- HOMOLYTIC REPLACEMENT OF A HYDROGEN ATOM IN 2-METHYLQUINOLINE
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The reaction of 1,3-dioxolane with sulfuric-acid-protonated 2-methylquinoline initiated by the ROOH + Fe2+ system at 5-10 deg C in water forms 4-(1,3-dioxacyclopent-2-yl)-2-methylquinoline and 4-(1,3-dioxacyclopent-4-yl)-2-methylquinoline.The selectivity of the formation of the first reaction product increases on passing from hydrogen peroxide to cumyl and tert-butyl hydroperoxide and with an increase in the pH of the medium.
- Zorin, V. V.,Zelechonok, Yu. B.,Zlotskii, S. S.,Rakhmankulov, D. L.
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Read Online
- Identification of an Adduct Impurity of an Active Pharmaceutical Ingredient and a Leachable in an Ophthalmic Drug Product Using LC-QTOF
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Impurity investigations are important in pharmaceutical development to ensure drug purity and safety for the patient. The impurities typically found in drug products are degradants or reaction products of the active pharmaceutical ingredient (API) or leachable compounds from the container closure system. However, secondary reactions may also occur between API degradants, excipient impurities, residual solvents, and leachables to form adduct impurities. We hereby report an adduct-forming interaction of API (moxifloxacin) with a leachable compound (ethylene glycol monoformate) in moxifloxacin ophthalmic solution. The leachable compound originated from a low-density polyethylene bottle used in the packaging of drug products. The adduct impurity was tentatively identified as 1-cyclopropyl-6-fluoro-7-(1-(2-(formyloxy)ethyl) octahydro-6H-pyrrolo[3,4-b]pyridin-6-yl)-8-methoxy-4-oxo-1,4-dihydroquinoline-3-carboxylic acid (C24H28FN3O6, MW = 473.19621) using accurate mass LC-QTOF analysis. The mass accuracy error between the theoretical mass and the experimental mass of an impurity was found to be 0.2 ppm. An MS/MS analysis was utilized to provide mass spectrometry fragments to support verification of the proposed structure.
- Gollapalli, Ramarao,Singh, Gagandeep,Blinder, Alejandro,Brittin, Jeremiah,Sengupta, Arijit,Mondal, Bikash,Patel, Milan,Pati, Biswajit,Lee, James,Ghode, Amit,Kote, Mahesh
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Read Online
- Mechanism of the degradation of 1,4-dioxane in dilute aqueous solution using the UV/hydrogen peroxide process
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1,4-Dioxane is an EPA priority pollutant often found in contaminated groundwaters and industrial effluents. The common techniques used for water purification are not applicable to 1,4-dioxane, and the currently used method (distillation) is laborious and expensive. This study aims to understand the degradation mechanism of 1,4-dioxane and its byproducts in dilute aqueous solution toward complete mineralization, by using the UV/H2O2 process in a UV semibatch reactor. The decay of 1,4-dioxane generated several intermediates identified and quantified as aldehydes (formaldehyde, acetaldehyde, and glyoxal), organic acids (formic, methoxyacetic, acetic, glycolic, glyoxylic, and oxalic) and the mono- and diformate esters of 1,2- ethanediol. Measurement of the total organic carbon (TOC) during the treatment indicated a good agreement between the experimentally determined TOC values and those calculated from the quantified reaction intermediates, ending in complete mineralization. A reaction mechanism, which accounts for the observed intermediate products and their time profiles during the treatment, is proposed. Considering the efficacy of the 1,4-dioxane removal from dilute aqueous solutions, as shown in this work, the present study can be regarded as a model for industrially affordable Advanced Oxidation Technologies. 1,4-Dioxane is an EPA priority pollutant often found in contaminated groundwaters and industrial effluents. The common techniques used for water purification are not applicable to 1,4-dioxane, and the currently used method (distillation) is laborious and expensive. This study aims to understand the degradation mechanism of 1,4-dioxane and its byproducts in dilute aqueous solution toward complete mineralization, by using the UV/H2O2 process in a UV semibatch reactor. The decay of 1,4-dioxane generated several intermediates identified and quantified as aldehydes (formaldehyde, acetaldehyde, and glyoxal), organic acids (formic, methoxyacetic, acetic, glycolic, glyoxylic, and oxalic) and the mono- and diformate esters of 1,2-ethanediol. Measurement of the total organic carbon (TOC) during the treatment indicated a good agreement between the experimentally determined TOC values and those calculated from the quantified reaction intermediates, ending in complete mineralization. A reaction mechanism, which accounts for the observed intermediate products and their time profiles during the treatment, is proposed. Considering the efficacy of the 1,4-dioxane removal from dilute aqueous solutions, as shown in this work, the present study can be regarded as a model for industrially affordable Advanced Oxidation Technologies.
