- Methane oxidation to methyl bisulfate in oleum at ambient pressure in the presence of iodine as a catalyst
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Methane oxidation to methyl bisulfate at ambient pressure in absorption reactor packed with glass balls in presence of iodine as a catalyst was investigated. The process was performed at temperature 120-130 °C, sulfur trioxide concentration in oleum 16-25 wt.%, catalyst concentration 0.008-0.024 mol dm-3, methane flow: 8.69 cm3 min-1. The optimal conditions for high ester concentration were defined.
- Michalkiewicz, Beata
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Read Online
- Direct methane conversion to methanol by ionic liquid-dissolved platinum catalysts
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Ternary systems of inorganic Pt salts and oxides, ionic liquids and concentrated sulfuric acid are effective at catalyzing the direct, selective oxidation of methane to methanol and appear to be more water tolerant than the Catalytica reaction. The Royal Society of Chemistry 2006.
- Cheng, Jihong,Li, Zaiwei,Haught, Mark,Tang, Yongchun
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Read Online
- Sulfation of polysaccharides using monomethyl sulfate
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The polysaccharides, curdlan, starch and dextran were sulfated when heated in DMSO with sodium methyl sulfate and a catalytic amount of H2SO4 or with pyridinium methyl sulfate. Use of diminished pressure and anhydrous CaSO4 as a desiccant improved the degree of sulfation and recovery. Under conditions using sodium methyl sulfate, H2SO4 and CaSO4 in vacuo, sulfation at 0-6 was predominant in the cases of curdlan and starch, while sulfation at O-2 and O-3 was preferential in the case of dextran.
- Takano, Ryo,Nagai, Tomomi,Wu, Xiaofen,Xu, Xin-Yan,Huy, Nguyen Tien,Kamei, Kaeko,Hara, Saburo
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Read Online
- High yield conversion of methane to methyl bisulfate catalyzed by iodine cations
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Iodine in 2% oleum is an efficient catalyst for the selective, high yield oxidation of methane to methyl bisulfate.
- Periana, Roy A.,Mirinov, Oleg,Taube, Douglas J.,Gamble, Scott
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Read Online
- Uptake of methanol vapor in sulfuric acid solutions
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The uptake of gas-phase methanol by liquid sulfuric acid has been investigated over the composition range of 40-85 wt% H2SO4 and the temperature range of 210-235 K. Laboratory studies were performed with a flow-tube reactor coupled to an electron-impact ionization mass spectrometer to detect trace gases. While reversible uptake was the primary mechanism at low acid concentrations, an irreversible reaction between methanol and sulfuric acid at low temperatures, forming methyl hydrogen sulfate and dimethyl sulfate, was observed at all concentrations. At compositions >65 wt% H2SO4, more than 90% of uptake was found to be reactive. On the basis of the uptake data and the calculated liquid-phase diffusion coefficients, the product of the effective Henry's law constant (H*) and the square root of the overall liquid-phase reaction rate (k1) was calculated as a function of acid concentration and temperature. The results suggest that the reaction with sulfuric acid forming methyl hydrogen sulfate and dimethyl sulfate is the dominant loss mechanism of methanol and that the oxidation of methanol is only a minor source of hydroxyl radicals in the upper troposphere.
- Kane, Scan M.,Leu, Ming-Taun
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Read Online
- Methods for producing a methanol precursor, methanol, and a methyl ester from methane in high purities
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A method for producing a methanol precursor, methyl trifluoroacetate, having high-purity includes the steps of (a) preparing methyl bisulfate by mixing a catalyst with an acid solution comprising a sulfur-containing acid to provide a first mixture and supplying methane gas to the first mixture to prepare the methyl bisulfate; and (b) preparing methyl trifluoroacetate (CF3CO2CH3) by adding trifluoroacetic acid (CF3CO2H) to the first mixture including the methyl bisulfate to provide a second mixture and distilling the second mixture under heating to prepare, separate and purify the methyl trifluoroacetate (CF3CO2CH3). Methanol may be produced by adding water to the methyl trifluoroacetate (CF3CO2CH3). A methyl ester represented by Formula 2 below may be produced by adding a carboxylic acid represented by Formula 1 below to the methyl trifluoroacetate (CF3CO2CH3): R1CO2H??(1),where R1 is selected from C1-C10 alkyl groups, R1CO2CH3??(2),where R1 is as defined in Formula 1.
