首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到19条相似文献,搜索用时 109 毫秒
1.
固态有机合成反应进展   总被引:20,自引:2,他引:20  
臧洪俊  李正名  王宝雷 《有机化学》2003,23(10):1058-1063
以绿色合成为主题,综述了近期固相有机合成研究方面的一些新进展和典型反 应类型。由于固相反应的特征,多数固相有机反应表现出较溶液中更高的反应效率 和更好的选择性,并讨论了固态反应中的分子运动及其固态反应的因素。  相似文献   

2.
研磨法在固相有机合成中的应用   总被引:1,自引:0,他引:1  
近几十年来有机工作者将研磨法用于固态有机合成, 取得了一些成效, 综述了近年来典型的固相有机研磨反应.  相似文献   

3.
天然气与硫酸盐热化学还原反应的模拟实验研究   总被引:4,自引:1,他引:4  
为探讨天然气中高含量硫化氢形成的化学机制,利用高温高压反应装置,对天然气与固态硫酸钙反应体系进行了热模拟实验研究。使用气相色谱仪、微库仑仪、傅里叶变换红外光谱仪和X射线衍射仪对产物进行了分析,探讨了硫酸盐热化学还原反应的热力学特征,并进行了反应动力学研究。结果表明,高温下天然气与固态硫酸钙可以发生反应,产物主要为硫化氢、二氧化碳、碳酸钙、水和炭。热力学研究表明,天然气与固态硫酸钙的反应可行,升高温度对反应有利,同一温度下长链烷烃与固态硫酸钙发生反应的可能性要比短链烷烃大。根据动力学模型得到反应活化能为96.824kJ/mol。  相似文献   

4.
金属有机化学中的绿色化学反应进展   总被引:4,自引:0,他引:4  
宋礼成  范洪涛  胡青眉 《有机化学》2001,21(10):713-720
着重综述了金属有机化学领域中所涉及的与绿色化学概念有关的一些化学反应,如水相反应、超临界流体及离子液体中的反应、固态反应、原子经济性及过渡金属催化的有机反应。  相似文献   

5.
雷立旭  周益明 《化学进展》2020,32(8):1158-1171
根据热力学,固态化学反应一般具有一旦发生就必完全的特征;但在固体之间存在组成可连续变化的溶液(固熔体)时,固态化学反应体系有可能出现化学平衡。固态化学反应还可能导致立体选择性产物、产物颗粒不易长大、最低反应温度等特征。本文特别指出,为了促进固态化学反应快速、有效、安全地发生,可使用少量溶剂而不用担心固态化学反应无平衡特征的丧失,同时获得良好流动性的反应物浆料,并因此能使用适当的搅拌技术来促进反应;其次,任何复杂的固态化学反应都可以分解成若干双组分反应,可以按一定步骤实现复杂化合物的合成或装配。因此,研究固态化学反应可能会产生更加绿色的化学过程,具有非常现实的理论和应用价值。本文以固态配位化学反应为例来说明如上理论推演结果。这里,固态配位化学反应是固体无机金属化合物与固体有机或无机配体之间的化学反应,它们与固态有机化学反应一样,可以在室温~300 ℃的温度下、不存在任何溶剂的情况下发生。  相似文献   

6.
胡秀贞 《化学通报》1994,(6):59-64,F003
有机反应的竞争性胡秀贞(南京师范大学化学系,210024)竞争反应是有机化学中一个相当普遍的反应,所以我们研究有机反应机理时,必须具有有关这个反应的热力学和动力学的基本知识。大家知道热力学研究的一个重要内容是反应的起始状态和终止状态的能量变化,而动力...  相似文献   

7.
微波辐射下,聚合物支载的有机反应易于进行,操作简便,反应速率高,反应 时间短,产率高,纯度好,聚合物载体稳定,综述了微波辅助不溶性聚合物和可溶 性聚合物支载的有机反应。  相似文献   

8.
固态反应合成2,4,6-三苯氧基-1,3,5-均三嗪衍生物   总被引:3,自引:0,他引:3  
固态反应合成2;4;6-三苯氧基-1;3;5-均三嗪衍生物;固态反应;缩合;氰尿酰氯;三苯氧基均三嗪  相似文献   

9.
近年来,有机锑化合物在交叉偶联反应中的应用引起了人们的广泛关注。本文主要对有机锑化合物在交叉偶联反应中的应用作了综述,重点介绍了其在Suzuki交叉偶联反应、Heck偶联反应以及Sonogashira偶联反应中的应用,并展望了其未来的发展方向。  相似文献   

10.
方小牛 《大学化学》1994,9(6):48-52
关于有机竞争反应产物控制的讨论方小牛(江西吉安师范专科学校化学系343009)在有机化学中,竞争反应极为普遍。而对于一组竞争反应来说,其产物的控制有动力学控制和热力学控制两种,因此,动力学控制和热力学控制也成为有机化学中很普遍又很重要的概念。多数有机...  相似文献   

11.
Selected kinetic and mechanistic studies of thermal reactions of initially solid substances are reviewed with emphasis on the evidence that some of these chemical changes proceed with the essential participation of melting. The reactions considered are classified on the extent and the role of such melting and the various types of behaviour observed are discussed with reference to solid state rate processes in crystals. It is stressed that melting is an important feature in theoretical considerations of crystal reactivity because chemical changes often proceed more rapidly in a melt than in the solid state. However, literature reports concerned with reactions of solids do not always explicitly mention the possibility of melting during discussions of reactions mechanisms. The present paper comments on methods capable of detecting liquefaction during reaction, a feature of behaviour that is not always easily identified experimentally. Also considered here is the recognition of reaction intermediates, which provide important evidence concerning the course of the chemical changes through which the reactant is transformed into product. This short review draws attention to the considerable value of chemical evidence in elucidating mechanisms of reactions of solids including the necessity for identifying intermediates and the role of any melt or liquid participating.  相似文献   

