- Zeolitic imidazolate framework as efficient heterogeneous catalyst for the synthesis of ethyl methyl carbonate
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A zeolitic imidazolate framework (ZIF-8) was developed as a novel efficient heterogeneous catalyst for the synthesis of ethyl methyl carbonate from dimethyl carbonate and diethyl carbonate. ZIF-8 was characterized by element analysis, X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR), temperature programmed desorption (TPD), N2 adsorption-desorption and thermogravimetric analysis. The effects of catalyst amount, temperature and reaction time on the yield of ethyl methyl carbonate were also tested. The results showed that ZIF-8 performed excellent activity, selectivity and reusability under mild reaction conditions.
- Zhou, Xi,Zhang, Hong Ping,Wang, Gong Ying,Yao, Zhi Gang,Tang, Ying Ran,Zheng, Shan Shan
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Read Online
- Efficient porous carbon-supported MgO catalysts for the transesterification of dimethyl carbonate with diethyl carbonate
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Well-dispersed carbon-supported MgO catalysts were prepared using a kind of porous carbon (NC-2) as support and magnesium nitrate solution as MgO precursor by a simple wet impregnation technique. Various characterization techniques, including XRD, N2 sorption, DRIFT, XPS and TPD, were carried out to investigate their physical-chemical properties, the states of MgO species and the interaction between MgO and NC-2 materials. The catalytic properties of MgO/NC-2 catalysts were investigated in the liquid-phase transesterification of dimethyl carbonate (DMC) with diethyl carbonate (DEC). Compared with other kinds of carbon-supported MgO catalysts, MgO/NC-2 shows remarkably higher activity for the formation of ethyl methyl carbonate (EMC). Moreover, the NC-2 supported catalyst possesses very high stability against leaching of active species under test reaction conditions, indicating the truly heterogeneous nature of this catalyst. The presence of relatively rich oxygen-containing surface groups on the NC-2 carbon support should be in favor of the high dispersion of MgO particles, thus being beneficial to the fabrication of active and stable heterogeneous catalysts for the transesterificaiton reaction.
- Zhao, Guoming,Shi, Jinghui,Liu, Gang,Liu, Yan,Wang, Zhenlu,Zhang, Wenxiang,Jia, Mingjun
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Read Online
- Amorphous mesoporous aluminophosphate as highly efficient heterogeneous catalysts for transesterification of diethyl carbonate with dimethyl carbonate
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The catalytic performance of an amorphous mesoporous aluminophosphate (AlPO) was investigated for the transesterification of diethyl carbonate (DEC) with dimethyl carbonate (DMC) to synthesize ethyl methyl carbonate (EMC). Compared with other solid acid a
- Shi, Jinghui,Liu, Gang,Fan, Zhiqiang,Nie, Liying,Zhang, Zhihui,Zhang, Wenxiang,Huo, Qisheng,Yan, Wenfu,Jia, Mingjun
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- Magnesium aluminum spinel as an acid-base catalyst for transesterification of diethyl carbonate with dimethyl carbonate
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Mesoporous MgAl2O4 spinel (MAO), prepared via one-pot evaporation induced self-assembly strategy, was reported here as an acid-base bifunctionalization catalyst for the reaction for ethyl methyl carbonate from dimethyl carbonate and
- Wang, Jun,Han, Lu,Wang, Shuping,Zhang, Jingcai,Yang, Yanzhao
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Read Online
- Zeolitic imidazole framework-67 as an efficient heterogeneous catalyst for the synthesis of ethyl methyl carbonate
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Zeolitic imidazole framework (ZIF)-67, a novel environmentally benign catalyst, was developed for the preparation of ethyl methyl carbonate (EMC) from dimethyl carbonate and diethyl carbonate. EMC was obtained in 83.39% yield using ZIF-67 as the catalyst when compared to that obtained using ZIF-8 catalyst. NH3 and CO2 temperature-programmed desorption methods were used to evaluate the presence of both acidic and basic sites in ZIF-67 catalyst. The lager surface area of ZIF-67 favors for the adsorption of reactants over the solid surface of the catalyst, facilitating the formation of EMC. Moreover, ZIF-67 catalyst exhibited excellent reusability without significant loss in its catalytic activity.
- Yang, Lili,Yu, Lin,Sun, Ming,Gao, Cheng
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Read Online
- Binary Mg-Fe oxide as a highly active and magnetically separable catalyst for the synthesis of ethyl methyl carbonate
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Magnetic binary Mg-Fe oxides were prepared by a co-precipitation method, characterized and tested in the synthesis of ethyl methyl carbonate (EMC) from di methyl carbonate (DMC) and diethyl carbonate (DEC). The obtained results showed that the Mg/Fe oxide catalyst with a 1:1 molar ratio and calcined at 400 °C exhibited superior catalytic activity. The yield of EMC could reach 66% (at 100 °C for 1.5 h) with a TOF of 220 mmol h-1 gcat-1. The prepared catalysts could be magnetically separated, and reused for ten runs without noticeable deactivation. XRD and M?ssbauer spectra revealed that there was a synergistic effect between Mg and Fe oxides in the catalysts, which was consistent with the results of TPR, i.e. the introduction of the Mg component favored the reduction of the Fe2O3. XPS and IR characterizations indicated that there were a large number of accessible Fe-OHs on the surface of MgFe-400, and combining the Fe-OHs with the basic MgO may be related to the highly catalytic performance.
