循环微反应系统内间甲基苯甲醚的合成

间甲基苯甲醚是一种染料中间体,其传统合成方法是通过低温控制反应物混合,生产效率低下,通过微反应器改善反应物混合具有重要的研究价值。本文系统研究了微反应器辅助下的间甲基苯甲醚合成过程,发现体系内间甲酚与氢氧化钠可快速发生反应,形成间甲酚钠,进而发现间甲酚钠与硫酸二甲酯间的氧烷基化反应随着反应温度的提升而获得强化,60~80℃的高温更有利于氧烷基化反应与硫酸二甲酯水解反应的竞争。通过实验考察了反应物流量比、计量比、浓度等因素对间甲基苯甲醚收率的影响,发现微反应器保证两相反应物的快速均匀混合是成功实施高温快反应的关键。相对优化的实验结果表明：当硫酸二甲酯/间甲酚摩尔比大于1.05时,使用质量分数为30%的氢氧化钠溶液实施间甲基苯甲醚的合成反应的产率可达99%以上。     

微反应器内苯甲醚连续合成

苯甲醚是一种重要的溶剂和有机合成中间体，以往通过间歇反应合成，存在生产效率低下、操作周期长等问题，亟需开发连续化的生产装置和技术。提出以苯酚钠水溶液和硫酸二甲酯为原料通过连续微反应器合成苯甲醚的方法。该方法利用微混合器和局部收缩的反应管道强化反应物的混合，在近似绝热的反应条件下快速完成反应过程。报道了苯酚钠浓度、反应物流量和反应物摩尔比对于微反应器内苯酚钠转化率和硫酸二甲酯利用率的影响规律。与文献报道的间歇反应进行了对比，揭示了微反应技术的优势。     

氯化溴的微反应连续合成与应用

氯化溴是工业上重要的卤化试剂,其合成过程具有放热量大、生产效率低、存在安全隐患重等问题,生产装备的连续化和小型化是氯化溴合成技术的重要发展方向。本文针对通过溴素的二氯甲烷溶液吸收氯气制备氯化溴的微反应技术开发,考察了康宁G1反应器、金德C1反应器和自制的微混合器+微填充床反应器的传质性能,实现了氯化溴的连续稳定制备,反应器的时空收率达到2.25g/(min·mL)。利用微反应器所制得的氯化溴实施聚苯乙烯的溴化反应,取得了溴质量分数>66%和5%热失重温度>370℃的溴化聚苯乙烯产品。     

合成间甲基苯甲醚的新方法

研究了由间甲基苯酚与碳酸二甲酯在催化剂氯化三乙基苄基胺作用下合成间甲基苯甲醚的方法,在间甲基苯酚：碳酸二甲酯：催化剂＝1．0：1．2：0．10,反应温度50－60℃,反应时间3h的最佳条件下,反应产率稳定在88％－90％。     

微反应器一步法连续合成苯甲醚

苯甲醚是一种重要的化工中间体,其工业生产主要以硫酸二甲酯和苯酚钠为原料,在搅拌釜中通过批次反应获得。该过程生产效率低、原料单耗高,同时存在硫酸二甲酯泄漏的安全隐患。本文提出了由微分散混合器和含有微小填料的静态混合器组合而成的微反应装置,以苯酚、氢氧化钠和硫酸二甲酯为反应原料,实施苯酚钠的形成和苯酚甲基化反应的耦合,实现反应过程的连续化和过程强化。实验考察了进料流量、物料配比、碱液浓度等关键因素对反应的影响,证明了微反应器内传递控制的反应机制。基于微混合器和静态混合元件的传质强化作用,在低于2min的反应时间内获得了98.5%的苯甲醚收率,硫酸二甲酯单耗较传统工艺降低10%,为工业化生产技术的升级换代提供研究基础。     

间-甲基苯甲醚相转移催化合成研究

本文研究了由间-甲基苯酚与硫酸二甲酯在相转移催化剂四丁基溴化铵作用下合成间-甲基苯甲醚的反应。     

微反应器内叔丁醇氢溴化反应动力学研究

将叔丁醇氢溴化反应在微通道反应器内进行动力学研究。结果表明,温度与正、逆反应速率常数成正相关,与平衡常数成反相关;正、逆反应活化能分别为7 821.9和124 234.2 J/mol,反应级数均为一级,动力学方程为rC=2.399e-940.6/T(1-XA)-1.8×1017e-14 942.3/TX1A/2(6.75+XA)1/2。根据浓度和温度效应,分析得到了最优操作温度曲线方程,为今后研究工作中的设计和操作计算提供了理论依据与参考。     

