598-55-0Relevant articles and documents
CH3COONa as an effective catalyst for methoxycarbonylation of 1,6-hexanediamine by dimethyl carbonate to dimethylhexane-1,6-dicarbamate
Sun, Da-Lei,Xie, Shun-Ji,Deng, Jian-Ru,Huang, Cai-Juan,Ruckenstein, Eli,Chao, Zi-Sheng
, p. 483 - 490 (2010)
Methoxycarbonylation of 1,6-hexanediamine (HDA) by dimethyl carbonate (DMC) was carried out, using, for the first time, CH3COONa as catalyst. The effects of the solvent, reaction temperature, reaction time, and catalyst amount, were investigated. A yield as high as 99.0% of dimethylhexane-1,6- dicarbamate 2 has been obtained at a temperature of 348 K and a reaction time of 6 h. Mechanistic studies revealed that N-substituted acetamide, as the active intermediate product, and NaOH were first formed via the reaction between HDA and CH3COONa. A further reaction between the N-substituted acetamide and DMC generated carbamates and methyl acetate, via a hexatomic ring intermediate. The CH3COONa catalyst was finally recovered through the reaction between NaOH and methyl acetate, which thus completed the catalytic cycle.
Synthesis of dimethyl carbonate by urea alcoholysis over Zn/Al bi-functional catalysts
Wu, Xiaomin,Kang, Min,Yin, Yanlong,Wang, Feng,Zhao, Ning,Xiao, Fukui,Wei, Wei,Sun, Yuhan
, p. 13 - 20 (2014)
Zn/Al mixed oxides (ZAO) were prepared via thermal decomposition of hydrotalcite-type precursors derived from urea precipitation. Specially, ZAO catalysts with a Zn/Al molar ratio of 4:1 exhibited high dimethyl carbonate (DMC) yield (～36.5%) when utilized for the DMC synthesis from urea and methanol. The XRD, IR, TPD and computational analysis revealed that the formation of ZnAl2O4 spinel significantly modified the surface acidity and basicity of ZAO catalysts, which were beneficial for the DMC synthesis. We thus opened up a bi-functional mechanism that urea and methanol were respectively activated on the weak acidic and basic sites, advancing the DMC synthesis synergistically.
Synthesis of dimethyl carbonate from methanol and urea over zinc-strontia mixed oxide catalysts
D., Dhana Lakshmi,B., Srinivasa Rao,Lingaiah
, p. 1 - 4 (2019)
A series of ZnO-SrO mixed oxide catalysts were prepared by co-precipitation with different compositions and tested for dimethyl carbonate synthesis from urea and methanol. The catalysts were characterized by BET surface area, XRD, NH3-TPD and CO2-TPD. The catalyst with 1:1 mol ratio exhibited high DMC yield of 35%. The uniform distributions of moderate to strong basic sites along with considerable number of acidic sites are accountable for high activity. Different reaction parameters were also screened and best possible conditions were established. The catalyst was easily recovered and reused with consistent activity.
One-pot efficient synthesis of methyl carbamate by M5Ca5(PO4)6F2 (M?=?Co, Ni, Cu, Zn) catalysts
Wang, Wei,Xu, Feng,Du, Wenqiao,Zhang, Long
, p. 26 - 29 (2019)
A facile and efficient one-pot synthesis of methyl carbamate (MC) by urea and methanol was studied using metal modified fluorapatite as a catalyst. M5Ca5(PO4)6F2 (M5FAP, M = Co, Ni, Cu, Zn) was synthesized by co-precipitation. Among the catalysts, Zn5Ca5(PO4)6F2 (Zn5FAP) displayed the higher activity, selectivity and excellent stability after five times of reuse. A possible synthesis reaction mechanism over Zn5FAP catalyst was discussed.
