2,2-二芳基取代萘并吡喃类光致变色化合物的合成与性能研究

从光消色速度和最大吸收强度两个角度出发, 用Grignard试剂和萘并吡喃-2|酮合成了一系列2,2-二芳基取代萘并吡喃类光致变色化合物, 并用 1H NMR, IR, MS和元素分析确定其结构. 研究了其紫外-可见光谱, 并探讨了紫外-可见光谱和光致变色性能之间的关系, 分析了其结构和光消色速度之间的关系, 初步探索到光消色速度快慢和取代基位置之间的规律, 为实用化的有机光致变色化合物的合成提供了有价值的参考依据.     

Metastable-ion mass spectra of insect pheromones

The laws of the fragmentation of the metastable molecular and key fragmentary ions of mono- and dienic alcohols, acetates, aldehydes, hydrocarbons, and epoxy compounds forming components of the pheromones of the turnip, tomato, and bollworm moths and other pests of agricultural crops are discussed, and the use of the laws found in the identification of compounds of this class has been demonstrated.Institute of Bioorganic Chemistry, Academy of Sciences of the Republic of Uzbekistan, Tashkent, FAX 62 70 71. Tashkent State University, FAX 46 24 72. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 455–470, July–August, 1994.     

Specific Nature of the Polymerization of Heterocyclics

Abstract

This report deals primarily with oxyheterocyclics since this class of compounds is the best studied with regard to the laws of polymerization of heterocyclics.     

Retentivity and separability of silica gel modified by chiral selector <Emphasis Type="Italic">N</Emphasis>-(3-sulfo,3-carboxy)-propionylchitosan

A new sorbent based on silica gel modified by N-(3-sulfo,3-carboxy)-propionylchitosan (SCPC-modified silica gel) has been synthesized, and its chromatographic properties have been studied. The laws governing the retention and resolution of chiral compounds with the use of SCPC have been investigated. The enantioselectivity of the sorbent toward several basic compounds, including fluoxetine, chlorcyclizine, pindolol, and other medicinals, has been investigated.     

"元素化学实验"中的热致变色现象(二)——部分Cr(Ⅲ)化合物的热致变色现象及其变色机理探讨

在认识部分Co(Ⅱ)化合物的热致变色现象及变色机理的基础上,因势利导,创设问题“情境”,即再通过生动直观的演示实验,引导学生进一步认识一些Cr(Ⅲ)化合物的热致变色现象及其影响因素,引导和启发学生探讨和解释其热致变色的机理。进一步培养学生的观察、分析、判断、归纳、推理、总结和探索规律的能力以及“批判性”思维能力。     

Oxidation of atrazine by photoactivated potassium persulfate in aqueous solutions

General laws of the photochemical oxidation of atrazine by inorganic peroxo compounds under the impact of solar radiation are studied. It is found that almost complete conversion of atrazine can be achieved via photochemical oxidation with persulfate after 120 min, but no deep mineralization is observed. The effect an aqueous matrix has on the processes of atrazine degradation in combined oxidation systems is considered.     

Applications of1H and13C NMR spectroscopy in structural investigations of Vinca indole alkaloids

This review considers the laws connecting the parameters of the¹H and¹³C NMR spectra with the structure of the substances and the use of these laws for solving structural and stereochemical problems of theVinca indole alkaloids and other compounds of closely related structure. For each type of alkaloids, characteristic features of the PMR and¹³C NMR spectra are given that permit the structures of similar bases to be established and their stereochemical identification to be performed.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 3–15, January–February, 1986.     

Mining a chemical database for fragment co-occurrence: discovery of "chemical clichés"

Nowadays millions of different compounds are known, their structures stored in electronic databases. Analysis of these data could yield valuable insights into the laws of chemistry and the habits of chemists. We have therefore explored the public database of the National Cancer Institute (>250,000 compounds) by pattern searching. We split the molecules of this database into fragments to find out which fragments exist, how frequent they are, and whether the occurrence of one fragment in a molecule is related to the occurrence of another, nonoverlapping fragment. It turns out that some fragments and combinations of fragments are so frequent that they can be called "chemical clichés". We believe that the fragment data can give insight into the chemical space explored so far by synthesis. The lists of fragments and their (co-)occurrences can help create novel chemical compounds by (i) systematically listing the most popular and therefore most easily used substituents and ring systems for synthesizing new compounds, (ii) being an easily accessible repository for rarer fragments suitable for lead compound optimization, and (iii) pointing out some of the yet unexplored parts of chemical space.     