溴化钠在合成4-溴-3,5-二甲基苯甲醚中的应用

以3,5-二甲基苯酚为起始原料经溴化、醚化合成了产物4-溴-3,5-二甲基苯甲醚。该路线通过溴化钠的钝化作用,使得溴化定位选择性达到90%合成总收率达到78%,反应条件由低温反应调整到常温反应,使得更易工业化。     

KF/AC催化剂上碳酸二甲酯气固催化合成间甲基苯甲醚

对KF／AC催化剂上对间甲基苯酚(MC)和碳酸二甲酯(DMC)气固相催化合成间甲基苯甲醚(MM)反应进行了研究。结果表明，负载30％(mass)KF／AC具有最佳催化活性。随着反应温度升高，MC转化率增大．但高于608K后DMC会分解，而MM选择性却下降。当反应温度608K．DMC与MC的摩尔比为1．25；1时，MC转化率可达到95％，MM选择性高于98％。     

Continuous synthesis of 4-bromo-3-methylanisole in modular microreaction system

With the development of microreaction technology and the key issues of liquid-liquid batch bromination process for the synthesis of 4-bromo-3-methylanisole, a modular microreaction system was constructed by taking microreactor and microbead-packed bed as the major functional microdevice units to intensify the bromination of methylanisole. And in this modular microreaction system, the liquid-liquid heterogeneous continuous bromination of 4-bromo-3-methylanisole was studied. The following optimized conditions were obtained, concentration of Br₂ (x_Br2): 17.5 wt%, molar ratio of Br₂ to methylanisole (n_Br2/n_M): 1.01, initial reaction temperature (T): 0℃, residence time (τ): 0.78 min, with yield of 4-bromo-3-methylanisole more than 98%, and percentage of polybrominated side product less than 1%. Comparing with the conventional batch process, the continuous microreaction technology has obvious advantages. For example, it can change the traditional batch process to a continuous one with a significant increase of productivity (space time yield: 6.5×10⁴ kg/(m³·h)). Besides, since this process is mainly controlled by mass transfer, the modular microreaction system with excellent mass transfer could reduce 50% of polybrominated side product. The study might provide a good foundation for the continuously controllable synthesis of 4-bromo-3-methylanisole in safety.     

Continuous,homogeneous and rapid synthesis of 4-bromo-3-methylanisole in a modular microreaction system

4-Bromo-3-methylanisole is mainly used to synthesize black fluorane dye(2-anilino-3-methyl-6-dibutylaminofluorane, ODB-2), which is one of the most important heat and pressure-sensitive dyes in the manufacture of thermal papers. Compared to the industrial heterogeneous batch process, a continuous homogeneous bromination technology in a modular microreaction system has been developed, and 4-bromo-3-methylanisole has been successfully prepared through high-selective mono-bromination of 3-methylanisole with Br_2 solution in CHCl_3. In optimal conditions, the content of bis-brominated byproducts can be controlled less than 0.5%,which is superior to the industrial standard with 99.5% 3-methylanisole conversion at very short residence time and mild reaction temperature.     

Continuous,homogeneous and rapid synthesis of 4-bromo-3-methylanisole in a modular microreaction system

4-Bromo-3-methylanisole is mainly used to synthesize black fluorane dye (2-anilino-3-methyl-6- dibutylaminofluorane, ODB-2), which is one of the most important heat and pressure-sensitive dyes in the manufacture of thermal papers. Compared to the industrial heterogeneous batch process, a continuous homogeneous bromination technology in a modular microreaction system has been developed, and 4-bromo-3-methylanisole has been successfully prepared through high-selective mono-bromination of 3-methylanisole with Br₂ solution in CHCl₃. In optimal conditions, the content of bis-brominated byproducts can be controlled less than 0.5%, which is superior to the industrial standard with 99.5% 3-methylanisole conversion at very short residence time and mild reaction temperature.     

用溴酸钾-硫酸体系制备3-溴-4-氯苯腈

采用溴酸钾为溴化试剂,以对氯苯腈为底物,合成了未见文献报道的化合物3-溴-4-氯苯腈。对此反应的主要参数进行了条件优化。最佳反应条件为:n(对氯苯腈)∶n(溴酸钾)=1∶1.2,在25℃条件下反应7 h,产物纯度≥99.0%,收率85.3%。其结构经红外和核磁氢谱分析确证。     

Continuous synthesis of atomically dispersed Rh supported on MgAl2O4 using two-stage microreactor