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Page/Page column 10
(2021/06/02)
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- Theory and Experiment Demonstrate that Sb(V)-Promoted Methane C-H Activation and Functionalization Outcompete Superacid Protonolysis in Sulfuric Acid
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Sb(V) in strong Br?nsted acid solvents is traditionally assumed to react with light alkanes through superacid protonolysis, which results in carbocation intermediates, H2, and carbon oligomerization. In contrast to this general assumption, our density functional theory (DFT) calculations revealed an accessible barrier for C-H activation between methane and Sb(V) in sulfuric acid that could potentially outcompete superacid protonolysis. This prompted us to experimentally examine this reaction in sulfuric acid with oleum, which has never been reported because of presumed superacid reactivity. Reaction of methane at 180 °C for 3 h resulted in very high yields of methyl bisulfate without significant overoxidation. Our DFT calculations show that a C-H activation and Sb-Me bond functionalization mechanism to give methyl bisulfate outcompetes methane protonolysis and many other possible reaction mechanisms, such as electron transfer, proton-coupled electron transfer, and hydride abstraction. Our DFT calculations also explain experimental hydrogen-deuterium exchange studies and the absence of methane carbo-functionalization/oligomerization products. Overall, this work demonstrates that in very strong Br?nsted acid solvent, Sb(V) can induce innersphere reaction mechanisms akin to transition metals and outcompete superacid reactivity.
- Chen, Shu-Sen,Ess, Daniel H.,Koppaka, Anjaneyulu,Periana, Roy A.
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supporting information
p. 18242 - 18250
(2021/11/12)
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- Preparation method of cefpodoxime acid
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The invention discloses a preparation method of cefpodoxime acid. The method comprises the following steps: adding a proper amount of solvent, 7-amino-3-chloromethyl cephalosporanic acid as shown in a formula (III), sodium methoxide, a quaternary ammonium salt catalyst and potassium iodide into a reaction container, performing stirring reaction at 0-80 DEG C for 2-8 hours, then adding 2-(2-amino-4-thiazolyl)-2-(Z)-methoxy imino acetyl chloride as shown in a formula (IV), performing stirring reaction at 0-30 DEG C for 2-5 hours, and after the reaction is finished, performing post-treatment to obtain cefpodoxime acid as shown in a formula (II). The method is simple and easy to operate, high in reaction yield, green and environmentally friendly, avoids the use of inflammable and explosive raw materials with high toxicity, improves the purity of the product by the post-treatment process, and is suitable for industrial production.
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Paragraph 0028
(2021/07/31)
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- BISPHENOL COMPOSITION CONTAINING AROMATIC ALCOHOL SULFONATE AND METHOD FOR PRODUCING SAME, POLYCARBONATE RESIN AND METHOD FOR PRODUCING SAME, AND BISPHENOL PRODUCTION METHOD
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A bisphenol composition including a specific amount of aromatic alcohol sulfonate, and a simple method of producing it are provided. Also provided is a method of producing a polycarbonate resin in which, by using the bisphenol composition including a specific amount of aromatic alcohol sulfonate, melt polymerization reaction can be efficiently allowed to proceed to produce a polycarbonate resin having an excellent color tone. A bisphenol composition including an aromatic alcohol sulfonate at not less than 0.1 ppb by mass with respect to a bisphenol. A method of producing a bisphenol composition, including reacting a ketone or an aldehyde with an aromatic alcohol in the presence of sulfuric acid to produce a bisphenol composition. A method of producing a polycarbonate resin, including producing a polycarbonate resin using the bisphenol composition. A polycarbonate resin including a specific amount of aromatic alcohol sulfonate.
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Paragraph 0253; 0255; 0257; 0258; 0264; 0265
(2020/07/07)
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- Pt black catalyzed methane oxidation to methyl bisulfate in H2SO4-SO3
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Although chloride-ligated Pt compounds like (bpym)PtCl2, K2PtCl4, and (DMSO)2PtCl2 has been reported to be highly active catalysts for the methane oxidation to methyl bisulfate (MBS) in oleum media, their applications is hampered by the catalyst deactivation to PtCl2. In this study, we investigated Pt black catalyzed methane oxidation, which has no ligand. A MBS yield of 82.1% with a selectivity of 96.5% was obtained at a catalyst loading of 1.6 mM at 180 °C, which proved the highest catalytic activity of Pt-black for this reaction. The reaction was thought to proceed by the dissolved Pt species, and no deactivation was observed during four consecutive experiments. However, at a concentration of over 30 mM, MBS yield fell due to the decomposition of MBS to CO2 on the surface of heterogeneous Pt(0). Vacuum distillation experiments showed the potential for isolating MBS from the oxidation product mixture as a major component.