Thermochemistry of complex compounds

The main features of the experimental investigation of the thermochemistry of complexation reactions in solution and the mathematical treatment of the results of a calorimetric experiment have been considered. Some laws governing the thermodynamic and thermochemical characteristics of reactions resulting in the formation of complex compounds have been noted.Ivanovo Chemical-Engineering Institute. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 3, pp. 278–283, May–June, 1991. Original article submitted February 26, 1991.     

Gas-liquid chromatography-mass spectrometry of acetates of partially methylated methyl glycosides. VII. Tri- and tetramethylheptoses

Nine tri- and five tetramethyl ethers have been obtained by the partial methylation of methyl α- and β-glucoheptopyranosides and methyl 2,3,4,6,7-penta-O-acetyl1-α- and-β-glucoheptopyranosides. The retention indices of both types of methyl ethers on the liquid phase NPGS have been measured and the main directions of the fragmentation of these compounds under electron impact have been determined. The laws of the mass spectra of the position isomers that have been found will permit their use in GLC-MS analysis for determining the structure of a polysaccharide by the methylation method.     

Bioenergetics and bioremediation of contaminated soil

The microbial biodegradation of xenobiotic compounds in soil and ground water is constrained by the laws of thermodynamics. Bioremediation is being investigated in a rhizosphere environment in which higher plants provide carbon and energy to sustain the microbial population. Toluene, phenol, trichloroethylene and trichloroethane have been fed in separate experiments to a pilot scale system with alfalfa growing in sandy soil containing less than 10% of silt. It is well known that microbial populations are numerous in the root zone of healthy vegetation. Root exudates can stimulate aerobic microbial biodegradation of compounds which by themselves support growth poorly or not at all. Polynuclear aromatic compounds such as phenanthrene, anthracene, and pyrene, which are not very soluble in water, and chlorinated aliphatic hydrocarbons such as trichloroethylene are examples of compounds that can be biodegraded in the rhizosphere when root exudates are present to enhance and sustain microbial activity. Solar driven transport processes such as water and solute movements due to evapotranspiration increase the likelihood that the contaminants will come into contact with the microorganisms and be degraded. The thermodynamic and bioenergetic aspects of transport and biodegradation in the rhizosphere are examined through a review of the literature and the analysis of experimental data collected in the pilot scale system.     

工业过程在线控制气相色谱仪中柱切系统的研制

根据某石化总厂生产过程控制23套在线气相色谱仪中柱切系统国产化的实际需要,在气相色谱专家系统研究的基础上,通过选择正确的柱系统,并采用基于反吹、前吹、中心切割等基本柱切方法为基础的组合式柱切技术,配以往长、流量、流动方向和柱温的调节,取得了圆满成功。实际使用证明,所研制柱子的性能达到日本原装柱的水平,寿命为1～3年不等。     

Modelling of adsorption kinetics and calibration curves of gaseous volatile organic compounds with adsorptive solid-phase microextraction fibre: toluene and acetone for indoor air applications

Solid-phase microextraction (SPME) with adsorptive Carboxen/PDMS fibre is a powerful sampling device for volatile organic compounds (VOCs) at trace levels in air. However, owing to competitive adsorption, quantification remains a challenging task. In this area, a theoretical model, based on Fick's laws and an extended Langmuir equation, is proposed to deal with the adsorption kinetics of acetone/toluene mixture on SPME fibre under various static extraction conditions. The semipredictive model is first used to determine the axial diffusion coefficients of analytes in the sampling device. The model is then tested with a complex VOC mixture, showing good agreement with experimental data.     

关于氮族元素教学改革的几点建议

Based on the knowledge characteristics of the chapter on nitrogen group elements, and combined with the teaching experience of our excellent video open course, this paper has probed the teaching reform of inorganic elements chemistry from the following aspects:using the principle of chemistry to explain the structure and properties of substances, designing problems to guide students to think and cultivate their learning ability, instructing students to be good at inducing the changing laws of material properties, paying attention to the relationship between the elements and compounds and practices of production and life. It aims to guide students to learn, memorize and master the knowledge of element chemistry effectively, and improve the quality of classroom teaching.     

