二环丁烷[1.1.0]开环反应的量子化学研究

本文用MNDO方法研究了二环丁烷[1.1.0]开环反应的反应途径, 并优化了该反应的反应物、产物和过渡态的结构, 在理论上证明了此开环反应的反应机理。     

卡宾与氢氰酸加成反应机理的量子化学研究

用MNDO法研究单线态卡宾与氢氰酸的反应途径,通过两条不同反应途径的能量比较,得到了此反应可行的反应机理。     

铁(III)催化多卤代变色酸双偶氮胂类试剂的褪色反应特性及其应用

本文研究了铁(III)催化H2O2还原多卤代变色酸双偶氮胂类试剂(PHA)的褪色反应动力学行为, 测定了反应级数和反应活化能, 获得了经验速率方程, 探讨了反应机理, 稳态处理后的动力学方程与经验速率方程相吻合, 说明了机理的合理性。并以三氯偶氮胂为指示反应试剂, 测定了人发中痕量铁的含量, 得到了满意的结果。     

双硅烷热分解的理论研究

用量子化学方法研究了双硅烷１，２－氢迁移热分解，全参量优化了反应物及产物的平衡几何构型，找到了反应途径，获得了过渡态，并对过渡态进行了振动分析，活化能的计算值与实验值一致，从理论上证明双硅烷通过１，２－氢迁移的热分解途径的可行性。     

IRC analysis of methanol carbonylation reaction catalyzed by rhodium complex

In the reaction cycle for methanol carbonylation catalyzed by Rh complex, the structure geometries of the reactant, intermediates, transition states and product of each elemental reaction have been studied by using the energy gradient method at HF/LANL2DZ level, and the changes of their potential profiles have also been calculated. Through IRC analyses of the transition states for each elemental reaction, it is confirmed that the various structure geometries obtained are stationary points on the cycle reaction pathway of methanol carbonylation catalyzed by Rh complex, and the changes are given in energies and structure geometries of the reactant molecules along the reaction pathway of lowest energy. It has been proposed that the geometrical conversions of intermediates play an important role during the cycle reaction. Through analyses of structure geometries, it has been suggested that, in addition to cis- and trans-structure exchange linkage of catalysis reactive species, the two pathways, cis- and tra     

应用裂解色谱-质谱法研究乙烯等离子体聚合物结构

应用裂解色谱—质谱(PGC—MS)法研究化学法和等离子体法聚合得到的聚乙烯的裂解行为。比较了两种聚合物的结构差异。探讨了等离子体聚合条件对聚合物结构的影响及其聚合反应机理。     

Convergent and diastereoselective synthesis of the polycyclic pyran core of saudin

The natural product saudin was found to induce hypoglycemia in mice and, therefore, could be an appealing lead structure for the development of new agents to treat diabetes. A diastereoselective tandem Stille-oxa-electrocyclization reaction has been developed which provides access to the core structure of saudin in a rapid and convergent manner. This new reaction has been extended to the convergent preparation of a series of polycyclic pyran systems. Progress has been made on the advancement of these complex pyran systems toward the natural product. A complete account of these synthetic efforts is presented.     

Active site structure and mechanism of human glyoxalase I-an ab initio theoretical study.

The structure of the active site of human glyoxalase I and the reaction mechanism of the enzyme-catalyzed conversion of the thiohemiacetal, formed from methylglyoxal and glutathione, to S-D-lactoylglutathione has been investigated by ab initio quantum chemical calculations. To realistically represent the environment of the reaction center, the effective fragment potential methodology has been employed, which allows systems of several hundred atoms to be described quantum mechanically. The methodology and the active site model have been validated by optimizing the structure of a known enzyme-inhibitor complex, which yielded structures in good agreement with the experiment. The same crystal structure has been used to obtain the quantum motif for the investigation of the glyoxalase I reaction. The results of our study confirm that the metal center of the active site zinc complex plays a direct catalytic role by binding the substrate and stabilizing the proposed enediolate reaction intermediate. In addition, our calculations yielded detailed information about the interactions of the substrate, the reaction intermediates, and the product with the active site of the enzyme and about the mechanism of the glyoxalase I reaction. The proton transfers of the reaction proceed via the two highly flexible residues Glu172 and Glu99. Information about the structural and energetic effect of the protein on the first-shell complex has been attained by comparison of the structures optimized in the local protein environment and in a vacuum. The environment of the zinc complex disturbs the Cs symmetry found for the complex in a vacuum, which suggests an explanation for the stereochemical behavior of glyoxalase I.     

Synthesis and structure of 6-hydrazino-2,4,5-trichloronicotinonitrile

The reaction of tetrachloronicotinonitrile with hydrazine hydrate has been studied. The structure of the reaction product has been established based on x-ray structural analysis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 369–374, March, 1992.     

单重态H_2N=B:→HNBH重排反应的理论研究

用量子化学中的从头算方法, 在MP2/6-311++G(d,p)水平上研究了单重态H_2N=B→HNBH重排反应的机理。结果表明, 该重排反应经过一个三元环过渡态。根据计算结果，初步讨论了该反应的热力学及动力学函数。     

A new route to indazolone via amidation reaction of o-carboxyazobenzene

One new route for the synthesis of amino-substituted indazol-3,5-dione via the amidation reaction of o-carboxyazobenzenes is reported. Optimization which includes effects of the solvents, molar ratio of starting materials, and dehydrating agents on this reaction has been studied. A possible reaction mechanism has been proposed on the basis of the product's structure, and the steric hindrance could be the main reason for low yield.     