12.
An outline of equations allowing calculation, from calorimetric data, of both thermodynamic and kinetic parameters for reactions which proceed to completion is given. In addition equilibrium constants are calculable for reactions which proceed to an equilibrium position. Advantages of the methods for solid state kinetic and stability studies are briefly discussed.  相似文献   

13.
Mechanisms based on the 1,4-migration of metal centers have been proposed to explain some interesting transition-metal-catalyzed organic transformations. Despite the lack of solid evidence for the real nature of this process, the 1,4-metal migration reaction is proposed to proceed by the reductive elimination of trivalent intermediates for the Rh-involved reactions and of tetravalent intermediates for the Pd-catalyzed processes. These high-valent organometallic species would be formed by the oxidative addition to C-H and C-X bonds. This minireview summarizes the results in this area.  相似文献   

14.
固相有机反应和分析方法   总被引:2,自引:0,他引:2  
综述了近几年固相有机反应和分析方法的最新进展。固相有机反应包括取代、缩合、环加成、氧化还原反应等, 可以形成碳碳键、酰胺键等, 满足官能团的变换; 与固相有机反应相适应的有机分析方法包括对单个树脂微球所连接化合物进行官能团分析(FTIR)方法和结构确定方法(MAS NMR)。这些技术能够更好地使组合化学应用到药物开发研究之中。  相似文献   

15.
Monolayers of molybdenum disulfide MoS2 are considered to be prospective materials for nanoelectronics and various catalytic processes. Since in certain conditions they undergo 1T ? 2H phase transitions, studying these phase changes is an urgent task. We present a DFT research of these transitions to show that they can proceed as a solid‐state reaction. Two transition states were discovered with energy barriers 1.03 and 1.40 eV. Sulfur atoms in the transition states are shown to be displaced relative to molybdenum atoms so that a tendency of one structural modification to transform into the other modification is seen. This kind of displacements agrees with electron microscopy data reported earlier. The energy parameters indicate that 1T → 2H reactions are exothermic for both transition states and can possibly proceed in a self‐sustained manner when initially activated by some external energy impact. © 2015 Wiley Periodicals, Inc.  相似文献   

16.
铅(Ⅱ)化合物与NaOH室温条件下的固相化学反应研究   总被引:5,自引:1,他引:4  
研究了铅(Ⅱ)化合物与NaOH在室温条件下的固相反应。实验表明:铅(Ⅱ)化合物与NaOH的固相反应与其在溶液中的反应不同。着重研究了Pb(Ac)2·3H2O与NaOH的固相反应,用X衍射、热重、差热等实验手段测定了固相反应的过程及产物。  相似文献   

17.
A thermodynamically guided calculation of free energies of substrate and product molecules allows for the estimation of the yields of organic reactions. The non‐ideality of the system and the solvent effects are taken into account through the activity coefficients calculated at the molecular level by perturbed‐chain statistical associating fluid theory (PC‐SAFT). The model is iteratively trained using a diverse set of reactions with yields that have been reported previously. This trained model can then estimate a priori the yields of reactions not included in the training set with an accuracy of ca. ±15 %. This ability has the potential to translate into significant economic savings through the selection and then execution of only those reactions that can proceed in good yields.  相似文献   

18.
Photolysis of α-bromopropiophenones in acetonitrile results in formation of β-bromopropiophenones with good product selectivity, which can be coined as 1,2-Br shift reaction. The product selectivity increases when the reaction is done in neat or solid state, where only the 1,2-Br shift product is formed in some cases. The reaction is suggested to proceed by CBr bond homolysis to give a radical pair, followed by disproportionation and conjugate addition of HBr to the α,β-unsaturated ketone intermediate. When the unsaturated intermediate is stabilized by an extra conjugation, the reaction stops at the stage, in which the unsaturated ketone becomes a major product. The synthetic method described in this research fits in a category of eco-friendly organic synthesis nicely since the reaction does not use volatile organic solvents and any other additives such as acid, base or metal catalysts, etc. Besides, the method fits into perfect atom economy, which does not give any side products. The synthetic method should find much advantage over other alternative methods to obtain β-bromo carbonyl compounds.  相似文献   

19.
A new class of Pummerer chemistry has emerged as a powerful tool in organic synthesis. The new technology consists of a beautiful cascade of an interrupted Pummerer reaction and the subsequent [3,3] sigmatropic rearrangement. The interrupted Pummerer reactions of alkenyl or aryl sulfoxides with unsaturated nucleophiles such as allylic silanes, ketones, and phenols provide sulfonium intermediates, which are ready to undergo smooth charge‐accelerated [3,3] sigmatropic rearrangement with excellent to exclusive regioselectivity. Some of the transformations proceed with transient loss of aromaticity. The reactions afforded five‐membered heterocycles, benzofurans, and biaryls of importance, depending on the sulfoxides and nucleophiles used. The reactions are unique and game‐changing because they are efficient, robust, redox‐neutral, regioselective, and metal‐free, which perfectly fits the need of modern organic synthesis. This chemistry also underscores the synthetic potential of organosulfur chemistry.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号