Dimethyl carbonate synthesis over ZnO-CaO bi-functional catalysts
Wu, Xiaomin,Kang, Min,Zhao, Ning,Wei, Wei,Sun, Yuhan
, p. 46 - 50 (2014)
ZnO-CaO catalysts were prepared and tested for the synthesis of dimethyl carbonate (DMC) from urea and methanol. Meaningfully, the bi-functional catalysts ZnO-CaO exhibited noticeable DMC yield (41.2%) with the Zn/Ca molar ratio of 4:1, which might ascribe to the synergistic effect between ZnO and CaO. The plausible mechanism for the DMC synthesis was as follows: urea was activated to generate metal isocyanato group on the acid sites and subsequently nucleophilic attacked by the activated methanol on the basic sites.
Preparation method of carbamate
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Paragraph 0034; 0038-0040, (2020/09/23)
The invention belongs to the technical field of synthesis of amino and carboxyl compounds connected to the same carbon frame through urea alcoholysis, and particularly relates to a preparation methodof carbamate. The preparation method of the carbamate comprises the following steps of: sequentially introducing urea, alcohol and a catalyst into a reactor, sealing, and reacting at 90-120 DEG C for8-12 hours to obtain the carbamate, wherein the catalyst includes an alumina supported metal oxide. By adopting the method for preparation of the carbamate, the side reaction of urea decomposition canbe effectively avoided, impurities such as carbamate are not detected, and the yield of the carbamate is high.
Carbamate preparation method
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Paragraph 0026-0046, (2020/03/12)
The invention relates to a carbamate preparation method. According to the invention, dimethyl carbonate is used as a reaction raw material for urea alcoholysis, and a novel composite catalyst is used,so that the technical problems of high energy consumption and high equipment cost caused by cold energy ammonia removal in the prior art are avoided, and the yield of carbamate is up to more than 96%.
Method for directly preparing dimethyl carbonate through reaction of low-temperature high-efficiency catalytic urea and methanol (by machine translation)
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Paragraph 0047; 0050-0052; 0054, (2020/02/05)
The invention relates to a method for directly preparing dimethyl carbonate through reaction of urea and methanol at low temperature, and a method for directly preparing dimethyl carbonate by using the high-efficiency solid-phase Mg - Ga catalyst. 2 O3 /CeO2 - Al2 O3 The, method has the advantages that the yield of, dimethyl carbonate can be further improved, the, reaction activity and, selectivity are high, 100%, the conversion rate of the by-product is lower than that of dimethyl carbonate, and the selectivity of dimethyl carbonate to dimethyl carbonate is greater than or equal to and equal to or greater than or equal to and equal. 99.2% to or greater than about. (by machine translation)
Method for producing methyl carbamate
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Paragraph 0018-0024, (2019/12/31)
The invention provides a method for producing methyl carbamate. The method comprises the following steps: performing sectional temperature control on an exhaust channel of a reaction kettle, controlling the temperature of a pipeline section of the exhaust channel close to the reaction kettle to 4-20 DEG C, and increasing the temperatures of later pipeline sections gradually till the temperature ofa pipeline section of the exhaust channel far away from the reaction kettle is 75-85 DEG C; and performing pressurization on a reaction process for preparing methyl carbamate by using a urea alcoholysis method to release a gas, and maintaining the pressure of the reaction system in the reaction kettle to 1.8-2.8MPa. By adopting the method, the technical problem that the exhaust channel of the reaction kettle is blocked can be solved, industrial conditions of production of methyl carbamate can be completed, production reactions can be performed smoothly, and in addition, the yield of the methyl carbamate can be increased.
Method for preparing methyl carbamate by taking urea as raw material
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Paragraph 0027-0029, (2019/12/25)
The invention belongs to the technical field of preparation of compounds containing amino and carboxyl connected to a same carbon frame from natural products, and particularly relates to a method forpreparing methyl carbamate by taking urea as a raw material. The preparation method of the methyl carbamate comprises the following steps: sequentially introducing urea, methanol and a catalyst into areactor, sealing, and reacting at 130 to 150 DEG C for 4-6 hours to obtain the methyl carbamate, wherein the catalyst comprises titanium dioxide-bismuth oxide supported by silicon dioxide. The content of impurities such as methyl carbamate analogues is low, and the yield of methyl carbamate is high.
