二苯脲与碳酸二甲酯合成苯氨基甲酸甲酯研究

以氧化铅为催化剂,考察了温度、时间、催化剂的量及原料配比等条件对合成苯氨基甲酸甲酯反应的影响,确定了适宜的反应条件,并试验了不同附载型固体催化剂,发现以三氧化二铝为载体效果最好。结果表明,附载型固体催化剂可使二苯脲的转化率达到94.7%,苯氨基甲酸甲酯收率可达98.2%。     

离子交换树脂催化合成二苯甲烷二氨基甲酸酯的研究

二苯甲烷二氨基甲酸酯是非光气合成二苯甲烷二异氰酸酯(MDI)的重要中间体。以离子交换树脂为催化剂,对苯氨基甲酸甲酯与甲醛缩合反应制备二氨基甲酸酯进行了研究,考察了催化剂、反应温度、原料配比、催化剂用量和反应时间对反应的影响。优惠条件:温度100℃,原料配比n(对苯氨基甲酸甲酯)∶n(甲醛)=6∶1,催化剂用量为苯氨基甲酸甲酯质量的10%,反应时间4h。此条件下,二氨基甲酸酯收率为57%,选择性为60%。     

苯氨基甲酸甲酯热解制备苯基异氰酸酯的非等温动力学

采用热分析与红外联用技术对苯氨基甲酸甲酯(MPC)热解历程进行分析,结果表明,苯氨基甲酸甲酯的热解过程是一步生成苯基异氰酸酯同时释放出甲醇气体. 进一步对该热解反应进行了非等温动力学研究,对MPC的热解数据采用Flynn-Wall-Ozawa法计算得到反应活化能. 采用5种方法考察反应动力学参数,结果表明,MPC热解机理为相边界反应模型,机理函数为G(a)=a1/3,热解反应活化能E=20.52 kJ/mol,指前因子lgA=2.23,动力学方程为a1/3= 169.82exp[20.52′103/(8.314T)]t.     

One Pot Synthesis of Methyl N-Phenyl Carbamate from Aniline, Urea and Methanol

Methyl N-phenyl carbamate (MPC) was synthesized from aniline, urea and methanol. The effects of catalysts, loading amounts, preparation condition of catalyst and reaction condition on the synthesis of MPC were investigated. It was shown that KNO₃ modified zeolite HY gave the best performance to MPC formation among the evaluated catalysts, over which 93.1% aniline conversion and 82.6% MPC selectivity were obtained under the optimum reaction condition. Additionally, a possible catalytic mechanism to the formation of MPC in this reaction was proposed.     

尿素醇解法合成氨基甲酸甲酯平衡常数的测定

文章测定了尿素醇解法合成氨基甲酸甲酯的平衡常数。在433.15K时,无催化剂条件下,甲醇和尿素在高压釜内反应生成氨基甲酸甲酯,待反应达到平衡后,通过气相色谱仪和液相色谱仪测定平衡混合物的组成来计算反应的平衡常数。气相可近似认为是氨气和甲醇组成的二元混合物,液相近似认为是尿素、甲醇和氨基甲酸甲酯组成的三元混合物。实验结果表明,实验重现性较好,平衡常数数值是可靠的。     

A Semi‐continuous Process for the Synthesis of Methyl Carbamate from Urea and Methanol

A semicontinuous process for the synthesis of methyl carbamate from urea and methanol was investigated in the autoclave without the catalyst. Some significant parameters were determined in terms of the methyl carbamate yield. The optimal reaction conditions were found at an initial molar ratio of methanol/urea of 6:1, a reaction temperature of 423 K, a flow rate of fresh methanol at 4 mL/min, a stirring speed of 800 rpm and a reaction time of 6 hours, respectively. A MC yield of 98.7 % was obtained at the optimal reaction conditions. Furthermore, the kinetics of this reaction were researched and the reaction activation energy was obtained as 110.498 kJ/mol. It was demonstrated that removing methanol containing ammonia from the autoclave and replacing it with continuously feeding fresh methanol resulted in a higher reaction rate and a high MC yield.     

磷钨酸催化合成二苯甲烷二氨基甲酸甲酯

以磷钨酸为催化剂,考察了苯氨基甲酸甲酯(MPC)与甲醛缩合制备二苯甲烷二氨基甲酸甲酯(MDC)的工艺条件。结果表明,磷钨酸对二苯甲烷二氨基甲酸甲酯的合成具有较好的催化效果;在二乙二醇二乙醚为溶剂,n(MPC)∶n(HCHO)=5∶1,催化剂用量m(磷钨酸)∶m(MPC+HCHO)=(0.08～0.10)∶1,于110℃反应4.5h的条件下,MDC的收率为64.9%,选择性达到80.9%。     