- Stefan, Mihaela I.,Bolton, James R.
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Read Online
- Hydroxide Based Integrated CO2 Capture from Air and Conversion to Methanol
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The first example of an alkali hydroxide-based system for CO2 capture and conversion to methanol has been established. Bicarbonate and formate salts were hydrogenated to methanol with high yields in a solution of ethylene glycol. In an integrated one-pot system, CO2 was efficiently captured by an ethylene glycol solution of the base and subsequently hydrogenated to CH3OH at relatively mild temperatures (100-140 °C) using Ru-PNP catalysts. The produced methanol can be easily separated by distillation. Hydroxide base regeneration at low temperatures was observed for the first time. Finally, CO2 capture from ambient air and hydrogenation to CH3OH was demonstrated. We postulate that the high capture efficiency and stability of hydroxide bases make them superior to existing amine-based routes for direct air capture and conversion to methanol in a scalable process.
- Sen, Raktim,Goeppert, Alain,Kar, Sayan,Prakash, G. K. Surya
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supporting information
p. 4544 - 4549
(2020/02/27)
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- Ruthenium-Catalyzed Synthesis of Cyclic and Linear Acetals by the Combined Utilization of CO2, H2, and Biomass Derived Diols
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Herein a transition-metal catalyst system for the selective synthesis of cyclic and linear acetals from the combined utilization of carbon dioxide, molecular hydrogen, and biomass derived diols is presented. Detailed investigations on the substrate scope enabled the selectivity of the reaction to be largely guided and demonstrated the possibility of integrating a broad variety of substrate molecules. This approach allowed a change between the favored formation of cyclic acetals and linear acetals, originating from the bridging of two diols with a carbon-dioxide based methylene unit. This new synthesis option paves the way to novel fuels, solvents, or polymer building blocks, by the recently established “bio-hybrid” approach of integrating renewable energy, carbon dioxide, and biomass in a direct catalytic transformation.
- Beydoun, Kassem,Klankermayer, Jürgen
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supporting information
p. 11412 - 11415
(2019/07/18)
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- Oxidative C-C bond cleavage of primary alcohols and vicinal diols catalyzed by H5PV2Mo10O40 by an electron transfer and oxygen transfer reaction mechanism
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Primary alcohols such as 1-butanol were oxidized by the H5PV2Mo10O40 polyoxometalate in an atypical manner. Instead of C-H bond activation leading to the formation of butanal and butanoic acid, C-C bond cleavage took place leading to the formation of propanal and formaldehyde as initial products. The latter reacted with the excess 1-butanol present to yield butylformate and butylpropanate in additional oxidative transformations. Kinetic studies including measurement of kinetic isotope effects, labeling studies with 18O labeled H5PV2Mo10O40, and observation of a prerate determining step intermediate by 13C NMR leads to the formulation of a reaction mechanism based on electron transfer from the substrate to the polyoxometalate and oxygen transfer from the reduced polyoxometalate to the organic substrate. It was also shown that vicinal diols such as 1,2-ethanediol apparently react by a similar reaction mechanism. Copyright
- Khenkin, Alexander M.,Neumann, Ronny
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supporting information; experimental part
p. 14474 - 14476
(2009/02/08)
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- METHOD OF OBTAINING POLYOXYGENATED ORGANIC COMPOUNDS
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The invention relates to a method of obtaining polyoxygenated organic compounds. The inventive method is characterized in that it comprises the oxidation reaction of a diether, preferably an acetal, with an oxygen source, in the presence of: one or more radical initiating agents, one or more additives that generate a basic reaction medium, and one or more catalysts.
