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1.
采用自洽场分子轨道UHF/6-31G**从头算法,研究了1,2-C4H6→2-C4H6异构化反应机理,优化了基态势能面上反应物,过渡态,中间体和产物的几何构型,并对各驻点能量进行了零点能校准。结果表明该反应经历了一个1-甲基环丙烯生产产物比较两步氢迁移反应历程更易发生。  相似文献   

2.
报道了3种含双官能团苯基醚化合物2-(2,6-二氯苯氧基)丙腈,N-羟基-4-丁基苯乙酰胺,2-(1-甲基乙氧基)苯酚甲氨基酸甲酸酯的电子轰击质谱破裂,用亚稳分析和低能碰撞诱导解离子研究了3种化合物的分子离子碎裂规律,除简单的直接键断裂外,还证实经历了离子/中性(碎片)复合物中间体的单分子解离反应同时存在的竞争机理,解释了观察到分子内单氢迁移,双氢迁移现象。  相似文献   

3.
李宝山 《大学化学》1996,11(5):31-33
人体皮肤中所含7-脱氢胆甾醇在阳光照射下转变为维生素D3的反应机理是,由两个连续的协同反应组成:(1)7-脱氢胆甾醇分子中的环己二烯开环转变为开链共轭三烯;(2)预钙化醇分子内发生1,7-氢迁移反应。在温和的生理条件下要发生非酶促反应,通过环状过渡态按协同方式进行反应,当为大自然的最佳选择  相似文献   

4.
十一碳烯氧甲基一缩二乙二醇、二缩三乙二醇分别与1,2-双(β-羟乙氧基)苯双对甲苯磺酸酯在氢化钠存在下关环缩合,得到9-十一碳烯氧甲基-2,3-苯并15-冠-5与9-十一碳烯氧甲基-2,3-苯并18-冠-6。二者与三乙氧基硅烷反应产物以二氧化硅固载化。得到具有十一烯氧甲基连接基团的二氧化硅固载苯并冠醚,它们可与铂形成配合物。铂配合物对烯烃与三乙氧基硅烷的硅氢加成反应具有极好的催化效能。  相似文献   

5.
本文通过双(2-羟基乙基)硫醚与1,2-双(2'-对甲苯磺酰氧基乙氧基)苯缩合闭环,得到10-硫杂苯并-15冠-5,后者再与氯亚铂酸钾反应得到标配合物;同时研究了该配合物对烯烃与三乙氧基硅烷的硅氢加成反应的催化特性,并与硒,碲的类似配合物进行了比较,结果表明,此配合物是烯烃硅氢化反应的高效催化剂。  相似文献   

6.
本文通过双(2-羟基乙基)硫酸与1,2一双(2’-对甲苯磺酞氧基乙氧基)苯缩合闭环,得到10-硫杂苯并-15-冠-5,后者再与氯亚铂酸钾反应得到标题配合物;同时研究了该配合物对烯烃与三乙氧基硅烷的硅氢加成反应的催化特性,并与硒、碲的类似配合物进行了比较.结果表明,此配合物是烯烃硅氢化反应的高效催化剂.  相似文献   

7.
α-溴代丙酰氯分别同四氢噻唑-2-硫酮及(R)-四氢噻唑-2-硫酮-4-羧酸乙酯反应得到四氢噻唑-2-α-溴代丙酰硫酯2a及光学活性4-乙氧羰基四氢噻唑-2-α-溴代丙酰硫酯2b.用半经验的量子化学PM3方法研究了反应物和产物的电子结构和反应的焓变,得到反应物1a异构化的过渡态.  相似文献   

8.
十一碳烯氧甲基一缩二乙二醇、二缩三乙二醇分别与1,2-β(β-羟乙氧基)苯双对甲苯磺酸酯在氢化钠存在下关环缩合,得到9-十一碳烯氧甲基-2,3-苯并15-冠-5与9-十一碳烯氧甲基-2,3-苯并18-冠-6.二者与三乙氧基硅烷反应产物以二氧化硅固载化,得到具有十一烯氧甲基连接基团的二氧化硅固载苯并冠醚.它们可与铂形成配合物.铂配合物对烯烃与三乙氧基硅烷的硅氢加成反应具有极好的催化效能  相似文献   