- Lee, Hee Won,Dang, Huyen Tran,Kim, Honggon,Lee, Ung,Ha, Jeong-Myeong,Jae, Jungho,Cheong, Minserk,Lee, Hyunjoo
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p. 230 - 236
(2019/05/17)
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- Enhanced Catalytic Activity of (DMSO)2PtCl2 for the Methane Oxidation in the SO3-H2SO4 System
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Among the various methane activation reactions, oleum-mediated (SO3-H2SO4) methane oxidation to methyl bisulfate (MBS), a methanol precursor, is one of the best methods in terms of methane conversion and product selectivity. In this report, we investigated the effect of the catalyst concentration on the MBS yield using the catalyst systems (bpym)PtCl2, K2PtCl4, and (DMSO)2PtCl2 at 180 °C for 3 h. (bpym)PtCl2 showed a very high stability as well as a high MBS yield of over 84%, but its catalytic activity expressed in terms of turnovers for 3 h was in the range 50-500. K2PtCl4 showed very high catalyst turnovers of over 17 000 at a low catalyst concentration; however, it deactivated rapidly to PtCl2 which prevents achieving a high MBS yield that was achieved by (bpym)PtCl2. However, (DMSO)2PtCl2 showed an enhanced catalytic performance for both the MBS yield and the turnovers. An MBS yield of over 84% with a selectivity of 94% was obtained at a catalyst concentration of 3.0 mM, and its turnovers reached over 19 000 at a low catalyst concentration. This higher catalytic performance of (DMSO)2PtCl2 compared to the other chloride-ligated Pt compounds is due to the DMSO ligand on the Pt, which increases the solubility of the Pt species in oleum. Furthermore, as the DFT study revealed, the low dissociation energy of DMSO from the Pt center can facilitate the coordination of methane on the Pt reaction center. Although (DMSO)2PtCl2 was deactivated to PtCl2 after the reaction like the other Pt compounds with the chloride ligand, it can be reactivated to some extent by adding DMSO.
- Dang, Huyen Tran,Lee, Hee Won,Lee, Jieon,Choo, Hyunah,Hong, Soon Hyeok,Cheong, Minserk,Lee, Hyunjoo
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p. 11854 - 11862
(2019/01/03)
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- CATALYST FOR SYNTHESIZING METHANOL OR ITS PRECURSOR, METHOD FOR PREPARING THE CATALYST AND METHOD FOR PRODUCING METHANOL OR ITS PRECURSOR USING THE CATALYST
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Disclosed is a novel catalyst having amine ligands for synthesizing methanol or its precursor. When the catalyst is allowed to react with an alkane in the presence of an acid, at least one C—H bond of the alkane is catalytically oxidized. Therefore, the catalyst is suitable for use in forming an alkyl ester from an alkane.
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Paragraph 0093-0110
(2018/05/16)
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- CATALYST FOR PRODUCING METHANOL PRECURSOR, METHANOL PRECURSOR PRODUCED USING THE CATALYST AND METHANOL PRODUCED USING THE METHANOL PRECURSOR
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Disclosed is a novel catalyst for producing a methanol precursor. The use of the catalyst enables the production of a methanol precursor and methanol with high efficiency under low temperature and low pressure conditions. Also disclosed are a methanol precursor produced using the catalyst and methanol produced using the methanol precursor.
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Paragraph 0081-0083; 0094-0100
(2018/07/15)
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- Synthesis method of cefpodoxime proxetil intermediate
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The invention discloses a synthesis method of a cefpodoxime proxetil intermediate, namely (6R,7R)-7-[2-(2-amino-4-thiazolyl)-(Z)-2-(methoxyimino)acetamido]-3-methoxymethyl-8-oxo-5-thio-1-azabicyclo[4.2.0]oct-2-ene-2-methanoic acid. The synthesis method includes: enabling chlorosulfonic acid and methanol to react to prepare methoxy sulfonic acid; under the action of the methoxy sulfonic acid and dimethylformamide, etherifying 7-ACA (7-aminocephalosporanic acid) and trimethyl borate prior to aftertreatment, adding into a water and methanol solution reversely to guarantee that the obtained intermediate isn't sticky and is loose, drying and grafting with AE active ester so as to obtain a target product, namely the cefpodoxime proxetil intermediate. The synthesis method of the cefpodoxime proxetil intermediate has the advantages that synthesis steps of 3-position and 7-position protection and desorption of 7-ACA can be omitted, so that low step cost, high yield and high purity are achieved, all materials are cheap and available, and industrial production and little pollution are benefited.