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Page/Page column 12
(2008/06/13)
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- Method for producing diol derivatives
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A method of producing a diol derivative efficiently and to high purity is provided. Specifically, the present invention relates to a method of producing a diol derivative having, as a fundamental step, a step of obtaining an α-hydroxycarboxylic acid ester by reacting (i) one or more 1,2-diols or (ii) a 1,2-diol and a primary alcohol as starting material(s) with oxygen in the presence of a catalyst comprising metal loaded on a carrier.
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- Kinetic and product studies of the reactions of selected glycol ethers with OH radicals
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Glycol ethers are widely used as solvents and are hence liable to be released into the atmosphere where they may contribute to the formation of photochemical air pollution in urban and regional areas. The dominant reaction of glycol ethers in the atmosphere has been previously shown to be with OH radicals. Using a relative rate method, rate constants have been measured at 296 ± 2 K for the gasphase reactions of the OH radical with 1-butoxy-2propanol [CH3CH2CH2CH2OCH2CH (OH)CH3], diethylene glycol ethyl ether [CH3CH2OCH2 CH2OCH2CH2OH], and diethylene glycol n-butyl ether [CH3CH2CH2CH2OCH2 CH2OCH2CH2OH] of (in units of 10-11 cm3 molecule-1 s-1) 3.76 ± 0.54, 5.72 ± 0.85, and 7.44 ± 0.94, respectively, where the error limits include the estimated overall uncertainties in the rate constants for the reference compounds. Products of the OH radical-initiated reactions of these glycol ethers have been investigated using gas chromatography with flame ionization detection (GC-FID), combined gas chromatography-mass spectrometry(GC-MS), in situ Fourier transform infrared (FT-IR) spectroscopy, and in situ atmospheric pressure ionization tandem mass spectrometry (API-MS). The products identified and quantified account for 102 ± 11% of the reaction products from 1-butoxy-2-propanol, 87 ± 9% of those from diethylene glycol ethyl ether, and 83 ± 12% of those from diethylene glycol n-butyl ether. An empirical estimation method for calculating reaction rates of alkoxy radicals under atmospheric conditions appears to fairly well predict the products formed and their yields. Detailed reaction schemes after the initial OH radical reactions are formulated for each of these glycol ethers, with the majority of the reactions involving H-atom abstraction from the CH2 groups adjacent to the ether linkage.
- Aschmann,Martin,Tuazon,Arey,Atkinson
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p. 4080 - 4088
(2007/10/03)
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- A kinetic evaluation of carbon-hydrogen, carbon-carbon, and carbon-silicon bond activation in benzylic radical cations
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A detailed study of the competition between C-C, C-H, and C-Si bond fragmentation in a series of 4-methoxy-α-substituted toluene radical cations (1.+), involving both product studies and kinetic analysis, is presented. C-C bond fragmentation occurs with several radical cations in acetonitrile. The rate constants for such processes, determined by laser flash photolysis, varied from 2.8 x 104 (1c.+) to 1.53 x 106 (1f.+) s-1. The activation parameters for C-C bond fragmentation are characterized by low activation enthalpies on the order of 30 kJ mol-1 and negative activation entropies in the range -34 to -55 J mol-1 K-1. Deprotonation of the radical cations is always a second-order process induced by nucleophiles [cerium(IV) ammonium nitrate (CAN) or nitrate anion], with second-order rate constants from 7.7 x 107 (1h.+) to 8.8 x 108 (1i.+) M-1 s-1 in neat acetonitrile (CAN assisted) and from 0.4 x 108 (1j.+) to 7.1 x 108 (1i.+) M-1 s-1 in the presence of nitrate anion. The rate constant for nitrate-induced decarboxylation was higher, 13.6 x 108 M-1 s-1 (1d.+). In a few cases C-C (1e.+, 1f.+) and C-Si (1g.+) fragmentations occurred, also as second-order processes induced by nitrate, with rate constants from 4.4 x 108 (1f.+) to 8.2 x 108 (1g.+) M-1 s-1. ΔH and ΔS had opposing influences on C-H and C-C fragmentation, and in the case of 1e.+ a temperature-dependent product distribution was obtained. The activation parameters for the observed C-H, C-C, and C-Si fragmentations have been compared, and suggest a rationale for the mechanisms and selectively of such processes in radical cations.
