温度和压力对化学反应方向和化学平衡的调控

根据一般化学反应方程式,给出了理想气体化学反应Gibbs自由能随反应进度变化的关系式。该式由3部分组成,第1部分对应于标准压力和给定温度下,反应物和生成物摩尔生成Gibbs自由能之和随反应进度的变化,是化学反应的温度调控项;第2部分对应于压力对Gibbs自由能的贡献,是压力调控项;第3部分是混合熵的贡献,是决定化学平衡的重要因素。因此,一个化学反应,向什么方向进行,进行到什么程度,可以通过温度和压力的调控来实现。以合成氨和工业合成气为例,讨论了如何利用压力和温度的调控,实现反应方向和平衡的控制。     

著名化学家和教育家——院士伉俪徐光宪和高小霞

1主要简历 徐光宪和高小霞是一对令人羡慕的院士,也是一对相敬如宾的恩爱夫妻,他们相濡以沫52年,同舟相伴、互助互敬,携手共进,在科研、教学和社会活动生涯中走过了光辉的历程。     

单硝基甲苯和多硝基甲苯偶极矩的理论计算和实验测定

用 MINDO/3和 CNDO/2法对单硝基甲苯和多硝基甲苯的平衡几何构型进行了全优化和 SCF 计算,求得了o,m,p-MNT,2,3-,2,4-,2,5-,2,6-,3,4-,3,5-DNT 和2,3,4-,2,3,5-,2,3,6-,2,4,5-,2,4,6-以及3,4,5-TNT 的“气相”偶极矩。用折射法实测了 MNT 和 DNT 共9种化合物在 CCl_4溶液中的偶极矩。计算值和实测值之间存在良好的线性关系。以甲苯和硝基苯的计算值通过“向量加和”近似地估算了 MNT,DNT 和 TNT的偶极矩,估算值与上述实验值和量子化学计算值之间也线性相关。     

拉丁语alchemia和chemia的词源考据和意义分析

在古埃及、希腊和阿拉伯语文献中没有“炼金术”和“化学”的区别。文艺复兴以后的拉丁语文献中逐渐出现了alchemia和chemia两个词。其中alchemia直接来源于阿拉伯语(al-kīmiya),而chemia更多地来源于希腊语文献中的χημεíα。尽管这2个词的来源不同,但它们基本上是同义词,很难从字面上把它们区分为现代意义上的神秘“炼金术”和实验“化学”。所以,这2个词的出现不能作为“炼金术”与“化学”两个学科独立的依据,在拉丁语文献中炼金术与化学没有明显区别,这也是近代科学发展中神秘法术与经验知识混合的一个典型例证。     

槐花和槐米中芦丁和槲皮素的毛细管电泳分析

采用β-环糊精修饰区带毛细管电泳-内标定量法分析槐花和槐米中芦丁和槲皮素。在优化的条件下,芦丁和槲皮素在7min内得到基线分离。芦丁和槲皮素线性范围分别为1-200μg／mL、0.4-100μg／mL,检出限分别为0.3μg／mL、0.1μg／mL,相对标准偏差分别为4．4％、2．6％。     

Kr和Kr2的实验和理论研究

利用超声分子束技术、同步辐射和反射式飞行时间质谱仪得到了Kr和Kr2的光电离质谱和光电离效率谱,确定了Kr和Kr2的电离能,利用Gaussian-03程序中的MP2(Full)/6-31G*,QCISD/cc-pVTZ以及B3LYP/6-31G方法优化了Kr2的结构,计算了它们的振动频率和电离能,计算结果显示:当采用相同的理论水平和皋组时,随着Kr同位素质荷比(m/z)的增大,它们结构和电离能保持不变,而振动频率逐渐变小.与此同时,用G2方法计算了Kr(84)和Kr2(168)的电离能,它们的电离能的理论值与实验结果符合得比较好.     

分子工程和化学工程

分子工程从分子水平研究产品的设计和开发以及过程的设计和开发问题,在化学工程领域中,是一个活跃的前沿。它的重要基础是分子结构与热力学性质、传递性质以及反应动力学性质之间的定量关系。研究这些关系分别是分子热力学、分子传递现象和分子反应动力学的任务。本文着重讨论它们的进展。     

光学活性和手性光谱的溯源和发展

概述了19世纪以来光学活性和手性光谱的发现和发展,着重对旋光色散(ORD)、电子圆二色(ECD)和振动圆二色(VCD)光谱的发展背景和基本原理作出介绍。其中特别提及华人科学家徐光宪和徐云洁在手性光谱发展历程中的杰出贡献。     