- Wang, Peixue,Liu, Shimin,Ma, Xiangyuan,He, Yude,Alshammari, Ahmad S.,Deng, Youquan
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Read Online
- Mg and Al dual-metal functionalized mesoporous carbon as highly efficient heterogeneous catalysts for the synthesis of ethyl methyl carbonate
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Mg and Al dual-metal functionalized nanoscale porous carbon materials (MgAl@NC) with highly ordered mesoporous structures and mixed active sites were successfully prepared using a simple one-pot synthesis method. The catalytic properties of the resultant MgAl@NC catalysts were investigated for the synthesis of ethyl methyl carbonate (EMC) in a fixed bed reactor. The catalysts exhibited remarkably high activity, selectivity and stability for the transesterification of diethyl carbonates (DEC) with dimethyl carbonates (DMC) even under high LHSV conditions. A 50.0% DEC conversion and a 99.2% EMC selectivity could be obtained at 103 °C and an LHSV = 7.8 h-1. The catalyst maintained a high product yield with almost no decrease in catalytic performance after 360 h. The well-dispersed magnesium aluminate spinel and α-cristobalite formed neighboring acid-base sites, while the synergistic catalytic effects of the mixed active sites should be critical for activation of the reactants. It may also be the reason for the efficient production of EMC under very high LHSV conditions.
- Cui, Yunzuo,Hao, Xiyun,Lin, Yanan,Liu, Chunling,Shi, Jinghui,Wang, He,Xue, Xiangxin,Zhang, Zhihui
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p. 21199 - 21205
(2021/12/09)
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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 0064-0066
(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; 0021
(2020/06/02)
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- Method for synthesizing aryl pyrazonitrile and by-producing carbonic acid diester
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The invention discloses a method for synthesizing aryl pyrazonitrile and by-producing carbonic acid diester. The method comprises the steps: taking 2,6-dichloro-4-trifluoromethylaniline, 2,3-dicyanopropionate and nitrite as main raw materials, carrying out diazotization and coupling reaction in a solvent containing fatty alcohol, adding a reaction terminating agent after coupling, and then carrying out alcoholysis and cyclization under an alkaline condition to generate aryl pyrazonitrile and carbonic acid diester. Different raw materials and process conditions are selected, the quality and theyield of the aryl pyrazonitrile are not influenced, and the generated by-product is purposefully controlled, so that after the cyclization liquid for synthesizing aryl pyrazonitrile is distilled andseparated, the distillate is subjected to multi-stage rectification, and solvents (methanol, ethanol or propanol and the like) can be recycled; meanwhile, carbonic acid diester of which the quality meets the industrial standard is obtained, and reduction and resource utilization of aryl pyrazonitrile synthesis waste liquid are realized.
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Paragraph 0008; 0029; 0032-0033
(2020/05/01)
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- Method for catalytic synthesis of methyl ethyl carbonate with long-service life solid alkali
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The invention discloses a method for catalytic synthesis of methyl ethyl carbonate with long-service life solid alkali and relates to a method for synthesizing the methyl ethyl carbonate. In the method, a mesoporous-microporous composite solid catalytic material with strong alkali active center and an L acid catalytic active center at the same time are prepared with a homogeneous-phase depositionmethod to be used for efficiently catalyzing dimethyl carbonate and ethanol carbonate to synthesize the methyl ethyl carbonate; by adopting a urea hydrolysis method to prepare a composite carrier andsupported metal oxide with alkalinity or acidity-alkalinity, a supported metal catalyst is prepared by taking one or a mixed salt solution of more of metal nitrate, sulfate and hydrochloride as a source of the active components and is used for a fixed bed reaction technology, the catalytic activity is essentially invariable, and the yield of the methyl ethyl carbonate is kept at about 50 percent;and the supported metal catalyst prepared by adopting the urea hydrolysis method has the advantages that the dispersity of the active center is high, the degree of crystallinity is good, and the catalytic effect is superior to the catalytic material prepared with a impregnation method or a co-precipitation method.
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Paragraph 0023-0033
(2019/04/04)
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- Improved Synthesis of Unsymmetrical Carbonate Derivatives Using Calcium Salts
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An effective synthetic method for unsymmetrical carbonate species has been developed. Calcium oxide and calcium hydroxide were found to be highly effective for this reaction, affording unsymmetrical carbonates in high yield and purity. Calcium chloride, which is a coproduct, serves as a water scavenger that can be easily removed. Additional drying processes and complicated purification steps are not necessary in this reaction. This improved process is important in terms of green sustainable chemistry principles.
- Hamada, Tomohito,Okada, Michiaki,Yamauchi, Akiyoshi,Kishikawa, Yosuke
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p. 667 - 673
(2019/04/25)
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- PRODUCTION METHOD OF ASYMMETRIC CHAIN CARBONATE
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A method for producing an asymmetric chain carbonate by reacting an alcohol with a halocarbonate ester compound in the presence of a basic magnesium salt.
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Paragraph 0125; 0130; 0135; 0137
(2019/01/04)
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- Method for preparing asymmetric carbonate esters
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The invention discloses a method for preparing asymmetric carbonate esters, and relates to a preparation method of a chemical raw material. At the same time, the invention provides a high-efficiency alkaline catalyst with a composite pore structure used for one-step synthesis of asymmetric carbonate esters from ethylene carbonate, methanol and various alcohols (ROH, wherein R can be various alcohols such as linear alcohols, isomeric alcohols, aromatic alcohols, phenols, and glycols such as ethylene glycol, diethylene glycol and polyols). The obtained crude product of the reaction contains dimethyl carbonate, asymmetric carbonate esters, symmetric carbonate esters and ethylene glycol, wherein the conversion rate of ethylene carbonate can reach up to 99% at maximum, and the byproduct ethylene glycol as a bulk raw material can be separated through simple distillation. The entire reaction process is clean, efficient, non-polluting and free of generating any waste. When the molar ratio of ethylene carbonate: methanol: various alcohols is 1:3:2, the reaction pressure is 5 MPa, the reaction temperature is 100 DEG C, and the space velocity is 5 h, the catalyst does not lose activity after being used for 5000 h, and the stability is better.
