基于Willgerodt-Kindler反应的两种二茂铁羧酸的合成及机理研究

以Na2S•9H2O为催化剂, 通过Willgerodt-Kindler反应分别合成了二茂铁乙酸和1,1’-二茂铁二乙酸, 用IR, 1H NMR, MS和元素分析对产物分别进行了结构表征, 并利用GC-MS研究了该反应机理, 推测反应是由多硫阴离子进攻羰基α碳所引发, 同时讨论了影响反应的各种因素.     

羧酸加氢反应机理及催化剂的研究进展

生物质衍生羧酸化合物的加氢反应是生产生物质化学品的重要过程之一.我们从羧酸分子加氢反应机理与加氢催化剂两个方面进行概述,着重介绍了第VIII族金属,尤其贵金属作为活性金属的羧酸加氢反应机理,以及不同催化剂对羧酸加氢反应途径的影响.此外,还介绍了羧酸水相加氢反应中Ru基催化剂的研究进展.     

3-芳基-5-巯基-1,2,4-三唑衍生物的亲核反应研究

研究了碱性条件下3-芳基-5-巯基-1,2,4-三唑与丙烯腈或丙烯酸甲酯的亲核反应,得到31个新的3-芳基-1,2,4-三唑-5-硫酮类衍生物,其结构经NMR, IR, MS和元素分析表征.     

New representatives of nitroamine-containing 1,2,4-triazoles: Synthesis and structure

The interaction of 1-methyl-1-nitroso-2-nitroguanidine with carboxylic acid hydrazides results in formation of N-(2-nitroguanidino)amides that easily give 3(5)-nitroamino-5(3)-alkyl(aryl)-1,2,4-triazoles under refluxing in aqueous alkaline medium. We have developed a one-pot method to prepare such heterocyclic structures; the synthesis of one of the sample compound has given an example of the method applicability. The compounds structures have been confirmed by UV, IR, ¹H, and ¹³C-{¹H} NMR spectroscopy.     

Synthesis of 1,3,5-trisubstituted-1,2,4-triazoles by microwave-assisted N-acylation of amide derivatives and the consecutive reaction with hydrazine hydrochlorides

Facile and efficient procedures for the N-acylation reaction of amide derivatives with various acid anhydrides and the cyclization reaction of N-acylated amide derivatives with various hydrazine hydrochlorides were described. The reactions were carried out under microwave irradiation to give products in good yields in a few minutes. The synthesis of 1,3,5-trisubstituted-1,2,4-triazoles from benzamides can also be accomplished in a simple one-pot sequential reaction.     

Rapid synthesis of 1,3,5-substituted 1,2,4-triazoles from carboxylic acids, amidines, and hydrazines

A general method for the synthesis of 1,3,5-trisubstituted 1,2,4-triazoles has been developed from reaction of carboxylic acids, primary amidines, and monosubstituted hydrazines. This highly regioselective and one-pot process provides rapid access to highly diverse triazoles.     

Synthesis, spectral characterization and antihaemostatic activity of 1,2,4-triazoles incorporating 1,2,4-triazine rings

A simple and high yielding method for the integration of a 1,2,4-triazole ring with 1,2,4-triazine-5-one (4a-j) has been developed starting from 3-arylsydnones (1a-d). The structures were proved by their spectral data and screened for antihaemostatic activity.     

Modeling the Reaction of Carboxylic Acids and Isonitriles in a Self-Assembled Capsule

Quantum chemical calculations were used to study the reaction of carboxylic acids with isonitriles inside a resorcinarene-based self-assembled capsule. Experimentally, it has been shown that the reactions between p-tolylacetic acid and n-butyl isonitrile or isopropyl isonitrile behave differently in the presence of the capsule compared both with each other and also with their solution counterparts. Herein, the reasons for these divergent behaviors are addressed by comparing the detailed energy profiles for the reactions of the two isonitriles inside and outside the capsule. An energy decomposition analysis was conducted to quantify the different factors affecting the reactivity. The calculations reproduce the experimental findings very well. Thus, encapsulation leads to lowering of the energy barrier for the first step of the reaction, the concerted α-addition and proton transfer, which in solution is rate-determining, and this explains the rate acceleration observed in the presence of the capsule. The barrier for the final step of the reaction, the 1,3 O→N acyl transfer, is calculated to be higher with the isopropyl substituent inside the capsule compared with n-butyl. With the isopropyl substituent, the transition state and the product of this step are significantly shorter than the preceding intermediate, and this results in energetically unfavorable empty spaces inside the capsule, which cause a higher barrier. With the n-butyl substituent, on the other hand, the carbon chain can untwine and hence uphold an appropriate guest length.     

