超滤和反应器偶联组合进行干酪素酶解反应

在研究底物浓度对干酪素酶解反应影响的基础上 ,提出干酪素酶解反应应当以边分离边反应的形式进行。因此以三种不同的操作方法 (反应与膜分离分别进行 ;连续偶联反应 ;半连续反应和连续偶联反应组合 ) ,对超滤和反应器的偶联组合进行了研究。其中以半间歇与连续偶联反应器的偶联组合为最佳。当底物浓度为 10 0 g· L-1时 ,得率达到 97% ,比反应与分离分别进行的方式提高了 16 .7%。在此三种方法中 ,超滤对总氮的截留率分别为 σ1=0 .11+0 .0 81t;σ2 =0 .15 +0 .0 0 7t;σ3 =0 .2 1- 8.8× 10 -6t。反应与超滤同时进行时透过液的稳定膜通量为 3.5 L·h-1· m-2     

偶联反应合成多氟联苯液晶化合物

以丙基(双环己基)苯为原料,经碘代和偶联反应合成多氟联苯液晶化合物3,4 二氟(4′ 丙基双环己基)联苯,两步总收率为58 3%。目标化合物经IR,1HNMR和元素分析仪确证了分子结构,运用差示扫描量热仪(DSC)测定了液晶相态温度范围。偶联反应工艺条件为:采用四(三苯基膦)合钯作为催化剂,反应时间为6h,收率达到81%。     

丁二烯,苯乙烯溶液共聚体系的偶联反应

以ｎ－ＢｕＬｉ为引发剂,ＴＨＦ／ｎ－ＢｕＬｉ为８０－３００,在丁二烯、本乙烯负离子共聚体系中加入ＳｎＣｌ４或己二酸二乙酯（ＤＥＡＰ）进行偶联反应,研究了ＴＨＦ和偶剂用量、偶联反应温度和时间及共的不同链末端结构对偶联反应的影响。结果表明,ＳｎＣｌ４的偶联效率（５１．６％）高地ＤＥＡＰ（４３．８％）,且该体系共聚物链末端结构时偶联效率无影响;ＳｎＣｌ４较佳的偶联反应条件为：５０℃,３０ｍｉｎ,ＳｎＣｌ     

金属钯催化的偶联反应的研究总结

偶联反应是一类构建碳-碳键的重要化学反应,其应用十分广泛。本文对钯催化的Suzuki、Heck、Sonogashira、Kumada、Negishi、Stille、Hiyama等偶联反应的研究进行了综述,分析了上述反应的优缺点及研究成果,并对该类反应的发展前景进行了归纳总结。     

一氧化碳偶联制草酸酯反应工程研究

以工业应用为背景，研究了一氧化碳在钯系双金属催化剂上气相催化偶联合或草酸二乙酯的反应特性，得出偶联反应和再生反应的可控的匹配条件为：偶联反应温度为３５３Ｋ－３９３Ｋ，反应系统中一氧化碳浓度为２５－３５％，一氧化氮浓度为２０－３０％，亚硝酸酯深度为１０－１５％。     

铜基纳米材料在偶联反应中的应用

纳米催化剂由于其具有高的比表面积和表面原子不饱和度等特性而表现出优异的催化性能。与贵金属相比,铜基纳米催化剂具有价格低廉、催化活性高、应用范围广、环境友好等优点,受到了研究人员越来越多的重视。本文综述了铜基纳米材料在偶联反应中的应用进展。     

星形SBS的偶联反应

以环己烷为溶剂、四氢呋喃为活化剂、正丁基锂为引发剂、四氯化硅为偶联剂合成了星形ＳＢＳ,讨论了偶联反应温度、活性双嵌段聚合物ＳＢ的相对分子质量、偶联剂用量与加入方式、单体质量分数及苯乙聚合程度对偶联反应的影响。结果表明,反应温度为９０￣１１０℃,偶联剂用量为理论用量的９０￣１１０％及采用２次加料方式,单体质量分数为１８．０￣１９．５％时,试样的偶联度及偶联效率较佳。     

偶联反应在农药合成中的应用

偶联反应具有反应条件温和、选择性好和产率高等优点,在有机合成领域中有很广泛的应用.简要概述了偶联反应如Heck反应、Suzuki反应、Negishi反应、Sonogashira反应等在合成农药品种如唑啉草酯、联苯菊酯、啶酰菌胺、bixafen和fluxapyroxad等中的应用,并对各反应的优缺点加以简要的评述.     

负载钯及非钯型Suzuki偶联反应催化剂体系的研究进展

Suzuki偶联反应是现代有机合成化学中构筑碳碳键的最有效方法之一。传统的Suzuki反应催化剂主要是Pd(PPh3)4、Pd(OAc)2等均相催化剂。这类催化剂的活性较高,但其价格高、化学稳定性较差、难以与反应液分离和回收再利用等缺点也是不容忽视的。近年来,人们开发了一系列具有不同的钯材料载体(碳材料、高分子材料以及无机材料等)的非均相催化剂体系,以及基于Ni、Cu、Mn等过渡金属的新型催化体系。这些新型的催化剂体系的发展有效地解决了上述均相催化剂的不足。综述了近来Suzuki反应在负载催化剂和非钯催化剂方面的研究进展。     