- Freccero, Mauro,Pratt, Albert,Albini, Angelo,Long, Conor
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p. 284 - 297
(2007/10/03)
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- Products of the gas-phase reactions of the OH radical with 1-methoxy-2-propanol and 2-butoxyethanol
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Glycol ethers are used as solvents and are hence liable to b;e released to the atmosphere, where they react and contribute to the formation of photochemical air pollution. In this work, products of the gas-phase reactions of the OH radical with 1-methoxy-2-propanol and 2-butoxyethanol in the presence of NO have been investigated at 298 ± 2 K and 740 Torr total pressure of air by gas chromatography, in situ Fourier transform infrared spectroscopy, and in situ atmospheric pressure ionization tandem mass spectrometry. The products observed from 1-methoxy-2-propanol were methyl formate, methoxyacetone, and acetaldehyde with molar formation yields of 0.59 ± 0.05, 0.39 ± 0.04, and 0.56 ± 0.07, respectively. The products observed and quantified from 2-butoxyethanol were n-butyl formate, 2-hydroxyethyl formate, propanal, 3-hydroxybutyl formate, and an organic nitrate (attributed to CHsChbCHaCH2OCH(ON02)CH2OH and its isomers), with molar formation yields of 0.57 ± 0.05, 0.22 ± 0.05, 0.21 ± 0.02, 0.07 ± 0.03, and 0.10 ± 0.03, respectively. An additional product of molecular weight 132, attributed to one or more hydroxycarbonyl products, was also observed from the 2-butoxyethanol reaction by atmospheric pressure ionization mass spectrometry. For both glycol ethers, the majority of the reaction products and reaction pathways are accounted for, and detailed reaction mechanisms are presented which account for the observed products.
- Tuazon, Ernesto C.,Aschmann, Sara M.,Atkinson, Roger
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p. 3336 - 3345
(2007/10/03)
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- Oh radical-initiated oxidation of 2-butoxyethanol under laboratory conditions related to the troposphere: Product studies and proposed mechanism
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This type of study provides information on the reaction mechanism of the conversion of a substrate molecule, in this case a glycol ether, into its oxidation products under polluted tropospheric conditions. Such detailed pathways for the breakdown of the substrate molecule lead to the generation of photooxidants, mainly ozone, and are essential input data for computer modeling studies used to derive ozone-creating potentials of volatile organic compounds released into the atmosphere. The products formed by the hydroxyl radical-initiated oxidation of 2-butoxyethanol (C4H9OCH2CH2OH) have been investigated by irradiating synthetic air mixtures containing the substrate, methyl nitrite, and nitric oxide at ppm levels in a Teflon bag reactor at room temperature. The decay of reactant and the formation of products were monitored by gas chromatography and by mass spectrometry. The molar yields of the major products (mol of product formed/mol of 2-butoxyethanol consumed) were as follows: butyl formate (HC(O)OCH2CH2CH2CH3), 0.35 ± 0.11; ethylene glycol monoformate (HC(O)OCH2CH2OH), 0.39 ± 0.18; butoxyacetaldehyde (CH3CH2CH2CH2OCH2C(O)H), 0.12 ± 0.09; 3-hydroxybutyl formate (HC(O)OCH2CH2CHOHCH3), ~0.20; and propionaldehyde, ~0.2-0.3. The yields of minor products were as follows: 2-propyl-1,3-dioxolane (CH3CH2CH2CHOCH2CH2O), 0.025 ± 0.005; ethylene glycol monobutyrate (CH3CH2CH2C(O)OCH2CH2OH), ~0.02-0.03; 2-hydroxybutyl formate (HC(O)OCH2CHOHCH2CH3), ~0.05, acetaldehyde, 2- groups in 2- butoxyethanol followed by the subsequent reactions of the resulting alkyl and alkoxy radicals. The mechanism is analogous to that proposed for 2- ethoxyethanol (Stemmler et al. Environ. Sci. Technol. 1996, 20, 3385-3391), in which the alkoxy radicals predominantly undergo decomposition reactions, but also includes isomerization reactions for the alkoxy radicals that are derived from the butyl side chain in 2-butoxyethanol. The observed products, in conjunction with the proposed mechanism, account for a total molar yield of about 1.1, indicating that all the main routes are accounted for in the degradation of this hydroxy ether. Rate coefficients at room temperature for the reactions of OH radicals with butoxyacetaldehyde and 2-propyl-1,3- dioxolane have been determined to be 20.6 x 10-12 and 10.8 x 10-12 cm3 molecule-1 s-1, respectively, with error limits of about ±40%, in each case.
