- Superbase-catalysed addition of methanol to propyne and allene: An expedient synthesis of 2-methoxypropene
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In the superbase catalytic systems ButOK/NMP, Am tOCs/NMP and KOH/DMSO, methanol readily adds to propyne and allene at 100-120°C and atmospheric pressure to afford 2-methoxypropene in 80-97% yield with 75-94% methanol conversion.
- Trofimov, Boris A.,Oparina, Ludmila A.,Gusarova, Nina K.,Khil'ko, Marina Ya.,Parshina, Lidiya N.,Henkelmann, Jochem
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- A unique Au-Ag-Au triangular motif in a trimetallic halonium dication: Silver incorporation in a gold(I) catalyst
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As a result of explorations into the solution chemistry of silver/gold mixtures, a unique diphosphine trimetallic chloronium dication was discovered that incorporates silver-arene chelation and a triangular mixed gold/silver core in the solid state. Notably, it was isolated from a Celite prefiltered solution initially thought to be silver-free. The crystal structure also incorporates the coordination to silver of one fluorine atom of one SbF6 - counterion. The structure was compared to two new, but well-precedented, phosphine digold chloride cations. DFT calculations supported significant silver-halide and silver-arene interactions in the mixed gold/silver complex and metallophilic interactions in all three complexes. Comparison of computed data revealed that the ωB97X-D functional, which has a long-range corrected hybrid with atom-atom dispersion corrections, gave a better fit to the experimental data compared with the PBE0 functional, which has previously failed to capture aurophilic interactions. Preliminary studies support the presence of the mixed gold/silver structure in solution. Silver lining! As a result of explorations into the solution chemistry of silver/gold mixtures, a unique trimetallic chloronium dication was discovered that incorporates silver-arene chelation and a triangular mixed gold/silver core (see figure). Notably, it was isolated from a previously Celite-filtered solution, a procedure generally believed to be efficient at removing silver. The solid-state and solution structure, as well as DFT calculations are reported herein. Copyright
- Zhu, Yuyang,Day, Cynthia S.,Zhang, Lin,Hauser, Katarina J.,Jones, Amanda C.
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- ORGANIC TRANSFORMATIONS VIA METAL SILANE REAGENTS: SYNTHESES OF VINYL ETHERS FROM DIMETHYL KETALS AND (CO)5MnSi(CH3)3
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The reaction of dimethyl ketals wit (CO)5MnSi(CH3)3 (1) at 50 deg C in CH3CN affords methyl enol ethers, generally in 75-95percent yields.
- Marsi, Marianne,Gladysz, J. A.
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- Infrared spectra and conformational structure of 2-methoxypropene
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The rotational isomerism of the title compound, CH2=C(CH3)OCH3, has been studied by i.r. spectroscopy.The spectrea reveal the presence of two conformational isomers in the fluid phases.The energy difference between them is estimated to be 0.85 kcal/mole in the liquid state.From the shapes of the band envelopes in the vapour phase spectra evidence is obtained that the more stable isomer has a planar configuration of the heavy atoms.A vibrational assignment of the observed fundamental bands has been attempted on the basis of characteristic group frequencies.
- Diallo, A. O.
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Read Online
- Direct transformation of silica from natural resources to form tetramethoxysilane
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A simple and practical method for direct synthesis of tetramethoxysilane (TMOS) from silica (SiO2) and methanol was achieved using a base catalyst and acetal as a dehydrant under carbon dioxide (CO2). The production of TMOS was strongly influenced by the kind of the acetal used, with 2,2-dimeth-oxypropane identified as the most effective dehydrant. We observed that the acetal used enabled the production of a high yield of dimethyl carbonate (DMC), which promoted the TMOS production. DMC is an intermediate product from the reaction of CO2 and methanol, which supported the SiO2 depolymerization process. When the reaction is conducted with 2,2-dimethoxypropane at 260 °C for 24 h, TMOS can be produced in up to 59percent yield. For practical applications, the TMOS synthesis has been developed on a 250 mL and 1 L-scale reaction with constant yield (>50percent) from various silica resources.