离子的极化和形变

离子的极化和形变是无机化学教学中的一对重要概念,这对概念可以用于解释化合物的结构及许多物理和化学性质。然而一些教科书在介绍这对概念时,大都把极化作用限于阳离子,把形变作用限于阴离子,而忽略了阴离子的极化作用和阳离子的形变作用。同时,在应用这对概念解释化合物结构和性质时,条理上也不十分清晰,甚至还出现自相矛盾的情况,使得学生在学习这对概念时感到困惑。本文介绍了离子的极化和形变这对概念的基本含义,讨论了影响极化能力和形变程度的因素,分析了一些化合物的结构以及溶解度、颜色和热稳定性等物理和化学性质。特别是对一些教学中有争议的问题给出了合理解释。在分析小分子结构时,极化和形变概念的运用可以弥补杂化轨道理论和价层电子对互斥理论的不足。     

川芎和抚芎的多糖和重金属含量分析

为提高川芎质量,控制重金属含量,采用苯酚-硫酸法测定了川芎和抚芎中的多糖含量,采用原子吸收光谱法测定了其中重金属含量。结果表明,川芎和抚芎多糖含量分别为(25.35±0.23)和(23.52±0.51)mg/g,重金属铅、汞、镉的含量分别为(1.28±0.12)、(0.21±0.22)、(0.25±0.11)μg/g和(2.24±0.21)、(0.16±0.22)、(0.35±0.20)μg/g。苯酚-硫酸法简单、快速、准确度高,重现性好,用于测定川芎和抚芎多糖结果可靠。川芎汞含量有一定超标,抚芎镉含量超标,应引起注意。     

Spectra and structure of binary azeotropes VI-benzene-methanol

Benzene and methanol make a minimum boiling point homogeneous binary azeotrope with the mole ratio 2:3. Some characteristic vibrational modes, as well as ¹H NMR signals change due to the azeotrope formation. The extend of interaction of these molecules causes significant changes on some vibrational modes involved, and ¹H NMR signals show some changes on their position. No IR, Raman, and NMR spectra have been reported for this constant boiling mixture, also there has not been any attempt to investigate the unit-structure of this azeotrope. In this work the FTIR, FT-Raman, and ¹H NMR spectra of pure benzene, pure methanol, and corresponding azeotrope were recorded, mutual influences resulting from azeotrope formation have been analyzed, and spectral changes has been discussed. The unit-structure of cluster has been deduced based on mole ratio, boiling point depression of constituents, and comparison among the spectra obtained by FTIR, FT-Raman, and ¹H NMR techniques.     

Preparation and study on the novel solid inclusion complex of ciprofloxacin with HP-beta-cyclodextrin

The interaction of ciprofloxacin with HP-beta-cyclodextrin (HP-beta-CD) has been studied by several analytical techniques, including 1H nuclear magnetic resonance (NMR), 13C NMR, fluorescence spectra, infrared spectroscopy, thermal analyzer and scanning electron microscope. In this paper, solid inclusion complex of ciprofloxacin with HP-beta-CD was synthesized by the coprecipitation method. In addition, the characterization of the inclusion complex has been proved by fluorimetry, infrared, differential scanning calorimetry and one-dimensional (1D), 2D NMR. The experimental results confirmed the existence of 1:1 inclusion complex of ciprofloxacin with HP-beta-CD. The formation constant of complex was determined by fluorescence method and 1H NMR. Spacial configuration of complex has been proposed on two-dimensional NMR technique.     

Quantitative estimation of the degree of derivatization: an alternative methodology using 1-D and 2-D NMR experiments

The precise estimation of the degree of derivatization of functional groups in polymers is important for determining their macroscopic properties. In this work, the quantitative estimation of the extent of esterification of novolac copolymers with di-tert-butyl dicarbonate was studied. Although the extent of esterification has been calculated previously by quantifying the signals from FT-IR and UV-Vis spectroscopy, these were restricted to monitoring the progress of the derivatization process. The 13C NMR signal intensities from the inverse-gated 1H-decoupled NMR spectrum have been used recently for the quantitative estimation of the degree of esterification of polymers. An alternative methodology has been suggested by us based on the fully relaxed 1H chemical shift intensities. However, since the proton signals of novolac resins are generally broad and overlapping, the proton decoupled 13C NMR spectrum was used to identify the 1H NMR signals using the 2-D HSQC technique. A TOCSY experiment was also performed to confirm further the 1H NMR signal assignments and, finally, the deconvoluted 1H NMR spectrum was used for the calculation of the extent of derivatization.     