- Stemmler, Konrad,Mengon, Wolfgang,Kinnison, David J.,Kerr, J. Alistair
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p. 1496 - 1504
(2007/10/03)
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- OH radical initiated photooxidation of 2-ethoxyethanol under laboratory conditions related to the troposphere: Product studies and proposed mechanism
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The products formed by the hydroxyl radical-initiated oxidation of 2- ethoxyethanol (CH3CH2OCH2CH2OH) have been investigated by irradiating synthetic air mixtures containing the substrate, methyl nitrite, and nitric oxide at ppm levels in a Teflon bag reactor at room temperature. The decay of reactants and the formation of products were monitored by gas chromatography and mass spectrometry. The major products ethyl formate [HC(O)OCH2CH3], ethylene glycol monaformate [HC(O)OCH2CH2OH], ethylene glycol monaacetate [CH3C(O)OCH2CH2OH], and ethoxyacetaldehyde [CH3CH2OCH2C(O)H] give a quantitative mass balance with the decay of the substrate molecule. The yields of these products were 34 ± 10%, 36 ± 7%, 7.8 ± 2.4%, and 24 ± 13%, respectively, in terms of percent of 2-ethoxyethanol removed by the OH radical. The product distribution is explained by a mechanism involving initial OH attack at the three CH2 groups in 2-ethoxyethanol followed by the subsequent reactions of the resulting alkyl and alkoxy radicals. The decomposition reactions of the alkoxy radicals from 2-ethoxyethanol, which can take place either by C-C or C-O bond breaking, involve preferential C-C cleavage rather than C-O cleavage. Rate coefficients at room temperature for the reactions of OH radicals with ethoxyacetaldehyde and 2-methyl-1,3- dioxolane (CH3CHOCH2CH2O, a minor product) have been determined to be 16.6 x 10-12 and 9.4 x 10-12 cm3 molecule-1 s-1, respectively.
- Stemmler, Konrad,Mengon, Wolfgang,Kerr, J. Alistair
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p. 3385 - 3391
(2007/10/03)
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- Oxidation vs. fragmentation in radiosensitization. Reactions of α-alkoxyalkyl radicals with 4-nitrobenzonitrile and oxygen. A pulse radiolysis and product analysis study
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α-Monoalkoxyalkyl radicals produced from 1,4-dioxane (100percent), 1,3-dioxane (56percent), tetrahydrofuran (92percent) and dimethyl ether (100percent) by H-abstraction by hydroxyl radicals generated in the radiolysis of water were found to react with 4-nitrobenzonitrile (NBN) by addition to give N-alkoxyaminoxyl-type radicals, which have absorption maxima at about 310 nm and decay very slowly (k = 0.4 - 1.0 s-1).On the other hand, the reaction of the α-dialkoxyalkyl radical, 1,3-dioxan-2-yl 3 with NBN leads to the rapid formation of the radical anion NBN.The N-alkoxyaminoxyl-type radicals (A in the case of 1,4-dioxane and D in the case of dimethyl ether) react with ascorbate (k ca. 2*104 dm3 mol-1 s-1).They have a very low reactivity with oxygen (k 3 dm3 mol-1 s-1 in the case of tetrahydrofuran).On the other hand, they are rapidly reduced by NBN radical anion (k ca. 109 dm3 mol-1 s-1 as observed with A and with B derived from 1,3-dioxane).The products -7 mol J-1> in the γ-radiolysis of N2O-saturated solution of 1,4-dioxane in the presence of NBN are 1,4-dioxan-2-one (0.3), 2-hydroxy-1,4-dioxane (2.5), ethane-1,2-diol monoformate (2.1), ethane-1,2-diol diformate (0.7), formaldehyde (2.1), 4-nitrosobenzonitrile and other reduction products of 4-nitrobenzonitrile.These products are accounted for as resulting from the fragmentation of the aminoxyl radical A by (a) heterolysis of the C-O bond (45percent leading to the one-electron oxidation of the 1,4-dioxan-2-yl radical) and (b) homolysis of the N-O bond (55percent leading to the formation of the 1,4-dioxan-2-oxyl radical which undergoes further fragmentation.The