit Y-37 ion exchanger neutralized from 10percent of its total exchange capacity by several transition metal ions and by sodium has been studied in isomerization of cyclohexene and dehydration of 1-propanol in the gas phase at 130 deg C.It was demonstrated that in both reactions transition metal ions exhibit additional effect to the expected neutralization of the polymer acid groups.In the case of cyclohexene isomerization, this effect depends on the degree of crosslinking of polymer mass of the catalyst.Such dependence has not been, however, observed in dehydration of 1-propanol.The type of transition metal ions did not exhibit any significant effect on the catalytic activity of the polymer catalysts studied.
- Kmostak, Svatomir,Setinek, Karel
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p. 2354 - 2363
(2007/10/02)
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