- Carbonate phosphonium salts as catalysts for the transesterification of dialkyl carbonates with diols. The competition between cyclic carbonates and linear dicarbonate products
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At 90-120 °C, in the presence of methylcarbonate and bicarbonate methyltrioctylphosphonium salts as catalysts ([P8881][A]; [A] = MeOCO2 and HOCO2), the transesterification of non-toxic dimethyl- and diethyl-carbonate (DMC and DEC, respectively) with 1,X-diols (2 ≤ X ≤ 6) proceeds towards the formation of cyclic and linear products. In particular, 1,2-propanediol and ethylene glycol afford propylene- and ethylene-carbonate with selectivity and yields up to 95 and 90%, respectively; while, the reaction of DMC with higher diols such 1,3-butanediol, 2-methyl-1,3-propanediol, 1,3-propanediol, 2,2-dimethyl, 1,3-propanediol, 1,4-butanediol and 1,6-hexanediol produce linear C8-C10 dicarbonates of general formula MeOC(O)O~~~OC(O)OMe as the almost exclusive products. Of note, these dicarbonate derivatives are not otherwise accessible in good yields by other conventional base catalyzed methods. Among 1,3-diols, the only exception was 2-methyl 2,4-pentandiol that yields the corresponding cyclic carbonate, i.e. 4,4,6-trimethyl-1,3-dioxan-2-one. In no one case, polycarbonates are observed. Such remarkable differences of product distributions are ascribed to the structure (branching and relative position of OH groups) of diols and to the role of cooperative (nucleophilic and electrophilic) catalysis which has been proved for onium salts. The investigated carbonate salts are not only effective in amounts as low as 0.5 mol%, but they are highly stable and recyclable. This journal is the Partner Organisations 2014.
- Selva, Maurizio,Caretto, Alessio,Noe, Marco,Perosa, Alvise
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- Protic ionic liquid-promoted synthesis of dimethyl carbonate from ethylene carbonate and methanol
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In this work, the protic ionic liquid [DBUH][Im] (1,8-diazabicyclo[5.4.0]-7-undeceniumimidazolide) was developed as an efficient catalyst for the transesterification of ethylene carbonate with methanol to produce dimethyl carbonate. At 70 °C, up to 97% conversion of ethylene carbonate and 91% yield of dimethyl carbonate were obtained with 1 mol% [DBUH][Im] (relative to ethylene carbonate) as catalyst in 2 h. Even at room temperature, the conversion of ethylene carbonate can reach 94% and the yield of dimethyl carbonate can approach 81% for 6 h. Catalytic mechanism investigation showed the high catalytic efficiency of this ionic liquid results from the synergistic activation effect, wherein the cation can activate ethylene carbonate and the anion can activate methanol through hydrogen bond formation. Although the reusability of the ionic liquid need to be further improved, high efficiency and commercial availability of [DBUH][Im] render it a promising catalyst for the preparation of dimethyl carbonate.
- Song, Yu,He, Xing,Yu, Bing,Li, Hong-Ru,He, Liang-Nian
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p. 667 - 672
(2019/08/16)
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- Fast and facile preparation of metal-doped g-C3N4 composites for catalytic synthesis of dimethyl carbonate
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Zn-doped g-C3N4 materials (Zn-g-C3N4) were prepared by a simple mixing and calcination, using dicyandiamide as a precursor and zinc halide as a dopant. The characterization results of CO2 temperature-programmed desorption and elemental analysis revealed that the introduction of Zn species enhanced the overall basic quantity of g-C3N4. In the transesterification of ethylene carbonate with CH3OH to dimethyl carbonate (DMC), the Zn-g-C3N4 catalysts showed superior catalytic activity to the pure g-C3N4, and the highest DMC yield reached 83.3%, along with stable catalytic reusability and reproducibility. Furthermore, other transition-metal halides (including FeCl3, CuCl2, NiCl2, etc.) could be utilized as dopants for g-C3N4, and the obtained doped g-C3N4 materials also showed high EC conversions above 70%. The upgradation of basic quantity of g-C3N4 was attributed to the reaction between metal halide and the active amine species of g-C3N4. Despite their low surface areas, under the same catalytic conditions, Zn-g-C3N4 catalysts demonstrated remarkably higher catalytic activity than other mesoporous carbon nitride materials.