products from the reaction of methoxymethyl radicals with NBN under γ-radiolysis conditions are formaldehyde (5.7), methanol (2.5) and methyl formate (1.3).It is concluded that also in this case the decay of the aminoxyl radical D occurs by two pathways: the heterolysis route (46percent) and the homolysis route (54percent).In the presence of oxygen the 1,4-dioxan-2-yl radicals are converted into the corresponding peroxyl radicals.Their bimolecular decay (2k = 2.0*108 dm3 mol-1 s-1) yields the same products as in the case of NBN (albeit with a different product distribution and the formation of some peroxides): 1,4-dioxan-2-one (0.4), 2-hydroxy-1,4-dioxane (0.4), ethane-1,2-diol monoformate (0.6), ethane-1,2-diol diformate (2.8) and formaldehyde (0.6).These results indicate that fragmentation reactions involving the carbon-skeleton of organic radicals are important not only in the case of peroxyl radicals but they can also be induced by nitroaromatic sensitizers.In cells, reduction of the long-lived sensitizer adduct radicals by reducing agents such as ascorbate to give (toxic) hydroxylamine type products may compete with the homolytic or heterolytic fragmentation of the N-alkoxyaminoxyl radicals.
- Nese, Chandrasekhar,Schuchmann, Man Nien,Steenken, Steen,Sonntag, Clemens von
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p. 1037 - 1044
(2007/10/02)
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- Ethylene Oxide-mediated Reduction of CO2 to CO and Ethylene Glycol catalysed by Ruthenium Complexes
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In the presence of ethylene oxide, CO2 is efficiently hydrogenated to give CO and ethylene glycol in good yields using ruthenium complexes as homogeneous catalysts.
- Tominaga, Ken-ichi,Sasaki, Yoshiyuki,Watanabe, Taiki,Saito, Masahiro
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p. 1489 - 1490
(2007/10/02)
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- Liquid Phase Oxidation of 1,3-Dioxolanes
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The oxidation rate and the kind of oxidation products in the oxidation reactions of the 1,3-dioxolanes (1a to 1f) with molecular oxygen in liquid phase were investigated.The 2-methyl-substituted 1,3-dioxolane (1b) has a lower, the 4-methyl-substituted 1,3-dioxolane (1d) has a higher oxidation rate than the non-substituted 1,3-dioxolane (1a).The 2,2-disubstituted 1,3-dioxolanes show no oxidation but a hydrolytic reaction.The main-products of the liquid-phase oxidation of the 1,3-dioxolanes 1a, 1b, 1d and 1e are the glycol-carbonic acid-monoesters 8 and the 2-oxo-1,3-dioxolanes 6.Their formation is proved by gaschromatography, GC/MS-coupling, DC and 13C-n.m.r.-spectroscopy.
- Schnurpfeil, D.,Teubner, M.
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p. 155 - 159
(2007/10/02)
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- Cobalt(II) catalyzed oxidation of 2-substituted 1,3-dioxolanes with molecular oxygen
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Cobalt(II) chloride catalyzed oxidation of 2-substituted 1,3-dioxolanes in 1,2-dimethoxyethane afforded formate esters and acids in high yields.Is was found that the presence of catalytic amounts of ZnCl2 increased the rate of oxidation.A free-radical mechanism is proposed, involving participation of superoxocobalt, and the esterification of the alcohol and acid.
- Li, Pei,Alper, Howard
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- Oxidation of Cyclic Acetals as a Preparative Method of Diol Monoester Production
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Glycol monoesters were produced by oxidation of acetals with oxygen, hydroperoxides, hydrogen peroxide, hydrotrioxide and ozon.Addition of salts of metals of variable valency and crown-ether substantially increase the rate of oxidation and hydroxylation.The most efficient oxidizer is ozon.