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Paragraph 0052; 0053; 0059; 0061
(2018/07/30)
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- CO2 promoted synthesis of unsymmetrical organic carbonate using switchable agents based on DBU and alcohols
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1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) is an effective nucleophilic catalyst for the transesterification of dimethyl carbonate (DMC) with various alcohols and amines, which afforded unsymmetrical organic carbonate and carbamate. It was observed that the transesterification was accelerated under pressurized CO2 in this work. The activity is very high and the best result (89% conversion with 98% selectivity to unsymmetrical carbonate) was obtained for the DBU/alcohol/DMC/CO2 system. The addition of CO2 to DBU/ethanol generated the DBU cation salt, [DBUH][OCOOCH2CH3], which dissociated more favorably under increasing reaction temperature even under pressurized CO2. The salt could also help to activate DMC by H-bond interaction. The reaction system can be extended easily for the catalytic synthesis of carbamates from amines and DMC. After the reaction, the salt was separated from the reaction mixture and DBU can be recovered by the feasible thermal decomposition, offering a straightforward strategy for the recycling of DBU. On the basis of these results, a plausible mechanism involving the role of both DBU and CO2 has been proposed.
- Gu, Qingwen,Fang, Jian,Xu, Zichen,Ni, Wenxiu,Kong, Kang,Hou, Zhenshan
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supporting information
p. 13054 - 13064
(2018/08/01)
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- Method for preparing methyl ethyl carbonate through transesterification of dimethyl carbonate and ethyl alcohol
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The invention relates to a method for preparing methyl ethyl carbonate through transesterification of dimethyl carbonate and ethyl alcohol. Dimethyl carbonate and ethyl alcohol are taken as raw materials; one or two of titanium glycine, titanium alanine, titanium proline, titanium isoleucine, titanium leucine, titanium phenylalanine, titanium valine and titanium glutamate are taken as catalysts; the mole ratio of ethyl alcohol to dimethyl carbonate is at 1-4; the dosage of the catalysts is 0.02-0.2% of the mass of dimethyl carbonate; the reaction temperature is at 70-90 DEG C; the reaction time is 1-5 hours; the maximal conversion rate of dimethyl carbonate and the maximal selectivity of methyl ethyl carbonate both can reach up to above 99%. The method disclosed by the invention has the advantages of low toxicity of raw materials, low pollution, mild reaction condition, no corrosion and less dosage of catalysts, high conversion rate of raw material dimethyl carbonate, high selectivityof product methyl ethyl carbonate, and the like.
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Paragraph 0011; 0020; 0021; 0022; 0024; 0026; 0028
(2019/01/08)
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- Method for preparing methyl ethyl carbonate through transesterification
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The invention relates to a method for preparing methyl ethyl carbonate through transesterification. Dimethyl carbonate and diethyl carbonate are taken as raw materials; one or more than two of titanium citrate, titanium malate, titanium tartrate, titanium oxalate, titanium malonate, titanium succinate, titanium glutarate and titanium adipate are taken as catalysts; the mole ratio of dimethyl carbonate to diethyl carbonate is at 1:1; the dosage of catalysts is 0.02-0.2% of the total weight of the dimethyl carbonate and diethyl carbonate; the reaction temperature is at 80-100 DEG C; the reactiontime is 2-6 hours; the conversion rate of dimethyl carbonate is above 85%; the selectivity of methyl ethyl carbonate is above 99%. The method provided by the invention has the advantages of low toxicity of raw materials, little pollution, simple technology, mild reaction condition, no corrosion and little dosage of catalysts, high conversion rate of raw materials, high product selectivity, and the like.
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Paragraph 0016-0026
(2019/01/08)
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- Method for preparation of methyl ethyl carbonate with co-precipitation catalyst
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The invention relates to a preparation method of chemical raw materials, in particular to a method for preparation of methyl ethyl carbonate with a co-precipitation catalyst. The method adopts coprecipitation technique to carry one or more of the active components Al2O3, CaO, La2O3, Fe2O3, Mn2O3, Cs2O, MgO, BaO, SrO and K2O, wherein Y is one or more oxides of Si and Al, and Z is one or more oxides of Si, Al and Ti. The invention has the advantages that: macropore can significantly improve the mass transfer effect, and micropore can significantly increase the specific surface area of the carrier and improve the dispersity of the active center. Magnesium nitrate, aluminum chloride and lanthanum sulfate are adopted as the active components and are mixed with a precursor to obtain the 15%MgO-5%Al2O3-3%La2O3/Al2O3-SiO2 catalyst, which can be applied to dimethyl carbonate and ethanol ester exchange fixed bed continuous reaction. The catalyst active center metal oxide prepared by precipitation method has smaller crystal grains, higher dispersity and surface area, and the prepared catalyst has catalytic effect superior to the catalyst prepared by impregnation method.