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Paragraph 0008
(2016/11/09)
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- Direct methane oxidation over Pt-modified nitrogen-doped carbons
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Nitrogen-doped carbons derived from biomass precursors were modified with Pt2+ and successfully tested as solid catalysts in the direct oxidation of methane in fuming sulfuric acid. Remarkably, the catalytic performance was found to be substantially better than the Pt-modified Covalent Triazine Framework (CTF) system previously reported, although deactivation is more pronounced for the biomass derived catalyst supports.
- Soorholtz, Mario,White, Robin J.,Zimmermann, Tobias,Titirici, Maria-Magdalena,Antonietti, Markus,Palkovits, Regina,Schueth, Ferdi
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supporting information
p. 240 - 242
(2013/02/22)
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- Understanding and control of dimethyl sulfate in a manufacturing process: Kinetic modeling of a fischer esterification catalyzed by H2SO 4
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The formation and fate of monomethyl sulfate (MMS) and dimethyl sulfate (DMS) were studied by proton NMR for a sulfuric acid catalyzed esterification reaction in methanol. The kinetic rate constants for DMS and MMS were determined at 65 °C by fitting time-dependent experimental data to a model using DynoChem. In refluxing methanol, sulfuric acid was converted to monomethyl sulfate (MMS) in nearly quantitative yield within 45 min. Once formed, the MMS underwent a reversible esterification reaction to form DMS. Dimethylsulfate reacted with methanol to regenerate MMS and form dimethyl ether. A byproduct of the esterification reaction was water, which further consumed DMS through hydrolysis. On the basis of derived rate constants, in refluxing methanol, DMS would not be expected to exceed 4 ppm in the reaction mixture at equilibrium. In the presence of the carboxylic acid substrate, DMS was not detected in the reaction mixture. The reaction pathways of this system have been systematically investigated, and the results of this study will be presented.
- Guzowski Jr., John P.,Delaney, Edward J.,Humora, Michael J.,Irdam, Erwin,Kiesman, William F.,Kwok, Albert,Moran, Amy D.
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body text
p. 232 - 239
(2012/06/18)
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- PROCESS FOR PREPARING HIGH PURITY AND CRYSTALLINE DIMETHYL FUMARATE
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The present invention describes a process for the preparation of dimethyl fumarate. The process involves the esterification of fumaric acid and methanol in the presence of sulfuric acid as an acid catalyst. The high purity dimethyl fumarate contains no more than trace amounts of dimethyl sulfate. The present invention also provides a process for the preparation of highly pure dimethyl fumarate with a particle size from 20 to 250 μπι.
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Page/Page column 31
(2013/02/27)
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- 4′-hydrazone derivatives of 2,2′:6′,2″-terpyridine: Protonation and substituent effects
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Four 4′-hydrazone derivatives of 2,2′:6′,2″- terpyridine which vary in their N- and C-substitution in the R′NN=CRPh unit have been prepared and structurally characterized. Protonation studies and solution behaviour of these compounds are described, as well as representative crystal structures of mono- and diprotonated derivatives. In the solid-state structures of each neutral compound, the tpy domain adopts the anticipated trans,trans-conformation, and intramolecular steric factors compete with π-stacking effects to control the amount to which the C-phenyl substituent twists out of the plane of the tpy unit. When R′ = H, the imine NH group engages in hydrogen bonding interactions in the solid state, except where R = Ph. In solution, variable temperature 1H NMR spectroscopy shows that on going from R = Me to Ph (with R′ = H), the barrier to rotation about the Cpy-Nimine bond increases; with R = R′ = H, the hydrogen bonding capabilities of the solvent to the imine NH influence this dynamic process. In the N-methyl derivative (R = H and R′ =Me), rotation about the Cpy-Nimine bond is facile at room temperature. Protonation of the derivative with R = R′ = H results in an increase in the activation barrier to rotation, consistent with a greater π-contribution to the Cpy-Nimine bond. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Beves, Jonathon E.,Constable, Edwin C.,Housecroft, Catherine E.,Neuburger, Markus,Schaffner, Silvia,Zampese, Jennifer A.
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experimental part
p. 3569 - 3581
(2009/04/11)
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- Process for oxidation of methane to acetic acid
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Acetic acid or derivatives such as methyl acetate and acetyl sulfate, are produced from methane by contacting a methane-containing feed with an oxygen-containing gas in the presence of a palladium-containing catalyst and an acid selected from concentrated sulfuric acid and fuming sulfuric acid. The process is carried out using an oxygen partial pressure of from about 30 to about 300 psi and most preferably from about 60 to about 200 psi, a methane partial pressure of from about 100 to about 1000 psi, and most preferably from about 100 to about 400 psi, and a total pressure of oxygen and methane of from about 130 to about 1300 psi, preferably from about 200 to about 600 psi. The process is carried out in the absence of a catalyst promoter.