9.
叔-丁基醚热分解反应的量子化学研究   总被引:2,自引:0,他引:2  
用AM1方法研究了叔-丁基醚热分解反应,发现这类化合物可经过四元环过渡态分解成丁烯和醇或酚。  相似文献   

10.
应用半经验分子轨道AM1法,辅以Berny梯度优化法对3-氯丙酸和2-氯丁酸在气相中的热消除反应进行了理论研究。计算结果表明:(1)3-氯丙酸在气相中的热消除反应可以通过六元环过渡态机理和四元环过渡态机平行进行得到产物;(2)2-氯丁酸的热消除则可以通过五元环过渡态机理和四元环过渡态机理平行进行;(3)对3-氯丙酸的热消除反应,以了环过渡态进行反应的活化势垒较低,而2-氯丁酸的热消除反应则是五元环  相似文献   

11.
Reactions of silicon and germanium dichlorides L ⋅ ECl2 (E=Si, L=IPr; E=Ge, L=dioxane) with the phosphinoamidinato-supported disilylene ({κ2(N,P)-NNP}Si)2 resulted in formal tetrylene insertions into the Si−Si bond. In the case of the reaction with silylene, two products were isolated. The first product ({κ2(N,P)-NNP}Si)2SiCl2, is the formal product of direct SiCl2 insertion into the Si−Si bond of ({κ2(N,P)-NNP}Si)2 and thus features two separated silylamido silylene centers. Over time, migration of the SiCl2 group to a lateral position afforded the second product, the disilylene {κ2(Si,P)−SiCl2NNP}Si−Si{κ2(N,P)-NNP}. In contrast, insertion of GeCl2 resulted only in the isolation of the germanium analogue of {κ2(Si,P)−SiCl2NNP}Si−Si{κ2(N,P)-NNP}, containing a Ge atom in the central position namely, compound {κ2(Si,P)−SiCl2NNP}Ge−Si{κ2(N,P)-NNP}, which is a rare example of a silylene-germylene. Finally, reaction of disilylene ({κ2(N,P)−NNP}Si)2 with SiCl4 and SiHCl3 led to the formation of the new bis(silyl)silylene, ({NNP}SiCl2)2Si:. All four new products from these insertion reactions have been characterized by multinuclear NMR and single-crystal X-ray diffraction studies.  相似文献   

12.
《Thermochimica Acta》1987,112(1):31-46
Flash vacuum pyrolysis has been used to prepare a variety of differently substituted derivatives of the benzocyclobutene ring system starting with simple precursors. An analytical gas flow reactor is described which simulates reaction conditions of flash vacuum pyrolysis experiments. This reactor allows to optimise reaction conditions and to obtain structure reactivity correlations for thermolytic gas phase reactions.  相似文献   

13.
讨论了裂解二次反应对气相色谱—裂解气相色谱联用定性分析起的作用,改进了气相色谱—裂解气相色谱联用装置,对7组分的香精作定性分析,研究了多种实验条件与定性参数的关系,提出可用一组裂解色谱参数作为实用的主要定性依据,另一组参数作为辅助依据。  相似文献   

14.
垃圾衍生燃料等温快速热解和燃烧反应特性   总被引:4,自引:4,他引:4  
利用热天平和管式炉对RDF(Refuse Derived Fuel)等温快速热解和燃烧反应特性进行了研究。实验发现,在等温快速升温的条件下,RDF热解和燃烧的反应速率都非常快,从受热开始到反应结束需60 s~80 s;从开始失重到完成反应为20 s。RDF热解和燃烧热重反应曲线非常类似,都只有一个反应失重区;RDF组成对其燃烧和热解反应性有重要影响,含有橡胶的RDF的热解和燃烧反应速率较小。在650 ℃~800 ℃RDF快速热解产物中气、液产物的产率可达80%~90%,而固体产物的产率只有10%~20%,热解气体的热值为20kJ/m3,RDF较适合进行热解处理。  相似文献   