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Paragraph 0022; 0023; 0024; 0025; 0026; 0027-0075
(2018/01/11)
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- Method for preparing ethyl methyl carbonate through ester exchange method
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The invention provides a method for preparing ethyl methyl carbonate through an ester exchange method, and relates to a method for preparing a chemical raw material. A first catalyst prepared by the method simultaneously has macropore and micropore structures, wherein the macropores can obviously improve the mass transfer effect; and the micropores can obviously improve the specific surface area of a carrier and simultaneously improve the dispersity of active centers. Meanwhile, the prepared first catalyst simultaneously has an alkali active center and a Lewis acid catalytic active center. The prepared 15%MgO-5%MgCl2-2%La2O3/Al2O3-SiO2 is used in a dimethyl carbonate and ethanol ester exchange fixed bed continuous reaction; when the reaction temperature is 200 DEG C and the space velocity is 30h, the catalyst is not inactivated after 5000h of continuous reaction, the dimethyl carbonate conversion rate can be kept at 70%, the ethanol conversion rate can be kept at 80%, and the yield of the product ethyl methyl carbonate is 56%; and after the reaction, the catalyst can be reused through simple filtration treatment, and the activity of the catalyst can still be kept unchanged after the catalyst is reused for multiple times.
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Paragraph 0026; 0027; 0030; 0032; 0034; 0041; 0044; 0048
(2018/03/24)
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- The design of efficient carbonate interchange reactions with catechol carbonate
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Catechol carbonate (CC) has been investigated as an innovative and highly active reactant for carbonate interchange reactions (CIRs). Under mild conditions (atmospheric pressure, and 60-80°C), the selective synthesis of symmetric aliphatic carbonates (ROCO2R) has been achieved by the reaction of a slight excess of both primary and secondary alcohols with CC in the presence of NaOMe or MgO as a catalyst. Quantitative conversions have been reached in only 1 hour and products have been isolated in yields of up to 58% for dibutylcarbonate. Of note is that the reaction of glycerol with CC also proceeded under similar conditions (40-60°C, 1 atm) to afford glycerol carbonate (96-98%). The comparison of the reactivity of CC with that of conventional dialkyl carbonates, including dimethyl carbonate (DMC) and ethylene carbonate (EC), proved the superior performance of CC in all the investigated CIR processes. Accordingly, a mechanism has been formulated based on the leaving group ability of a catecholate anion originating from CC.
- Tabanelli,Monti,Cavani,Selva
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p. 1519 - 1528
(2017/05/01)
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- Method for preparing ethyl methyl carbonate
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The invention relates to a method for preparing ethyl methyl carbonate to mainly solve the problems that a catalyst used for preparing methyl ethyl carbonate through a reaction of dimethyl carbonate and ethyl alcohol at present is difficult to prepare and cannot be reused. Ethyl methyl carbonate is prepared from, by mass, 90.8 kg of dimethyl carbonate, 92.14 kg of ethyl alcohol and 3.64 kg of calcium methoxide. All the raw materials are continuously put into a reaction kettle according to the mass ratio, a backflow reaction is carried out for one hour at the normal pressure, and the reaction temperature is 80 DEG C; after balancing is achieved, methyl alcohol generated in the reaction is distilled out through reduced pressure distillation, is condensed and then enters a methyl alcohol storage tank, diethyl carbonate and ethyl methyl carbonate which are generated in the reaction, unreacted ethyl alcohol and unreacted dimethyl carbonate enter a rectifying tower for rectification separation, separated ethyl alcohol and separated dimethyl carbonate return to the reaction kettle to continue to participate in the reaction, ethyl methyl carbonate separated and distilled out enters a ethyl methyl carbonate storage tank, and diethyl carbonate separated and distilled out enters a diethyl carbonate storage tank. The method has the advantages that a catalyst is easy to prepare, and reuse can be achieved.
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Paragraph 0007
(2016/10/27)
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- A method of synthesizing methyl ethyl carbonate ester
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The invention relates to a method for synthesizing ethyl methyl carbonate through ester exchange. The method comprises the following steps: filling a fixed bed reactor with catalysts, pumping dimethyl carbonate and ethyl alcohol into the fixed bed reactor according to the molar ratio of 0.5-2:1 after nitrogen purging is carried out, reacting at the air speed of 0.5-15h-1, the temperature of 100-240DEG C and the reaction operation pressure of 0-1MPa, and finally the ethyl methyl carbonate is obtained. The catalysts are modified molecular sieve based catalysts. The method is simple in technology condition, easy to control, capable of achieving continuous production due to the gas-solid phase reaction and low in cost of the adopted catalysts. The selectivity of the ethyl methyl carbonate can be higher than 90%, and the yield can be higher than 55%.
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Paragraph 0024; 0025
(2017/01/05)
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- Geminal systems: 64. N-alkoxy-N-chloroureas and N,N-dialkoxyureas
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Molecular and crystal structures of N-alkoxy-N-chloroureas and N,N-dialkoxyureas were studied together with those of N-alkoxyureas as reference compounds. N-Alkoxy-N-chloroureas were found to have an elongated N - Cl bond and a shortened N-O(Alk) bond due to the nO(Alk)→σN-Cl anomeric effect. Alcoholysis of N-alkoxy-N-chloro derivatives of urea, N′-arylureas, and carbamates in the presence of silver trifluoroacetate leads to sterically hindered N,N-dialkoxyureas, N,N-dialkoxy-N′-arylureas, and N,N-dialkoxycarbamates, respectively.