- Putro, Wahyu S.,Fukaya, Keisuke,Choi, Jun-Chul,Choi, Seong Jib,Horikoshi, Toshio,Sato, Kazuhiko,Fukaya, Norihisa
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supporting information
p. 958 - 962
(2020/09/04)
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- Enantioselective Radical-Polar Crossover Reactions of Indanonecarboxamides with Alkenes
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Highly efficient asymmetric intermolecular radical-polar crossover reactions were realized by combining a chiral N,N′-dioxide/NiII complex catalyst with Ag2O under mild reaction conditions. Various terminal alkenes and indanonecarboxamides/esters underwent radical addition/cyclization reactions to afford spiro-iminolactones and spirolactones with good to excellent yields (up to 99 %) and enantioselectivities (up to 97 % ee). Furthermore, a range of different radical-mediated oxidation/elimination or epoxide ring-opening products were obtained under mild reaction conditions. The Lewis acid catalysts exhibited excellent performance and precluded the strong background reaction.
- Cao, Weidi,Feng, Xiaoming,Liu, Xiaohua,Wu, Wangbin,Xu, Xi,Yu, Han,Zhang, Xiying
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supporting information
p. 4846 - 4850
(2020/02/11)
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- Method for continuously preparing 2-methoxypropene
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The invention discloses a method for continuously preparing 2-methoxypropene. According to the method, 2-methoxypropene is prepared through catalytic cracking of 2,2-dimethoxypropane under the synergistic effect between acid ceramic filler and a promoter, and is separated and purified by combining membrane separation and rectification. Through the method, the problem that 2-methoxypropene, 2,2-dimethoxypropane and methanol are hard to separate due to azeotropy is avoided, and 2-methoxypropene with purity higher than 99% is obtained.
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Paragraph 0033; 0034
(2019/10/01)
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- Method for preparing 2-methoxypropylene
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The invention relates to a method for preparing 2-methoxypropylene. In existing synthetic systems, a solvent is used in some systems; and in some systems, although no solvent is used, usage amount ofacid is especially large such that industrial production is not feasible. By using p-toluenesulfonic acid as a catalyst and using pyridine, quinoline or hydroquinone, etc. as a cocatalyst, catalytic cracking of 2,2-dimethoxypropane is carried out to prepare 2-methoxypropylene. The reaction time is 5-15h; the reaction temperature is 60-150 DEG C; the reaction pressure is normal pressure; the product yield can reach 93.0%; and purity of the product obtained by rectification is 99.5%. According to the method, no solvent is used, no acid anhydride is introduced, reaction condition is mild, and continuous industrial production can be realized.
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Paragraph 0019-0027
(2019/01/08)
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- Synthesis of methyl acetoacetate from acetone and dimethyl carbonate with alkali-promoted MgO catalysts
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The synthesis of methyl acetoacetate (MAA) by methoxycarbonylation of acetone with dimethyl carbonate (DMC) was carried out in the presence of MgO and alkali-promoted MgO catalysts. From among Li, Na, K, and Cs, potassium was found to be the most effective promoter to improve the activity of MgO. The effect of K/MgO with variable content of K was also investigated, and the individual catalysts were characterised by the XRD, BET, SEM, CO2-TPD, and in situ CO2 IR techniques. The results showed that the addition of a small amount of K (1.97 mass %) could promote MAA formation, but a higher K loading caused a decrease in the yield of MAA, which might result from particle agglomeration and the presence of stable potassium carbonates. In situ FTIR experiments of co-adsorbed reactants indicated that the reaction probably proceeded via abstraction of Hα from acetone by base sites.
- Wu, Dudu,Chen, Zhi
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experimental part
p. 758 - 766
(2011/11/29)
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- Process for isolating highly pure 2-methoxypropene
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A process for isolating purified 2-methoxypropene from a mixture which comprises 2,2-dimethoxypropane, 2-methoxypropene, methanol, acetone, and optionally other carbonyl group-containing compounds, which process involves subjecting the mixture to distillation, adding 2-aminoethanol and at least one base as assistants in the distillation, and isolating purified 2-methoxypropene.
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Page/Page column 5-6
(2008/06/13)
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- METHOD FOR THE PRODUCTION OF ISOPROPENYL ETHERS
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The invention relates to a method for the production of isopropenyl ethers of formula (A), wherein R represents an aliphatic, cycloaliphatic, aralyphatic, aromatic or heterocyclic radical which can include other substituents which do not react with acetylenes or allens, by reacting a gaseous flow (I), containing MAPD which is obtained from an olefin system and which is used to separate C3-sections, with at least one gaseous flow selected from a gaseous flow (II) containing an acetone ketal of formula (B), wherein R has the above-mentioned meaning, and a gaseous flow (III) containing a monohydroxyalcohol ROH, wherein R has the above-mentioned meaning, in the presence of a heterogeneous catalyst.