Spectra and structure of binary azeotropes V-acetone-cyclopentane

Acetone and cyclopentane make a minimum boiling homogeneous binary azeotrope with mole ratio 2:3. Some characteristic vibrational modes, as well as (1)H NMR signals change due to the azeotrope formation. The extend of interaction of these molecules causes significant changes on some vibrational modes involved and (1)H NMR signals show some changes on their position. In this work the FTIR and (1)H NMR spectra of pure acetone, pure cyclopentane and corresponding azeotrope were recorded, mutual influences resulting from azeotrope formation have been analyzed, and spectral changes has been discussed. The unit-structure of cluster have been deduced, based on mole ratio, boiling point depression of constituents, and comparison between the spectra obtained by FTIR and (1)H NMR techniques.     

Preparation and study on the solid inclusion complex of cloxacillin sodium with beta-cyclodextrin

The interaction of cloxacillin sodium with beta-cyclodextrin (beta-CD) has been studied by several analytical techniques, including (1)H NMR, fluorescence spectroscopy, infrared spectroscopy. In this paper, solid inclusion complex of cloxacillin sodium with beta-CD was synthesized by the coprecipitation method. In addition, the characterization of the inclusion complex has been proved by fluorimetry, infrared spectroscopy and 1D, 2D NMR. The experimental results confirmed the existence of 1:1 inclusion complex of cloxacillin sodium with beta-CD. The formation constant of complex was determined by fluorescence method and (1)H NMR. Spacial configuration of complex has been proposed on 2D NMR technique.     

Preparation and study on the solid inclusion complex of sparfloxacin with HP-beta-cyclodextrin

The interaction of sparfloxacin with HP-beta-cyclodextrin (HP-beta-CD) has been studied by several analytical techniques, including 1H NMR, fluorescence spectroscopy, infrared spectroscopy, thermal analysis and scanning electron microscopy. In this paper, solid inclusion complex of sparfloxacin with HP-beta-CD was synthesized by the coprecipitation method. In addition, the characterization of the inclusion complex has been proved by fluorimetry, infrared, differential scanning calorimetry and 1D, 2D NMR. The experimental results confirmed the existence of 1:1 inclusion complex of sparfloxacin with HP-beta-CD. The formation constant of complex was determined by the fluorescence method and 1H NMR. Spacial configuration of complex has been proposed on 2D NMR technique.     

Complete assignments of 1H and 13C NMR spectral data for benzylidenebenzyl butyrolactone lignans

The structures of three benzylidenebenzyl butyrolactone lignans (gossypifan, carthamogenin, and savinin) have been established on basis of 1H NMR and 13C NMR spectroscopic data. The 1H NMR and 13C NMR spectra of these lignans have been fully assigned by the use of techniques such as gCOSY, non-edited gHSQC, and gHMBC. Complete assignment and most homonuclear hydrogen coupling constant measurements were performed, also providing enough data for the determination of the relative stereochemistry.     

Synthesis and Chemical Shifts Calculation of a-Acyloxycarboxamides Derived from Indane-l,2,3-trione by DFT and HF Methods

α-Acyloxycarboxamides are synthesized from three-component Passerini reaction between indane-1,2,3-trione, isocyanides, and thiophenecarboxylic acids in quantitative yields. The structures of the final products were confirmed by IR, 1H and 13C NMR spectroscopy, mass spectrometry, and elemental analysis. The B3LYP/HF calculations for computation of 1H and 13C NMR chemical shifts have been carried out for the title compounds at the 6-311+G** and 6-311++G** basis set levels within GIAO and CSGT approaches. Predicted 1H and 13C NMR che-mical shifts have been assigned and compared with experimental 1H and 13C NMR spectra and they are supported each other.     

FT-IR and NMR investigation of 1-phenylpiperazine: a combined experimental and theoretical study

FT-IR and (1)H, (13)C, DEPT, COSY, NOESY, HETCOR, INADEQUATE NMR spectra of 1-phenylpiperazine (pp) have been reported for the first time except for its (1)H NMR spectrum. The vibrational frequencies and (1)H, (13)C NMR chemical shifts of pp (C(10)H(14)N(2)) have been calculated by means of the Hartree-Fock (HF) and Becke-Lee-Yang-Parr (BLYP) or Becke-3-Lee-Yang-Parr (B3LYP) density functional methods with 6-31G(d) and 6-31G(d,p) basis sets, respectively. Comparison between the experimental and the theoretical results indicates that density functional B3LYP method is superior to the scaled HF and BLYP approach for predicting vibrational frequencies and NMR properties.     

一维多重接力COSY和选择性远程DEPT核磁共振技术在新分子骨架生物碱结构测定和谱峰归属研究中的应用

自防已科千金藤根中分得一个新型分子骨架的四氢异喹啉类生物碱-excentricine(1)。本工作采用一维多重接力COSY和选择性远程DEPT核磁共振新技术成功地确定谱峰归属, 鉴别和连结被季碳和杂原子分割开的自旋体系, 测定了其结构。