- Kuramshin, E. M.,Kulak, L. G.,Nazarov, M. N.,Zlotsky, S. S.,Rakhmankulov, D. L.
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p. 591 - 599
(2007/10/02)
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- Free Radicals in Organic Synthesis. A Novel Synthesis of Ethylene Glycol Based on Formaldehyde
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1,3-Dioxolane reacted with formaldehyde in the presence of free radical initiators to produce 2-(hydroxymethyl)-1,3-dioxolane in moderate yield. 2-(Hydroxymethyl)-1,3-dioxolane was catalytically hydrogenated to ethylene glycol.
- Sanderson, John R.,Yeakey, Ernest L.,Lin, Jiang J.,Duranleau, Roger,Marquis, Edward T.
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p. 3243 - 3246
(2007/10/02)
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- AUTOOXIDATION OF DIETHYLENE GLYCOL.
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The authors studied certain characteristics of the kinetics of accumulation of the products of autooxidation of diethylene glycol. Experiments show that both methylene groups in diethylene glycol exhibit reactivity during liquid-phase oxidation by atmospheric oxygen. During oxidation near the lower limit of the temperature range studied (90-130+ZZproducts whose formation involve cleavage of the C-O ether bond are formed at the higher rate, whereas at higher temperatures the products of conversion of the hydroxyl group predominate.
- Gordienok,Freidin,Proskurina
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p. 1441 - 1445
(2007/10/02)
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- SYNTHESIS AND DECOMPOSITION OF THE HYDROTRIOXIDES OF 1,3-DIOXOLANES
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The hydrotrioxides of 1,3-dioxolane and 2-methyl-1,3-dioxolane were synthesized.Their thermal decomposition leads to the formation of glycol monoesters.The hydrotrioxides exhibit high oxidizing activity and oxidize the initial cyclic acetal to the corresponding monoester.The possibility of using hydrotrioxides as oxidizing agents for organic substances such as phosphines and sulfides was examined.
- Kuramshin, E. M.,Kulak, L. G.,Zlot-skii, S. S.,Rakhmankulov, D. L.
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p. 1783 - 1786
(2007/10/02)
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- Deacylation of Pyrrole and other Aromatic Ketones
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Ethyl 4-acetyl-3,5-dimethyl-1H-pyrrole-2-carboxylate (1a) reacts rapidly with ethylene glycol in refluxing benzene with p-toluenesulfonic acid or perchloric acid as a catalyst to give ethyl 3,5-dimethyl-1H-pyrrole-2-carboxylate (3) in high yield (96 percent).Various 2- and 3-acylpyrroles can be efficiently deacylated by using this procedure.Other ketones which undergo deacylation include phenyl(2-phenylindol-3-yl)methanone (19), 1-(5-methyl-1-phenylpyrazol-4-yl)ethanone (20), and 2,4-dimethoxybenzophenone.Certain pyrrole ketones where the acyl group is flanked by two ring methyl groups are also cleaved under acidic conditions by using ethanedithiol.
- Moon, M. W.,Wade, R. A.
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p. 2663 - 2669
(2007/10/02)
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- KINETIC ISOTOPE EFFECT IN THE OXIDATION OF CYCLIC AND LINEAR ACETALS WITH OZONE AND MOLECULAR OXYGEN
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Substitution of hydrogen atoms at the acetal carbon by deuterium in 1,3-dioxolane, 1,3-dioxane, and dipropoxymethane leads to a decrease in the rate constant of ozonization and oxidation.The magnitude of the kinetic isotope effect lies in the range of 2-3 and is somewhat lower than the known values (4-6) for alcohols, ethers, and carboxylic acids.This is evidently due to the smaller extension of the C-H bond in the transition state of the reaction of acetals with ozone molecules and peroxide radicals.
- Kuramshin, E. M.,Sadaeva, R. Kh.,Gumerova, V. K.,Zlot-skii, S. S.,Rakhmankulov, D. L.