- Xu, Jie,Long, Kai-Zhou,Wang, Yue,Xue, Bing,Li, Yong-Xin
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- Efficient synthesis of dimethyl carbonate via transesterification of ethylene carbonate over a new mesoporous ceria catalyst
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Mesoporous ceria materials (CeO2-meso) have been prepared through a soft-templating method using cetyltrimethylammonium bromide as a template and cerium nitrate as a precursor. The synthesized CeO2-meso materials possess narrow pore size distributions of 5.1-5.4 nm and tunable surface areas (109-182 m2 g-1). As heterogeneous catalysts in the transesterification of ethylene carbonate (EC) with methanol to dimethyl carbonate (DMC), CeO2-meso materials demonstrate superior catalytic performance to the commercial ceria. N2 adsorption-desorption and CO2-TPD characterization results indicate that the catalytic activity obtained over various CeO2-meso samples depends on their surface areas and basicity. The highest activity is achieved over CeO 2-meso-400, affording a DMC yield as much as 73.3%, together with excellent recycling ability. Besides the transesterification of EC with methanol, CeO2-meso is found to be able to catalyze the reactions of other cyclic carbonates and alcohols. In view of the high catalytic performance along with the convenience in catalyst preparation, CeO2-meso-400 compares favorably with the ionic liquids as well as other ceria-based catalytic systems.
- Xu, Jie,Long, Kai-Zhou,Wu, Fei,Xue, Bing,Li, Yong-Xin,Cao, Yong
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- PROCESS FOR PREPARING CARBONATE AND DIOL PRODUCTS
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A method of forming a cyclic carbonate product is carried out by reacting an alkylene oxide, such as ethylene oxide, with carbon dioxide in the presence of a metal organic framework (MOF) catalyst with less than 0.5 mol % of any potassium or quaternary ammonium salts present based on moles of alkylene oxide feed in a reaction zone under reaction conditions to form a cyclic carbonate product. The cyclic carbonate product may be optionally fed as a crude carbonate product that does not undergo any purification or separation, other than the optional removal of any portion of unreacted alkylene oxide, carbon dioxide, and light hydrocarbon gases, to a second reaction zone containing a transesterification catalyst along with an aliphatic monohydric alcohol. The cyclic carbonate product and monohydric alcohol are allowed to react under reaction conditions to form the dialkyl carbonate and diol products.
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Paragraph 0065-00072
(2013/09/12)
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- PRODUCING PROCESS DIALKYL CARBONATE
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An object of the present invention is to provide an industrially advantageous process for simultaneously producing a symmetric dialkyl carbonate and an asymmetric dialkyl carbonate by performing a transesterification reaction of an alkylene carbonate with two or more kinds of alcohols; and a process for efficiently producing diethyl carbonate in high purity by performing transesterification of ethylene carbonate or propylene carbonate with ethanol, The present invention relates to a process for simultaneously producing a symmetric dialkyl carbonate and an asymmetric dialkyl carbonate, comprising performing a transesterification reaction of an alkylene carbonate with two or more kinds of alcohols in the same reactor, and a process for producing diethyl carbonate, comprising performing a transesterification reaction of ethylene carbonate or propylene carbonate with ethanol, wherein the process comprises a step of subjecting the reaction product obtained in the transesterification reaction to extractive distillation using ethylene glycol or propylene glycol as the extraction solvent to separate by distillation a fraction containing an ether compound.
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Page/Page column 14
(2011/11/07)
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- Dimethyl carbonate synthesis catalyzed by DABCO-derived basic ionic liquids via transesterification of ethylene carbonate with methanol
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Easily prepared DABCO-derived (1,4-diazobicyclo[2.2.2]octane) basic ionic liquids were developed for an efficient synthesis of dimethyl carbonate (DMC) via the transesterification of ethylene carbonate (EC) with methanol. 1-Butyl-4-azo-1-azoniabicyclo[2.2.2]octane hydroxide ([C4DABCO]OH) exhibited high catalytic activity and 81% DMC yield together with 90% EC conversion was obtained under mild reaction conditions. Notably, the catalyst could be recycled for four times without loss of catalytic activity. Moreover, a possible mechanism was also discussed.
- Yang, Zhen-Zhen,He, Liang-Nian,Dou, Xiao-Yong,Chanfreau, Sébastien
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supporting information; experimental part
p. 2931 - 2934
(2010/06/16)
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- Process for co-production of dialkyl carbonate and alkanediol
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A method is provided for co-producing dialkyl carbonate and alkanediol by reacting alkylene carbonate with alkanol in the presence of an amorphous aluminosilicate catalyst containing alkali metal, alkaline earth metal, or a combination thereof.
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Page column 4-6
(2008/06/13)
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