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Page/Page column 13
(2010/02/13)
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- METHOD FOR THE PRODUCTION OF KETALS AND ENOL ETHERS
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The invention relates to a method for the production of ketals and optionally enol ethers, wherein a) an alkyne and/or allene is reacted with an alcohol in a gaseous phase on a catalyst containing zinc oxide and/or cadmium oxide in order to obtain a reaction mixture which contains non-reacted alcohol, an enol ether and a ketal, b) optionally, a fraction is removed by distillation from the reaction mixture, containing the non-reacted alcohol and at least one part of the enol ether, and c) subjecting the reaction mixture from step a) or the fraction from step b), optionally adding an additional alcohol, and post-reacting in the liquid phase in the presence of an acidic catalyst.
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Page/Page column 7-8
(2008/06/13)
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- Preparation of enol ethers
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Enol ethers of the formula (I) where R1to R3are each, independently of one another, hydrogen or a carbon-containing organic radical and R4is an unsubstituted or substituted alkyl radical, are prepared by reacting alcohols of the formula (II) R4—OH??(II), with alkynes of the formula (IlIa), alkadienes of the formula (IIIb) R1—C≡C—CHR2R3??(IIIa), R1—CH═C═CR2R3??(IIIb) or mixtures thereof, where R1to R4are as defined above, in the presence of an alkali metal alkoxide and a polar, aprotic solvent.
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- Preparation of enol ethers
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A process for the preparation of enol ethers of the general formula I STR1 in which R1,R2,R3,R4,R5 denote C1 -C20 alkyl, C1 -C20 alkenyl, or C7 -C20 phenylalkyl, R2,R3,R4 denote hydrogen, aryl, cyano, --COOR5, C1 -C12 alkyl monosubstituted to trisubstituted or interrupted by --COOR5, --C=O, cyano, or C1 -C12 alkoxy, C1 -C12 alkyl monosubstituted to trisubstituted by --COOR5, --C=O, cyano, or C1 -C12 alkyl, or C7 -C20 phenylalkyl and R2 and R4 or R3 and R4 together form a C3 -C10 alkylene chain or a C2 -C20 alkylidene chain, from acetals or ketals.
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- Process for preparing unsaturated ethers
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A process for preparing unsaturated ethers of the formula (1) STR1 from acetals or ketal of the formula (2) STR2 is improved by heating the acetals or ketals at from 100° to 250° C. in a high-boiling, branched carboxylic acid and obtaining the unsaturated ether as a distillate. The process, which is insensitive to contaminants, gives the unsaturated ether in high yields.
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- Isomerization reactions of the n-C4H9O and n-OOC4H8OH radicals in oxygen
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Reactions of n-C4H9O radicals have been investigated in the temperature range 343-503 K in mixtures of O2/N2 at atmospheric pressure. Flow and static experiments have been performed in quartz and Pyrex vessels of different diameters, walls passivated or not towards reactions of radicals, and products were analyzed by GC/MS. The main products formed are butyraldehyde, hydroperoxide C4H8O3 of MW 104, 1-butanol, butyrolactone, and n-propyl hydroperoxide. It is shown that transformation of these RO radicals occurs through two reaction pathways, H shift isomerization (forming C4H8OH radicals) and decomposition. A difference of activation energies ΔE = (7.7 ± 0.1 (σ)) kcal/mol between these reactions and in favor of the H-shift is found, leading to an isomerization rate constant κisom (n-C4H9O) = 1.3 × 1012 exp(-9,700/RT). Oxidation, producing butyraldehyde, is proposed to occur after isomerization, in parallel with an association reaction of C4H8OH radicals with O2 producing OOC4H8OH radicals which, after further isomerization lead to an hydroperoxide of molecular weight 104 as a main product. Butyraldehyde is mainly formed from the isomerized radical HOCCCC. + O2 ? →O=CCCC + HO2, since (i) the ratio butyraldehyde/(butyraldehyde + isomerization products) = 0.290 ± 0.035 (σ) is independent of oxygen concentration from 448 to 496 K, and (ii) the addition of small quantities of NO has no influence on butyraldehyde formation, but decreases concentration of the hydroperoxides (that of MW 104 and rt-propyl hydroperoxide). By measuring the decay of [MW 104] in function of (NO] added (0-22.5 ppm) at 487 K, an estimation of the isomerization rate constant OOC4H8OH→ HOOC4H7OH, κ5 ≈ 1011exp(- 17,600/RT) is made. Implications of these results for atmospheric chemistry and combustion are discussed. ?1996 John Wiley and Sons, Inc.