Reaction of N-acylthioureas with electrophilic reagents : Synthesis of 1,3,5-oxadiazinium salts, 1,3,5-thiadiazinium salts, 1,2,4-dithiazolium salts and benzothiazoles

N-Acylthioureas 1 can be easily transformed into 2,4-diamino-6-aryl-1,3,5-oxadiazinium salts 12, 2,4-diamino-6-aryl-1,3,5-thiadiazinium salts 13,3-amino-5-aryl-1,2,4-dithiazolium salts 19 and 2-acylimino-benzothiazolines 22, respectively by reaction with different electrophiles. The structure of the compounds prepared is confirmed by analytical data as well as by chemical transformations.     

Synthesis of Aryl Ketones by Cross-Coupling Reaction of Arylboronic Acids with Carboxylic Anhydrides in Aqueous Phase

A highly efficient aqueous system of PdCl₂-catalyzed cross-coupling reaction of arylboronic acid with carboxylic anhydride (Suzuki-type reaction) without the use of phosphine ligands was developed. The reactions went smoothly in acetone/H₂O phase to give good yields of aryl ketones in short reaction times (1–3 h) at room temperature in air and were unaffected by the presence of electron-releasing and electron-withdrawing substituents in both the arylboronic acids and carboxylic anhydrides.     

一个方酸内鎓盐衍生物合成机理的理论研究

用ＰＭ３方法对新近合成的一个方酸内Ｗｅｎｇ盐衍生物：２－（Ｎ,Ｎ－二羟乙基）胺基－４－二甲胺苯基方酸内Ｗｅｎｇ盐的微观反应机理进行了研究,计算结果表明：以（Ｎ,Ｎ－二羟乙基）胺基负离子,二甲胺一方酸制备该方酸内Ｗｅｎｇ盐有邻位和对位两种产物,且对位更易生成,同时,还探讨了提高光致材料产率的可能方法。     

层状四水硫酸锆催化合成乙二醇单乙醚醋酸酯反应机理的理论研究

采用以量子化学ASED－MO（含原子对排斥的EHMO法）为基础的结构自动优化EHTOPT法,研究了层状四水硫酸锆催化合成乙二醇乙醚醋酸酯的反应机理;构筑了反应组分乙二醇单乙醚羟基上的氢原子通过氢 键与层状四水硫酸锆结晶水上的氧原子结合。同时,还研究了醋酸在四水硫酸锆表面形成正碳离子的结合状态,提出了相应的酯化反应机理,在此基础上推导出的动力学方程与实验结果相符。     

反相高效液相色谱分离果酸的研究

水果和蔬菜中含有的有机酸,称谓果酸,果酸的定量方法很多,气相色谱法需要将果酸衍生后才能分析。本文阐述用反相高效液相色谱及紫外与示差折光检测器,流动相为0.01M(NH_4)_2HPO_4,用H_3PO_4调节pH值为2.5,使果酸得到分离。用保留时间定性,用标准酸样的直线方程进行定量。并对橙子中的柠檬酸、健力宝饮料中的酒石酸作了定量测定。回收率达90%以上。此法快速,分离效果较好,是食品生产与分析发展的趋势。     

Study on the Intramolecular Mannich Reaction of 4-Amino-3-aryl-2,3-dihydrogen-5-mercapto-1,2,4-triazoles

Seventeen novel fused heterocycles have been prepared by the intramolecular Mannich reaction of 4-amino-3-aryl-5-mercapto-1,2,4-triazole with aldehydes in the presence of acid, Yield: 32 ～ 90%. These compounds were screened for their antimicrobial activities.     