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Page/Page column 3-5; sheet 1-3
(2008/06/13)
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- Use of ionic liquids as coordination ligands for organometallic catalysts
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Aspects of the present invention relate to compositions and methods for the use of ionic liquids with dissolved metal compounds as catalysts for a variety of chemical reactions. Ionic liquids are salts that generally are liquids at room temperature, and are capable of dissolving a many types of compounds that are relatively insoluble in aqueous or organic solvent systems. Specifically, ionic liquids may dissolve metal compounds to produce homogeneous and heterogeneous organometallic catalysts. One industrially-important chemical reaction that may be catalyzed by metal-containing ionic liquid catalysts is the conversion of methane to methanol.
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Page/Page column 8-9
(2008/06/13)
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- PROCESS FOR DIRECT OXIDATION OF METHANE TO ACETIC ACID
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Acetic acid is produced by oxidation of methane with an oxygen-containing gas in the presence of an acid selected from concentrated sulfuric acid and fuming sulfuric acid, a palladium-containing catalyst and a promoter, preferably a copper or iron salt. The addition of a promoter and O2 to a system that includes a palladium-containing catalyst such as PdCl2 increases the rate of acetic acid formation from methane by more than an order of magnitude as compared with prior art and, in addition, inhibits the precipitation of Pd black.
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Page/Page column 3; 4
(2008/06/13)
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- Process for production of acetyl anhydrides and optionally acetic acid from methane and carbon dioxide
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Acetyl anhydrides such as acetyl sulfate are produced by a process for comprising contacting methane and carbon dioxide in an anhydrous environment in the presence of effective amounts of a transition metal catalyst and a reaction promoter, and an acid anhydride compound, and optionally an acid. The acetyl anhydride can be contacted with water to produce acetic acid or with an alcohol to produce a product comprising an acetate ester and that may also comprise acetic acid.
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- A high-yield, liquid-phase approach for the partial oxidation of methane to methanol using SO3 as the oxidant
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A direct approach for producing methanol from methane in a three-step, liquid phase process is reported. In the first step, methane is reacted with SO3 to form methanesulfonic acid (MSA) at 75°C using a free-radical initiator and MSA as the solvent. Urea-H2O2 in combination with RhCl3 is found to be the most effective initiator (57% conversion of SO3; 7.2% conversion of CH4). MSA is then oxidized by SO3 at 160°C in a second step to produce a mixture containing methyl bisulfate and some methyl methanesulfonate (87% conversion of MSA). In the third step, the mixture of methyl bisulfate and methyl methanesulfonate is hydrolyzed in the presence of an organic solvent, to produce an organic phase containing methanol and an aqueous phase containing sulfuric acid and some MSA (63% conversion of methyl bisulfate; 72% conversion of methyl methanesulfonate). Overall, 58% of the MSA (of which 23% is derived from methane) is converted to methanol.
- Mukhopadhyay, Sudip,Zerella, Mark,Bell, Alexis T.
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p. 1203 - 1206
(2007/10/03)
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- Direct sulfonation of methane to methanesulfonic acid by sulfur trioxide catalyzed by cerium(IV) sulfate in the presence of molecular oxygen
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Direct sulfonation of methane with SO3 to methanesulfonic acid (MSA) is accomplished in sulfuric acid with almost 100% selectivity in the presence of a catalyst, namely, Ce and Rh salts and molecular oxygen as the catalyst regenerator. In the absence of O2, the catalyst remains effective but the selectivity to MSA decreases to 53% and byproducts, principally CH3OSO3H, are formed. The effects of O 2 pressure, catalyst concentration, temperature, SO3 concentration, and methane pressure have been examined on the rate of SO 3 conversion to MSA. The conversion of SO3 to MSA was the same when CF3SO3H was used as the solvent instead of H2SO4.
- Mukhopadhyay, Sudip,Bell, Alexis T.
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p. 913 - 916
(2007/10/03)
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- Imidazoline quats
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Mixture of dialkyl imidazoline quats with specified substitution content are provided. In one embodiment, at least a portion of the mixture includes at least one dialkyl imidazoline quat having at least one C16-C30 alkyl group; the C16-30 substitution content of the mixture being from about 10% to about 95% with respect to C10+ reference substitution range. Methods of making imidazoline quats and quat mixtures, personal care and cosmetic products and formulations that contain the imidazoline quats and quat mixtures, methods of making such personal care and cosmetic products and formulations, and methods of using the such imidazoline quats, quat mixtures, and personal care and cosmetic products and formulations are also provided. Various embodiments are disclosed.