- Shtamburg,Kostyanovsky,Tsygankov,Shtamburg,Shishkin,Zubatyuk,Mazepa,Kravchenko
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- METHOD OF MANUFACTURING DIETHYL CARBONATE
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A method manufactures diethyl carbonate by reaction distillation where transesterification and distillation are simultaneously performed in a multistage reaction distillation column provided with a catalyst introduction port and a raw material introduction port located below the catalyst introduction port, wherein: (a) the reaction is performed in a countercurrent flow format in which contact is brought about between a transesterification catalyst, dimethyl carbonate, and ethanol; (e) 1 to 250 mmol of catalyst is used per mole of dimethyl carbonate; (f) the ratio of the volume of air in the catalyst introduction port and the raw material introduction port regarding the volume of air in the reaction distillation part is 0.1 to 0.9; (g) the recirculation ratio in the reaction distillation column is 0.5 to 10; and (h) the temperature of the top part of the column and the reaction distillation part is 60 to 100° C.
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Paragraph 0142-0146
(2015/11/18)
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- Highly active and reusable ternary oxide catalyst for dialkyl carbonates synthesis
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The application of ternary oxides, prepared through calcination of rare-earth modified Mg/Al-hydrotalcite (HT), as highly active, selective, and reusable solid catalysts for dialkyl carbonates synthesis by transesterification reaction is reported. Dimethyl carbonate, for example, was prepared by reacting ethylene carbonate with methanol in 100 mol% selectivity at a yield of 95 mol%. Among several rare-earth modified precursors, La (10 mol%)-HT showed the highest activity. This catalyst was active even at ambient conditions. Basicity of the catalyst played crucial role on its performance. The activity of these catalysts was superior to the hitherto known solid catalysts for this reaction.
- Unnikrishnan,Srinivas
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- Synthesis of alkyl methyl ethers and alkyl methyl carbonates by reaction of alcohols with dimethyl carbonate in the presence of tungsten and cobalt complexes
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Alkyl methyl ethers and alkyl methyl carbonates were synthesized by reaction of alcohols with dimethyl carbonate in the presence of tungsten and cobalt carbonyls. Optimal reactant and catalyst ratios, as well as reaction conditions, were found for selective formation of alkyl methyl ethers or alkyl methyl carbonates.
- Khusnutdinov,Shchadneva,Mayakova
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p. 790 - 795
(2014/08/18)
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- Asymmetric organic carbonate synthesis catalyzed by an enzyme with dimethyl carbonate: A fruitful sustainable alliance
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We have successfully developed an easy and efficient bioprocess for asymmetric organic carbonate synthesis by performing Novozym 435 mediated esterification of DMC and alcohols in this work. Under the optimized conditions (60 °C, molar ratio of alcohol to DMC 1:12), the highest yield of carbonate can reach 95.6%. An additional advantage of the new process is the fact that 90% of the original activity of the enzyme is retained after being recycled nine times. Consequently it has potential as a useful enzyme-catalyzed process for the industrial production of asymmetric organic carbonates. The Royal Society of Chemistry 2014.
- Zhou, Yaoliang,Jin, Qiuyan,Gao, Zhanyan,Guo, Hongtao,Zhang, Haibo,Zhou, Xiaohai
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p. 7013 - 7018
(2014/02/14)
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- Zeolitic imidazole framework-67 as an efficient heterogeneous catalyst for the synthesis of ethyl methyl carbonate
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Zeolitic imidazole framework (ZIF)-67, a novel environmentally benign catalyst, was developed for the preparation of ethyl methyl carbonate (EMC) from dimethyl carbonate and diethyl carbonate. EMC was obtained in 83.39% yield using ZIF-67 as the catalyst when compared to that obtained using ZIF-8 catalyst. NH3 and CO2 temperature-programmed desorption methods were used to evaluate the presence of both acidic and basic sites in ZIF-67 catalyst. The lager surface area of ZIF-67 favors for the adsorption of reactants over the solid surface of the catalyst, facilitating the formation of EMC. Moreover, ZIF-67 catalyst exhibited excellent reusability without significant loss in its catalytic activity.
- Yang, Lili,Yu, Lin,Sun, Ming,Gao, Cheng
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- Activated metallic gold as an agent for direct methoxycarbonylation
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We have discovered that metallic gold is a highly effective vehicle for the low-temperature vapor-phase carbonylation of methanol by insertion of CO into the O-H bond to form methoxycarbonyl. This reaction contrasts sharply to the carbonylation pathway well known for homogeneously catalyzed carbonylation reactions, such as the synthesis of acetic acid. The methoxycarbonyl intermediate can be further employed in a variety of methoxycarbonylation reactions, without the use or production of toxic chemicals. More generally we observe facile, selective methoxycarbonylation of alkyl and aryl alcohols and secondary amines on metallic gold well below room temperature. A specific example is the synthesis of dimethyl carbonate, which has extensive use in organic synthesis. This work establishes a unique framework for using oxygen-activated metallic gold as a catalyst for energy-efficient, environmentally benign production of key synthetic chemical agents.
- Xu, Bingjun,Madix, Robert J.,Friend, Cynthia M.
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experimental part
p. 20378 - 20383
(2012/02/06)
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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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- METHOD FOR PRODUCING ASYMMETRIC CHAIN CARBONATE
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An asymmetric chain carbonate can be produced in a single-step reaction comprising a step of reacting methyl nitrite, carbon monoxide, and 0.05-1.5 moles of an aliphatic alcohol having 2-6 carbon atoms or an alicyclic alcohol having 5-6 carbon atoms per one mole of methyl nitrile in a gaseous phase in the presence of a solid catalyst comprising a platinum group metal or a compound thereof placed on a support.