HCN消除反应机理的理论研究

采用密度泛函理论方法从HCN氧化和水解两个方面研究了HCN消除反应机理,并考虑了HCN的直接消除反应(途径Ⅰ和途径Ⅱ)和CuO上的HCN消除反应(途径Ⅲ和途径Ⅳ)。途径Ⅰ为HCN与2个O2分子生成CO2、NO和H原子;途径Ⅱ为HCN与1个O2分子和1个H2O分子生成 CO2和NH3;途径Ⅲ为CuO上HNCO水解为CO2和NH3;途径Ⅳ为CuO上HCN水解为CO和NH3。研究发现,途径III速控步骤的活化自由能垒为157.32 kJ/mol,比途径Ⅱ中HNCO水解降低12.34 kJ/mol;比途径Ⅳ降低了63.8 kJ/mol。可见,HNCO是HCN净化过程中的重要中间体,CuO的加入降低了反应能垒,促进了HCN消除。     

Theoretical Study on the Mechanism of Sonogashira Coupling Reaction

The mechanism of palladium-catalyzed Sonogashira cross-coupling reaction has been studied theoretically by DFT （density functional theory） calculations. The model system studied consists of Pd（PH3）2 as the starting catalyst complex, phenyl bromide as the substrate and acetylene as the terminal alkyne, without regarding to the co-catalyst and base. Mechanistically and energetically plausible catalytic cycles for the cross-coupling have been identified. The DFT analysis shows that the catalytic cycle occurs in three stages： oxidative addition of phenyl bromide to the palladium center, alkynylation of palladium（Ⅱ） intermediate, and reductive elimination to phenylacetylene. In the oxidative addition, the neutral and anionic pathways have been investigated, which could both give rise to cis-configured palladium（Ⅱ） diphosphine intermediate. Starting from the palladium（Ⅱ） diphosphine intermediate, the only identifiable pathway in alkynylation involves the dissociation of Br group and the formation of square-planar palladium（Ⅱ） intermediate, in which the phenyl and alkynyl groups are oriented cis to each other. Due to the close proximity of phenyl and alkynyl groups, the reductive elimination of phenylacetylene proceeds smoothly.     

Decarboxylative Palladium(II)‐Catalyzed Synthesis of Aryl Amidines from Aryl Carboxylic Acids: Development and Mechanistic Investigation

A fast and convenient synthesis of aryl amidines starting from carboxylic acids and cyanamides is reported. The reaction was achieved by palladium(II)‐catalysis in a one‐step microwave protocol using [Pd(O₂CCF₃)₂], 6‐methyl‐2,2′‐bipyridyl and trifluoroacetic acid (TFA) in N‐methylpyrrolidinone (NMP), providing the corresponding aryl amidines in moderate to excellent yields. The protocol is very robust with regards to the cyanamide coupling partner but requires electron‐rich ortho‐substituted aryl carboxylic acids. Mechanistic insight was provided by a DFT investigation and direct ESI‐MS studies of the reaction. The results of the DFT study correlated well with the experimental findings and, together with the ESI‐MS study, support the suggested mechanism. Furthermore, a scale‐out (scale‐up) was performed with a non‐resonant microwave continuous‐flow system, achieving a maximum throughput of 11 mmol h^?1 by using a glass reactor with an inner diameter of 3 mm at a flow rate of 1 mL min^?1.     

铀酰与羧酸和肟基类配体相互作用的理论研究

深入了解各种功能基团与铀酰离子的络合行为有助于设计和开发高效海水提铀吸附剂. 本工作通过密度泛函理论(DFT)方法系统地研究了两种典型铀酰络合配体吡啶-2,6-二羧酸(H₂DPA)和戊二酰偕亚胺二肟(H₂A)与铀酰离子及碳酸根离子形成的配合物的结构、成键性质以及热力学稳定性. 研究结果表明, 所有配合物中, 配体与铀酰离子之间具有不同强度的共价相互作用. 由于H₂A配位时发生了质子重排, 而且配体的解离能较高, 使其更难与[UO₂(CO₃)₃]^4-发生取代反应, 因此H₂DPA配体是海水提铀中一种潜在的有效配体. 本工作的相关研究结果为海水提铀中高效吸附基团的设计和开发提供了理论线索.