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- Process for obtaining N-monosubstituted amides
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A process for obtaining an amide of the general formula R—(CO)—NH—CH2—X involves contacting a nitrile of the general formula R—CN with: a) an acid; and c) an alkoxy-containing compound comprising at least one alkoxy functionality of the general formula —OCH2—X; wherein R is hydrogen or an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, aryl, or heterocyclic substituent, which substituents can be substituted or unsubstituted; wherein X is hydrogen or a radical having the general formula —CHR1R2; and wherein R1and R2independently or collectively represent hydrogen or an alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, aryl, or heterocyclic substituent, or any combination thereof, which substituents can be substituted or unsubstituted. Moreover, the inventive process can involve other similar reactions, for example, at least one nitrile can be reacted with a reagent comprising both (i) at least one suitable alkoxy functionality; and (ii) at least one suitable acid functionality.
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- Nitrosation of anisole, stability constants of complexes of the nitrosonium ion with aromatic nitroso compounds, and NMR studies of restricted rotation in the complexes
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Anisole can be nitrosated in good yield under the acidic and anaerobic conditions previously reported for methylbenzenes. The product, 4-nitrosoanisole, is slowly converted into 4-nitrosophenol in acetic-sulfuric acid mixtures. The decrease in the rate constant for this reaction with increasing concentration of nitrosonium ion leads to an estimate of the stability constant of the complex between 4-nitrosoanisole and nitrosonium ion. Stability constants for the similar complexes formed by 4-nitrosotoluene and 1,3-dimethyl-4-nitrosobenzene with nitrosonium ion in trifluoroacetic acid have been determined by UV spectroscopy. Restricted rotation about the bond between nitrogen and aromatic carbon is evident from the 1H NMR spectra of the complexes; activation parameters for the rotation are reported and compared with similar data in the literature for restricted rotation in uncomplexed aromatic nitroso compounds.
- Atherton, John H.,Moodie, Roy B.,Noble, Darren R.
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p. 229 - 234
(2007/10/03)
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- The Decomposition of Acidic Karl Fischer Reagent in Methanol
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The reaction between sulfur dioxide and iodine in methanol is started by traces of water in the solvent. Hydrogen iodide is formed and reacts with methanol to produce more water until all iodine is used up. An addition compound between iodine and hydrogen sulfite was found as an intermediate and characterized by Raman spectroscopy. Elementary sulfur is formed in a second reaction.
- Fischer, Wolfgang,Beckenkamp, Konrad
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- The decomposition of aliphatic N-nitro amines in aqueous sulfuric acid. Bisulfate as a nucleophile
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In aqueous sulfuric acid, aliphatic N-nitro amines decompose to N2O and alcohols. An excess acidity analysis of the observed rate constants for the reaction shows that free carbocations are not formed. The reaction is an acid-catalyzed SN2 displacement from the protonated aci-nitro tautomer, the nucleophile being a water molecule at acidities below 82-85% H2SO4, and a bisulfate ion at higher acidities. Bisulfate is the poorer nucleophile by a factor of about 1000. Twelve compounds were studied, of which results obtained for nine at several different temperatures enabled calculation of activation parameters for both nucleophiles. The reaction appears to be mainly enthalpy controlled. The intercept standard-state rate constants are well correlated by the σ* values for the alkyl groups; the slopes are negative, with a more negative value for the slower bisulfate reaction. Interestingly the m?m* slopes also correlate with σ*, although the scatter is bad.
- Cox, Robin A.
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p. 1774 - 1778
(2007/10/03)
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- Solution reactivity of thiyl radicals with molecular oxygen: Unsensitized photooxidation of dimethyldisulfide
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Irradiation of dimethyldisulfide in a protic solvent in the presence of molecular oxygen leads to the formation of sulfonic and sulfuric acids as major products. The addition of molecular oxygen on the thiyl radical formed by S-S bond cleavage is postulated.
- Banchereau, Evelyne,Lacombe, Sylvie,Ollivier, Jean
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p. 8197 - 8200
(2007/10/02)
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- Activation of methane and ethane and their selective oxidation to the alcohols in protic media
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The selective oxidation of methane and ethane to the alcohols in solvents ranging from strong acids to neutral aqueous medium has been studied. In 98% sulfuric acid, methane is oxidized to CH3OSO3H by a variety of 1e- and 2e- oxidants, such as S2O82-, Ce(IV), Pd(II), and Hg(II). In the case of ethane, the observed products are CH3OSO3H and HO3SCH2CH2OSO3H. These oxidations appear to proceed through a series of electron-transfer steps involving the intermediacy of radicals and carbocations. We have determined the ratio of rate constants for methane versus methanol oxidation by the Pt(II) ion in water and an average value of 0.17(2) was obtained. The similarity in rate constants for methane and methanol oxidations under such mild conditions is remarkable. Moving to substrates with C-H bonds somewhat weaker than that in methane results in actual reversal of commonly observed selectivity. As an example, we have observed the exclusive oxidation of the methyl group in ethanol resulting in the formation of 1,2-ethanediol as the predominant product. In addition, when ethane was included as a substrate, the relative rate of C-H bond activation by the Pt(II) ion decreased in the order H-CH2CH3 > H-CH2CH2OH > H-CH(OH)CH3. Another example of unusual selectivity was the observation of 1,3-propanediol as the predominant product in the oxidation of 1-propanol by the Pt(II) ion in water.
