- Kinetic evaluation of the solvolysis of isobutyl chloro-and chlorothioformate esters
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The specific rates of solvolysis of isobutyl chloroformate (1) are reported at 40.0 °C and those for isobutyl chlorothioformate (2) are reported at 25.0 °C, in a variety of pure and binary aqueous organic mixtures with wide ranging nucleophilicity and ionizing power. For 1, we also report the first-order rate constants determined at different temperatures in pure ethanol (EtOH), methanol (MeOH), 80% EtOH, and in both 97% and 70% 2,2,2- trifluoroethanol (TFE). The enthalpy ΔH≠ and entropy ΔS≠ of activation values obtained from Arrhenius plots for 1 in these five solvents are reported. The specific rates of solvolysis were analyzed using the extended Grunwald-Winstein equation. Results obtained from correlation analysis using this linear free energy relationship (LFER) reinforce our previous suggestion that side-by-side addition-elimination and ionization mechanisms operate, and the relative importance is dependent on the type of chloro-or chlorothioformate substrate and the solvent.
- D'Souza, Malcolm J.,McAneny, Matthew J.,Kevill, Dennis N.,Kyong, Jin Burm,Choi, Song Heec
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- Room temperature and normal pressure preparation method of organic carbonate
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The invention relates to the technical field of organic synthesis, and provides a room temperature and normal pressure preparation method of organic carbonate. The method comprises the following steps: introducing carbon dioxide into an imidazole ionic liquid to obtain a mixture; mixing the obtained mixture with alcohol and halogenated hydrocarbon, and carrying out addition-substitution reactionsto obtain organic carbonate. The whole reaction process is carried out at a room temperature under a normal pressure. The activation energy of the reaction is reduced by using imidazole ionic liquid and halogenated hydrocarbon, and finally, organic carbonate is prepared from CO2 at a room temperature under a normal pressure.
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Paragraph 0094-0096
(2020/07/15)
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- Method for synthesizing organic carbonate from carbon dioxide, alcohol and brominated alkane under mild conditions
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The invention discloses a method for synthesizing organic carbonate from carbon dioxide, alcohol and brominated alkane under mild conditions, belonging to the field of chemical synthesis. According tothe method, carbon dioxide, alcohol and brominated alkane are used as raw materials, 1,8-diazabicycloundec-7-ene (DBU) is used as an activating agent, and acetonitrile is used as a solvent to preparethe organic carbonate. The target product, namely the organic carbonate with excellent yield can be obtained under optimized reaction conditions. The method is mild in reaction conditions, simple andconvenient to operate and high in yield, and is an excellent system for preparing the organic carbonate.
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Paragraph 0016-0017; 0018-0020; 0022; 0024
(2020/06/02)
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- METHOD OF PREPARING DIALKYLCARBONATES
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The present invention relates to a process of preparing dialkylcarbonates, and particularly to an improved process of preparing dialkylcarbonates, which comprises performing a reaction between an alcohol compound and a chloroformate derivative in the presence of an imidazole compound, thereby enabling to prepare dialkylcarbonates with high yield in a mild condition without using toxic raw materials and to easily separate impurities.
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Page/Page column 8; 9
(2008/06/13)
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- Deamination Reactions, 41. Reactions of Aliphatic Diazonium Ions and Carbocations with Ethers
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Aliphatic diazonium ions and carbocations were generated by deacylation of appropriate nitrosoureas (1, 5, 9) in alcohol-ether mixtures or in 2-alkoxyethanols.Ethers were generally inferior to alcohols in capturing cationic intermediates.Formation of trialkyloxonium ions led to alkyl exchange or ring opening.The observed reactivity orders were n-butyl > isobutyl for the diazonium ions, allyl > sec-butyl > tert-butyl for the carbocations, methoxy > ethoxy and oxirane > oxetane > tetrahydrofuran for the ethers, indicating the predominance of steric effects.Neighboring group participation in 4-methoxy-1-butanediazonium ions (58) and 4,5-epoxy-1-pentanediazonium ions (74) was detectable but inefficient ( 20percent of cyclic oxonium ions).
- Kirmse, Wolfgang,Jansen, Ulrich
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p. 2607 - 2625
(2007/10/02)
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- KINETIC RELATIONSHIPS GOVERNING THE ETHANOLYSIS OF HALOGENOFORMATES
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The kinetics of the ethanolysis of a series of halogenoformates at various temperatures were investigated by titrimetric and conductometric methods.It is suggested that the conformational composition of the chloroformates has an effect on the solvolysis rate.A parameter which takes account of the conformational factor is proposed, and the quantitative relation of the Taft type relating the solvolysis rate constant to the parameters of the substituents is obtained.The effect of the leaving group and the effect of substitution of the ether oxygen by sulfur in the chloroformate were investigated.The obtained data are interpreted in terms of an addition-elimination mechanism.
- Orlov, S. I.,Chimishkyan, A. L.,Grabarnik, M. S.
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p. 1981 - 1987
(2007/10/02)
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