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Page/Page column 5-6
(2011/06/24)
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- Asymmetric cyanation of aldehydes, ketones, aldimines, and ketimines catalyzed by a versatile catalyst generated from cinchona alkaloid, achiral substituted 2,2′-biphenol and tetraisopropyl titanate
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Full investigation of cyanation of aldehydes, ketones, aldimines and ketimines with trimethylsilyl cyanide (TMSCN) or ethyl cyanoformate (CNCOOEt) as the cyanide source has been accomplished by employing an in situ generated catalyst from cinchona alkaloid, tetraisopropyl titanate [Ti(OiPr)4] and an achiral modified biphenol. With TMSCN as the cyanide source, good to excellent results have been achieved for the Strecker reaction of N-Ts (Ts=p-toluenesulfonyl) aldimines and ketimines (up to >99% yield and >99% ee) as well as for the cyanation of ketones (up to 99% yield and 98% ee). By using CNCOOEt as the alternative cyanide source, cyanation of aldehyde was accomplished and various enantioenriched cyanohydrin carbonates were prepared in up to 99% yield and 96% ee. Noteworthy, CNCOOEt was successfully employed for the first time in the asymmetric Strecker reaction of aldimines and ketimines, affording various a-amino nitriles with excellent yields and ee values (up to >99% yield and >99% ee). The merits of current protocol involved facile availability of ligand components, operational simplicity and mild reaction conditions, which made it convenient to prepare synthetically important chiral cyanohydrins and examino nitriles. Furthermore, control ex-periments and NMR analyses were performed to shed light on the catalyst structure. It is indicated that all the hydroxyl groups in cinchona alkaloid and biphenol complex with TiIV, forming the catalyst with the structure of (biphenoxide) Ti(OR*)(Oi'Pr). The absolute configuration adopted by biphenol 4 m in the catalyst was identified as S configuration according to the evidence from control experiments and NMR analyses. Moreover, the roles of the protonic additive ((iPrOH) and the tertiary amine in the cinchona alkaloid were studied in detail, and the real cyanide reagent in the catalytic cycle was found to be hydrogen cyanide (HCN). Finally, two plausible catalytic cycles were proposed to elucidate the reaction mechanisms.
- Wang, Jun,Wang, Wentao,Li, Wei,Hu, Xiaolei,Shen, Ke,Tan, Cheng,Liu, Xiaohua,Feng, Xiaoming
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scheme or table
p. 11642 - 11659
(2010/04/28)
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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; 11
(2008/06/13)
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- METHOD FOR PREPARING ASYMMETRIC LINEAR CARBONATE
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A method for preparing asymmetric linear carbonate useful as an electrolyte for lithium secondary battery is disclosed. The method comprises the steps of: carrying out transesterification of symmetric linear carbonate with linear ester compound in the presence of a basic catalyst; and separating asymmetric linear carbonate from the transesterification product. Preferably, the linear ester compound is acetate compound.
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Page/Page column 6
(2008/06/13)
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- METHOD FOR PREPARING ASYMMETRIC LINEAR CARBONATE
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A method for preparing asymmetric linear carbonate useful as an electrolyte for lithium secondary battery is disclosed. The method comprises the steps of: removing methyl acetate by a distillation while carrying out a transesterification of dimethyl carbonate with acetate compound in the presence of a basic catalyst; and separating the asymmetric linear carbonate from the transesterification product.
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Page/Page column 5
(2008/06/13)
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- Mechanism of formation of organic carbonates from aliphatic alcohols and carbon dioxide under mild conditions promoted by carbodiimides. DFT calculation and experimental study
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Dicyclohexylcarbodiimide (CyN=C=NCy, DCC) promotes the facile formation of organic carbonates from aliphatic alcohols and carbon dioxide at temperatures as low as 310 K and moderate pressure of CO2 (from 0.1 MPa) with an acceptable rate. The conversion yield of DCC is quantitative, and the reaction has a very high selectivity toward carbonates at 330 K; increasing the temperature increases the conversion rate, but lowers the selectivity. A detailed study has allowed us to isolate or identify the intermediates formed in the reaction of an alcohol with DCC in the presence or absence of carbon dioxide. The first step is the addition of alcohol to the cumulene (a known reaction) with formation of an O-alkyl isourea [RHNC(ORO=NR] that may interact with a second alcohol molecule via H-bond (a reaction never described thus far). Such an adduct can be detected by NMR. In alcohol, in absence of CO 2, it converts into a carbamate and a secondary amine, while in the presence of CO2, the dialkyl carbonate, (RO)2CO, is formed together with urea [CyHN-CO-NHCy]. The reaction has been tested with various aliphatic alcohols such as methanol, ethanol, and allyl alcohol. It results in being a convenient route to the synthesis of diallyl carbonate, in particular. O-Methyl-N,N′-dicyclohexyl isourea also reacts with phenol in the presence of CO2 to directly afford for the very first time a mixed aliphatic-aromatic carbonate, (MeO)(PhO)CO. A DFT study has allowed us to estimate the energy of each intermediate and the relevant kinetic barriers in the described reactions, providing reasonable mechanistic details. Calculated data match very well the experimental results. The driving force of the reaction is the conversion of carbodiimide into the relevant urea, which is some 35 kcal/mol downhill with respect to the parent compound. The best operative conditions have been defined for achieving a quantitative yield of carbonate from carbodiimide. The role of temperature, pressure, and catalysts (Lewis acids and bases) has been established. As the urea can be reconverted into DCC, the reaction described in this article may further be developed for application to the synthesis of organic carbonates under selective and mild conditions.
