乙硼烷的简正振动频率和光谱熵

本文用群论方法讨论了Coriolis微扰,认为950cm~(-1)为ν_9是合理的.按非刚性转子-谐振子模型,采用直接加和法计算转动、振动配分函数.应用Cromemco微处理机计算了100～2500K范围内~(10)B_2H_6和~(11)B_2H_6的光谱熵.     

液体内聚能的统计热力学研究

用统计热力学方法建立了一个液体内聚能模型。它能用来计算各种液体的内聚能和溶解度参数。考虑到液体分子间的强相互作用,引入了一个阻障因子,以修正其转动和振动对内配分函数的贡献。这个因子依赖于液体的密度,它与密度间的关系也在模型中导得。对溶解度参数的计算结果表明,与文献值的一致性令人满意。     

数值微扰分子轨道法的研究进展*

本文介绍了分子内和分子间各类定量微扰分子轨道(PMO) 法数值计算的发展和现状。简要地介绍了Salem ,Wolfe,Bernardi, Imamura 和Morokuma 等对PMO 理论发展的贡献     

分子内旋转势垒的计算

乙烷类型分子中C—C单键的旋转,既不是完全自由的,也不是完全受阻的。这是K.S.Pitzer等人研究了乙烷分子的熵和热焓后得出的结论。他所建立的乙烷分子配分函数,只有考虑到在分子内存在有旋转势垒,才能使这些量的计算结果与实验值相符合。由此他得到的乙烷旋转势垒大约为3Kcal/mol。     

气液色谱法测定双-(O,O′-二正辛基二硫代磷酸酯)合镍(Ⅱ)和三乙胺加合反应的热力学参数

本文报道了用气液色谱法测定不同温度下,酸碱加合反应:的平衡常数,根据热力学公式,并利用最小二乘法求得。在实验温度范围内,实验数据可以用公式:来描述。     

两种哈密顿量划分的单参考态微扰展开式的大小一致性研究

利用一个含N个氢分子的超分子模型, 从解析的角度仔细地分析了相应于两种哈密顿量划分方式的单参考态微扰展开式前四级能量的大小一致性. 对于Epstein-Nesbet划分, 微扰展开式是大小一致的. 而对于另一种划分(Chen, F; Davidson, E. R.; Iwata, S. Int. J. Quantum Chem., 2002, 86: 256, 见公式(24)的讨论), 其展开式大小不一致. 但将它的分母作泰勒展开, 经过重新整理, 将那些大小不一致的项消去后, 得到的新微扰展开式是逐项大小一致的.     

用微扰分子轨道法研究饱和有机化合物的成环反应

在饱和有机化合物的成环反应中,五员环和六员环最易形成,这一事实通常是用环的张力和空间因素来解释的。但有些实验结果表明,五员环比六员环容易生成,三员环比四员环容易生成。这些事实用张力和空间因素都不能圆满解释。我们采用微扰分子轨道(PMO)法来计算成环反应中体系能量的变化。所得的计算结果可以较好地说明上述实验事实。     

同核双原子分子的PMO处理

微扰分子轨道(Perturbation Molecular Orbital,PMO)法能够为化学家提供一个简单、形象而又相当有效的化学键理论。本文介绍如何用这个方法来描述同核双原子分子,解决在无机化学和结构化学中,为何同核双原子分子有两种可能的分子轨道能级顺序这个在教学中难以说明的问題。     

旋转圆盘电极体系上的非稳态电极过程

本文用Laplace变换和正则摄动法求解旋转圆盘电极体系的对流扩散方程,得到精确的级数解,并拟合得到近似公式。从该公式出发,经Laplace变换运算,本文得到了大幅度电位阶跃过程的电流公式和脉冲电流过程的极限电流公式。     

旋转圆盘电极体系上的非稳态电极过程

本文用Laplace变换和正则摄动法求解旋转圆盘电极体系的对流扩散方程, 得到精确的级数解, 并拟合得到近似公式。从该公式出发, 经Laplace变换运算, 本文得到了大幅度电位阶跃过程的电流公式和脉冲电流过程的极限电流公式。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.