The reaction of monoethanolamine with cyanogen bromide

The reaction of monoethanolamine with cyanogen bromide has been studied. 2-Imino-1,3-oxazolidine has been obtained and its structure has been proved. It has been confirmed that the reaction of cyanamide or calcium cyanamide with organic oxides and their chlorohydrins forms, in the first stage, hydroxyalkyl derivatives of cyanamide which cyclize with the formation of the corresponding 2-iminooxazolidine derivatives. 2-Aminooxazone derivatives are obtained by the tautomerization of the 2-iminooxazolidine derivatives.     

Polymers with a graphitic-type structure. II

Further work has been done on the synthesis of a polymer from 1,4,5,8-tetraaminoanthraquinone on 1,3,6,8-tetraketo-1,2,3,6,7,8-hexahydropyrene which has a graphitic-type structure. Improved purity of the starting materials, particularly of the tetraketone, has given a final product of better quality. The reaction conditions have been improved by lowering the temperature and increasing the time of the reaction.     

(S,S)-(+)-pseudoephedrine as chiral auxiliary in asymmetric aza-Michael reactions. Unexpected selectivity change when manipulating the structure of the auxiliary

[reaction: see text] The asymmetric aza-Michael reaction of metal benzylamides to alpha,beta-unsaturated amides derived from the chiral amino alcohol (S,S)-(+)-pseudoephedrine has been studied in detail. A deep study of the most important experimental parameters (solvent, temperature, nucleophile structure, influence of additives) has been carried out, showing that the reaction usually proceeds with good yields and diastereoselectivities, although the experimental conditions have to be modified depending on the substitution pattern of the conjugate acceptor. Additionally, a very interesting facial selectivity inversion has been observed when manipulating the structure of the chiral auxiliary, which has allowed a diastereodivergent procedure to be set up for performing asymmetric aza-Michael reactions using the same chirality source. Finally, the adducts obtained in the asymmetric aza-Michael reaction have proven to be very versatile synthetic intermediates in the preparation of other interesting compounds such as beta-amino esters, gamma-amino alcohols, and beta-amino ketones in highly enantioenriched form.     

高分子钼铁硫原子簇催化剂的合成反应及其结构表征

以乙烯基吡啶的共聚物为高分子载体,用固相合成的方法,通过多步反应合成了一个高分子钼铁硫原子簇催化剂。用紫外可见光谱和红外光谱分析研究了该催化剂的结构,并说明它具有原子簇结构。本催化剂在KBH_4还原剂存在下,对乙炔加氢反应具有催化活性,可以循环使用。     

单重态二溴代乙叉重排反应的量子化学研究

采用量子化学中的ＡＭ１ 方法研究了单重态二溴代乙叉重排反应的机理．结果发现, 该重排反应经过１ 个三元环过渡态．根据计算结果,详细研究了该反应的热力学及动力学函数．     

The reaction of sodium salts of uracils with chlorides of acids of phosphorus. I

The reaction of the sodium salts of 6-methyluracil (I) and 3, 6-di-methyluracil (II) with methyl and ethyl phosphorochloridates and phosphorochloridothioates give the corresponding N-methyl and N-ethyluracils. The reaction of I with dimethyl phosphorochloridothioate has given a phosphorus- containing reaction product the structure of which has not been established.     

SSZ-13和RUB-50分子筛上甲醇制烯烃的对比研究

对比研究了SSZ-13(CHA拓扑结构)和RUB-50(LEV拓扑结构)硅铝分子筛笼大小对甲醇制烯烃反应性能的影响,并采用X射线衍射、N2吸附-脱附、固体核磁共振、热重和紫外-可见光谱等技术对催化剂的结构及反应后的碳物种进行了表征.结果表明,笼尺寸较大的SSZ-13分子筛在反应中的稳定性和产物丙烯选择性均较高;而笼尺寸...     

Etude theorique de la cycloaddition dipolaire 1–3

A theoretical study of the 1,3-dipolar cycloaddition reaction of: diazomethane with ethylene has been carried out by the LCAO-SCF-MO method. The potential energy hypersurface for the reaction and the electronic structure of the transition state have been investigated.     

Studies on the synthesis of landomycin A. Synthesis of the originally assigned structure of the aglycone, landomycinone, and revision of structure

The originally proposed structure (2) of landomycinone, the aglycone of landomycin A, has been synthesized and shown to be nonidentical to the naturally derived landomycin A aglycone. The synthesis of 2 features the D?tz benzannulation reaction of chromium carbene 5 and alkyne 6, and the intramolecular Michael-type cyclization reaction of the phenolic naphthoquinone 20. It is proposed that natural landomycinone possesses the alternative structure 3, but attempts to access this structure via the Michael-type cyclization of the isomeric phenolic naphthoquinone 38 have been unsuccessful.