- Aresta, Michele,Dibenedetto, Angela,Fracchiolla, Elisabetta,Giannoccaro, Potenzo,Pastore, Carlo,Papai, Imre,Schubert, Gabor
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p. 6177 - 6186
(2007/10/03)
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- PROCESS FOR PRODUCING CARBONIC ESTER
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A method for producing a carbonic ester, comprising (1) performing a reaction between an organometal compound having a metal-oxygen-carbon linkage and carbon dioxide to obtain a reaction mixture containing a carbonic ester formed by the reaction, (2) separating the carbonic ester from the reaction mixture to obtain a residual liquid, and (3) reacting the residual liquid with an alcohol to form an organometal compound having a metal-oxygen-carbon linkage and form water and removing the water from the organometal compound, wherein the organometal compound obtained in step (3) is recovered for recycle thereof to step (1).
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- Geminal systems 50. Synthesis and alcoholysis of N-acyloxy-N-alkoxy derivatives of ureas, carbamates, and benzamides
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Procedures were developed for the synthesis of N-acyloxy-N-alkoxy derivatives of ureas, carbamates, and benzamides by the reactions of the corresponding N-alkoxy-N-chloro derivatives with sodium carboxylates in MeCN. N-Chloro-N-ethoxy-p-toluenesulfonamide was inert in this reaction. Alcoholysis of N-acyloxy-N-alkoxy derivatives of ureas, carbamates, and tert-alkylamines afforded the corresponding N,N-dialkoxy derivatives, whereas alcoholysis of N-acetoxy-N-ethoxybenzamide gave rise to alkyl benzoates.
- Shtamburg,Klots,Pleshkova,Avramenko,Ivonin,Tsygankov,Kostyanovsky
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p. 2251 - 2260
(2007/10/03)
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- Mechanism and structure-reactivity correlation in the homogeneous, unimolecular elimination kinetics of 2-substituted ethyl methylcarbonates in the gas phase
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The gas-phase elimination kinetics of 2-substituted ethyl methylcarbonates were determined in a static reaction system over the temperature range of 323-435 °C and pressure range 28.5-242 Torr. The reactions are homogeneous, unimolecular and follow a first-order rate law. The kinetic and thermodynamic parameters are reported. The 2-substituents of the ethyl methylcarbonate (CH3OCOOCH2CH2Z, Z = substituent) give an approximate linear correlation when using the Taft-Topsom method, log(k z/kH)= -(0.57 ± 0.19)σα + (1.34 ± 0.49)σR (r = 0.9256; SD = 0.16) at 400 °C. This result implies the elimination process to be sensitive to steric factors, while the electronic effect is unimportant. However, the resonance factor has the greatest influence for a favorable abstraction of the β-hydrogen of the C3- H bond by the oxygen carbonyl. Because ρα is significant, a good correlation of the alkyl substituents of carbonates with Hancock's steric parameters was obtained: log(kR/kH versus Esc for CH 3OCOOCH2CH2R at 400°C, R = alkyl, δ= -0.17 (r=0.9993, SD = 0.01). An approximate straight line was obtained on plotting these data with the reported Hancock's correlation of 2-alkyl ethylacetates. This result leads to evidence for the β-hydrogen abstraction by the oxygen carbonyl and not by the alkoxy oxygen at the opposite side of the carbonate. The carbonate decompostion is best described in terms of a concerted six-membered cyclic transition state type of mechanism. Copyright
- Chuchani, Gabriel,Marquez, Edgar,Herize, Armando,Dominguez, Rosa Maria,Tosta, Maria,Brusco, Doris
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p. 839 - 848
(2007/10/03)
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- Reaction of diethyl dibromomalonate with methoxide: Evidence for a novel bromophilic attack
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Reaction of diethyl dibromomalonate (1) with sodium methoxide in cyclohexene yields dibromonorcarane (2) as the major product. This product forms via the capture of dibromocarbene (4) by cyclohexene. Dibromocarbene, in turn, is generated from ethyl tribromoacetate (6) which evidence suggests arises via a bromophilic attack between the carboethoxydibromomethyl carbanion (7) and diethyldibromomalonate (1).
- Mebane, Robert C.,Smith, Keegan M.,Rucker, Darlene R.,Foster, Michael P.
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p. 1459 - 1462
(2007/10/03)
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- Correlation of the rates of solvolysis of methyl chloroformate with solvent properties
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The specific rates of solvolyis of methyl chloroformate are very well correlated by the extended Grunwald-Winstein equation over a wide range of solvents; the pathway is believed to be predominantly addition-elimination, except that a positive deviation for solvolysis in 90% 1,1,1,3,3,3- hexafluoropropan-2-ol suggests an 80% contribution from an ionisation mechanism.
- Kevill, Dennis N.,Kim, Jong Chul,Kyong, Jin Burm
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p. 150 - 151
(2007/10/03)
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- Reactions of α-monochloro- and α,α-dichloro-β-oxoaldehyde acetals with bases
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α,α-Dichloro-β-oxoaldehyde diethyl acetals decompose under the action of bases (NaOH, MeONa) with cleavage of the carbon-carbon bond and formation of carboxylic acids or their esters and the dichloroacetaldehyde diethyl acetal carbanion. The latter reacts in situ with benzaldehyde to form stable α-chloro-α,β-epoxyacetal. α-Chloro-α-formyl-γ-butyrolactone diethyl acetal is transformed into α-chloro-α-diethoxymethyl-γ-hydroxybutyric acid under the action of an alkali.
- Guseinov
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p. 663 - 665
(2007/10/03)
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- Process for preparing carbonate compounds
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A process for preparing carbonate compounds having the following formula: STR1 wherein R and R' are, the same or different, C1 -C6 alkyl group, a C3 -C6 cycloalkyl group, an optionally substituted C6 -C14 aryl group, an alkylaryl group, or an arylalkyl group is proposed; the process comprises reacting urea or derivatives thereof with appropriate alcohols or phenols and preparing the carbonate compounds via a multiple-step synthesis process.