盐酸催化合成二苯甲烷二氨基甲酸甲酯

用碳酸二甲酯（DMC）代替光气,与苯胺甲氧羰基化反应制得苯氨基甲酸甲酯（MPC）,在盐酸催化剂的作用下,经甲基化缩合反应合成了4,4-二苯甲烷二氨基甲酸甲酯（MDC）;使用液-质联用仪分析了反应物组成;测定了MDC的熔点;采用核磁共振仪对产品结构进行了表征;考察了反应温度、物料配比、反应时间、催化剂用量对MDC收率的影响。实验结果表明,在n（MPC／甲醛）=6：1、15％盐酸用量15mL、反应温度90℃、反应时间3h的条件下,MDC收率达到63％。该合成方法具有便于光气法改造、反应条件温和、催化剂易得易分离等优点。     

苯氨基甲酸酯催化合成研究进展

综述了国内外苯氨基甲酸酯合成方法和催化剂的研究进展,重点阐述了近年来以苯胺和碳酸二甲酯(DMC)为原料,合成苯氨基甲酸甲酯(MPC)催化剂的研究进展.同时对今后催化合成路线的研究和发展进行了讨论和分析,由苯胺和DMC合成MPC,副产物甲醇回收合成DMC,是零排放绿色工艺,其研究方向是开发出活性和选择性高的负载型催化剂.     

Bu_2SnO催化反应耦合法清洁合成苯氨基甲酸甲酯

加压条件下,对反应耦合法清洁合成苯氨基甲酸甲酯(MPC)的催化剂进行了筛选,对反应工艺优化、催化剂的循环使用和表征等方面进行了研究.在筛选的催化剂中,Bu_2SnO是较为理想的催化剂.在反应物碳酸二甲酯(DMC)和二苯基脲(DPU)的摩尔比为10:1,催化剂Bu_2SnO的用量为2%,160℃时,反应2 h,MPC的收率达到98%,远高于文献结果(77%).催化剂Bu_2SnO循环使用4次后,催化活性基本不变.对反应前后的Bu_2SnO进行了FTIR、XPS和XRD表征,结果表明,反应后从釜液中用水作沉淀剂絮凝沉淀出的催化剂绝大部分仍为Bu_2SnO,并可能含有其他微量未水解的催化剂中间体.     

Bu2SnO催化反应耦合法清洁合成苯氨基甲酸甲酯

加压条件下,对反应耦合法清洁合成苯氨基甲酸甲酯（MPC）的催化剂进行了筛选,对反应工艺优化、催化剂的循环使用和表征等方面进行了研究。在筛选的催化剂中,Bu₂SnO是较为理想的催化剂。在反应物碳酸二甲酯（DMC）和二苯基脲（DPU）的摩尔比为10∶1,催化剂Bu2SnO的用量为2%,160℃时,反应2 h,MPC的收率达到98%,远高于文献结果（77%）。催化剂Bu₂SnO循环使用4次后,催化活性基本不变。对反应前后的Bu2SnO进行了FTIR、XPS和XRD表征,结果表明,反应后从釜液中用水作沉淀剂絮凝沉淀出的催化剂绝大部分仍为Bu₂SnO,并可能含有其他微量未水解的催化剂中间体。     

Influence of Solvent on Reaction Path to Synthesis of Methyl N-Phenyl Carbamate from Aniline,CO2 and Methanol

Methyl N-phenyl carbamate （MPC）, an important organic chemical, can be synthesized from aniline, CO2 and methanol. Catalyst Cu-Fe/ZrO2-SiO2 was first prepared and its catalytic performance for MPC synthesis was evaluated. Then the influence of solvent on the reaction path of MPC synthesis was investigated. It is found that the reaction intermediate is different with acetonitrile or methanol as a solvent. With acetonitrile as a solvent, the synthesis of MPC follows the reaction path with diphenyl urea as the intermediate, while with methanol as a solvent the reaction occurs via the reaction path with dimethyl carbonate as the intermediate. The catalytic mecha-nism of cooperative catalysis comprising metal sites, Lewis acid sites and Lewis base sites is proposed according to different reaction intermediates.     

Phosgene-Free Synthesis of Phenyl Isocyanate by Catalytic Decomposition of Methyl N-Phenyl Carbamate over Bi2O3 Catalyst

A phosgene-free approach for the synthesis of phenyl isocyanate (PI) was developed, using the heterogeneous catalytic decomposition of methyl N-phenyl carbamate (MPC). Twenty oxide-catalysts were investigated and compared; the Bi₂O₃ catalyst gave the better catalytic performance. From bismuth (III) nitrate pentahydrate, Bi₂O₃ was prepared by different methods, which included the direct decomposition, mechano-chemical method, direct precipitation and indirect precipitation. The catalysts were characterized by N₂ adsorption/desorption, XRD, FTIR and TEM analyses. After optimization, the Bi₂O₃ catalyst prepared by direct calcination of bismuth (III) nitrate pentahydrate at 723 K in air for 4 h gives the best activity. When the reaction was carried out at the boiling temperature of o-dichlorobenzene (ODCB) at normal pressure, the optimal reaction conditions over Bi₂O₃ catalyst are as follows: the mass ratio of catalyst/MPC is 0.05, mass ratio of ODCB/MPC is 15:1, reaction time of 60 min. The optimized conversion of MPC and the yield of PI are 86.2% and 78.5%, respectively. There was a good durability for the Bi₂O₃ catalyst, and the species of Bi (III) ions of catalyst were partially oxidized to Bi (IV) ions during the reaction, supported by the results of XRD and XPS techniques.     