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p. 136 - 139
(2007/10/02)
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- TRANSFORMATIONS OF 2-ETHOXY-1,3-DIOXOLANE AND 2-ETHOXY-1,3-OXATHIOLANE IN THE PRESENCE OF THE Fe(II) + H2O2 + Fe(III) SYSTEM
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In an inert atmosphere (argon) in reaction with ferrous sulfate and hydrogen peroxide in a saturated aqueous solution of ferric sulfate at 5-10 deg C 2-ethoxy-1,3-dioxolane and 2-ethoxy-1,3-oxathiolane change after 15 min into ethylene glycol monoformate and 2-mercaptoethyl formate with yields of 49 and 32percent respectively and with cca 50percent conversion in the substrate.
- Trifonova, V. N.,Zorin, V. V.,Zlot-skii, S. S.,Rakhmankulov, D. L.
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p. 764 - 767
(2007/10/02)
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- TRANSFORMATIONS OF 1,3-DIOXACYCLANES BY THE ACTION OF THE Fe(II) + H2O2 + Fe(III) SYSTEM
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The reaction of 1,3-dioxacyclanes with the Fe(II) + H2O2 + Fe(III) system in an aqueous medium leads to the formation of glycol monoesters, while the reaction in acetic acid leads to the formation of glycol diesters.The reaction takes place through the formation and one-electron oxidation of 1,3-dioxa-2-cycloalkyl radicals.If the ring is increased, the yield of the esters and the relative reactivity of the 1,3-dioxacyclanes are reduced. 2-Methyl-1,3-dioxacyclanes are more reactive than the corresponding formals.In the reaction of 1,3-dioxacyclanes with the Fe(II) + H2O2 + Fe(III) system in aqueous acetic acid a mixture of the monoesters and diesters is formed, and the ratios of their concentrations depends linearly on the ratio of the concentrations of water and acetic acid.
- Trifonova, V.N.,Zorin, V.V.,Zlot-skii, S.S.,Rakhmankulov, D.L.
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p. 909 - 912
(2007/10/02)
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- Rational Mechanism for Homogeneous Hydrogenation of Carbon Monoxide to Alcohols, Polyols, and Esters
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The products derived from synthesis gas conversion by homogeneous catalysis are concluded to be formed via the key intermediate formaldehyde.The intermediacy of formaldehyde is supported by reaction rate studies, comparison reactions of formaldehyde with synthesis gas, and the trapping of formaldehyde and glycolaldehyde intermediates during a reaction as their ethylene glycol acetals.Although the formation of formaldehyde from synthesis gas is themodynamically unfavorable, it is argued that the concentration of formaldehyde permitted by thermodynamics is more than sufficient for a transient intermediate.The overall mechanism incorporates only step that are already well established in the science of homogeneous catalysis.
- Fahey, Darryl R.
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p. 136 - 141
(2007/10/02)
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- The mechanism of oxidation of acetals by ozone. I. Stoichiometry, order of reaction, solvent effects, and substituent effects
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A systematic investigation of the reaction between ozone and acetals to form acetal hydrotrioxides A has been undertaken.The stoichiometry of the reaction has been shown to be 1:1 in each reactant and the order of the reaction was also one in each reactant.Substituent effects measured in a variety of systems and under several conditions of temperature and solvent were found to be small (ρ=-1.10 to -1.58).Solvent polarity was also found to have little effect on the rate of the reaction.Mechanistically, these facts are interpreted in terms of a 1,3-dipolar insertion of ozone into the C-H bond of the acetal function.
- Taillefer, Roland J.,Thomas, Shirley E.,Nadeau, Yves,Fliszar, S.,Henry, Herve
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p. 1138 - 1143
(2007/10/02)
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- Catalytic process for polyhydric alcohols and derivatives
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This invention relates to the manufacture of such valuable chemicals as polyhydric alcohols, their ether and ester derivatives, oligomers of such alcohols and monohydric alcohols and their ether and ester derivatives by reacting oxides of carbon and hydrogen in the presence of a quaternary ammonium cation and a rhodium carbonyl complex provided to the reaction as a rhodium carbonyl cluster anion which possesses an infrared spectrum which exhibits three intense wavelength bands between about plus and minus 10 cm-1 of about 1868 cm-1, about 1838 cm-1, and about 1785 cm-1 and said cation is present in the reaction mixture in about 0.8 to about 2.0 moles of cation for every six rhodium atoms present in the reaction mixture.
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