15.
矿物质对煤显微组分热解的影响   总被引:10,自引:2,他引:10  
用常压热天平考察了平朔气煤三种主要显微组分(镜质组、丝质组和稳定组)的热解特性及其原生矿物质和外加无机物对各显微组分热解的影响。用ST-03表面孔径测定仪测定了三种显微组分及焦样的比表面积。研究表明,各显微组分的热解反应性从强到弱的排列顺序为:稳定组>镜质组>丝质组;原生矿物质对各显微组分的热解具有抑制作用,对热解活化能也有影响,并使焦样的比表面积显著增加;外加CaO等无机物及其添加量对不同显微组分的热解有不同的影响,但都使焦样比表面积增加。用分段连续一级反应机理可以较好地描述各显微组分的热解过程,统一形式不同参数的动力学模型为dx_(ij)/dt_(ij)=k_(ij)(1-x_(ij))。  相似文献   

16.
The role of the back-biting reaction for generation of dimers and trimers on flash pyrolysis of poly(styrene-co-methacrylonitrile) by pyrolysis gas chromatography with the use of a Curie-point pyrolyzer has been investigated. Yields of each monomer, dimer, and trimer changed depending on the sequence distribution as well as on copolymer composition and pyrolysis temperature. The degradation behavior was explained by the competition between the back-biting reaction and depolymerization. It was found that the hybrid dimers and trimers were produced mainly by the back-biting reaction, which was followed by β-scission, and hence yields of hybrid dimers and trimers correctly reflect the sequence distribution of the copolymer of styrene and methacrylonitrile without interference from the second reaction of monomers regenerated in the flash pyrolysis. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2747–2753, 1999  相似文献   

17.
Propane pyrolysis at atmospheric pressures and temperatures of 500–700°C in the presence of a bimetallic catalyst containing 50 wt % Ni, 40 wt % Cu, and a silicon dioxide textural promoter has been investigated. It has been established experimentally that the reactor geometry and the way the reactants are let in and out exert an effect on the catalytic pyrolysis. The overall process rate is mainly determined by the heterogeneous reaction occurring on the catalyst surface. The homogeneous constituent of the process has an effect on the propane conversion at the early stages of the reaction.  相似文献   

18.
β-Carotene has ben heated under vacuum at temperatures ranging from 200 to 350°C for 24 h as a model of geothermal reaction of carotenoids in sediments and of a thermal reaction of highly conjugated polyene. Compounds with molecular weights of 138, 240, 346 and 444 and isomers of β-carotene were obtained in addition to toluene, xylene, ionene and 2,6-dimethylnaphthalene, which have been reported previously as pyrolysis products of β-carotene. Possible reaction mechanisms for the formation of the pyrolysis products are given.  相似文献   

19.
城市生活垃圾低温热解产气特性的实验研究   总被引:9,自引:2,他引:7  
用直径200 mm的外热式固定床反应器,以城市生活垃圾中9种典型成分的混合物为实验物料,在300 ℃~700 ℃对其进行了低温热解的实验研究。结果表明,在其他条件相同的情况下,随着热解温度的提高,热解反应所需时间缩短;热解气的总产率、最大瞬时产率均增加;热解气的各成分随温度的升高呈现出不同的变化趋势;热解气的热值在600 ℃达到最大值,为15.13 MJ/m3,可满足民用燃气的要求。  相似文献   

20.
The rate of the gas-phase thermolysis of N-acryloyl, N′acetohydrazide has been measured in the gas phase in the range 482–517 K. This is believed to be a first order elimination reaction for which log A = 10.8 s−1 and the activation energy En = 132 kJ mol−1. Product analysis for the monomer and polymer were used for the elucidation of the thennolysis mechanism. It has been concluded that pyrolysis of the polymer occurs by depolymerization reaction followed by the pyrolysis of the monomer produced.  相似文献   

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