吹扫捕集–气相色谱–质谱法同时测定环境水中101种挥发性有机物

建立吹扫捕集–气相色谱–质谱联用法测定环境水中101种常见挥发性有机物(VOCs)的方法。通过加热吹扫,样品水中的VOCs富集于捕集管中,以DB–624(60 m×0.25 mm,1.4μm)色谱柱分离,内标法定量。结果表明,101种挥发性有机物(VOCs)色谱分离效果良好,质量浓度在0.5~50 ng/mL范围内与色谱峰面积均呈线性关系,高沸点VOCs线性范围较窄。方法定量限(10 S/N)为0.11~0.77 ng/mL,均低于GB 3838–2002《地表水环境质量标准》、GB 5749–2006《生活饮用水卫生标准》及国外相关标准的限值。平均加标回收率在70.3%~123.6%之间,测定结果的相对标准偏差不大于8.8%(n=6)。该方法快速、简便,适用于环境水中挥发性有机化合物的分析检测。     

Kinetic Investigations of Reactions with Maleic Anhydride Copolymers and Model Compounds

Alternating copolymers that contain maleic anhydride (MAn) as a component occur in two different stereochemical configurations which are differentiated by their reactivity. Model compounds, 2, 3-dialkylsuccinic acids and their anhydrides, were investigated and it was demonstrated that there is a distinct difference between threo and erythro configurations in their chemical and physical behavior. Both configurations also occur in the alternating copolymers. Beside the model compounds, the alternating copolymers ethylene-MAn, propylene-MAn, and styrene-MAn were investigated in their reactions with amines, alcohols, and water (hydrolysis). The cis configurations showed the higher reaction rates. Reactions of the anhydride moieties with equimolar amounts of aniline, ethanol, and water demonstrated that reactions follow second-order rate laws. With excess reactant, the reaction follows a pseudo-first-order rate law. The rate constants depend on the degree of polymerization and on the comonomer. Increasing steric hindrance and molecular weight lead to a decrease of the reaction rate. Catalysis of the hydrolysis reaction by tertiary amines results in similar rate constants for the configurations of the substituted succinic acid anhydrides. The reasons are discussed.     

C36H2异构体的稳定性及其加成位置选择性的研究

使用AM1和PM3两种半经验方法,对所有的C₃₆H₂异构体实行非对称性限制的全优化,并结合频率分析及HF/6-31G单点能计算,确定了各异构体的基态结构及其相对稳定性.在此基础上,通过分析加成位置与异构体稳定性之间的关系,得出三条加成位置选择性的规律.最后,利用π-轨道轴矢量(POAV)方法计算了反应前后碳笼中张力的变化.张力与键级分析的结果表明加成位置选择性的规律不是由碳笼释放的张力决定的,而是由C₃₆H₂体系的总共轭性质决定的.     

Kinetic aspects of trace-component oxidation in environmental protection

Many and varied kinetic laws apply for the extensive oxidation of small amounts of organic compounds on platinum catalysts. Kinetic models for mixture oxidation are sometimes predicted on a principle for simple interaction between individual reactions. The transient response preceding the stationary state has been examined for various such reactions, which gives information for the kinetic models and also shows that the mechanisms are various. These models can be used in industrial catalytic purification.Zelinskii Organic Chemistry Institute, Russian Academy of Sciences, Moscow. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 5, pp. 525–535, September–October, 1991. Original article submitted July 12, 1991.     

The amazing story of semiconductor surface structures

A brief indication of the history of the determination and prediction of the structure of semiconductor surfaces is given. Only clean surfaces are considered, although adsorbate structures exhibit analogous features. Many of these surfaces are reconstructed, i.e., the symmetry of their surface structure is lower than that of the corresponding bulk lattice plane. During the 1980s and 1990s, the detailed atomic geometries of many of these structures were determined. They exhibit a wide variety of atomic motifs, many of which are not familiar from either small molecule geometries or solid state structures. Theoretical predictions exist for a few of the most heavily studied structures, but even in these cases not all the details of the structures are accepted. The enormous literature on this topic can be comprehended by recognizing that the surface regions of semiconductors constitute a new class of two dimensional chemical compounds, restricted by the requirement that they fit epitaxically on the bulk crystalline substrate. Five principles govern the formation of these compounds for clean tetrahedrally coordinated semiconductors, guiding even a novice to a rudimentary understanding of the origin of the observed rich variety of surface structures. In the case of the cleavage surfaces additional scaling laws are satisfied which further buttress the concept that these surfaces are two dimensional compounds governed by coordination chemistry considerations which are distinct from those appropriate for either molecules or bulk solids.