- Heiss, Adolphe,Sahetchian, Krikor
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p. 531 - 544
(2007/10/03)
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- Infrared Photochemistry of Oxetanes: Mechanism of Chemiluminescence
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The infrared multiphoton (IRMP) induced photolysis of several oxetanes is examined at low pressures (ca. 100 mtorr) while experimental variables such as laser frequency, laser energy, bath gas, and bath gas pressure are altered.The products of the IRMP induced photolysis of 2-acyl-3 ethoxy-2-methyloxetane, Ox1, are primarily biacetyl and ethyl vinyl ether.When the photolysis is run with the collimated beam of a CO2 laser (1-3 J/cm2) luminescence is observed.The intensity of the luminescence varies with the efficiency of the unimolecular decomposition of the oxetane.On the basis of the spectral distribution and temporal behavior of the luminescence following irradiation of Ox1, the emitter is believed to be vibrationally hot electronically excited biacetyl.Similar experiments with 2,2-dimethyl-3-ethoxyoxetane give a weaker emission apparently due to excited-state acetone.Results are discussed in terms of the reverse of the Paterno-Buchi reaction - a diabatic retrophotocycloaddition.
- Farneth, William E.,Johnson, Douglas G.
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p. 773 - 780
(2007/10/02)
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- The Decomposition of t-Butyl Heptafluoroperoxybutyrate in Aromatic and Aliphatic Solvents
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Kinetical studies and products analyses of the thermal decomposition of t-butyl heptafluoroperoxybutyrate (TBH) in benzene, octane, nitrobenzene, pyridine, and methoxybenzene have been carried out.In benzene and octane, the decoposition appears to be entirely a radical process.In nitrobenzene and pyridine, the reactions are found to give ionic decomposition proudcts exclusively.On the other hand, the decomposition of TBH in methoxybenzene is characteristic of mixed ionic and radical cleavages.
- Sawada, Hideo,Hagii, Hidehiko,Aoshima, Kazuyoshi,Yoshida, Masato,Kobayashi, Michio
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p. 3448 - 3452
(2007/10/02)
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- Thermal Decomposition of t-Butyl Heptafluoroperoxybutyrate
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The decomposition of t-butyl heptafluoroperoxybutyrate (TBH) was studied in both toluene and methanol.Kinetic and product studies from the thermolysis showed that this peroxy ester decomposes heterolytically in nonpolar solvents like toluene with homolysis, whereas in methanol this peroxy ester undergoes principally transesterification.
- Sawada, Hideo,Hagii, Hidehiko,Aoshima, Kazuyoshi,Arai, Takeshi
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p. 1161 - 1162
(2007/10/02)
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- Intrinsic Barriers in Nucleophilic Displacements. A General Model for Intrinsic Nucleophilicity toward Methyl Centers
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The applicability of the Marcus rate-equilibrium formalism to the double-minimum potential energy surface for gas-phase SN2 reactions is proposed and used to develop a model for intrinsic nucleophilicity toward methyl centers.The key quantities in this model are the energy barriers to degenerate reactions of the form X(-*)CH3X -> XCH3(*)X(-), in which the reacting species are ion-molecule cluster intermediates.Available experimental and theoretical data corroborate several of the model's predictions.A new structure-nucleophilicity correlation is proposed, involving methyl cation affinities.The model suggests that delocalization effects do not greatly influence nucleophile reactivity.
- Pellerite, Mark J.,Brauman, John I.
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p. 2672 - 2680
(2007/10/02)
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- The Effect of Pressure on the 4> Cycloaddition of Diphenylketen to Enol Ethers
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The volume profiles for the cycloaddition reactions between diphenylketen and butyl vinyl ether, 2-methoxypropene, and 2,3-dihydro-4H-pyran, respectively, have been determined.For the first example a wide range of solvents was studied.The Kirkwood theory seems to be not fully adequate for the description of the solvent effects found for the rate konstant and especially for the partial molar volumes.Solvent cohesive energy densities offer an alternative description.In the most solvents the volumes of activation are similar in magnitude and support a concerted mechanism for the cycloaddition.
- Swieton, Gernot,Jouanne, Joern von,Kelm, Hartwig,Huisgen, Rolf
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- 13-Cis prostaglandin derivatives
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13-Cis prostaglandin derivatives; cis-octenol ether copper(I) lithium reagents and methods of making such reagents and using the reagents to prepare the 13-cis prostaglandin derivatives. The 13-cis prostaglandin derivatives exhibit prostaglandin-like pharmacological properties and are further useful as intermediates for the corresponding prostaglandin isomers having the normal 13-trans configuration.
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