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- Catalytic decomposition of dialkyl pyrocarbonates to dialkyl carbonates and carbon dioxide in dichloromethane by a discrete cobalt(II) alkoxide species generated in situ
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Dimethyl pyrocarbonate (dmpc) [dimethyl μ-oxo-bis(dioxocarbonate)] and diethyl pyrocarbonate (depc) were catalytically decomposed to dimethyl and diethyl carbonate respectively and carbon dioxide in the presence of [CoL(OR)]+ [L = cis,cis-1,3,5-tris(E,E-cinnamylideneamino)cyclohexane, R = methyl or ethyl] which we propose to be generated in situ during reaction in dichloromethane. The activity of the catalyst is undiminished after 60 000 turnovers. In both cases the catalytic rate enhancement for the decomposition is in excess of 107 dm3 mol-1 of catalyst. The catalytic process follows Michaelis-Menten type kinetics and kobs is 2.2(2) s-1 for dmpc decomposition and 1.3(2) s-1 for depc decomposition. Activation energies for the catalytic decomposition are Edmpc = 113(5) and Edepc = 120(11) kJ mol-1. A mechanism involving cobalt-bound alkoxide attack on dialkyl pyrocarbonate is proposed. The crystal structure of [CoL(Cl)] BPh4 has been determined by single-crystal X-ray diffraction.
- Greener, Bryan,Walton, Paul H.
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p. 3733 - 3740
(2007/10/03)
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- Process for preparing carbonate compounds
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A process for preparing carbonate compounds having the following formula: wherein R and R' are, independently, a C1 - C6 alkyl group, a C3-C6 cycloalkyl group, an optionally substituted C6-C14 aryl group, an alkylaryl group, or an arylalkyl group is proposed; the process comprises preparing the carbonate compounds via a synthesis process comprising the step of, ???(3) allowing the compounds represented by formula [IV] to [VII]: ???wherein R5, R6, R7 and R8 are, independently, hydrogen, a C1-C6 alkyl group, a C1-C6 alkoxyl group, a C1-C6 alkoxy carbonyl group, a substituted or unsubstituted phenyl group; provided that at least one of R5 and R6 is a substituted or unsubstituted phenyl group, and at least one of R7 and R8 is a substituted or unsubstituted phenyl group,???to either each react with itself or to carry out replacement reaction between compounds [IV] and [V], [IV] and [V], [IV] and [VII], [V] and [V], [V] and [VII] or [V] and [VII] in the presence of a catalyst and a temperature from 100 to 300°C to obtain the compounds represented by formula [I].
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- Alkoxycarbonylation of alcohols and phenols by nitrosoformates
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Unstable neutral radicals [ROCONHO?] 2 and nitrosoformates 3 are formed by oxidation of N-hydroxycarbamates with lead dioxide. In the presence of alcohols or phenols and water they solvolyzed to mixtures of symmetrical 4 and asymmetrical 5 carbonates. The content of asymmetrical carbonates 5 increases with increasing reactivity of the nitrosoformates 3 formed, temperature, the content of water in the reaction mixture, and with decreasing reactivity of alcohol. The reactivities of individual alcohols have been evaluated with the help of competitive alcoholysis. The new method of alcohol or phenol alkoxylation has been verified experimentally by preparing six asymmetrical carbonates which were obtained in 34 to 47% yields.
- Mindl, Jaromir,Halama, Ales,Cernosek, Zdenek
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p. 1053 - 1063
(2007/10/03)
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- PYRIDINE SYNTHESIS VIA ANODIC OXIDATION OF 1-ACYLDIHYDROPYRIDINES
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The preparation of several substituted pyridines via anodic oxidation of 1-acyldihydropyridines is reported
- Comins, Daniel L.,Killpack, Michael O.
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p. 2025 - 2028
(2007/10/02)
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- The Mechanism of Thermal Eliminations. Part 15. Abnormal Rate Spread in Pyrolysis of Alkyl Methyl Carbonates and S-Alkyl O-Methyl Carbonates due to Enhanced Nucleophilicity of the Carbonyl Group
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Rate coefficients for pyrolytic elimination of ethyl, isopropyl, and t-butyl carbonates, and of di-t-butyl carbonate have been measured over a 50 K range for each compound.The relative rates at 600 K are 1:29.6:2934:3526 and the rate spread for the primary, secondary, and tertiary compounds is inconsistent with that obtained from elimination of a range of other esters including alkyl phenyl carbonates.The least reactive compounds are found to be more reactive than predicted, probably owing to a combination of the greater Ei character of their transition states and the high nucleophilicity of the carbonyl group in dialkyl carbonates.Rate data for pyrolysis of S-ethyl, S-isopropyl, and S-t-butyl O-methyl carbonates give the relative rates at 600 K as 1:22:1074.The But:Pri rate ratio (49:1) is therefore greater than the Pri:Et ratio, as it is for all other related eliminations; this confirms that the literature results (which show the converse) are in error.The seemingly anomalous relative reactivities of thiolacetates and thiolcarbonates as compared with their oxygen-containing analogues is also shown to be consistent with the effect of variable polarity of the transition state in ester pyrolysis upon the importance of carbonyl group nucleophilicity, and this also accounts for the relative reactivities of thiol-, thion-, and dithio-acetates.Steric acceleration appears less important for carbonates than for acetates, since the rate for di-t-butyl carbonate (statistically corrected) is lower than for t-butyl methyl carbonate, whereas pivalates are more reactive than acetates.
- Taylor, Roger
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p. 291 - 296
(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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