- Sen,Benvenuto,Lin,Hutson,Basickes
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p. 998 - 1003
(2007/10/02)
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- Cubane derivatives 1. Synthesis and molecular structures of the esters of 1,4-cubanedicarboxylic acid
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An effective methods of esterification of 1,4-cubanedicarboxylic acid with alkylsulfuric acids is proposed.The derivatives of alkanols with substantially different pKa values are obtained in high yields.Molecular structures of the esters obtained are confirmed by various methods.The X-ray study showed a remarcable effect of the nature of an alkyl radical on the geometry of the cubane core. - Key words: 1,4-cubanedicarboxylic acid, esterification, alkylsulfuric acids, X-ray method.
- Eremenko, L. T.,Romanova, L. B.,Ivanova, M. E.,Eremenko, I. L.,Nefedov, S. E.,Struchkov, Yu. T.
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p. 619 - 623
(2007/10/02)
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- Process for the preparation of S-alkyl-isothioureidoazines
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A process for the preparation of an S-alkyl-isothioureidoazine of the formula STR1 in which R is alkyl, X and Y each independently is selected from the group consisting of hydrogen, halogen, and alkyl, halogenoalkyl, alkoxyalkyl, halogenoalkoxy, alkoxy, alkylthio, halogenoalkylthio, alkylamino or dialkylamino, each of which is optionally substitued, and Z is nitrogen or CH which comprises in a first step reacting an thioureidoazine of the formula STR2 with a dialkyl sulphate of the formula at a temperature between about 20° C. and 150° C., thereby to form an adduct of the formula STR3 and in a second step reacting the adduct with an acid acceptor in the presence of an aprotic polar diluent at a temperature between about 0° C. and 50° C.
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- REACTION OF METHYL METHANESULFONATE WITH SULFUR TRIOXIDE AND CHLOROBENZENE
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The reactivity of methyl methanesulfonate in reaction with sulfur trioxide is lower than that of methyl arenesulfonates.Methyl methanesulfonate becomes exhausted when the ester and sulfur trioxide are in ratio of 1.85:1, while methyl p-toluenesulfonate becomes exhausted in ratio of 1:1 (25 deg C, 1 h).If an equimolar amount of chlorobenzene is added to the mixture of methyl methanesulfonate and sulfur trioxide in ratio of 1:1, the main reaction path is solvolysis of the pyrosulfonates to methanesulfonic acid and methylsulfuric acid and not the formation of sulfones, as in case of arenesulfonic esters.
- Andrashchuk, N. P.,Shapiro, Yu. E.,Timoshenko, G. N.,Moskvichev, Yu. A.,Mironov, G. S.,et al.
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p. 1144 - 1148
(2007/10/02)
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- EQUILIBRIA IN SOLUTIONS OF METHANOL OR ETHANOL, SULFURIC ACID, AND ALKYL SULFATES
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Equilibria in reactions of methanol and ethanol with sulfuric acid or in hydrolyses of alkyl sulfates were followed using 13C NMR, anion-exchange HPLC, and titrations.Variations of equilibrium constant K = (ester)(H2O)/(ROH)(HSO4(1-)) with acidity indicate participation of reactions ROH2(1+) + HSO4(1-) ROH(1+)SO3(1-) + H2O, accompanied by acid base equilibra involving the alcohol and ester.For mixtures containing initially 20percent (w/w) alcohol, pKMeOH2(1+) = -4.2, pKEtOH2(1+) = -3.7, pKMeOH(1+)SO3(1-) = -3.3 and pKEtOH(1+)SO3(1-) = -2.7.
- Almstead, N.,Christ, W.,Miller, G.,Reilly-Packard, S.,Vargas, K.,Zuman, P.