Single-atom catalysts with optimal atom utilization and outstanding activity have penetrated the frontier of heterogeneous catalysis. However, the large-scale synthesis of this class of catalysts is still a bottleneck for their industrialization. Herein, we suggest a two-stage micro-dispersion approach to synthesize mesoporous MgAl₂O₄-supported atomically dispersed Rh, which is more competitive than the batch method for boosting the uniform dispersion of Rh. By increasing the Rh loading, single-atom catalysts (SACs, <0.05 wt%), single-atom catalysts + nanoparticle catalysts (0.05–0.17 wt%), and nanoparticle catalyst (NPCs, 0.17–1.10 wt%) were obtained. For n-octane steam reforming, the turnover frequency of the 0.01-Rh-MgAl₂O₄ was approximately 30 times that of the 1.10-Rh-MgAl₂O₄, while the Rh amount of the 0.01-Rh-MgAl₂O₄ was only 3% that of the 1.10-Rh-MgAl₂O₄ for the same fuel conversion. Under a high-temperature (750°C) steam atmosphere for 15 h, the hydrogen formation rate only declined from 25.1 to 23.8 mol/mol-C₈H₁₈.     

A thin-gap cell for selective oxidation of 4-methylanisole to 4-methoxy-benzaldehyde-dimethylacetal

An electrochemical microreactor for organic electrosynthesis has been investigated for the anodic synthesis of 4-methylanisole to 4-methoxy-benzaldehyde-dimethylacetal in methanol solution. Selectivity and conversion in the single-pass thin-gap flow reactor were examined as a function of the composition of the electrolyte solution, the flow rate and the applied current. The experimental results indicate that potassium fluoride currently used for industrial synthesis and providing higher yields than sodium perchlorate, exerts an influence on the reaction mechanism: high KF concentrations facilitate the undesired oxidation of the diacetal. Nevertheless, a feed solution containing 0.1 M anisole in 0.01 M KF can be converted at 90% in the 100 μm thin-gap cell with acceptable voltages and a measured selectivity of nearly 87%. The selectivity observed substantially higher than that typically observed in conventional electrochemical cells.     

光化学微反应技术的基础及研究进展

光化学转化是有效利用光能实现化学反应的重要途径,微反应技术为提高其过程效率提供了一个强有力的平台。本文首先指出微反应器相比于传统釜式光反应器,在光强分布、过程放大、光能利用效率等诸多方面存在明显的优势,能够实现光化学反应过程的高效强化。简要地介绍了光化学转化及光化学微反应技术的基本特征,然后系统地综述了光化学微反应器的设计构建及其在有机合成、聚合等方面的应用,并详细介绍了自动化控制的光化学微反应系统及应用。重点介绍了微反应技术在紫外光、可见光辐照下的光化学合成进展及其过程放大。最后,对光化学微反应技术的研究进展进行总结,并对其发展趋势进行了展望。     

Highly efficient two-stage ring-opening of epichlorohydrin with carboxylic acid in a microreaction system

Ring-opening of epoxides with carboxylic acids has been widely used to prepare many high value intermediates in the polymer and pharmaceutical industries. Most of conventional processes proceeded in batch stirred reactors. As such they always suffer from low productivity and selectivity. Here we developed an advanced technology to perform the ring-opening reaction of epichlorohydrin with neodecanoic acid (NDA) for continuous production of 3-chloro-2-hydroxypropyl neodecanoate in a more efficient and safer way. A microreaction system where a microreactor connected to a stirred reactor was established. When the conversion of NDA rapidly reaching around 90% in a microreactor at 110°C, the reaction solution was transferred to a stirred reactor at 90°C. This two-stage operating mode can reduce the reaction time and improve the selectivity through free switching of temperature in the consecutive two reactors, thus substantially reducing the consumption of energy and materials.     

High-yield production of p-diethynylbenzene through consecutive bromination/dehydrobromination in a microreactor system

Polyarylacetylene resins have received great attention due to their outstanding heat resistance, while the absence of an efficient method to produce their monomer, p-diethynylbenzene (p-DEB), has discouraged their commercial development. Industrial production of p-DEB consists of bromination and dehydrobromination in a semi-batch reactor, state of the art yield from which is only 70%–75%. Herein, a combined effort of byproduct characterization and density functional theory calculations revealed that side reactions mainly consisted of aromatic substitution which would be promoted by thermal runaway derived from exothermic bromination due to higher activation energy of side reactions. From these considerations, we developed a microreactor system to enhance heat transfer thereby mitigating byproduct formation, from which a p-DEB yield of 99.2% could be achieved. Moreover, the high heat removal efficiency avoided the use of slow feeding and reactant dilution required in semi-batch operation, thereby shortening the reaction time to 14 s while generating more concentrated product.