盐酸盐助剂对硫酸催化合成二苯甲烷二氨基甲酸甲酯的影响

二苯甲烷二氨基甲酸甲酯（MDC）是非光气法合成二苯甲烷二异氰酸酯（MDI）的中间体。以硫酸为催化剂,盐酸盐为助剂,研究了苯氨基甲酸甲酯（MPC）与甲醛缩合制备MDC的反应。对助剂盐酸盐进行了筛选,发现氯化铜的效果较好,其MPC转化率达96%,4,4′-MDC产率可达76.7%。反应条件为：m(硫酸)∶m(MPC)=4∶1,n(MPC)∶n(HCHO)=1∶1,氯化铜用量为MPC物质的量的5.4%,100 ℃下反应3 h。将氯化铜分别与氯化镧和氯化亚铈以物质的量的比1∶1复合使用,发现单独使用氯化铜的效果好于复合盐酸盐的效果。分别使用甲醛溶液、三聚甲醛和多聚甲醛为亚甲基化剂,发现价廉易得的甲醛溶液效果最好。     

二丁基二甲氧基锡的合成研究

研究了以甲醇(MeOH)、二丁基氧化锡(Bu₂SnO)和氨基甲酸甲酯（MC）为原料,制备二丁基二甲氧基锡的方法。在密闭反应体系中，n(MC)∶n(MeOH)∶n(Bu₂SnO)= 2∶3∶1时，180 ℃反应5 h，可以获得目标产物。产品经ICP-MS法分析，二丁基二甲氧基锡含量为90.3%。     

Synthesis of dimethyl carbonate from methyl carbamate and methanol over lanthanum compounds

Various lanthanum compounds were used as the catalyst for the synthesis of dimethyl carbonate (DMC) from methyl carbamate and methanol. Among them, La(NO₃)₃ presented the best catalytic performance with the DMC yield of 53.7% under suitable reaction conditions. Based on the results of X-ray diffraction, Fourier transform infrared spectroscopy and element analysis, a possible reaction mechanism over lanthanum nitrate was proposed for this reaction.     

Synthesis of Dimethyl Carbonate from Methyl Carbamate and Methanol Using a Fixed‐Bed Reactor

Several mixed oxide catalysts were prepared by coprecipitation for dimethyl carbonate (DMC) synthesis from methyl carbamate and methanol. During the batch process, the DMC yield was below 35 %. In order to minimize the unfavorable thermodynamic equilibrium and side reactions for the DMC synthesis, a fixed‐bed reactor was designed. A maximum DMC yield of ～ 73 % could be realized over a ZnO‐Al₂O₃ catalyst. The effects of reaction conditions for this type of reactor were investigated in detail.     

催化羰基化合成N-环己基氨基甲酸甲酯的研究

对由碳酸二甲酯与环已胺化合生成N－环已基氨基甲酸甲酯的反应进行了研究。考察了催化剂CaCl2水溶液的催化活性。讨论了反应时间和反应温度以及催化剂的量对N－环已基氨基甲酸甲酯产率的影响。     

磷钨酸铋催化合成油酸甲酯

以磷钨酸铋为催化剂,对油酸和甲醇反应合成油酸甲酯进行了研究,考察了反应时间、催化剂用量、醇酸摩尔比、催化剂重复使用性等因素对油酸甲酯收率的影响.实验结果表明反应的最佳条件为:油酸用量为0.1 mol,醇酸摩尔比为1.4,催化剂磷钨酸铋用量为1.5 g,反应时间为4h,酯收率达93.4％,催化剂重复使用五次催化性能未见明...     

Optimization of the reaction parameters for fast pseudo single-phase transesterification of sunflower oil

Transesterification of sunflower oil with methanol was carried out using potassium hydroxide and methoxide as catalysts and MTBE as cosolvent. The aim of this work was to study and optimize the reaction parameters. Chosen parameters were reaction time, catalyst amount and methanol amount (expressed as catalyst-to-oil and methanol-to-oil molar ratios, respectively). The response variables were methyl ester content (ME) and acid value (AV) due to their relationship with the completion and yield reaction, respectively. A factorial plus composite design was developed to carry out the optimization. From this design, several quadratic models have been used to fit the experimental data. All the factors studied had a positive influence on methyl ester content and acid value, except the methanol amount on acid value. For methoxide catalyst, optimum values were 0.235 catalyst to oil molar ratio, 12 methanol to oil molar ratio and 5 min reaching 99 wt.% ME and 0.20 mg KOH/g of AV.