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p. 1627 - 1628
(2007/10/02)
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- KINETICS AND MECHANISM OF THE SOLVOLYSIS OF METHYL ESTERS OF AROMATIC SULFONIC ACIDS IN CONCENTRATED SULFURIC ACID AND WEAK OLEUM
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The effect rate constants for the solvolysis of methyl benzenesulfonate in 99.03-100.2percent sulfuric acid, methyl p-toluenesulfonate in 99.81-100percent sulfuric acid, and methyl p-chlorobenzenesulfonate in 100percent sulfuric acid were determined at 25 deg C by GLC.In the investigated range of sulfuric acid concentrations a linear relation is observed between lof keff and log aH2S2O7 with a slope close to unity against the abscissa axis.It is assumed that the rate-determining stage of the process is the decomposition of a complex formed by the molecules of the sulfonic ester and pyrosulfonic acid.The reaction takes place with cleavage of the S-O bond in the molecule of the sulfonic ester.In the transition state of the rate-determining stage the order of the S-OMe bond is lower than the order of the S-O bond.
- Gnedin, B. G.,Karmanova, T. V.,Chumakova, M. V.,Ivanov, S. N.
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p. 503 - 507
(2007/10/02)
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- Ylides of Heterocycles, VIII. Reactions of Iodonium-Ylides with Acids
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The reaction of various organic and inorganic acids (HX) with iodonium ylides 2 leads to nucleophilic substitution of the iodobenzene substituent by the anion X(-) to yield the heterocycles 5.Some of them are hydrolyzed to the hydroxy compounds 3 or reduced to the starting compounds 1 under the reaction conditions.Reaction of the iodonium ylide 2b with monomethyl sulfate gives the salt 9, which with bases undergoes nucleophilic substitution to compounds 8 and 10-12, respectively, or is converted to 2b again. - Keywords: 3-Acetoxy-4-hydroxy-2-quinolones; 2-Oxoquinoline-4-olates; 3-Substituted 4-hydroxy-2-quinolones
- Pongratz, Erik,Kappe, Thomas
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p. 231 - 242
(2007/10/02)
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- SULFATION OF ALCOHOLS OF DIFFERENT STRUCTURES WITH CONCENTRATED SULFURIC ACID.
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The authors report the results of a study of the applicability of these relationships to the whole series of aliphatic alcohols including industrial products. The concentration equilibrium constants of the reactions of these alcohols with 99. 5 mass % sulfuric acid are determined at 32. 5 degree , and it is shown that all the higher alcohols can be characterized by the same equilibrium constant, 3. 1 plus or minus 0. 5, which can therefore be recommended for practical calculations. The equilibrium constants were calculated from the rate constants of the forward and reverse reactions. It is shown that they depend on the relative basicities of sulfuric acid and monoalkyl sulfates.
- Savelyanov,Yakushin
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p. 1527 - 1531
(2007/10/02)
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- Phosphatosulfates. Metal-ion Effects on the Acid-catalyzed Hydrolysis of Phenyl Phosphatosulfate in an Acetonitrile-Water Mixed Solvent
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The rates of the acid-catalyzed hydrolysis of phenyl phosphatosulfate (PPS) have been found to be highly dependent on the water content in the mixed solvent of acetonitrile-water.A remarkable rate acceleration was observed with a rate maximum near the 1:1 ratio of PPS and metal ion, and with a solvent with a low water content.Under such conditions, the site of the cleavage of the P-O-S linkage was observed to be predominantly the S-O bond.
- Eiki, Toshio,Asai, Yoshio,Tagaki, Waichiro
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p. 1097 - 1101
(2007/10/02)
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- Oxidation of Sulfur Dioxide by Methylperoxy Radicals
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This study was made to resolve the apparent discrepancy between the finite rate constants observed for the CH3O2 reaction with SO2 in high-intensity flash photolysis and near zero values observed recently by us and others for this reaction in NO-free, CH3O2-SO2 experiments at low intensity.
- Kan, Charles S.,Calvert, Jack G.,Shaw, John H.
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p. 1126 - 1132
(2007/10/02)
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- On the Mechanism of Acetalization Reactions with Carboxamide-Dialkyl Sulfate Adducts; a New Method of Preparation of Orthocarboxylic Esters and of Cleavage of Carboxamides.
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It is shown that the efficiency of carboxamide-dialkyl-sulfate adducts in acetalization reactions depends on their alkylation ability.A mechanism of acetal formation using orthoformates as acetalization reagents is proposed.Alcoholysis of carboxamide-dialkyl sulfate adducts 1b, 11, 13 affords orthocarboxylic esters.Carboxamides and carboxmorpholides react with dimethyl sulfate/methanol to give methyl esters.
- Kantlehner, Willi,Gutbrod, Heinz-Dieter
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p. 1677 - 1688
(2007/10/02)
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