伴有辅酶再生的多酶反应技术进展

伴有辅酶再生的多酶反应技术是酶工程领域的重要课题。本文就辅酶再生及伴有辅酶再生的多酶反应器技术最新进展进行评述。     

Maximizing the Efficiency of Multienzyme Process by Stoichiometry Optimization

Multienzyme processes represent an important area of biocatalysis. Their efficiency can be enhanced by optimization of the stoichiometry of the biocatalysts. Here we present a workflow for maximizing the efficiency of a three‐enzyme system catalyzing a five‐step chemical conversion. Kinetic models of pathways with wild‐type or engineered enzymes were built, and the enzyme stoichiometry of each pathway was optimized. Mathematical modeling and one‐pot multienzyme experiments provided detailed insights into pathway dynamics, enabled the selection of a suitable engineered enzyme, and afforded high efficiency while minimizing biocatalyst loadings. Optimizing the stoichiometry in a pathway with an engineered enzyme reduced the total biocatalyst load by an impressive 56 %. Our new workflow represents a broadly applicable strategy for optimizing multienzyme processes.     

利用偶联反应光度法检测甲磺隆

在pH值为7．0的磷酸氢二钠-磷酸二氢钠体系中,甲磺隆与亚硝酸钠反应生成重氮盐,重氮盐与α-萘胺进行偶联反应生成红棕色化合物,该产物在500nm处有最大吸光值,据此,建立了利用偶联反应测定甲磺隆残留的新方法。在最佳条件下,甲磺隆质量浓度与吸光值呈良好的线形关系,线性范围为10～150mg／L。平均回收率为98．10％,相对标准偏差为2．12％。     

耦合反应在碳酸二甲酯合成反应中的应用

本文运用化学热力学基本原理,着重从热力学角度对碳酸二甲酯的合成反应进行了探讨,表明使用耦合反应是提高碳酸二甲酯产率的重要方向。     

Ritter反应的研究进展

Ritter反应是构筑C—N键最为重要的方法之一,可以广泛应用于精细有机合成中,包括药品、农药、高分子行业用的功能单体的合成。本文综述了从催化体系的选择、反应物的改变和其他辅助方法的选用等方面对Ritter反应进行改良的最新的应用研究进展。     

Multienzyme co-immobilization-based bioelectrode:Design of principles and bioelectrochemical applications

Enzyme cascade reactions play significant roles in bioelectrochemical processes because they permit more complex reactions. Co-immobilization of multienzyme on the electrode could help to facilitate substrate/intermediate transfer among different enzymes and electron transfer from enzyme active sites to the electrode with high stability and retrievability. Different co-immobilization strategies to construct multienzyme bioelectrodes have been widely reported, however, up to now, they have barely been reviewed. In this review, we focus on recent state-of-the-art techniques for constructing co-immobilized multienzyme electrodes including random and positional co-immobilization. Particular attention is given to strategies such as multienzyme complex and surface display. Cofactor co-immobilization on the electrode is also crucial for the enhancement of catalytic reaction and electron transfer, yet, few studies have been reported. The up-to-date advances in bioelectrochemical applications of multienzyme bioelectrodes are also presented. Finally, key challenges and future perspectives are discussed.     

渗透蒸发和化学反应的耦合

渗透蒸发是分离液相混合物的膜分离方法，常用于有机物脱水及有机物－－有机物的分离。借助于渗透蒸发把化学反应产物部分或全部从反应体系中脱去，可使产物收率不受化学平衡的限制。     

Application of Imine Reductases (IREDs) in Micro‐Aqueous Reaction Systems

Here we present the applicability of different imine reductases (IREDs) in micro‐aqueous reaction systems. Subjects of the study were the IREDs from Streptomyces aurantiacus (SaIR), Streptomyces sp. GF3587 (RGF3587IR), Streptomyces kanamyceticus (SkIR), Streptomyces ipomoeae 91‐03 (SiIR), Streptomyces sp. GF3546 (SGF3546IR), and Paenibacillus elgii B69 (PeIR). The IREDs were overexpressed in Escherichia coli (E. coli) cells and used directly after lyophilization. Several organic solvents and buffer amounts were screened for the reduction of the two substrates β‐carboline harmane and 1‐methyl‐3,4‐dihydroisoquinoline to the corresponding amines. Cyclopentyl methyl ether (CPME) proved to be the best solvent choice for the envisaged reduction. In addition, CPME is currently referred to as an environmentally benign solvent. Optimized reaction conditions were applied to 20 mM of the hardly water soluble substrates, leading to good conversions (up to 96%) and excellent enantiomeric excesses (>99%) in the best cases. The use of micro‐aqueous reaction systems opens the way to further applications of IREDs with hardly water soluble substrates.

     

Design of Extractive Reaction Systems

Product selectivity and yield in chemical reactions can be limited by side product formation or low conversions due to equilibrium limitations. Extractive reaction systems (ERS) employ an in situ liquid‐liquid extraction that separates the product from the reaction phase to overcome these difficulties. The design of ERS requires a broad knowledge of the discipline of process intensification and extraction and reaction engineering. Furthermore, specific knowledge about the interplay of reaction and extraction phenomena is unique to ERS. This review gives an overview of the design of ERS and enables their application to any suitable reaction.