低共熔溶剂催化有机合成反应的研究进展

低共熔溶剂(DESs)是一种新型的离子液体(ILs)类似物,与传统有机溶剂、离子液体相比,DESs具有低毒、廉价、易于合成、生物可降解性等特点,因此在众多领域广受关注。近年来DESs在有机合成领域备受关注,被广泛用作合成反应的溶剂、催化剂、反应物等,在有机反应方面存在很大发展空间,本文综述了DESs在有机合成反应中的应用,重点讨论其在氧化还原反应、取代反应、缩合反应、环化反应等方面的研究进展,为其开发应用提供新思路。     

美拉德反应的研究进展

美拉德反应主要指还原糖与氨基酸、蛋白质之间的复杂反应,它与食品加工、疾病生理过程等有重要关系.除该反应对食品品质影响的研究仍在进行外,近来美拉德反应的研究更多地集中在蛋白质交联、类黑素、动力学以及丙烯酰胺等与人类健康关系更密切的方面,本文从这些方面综述了美拉德反应的进展.     

Suzuki芳基偶联反应研究进展

综述了Suzuki芳基偶联反应在机理、底物、催化剂、碱及反应条件等方面的研究进展。     

有机钯配合物在催化反应中的应用研究进展

有机钯配合物由于其优异的催化性能在有机催化反应中得到了广泛应用.作者综述了有机钯配合物催化剂在聚合反应、偶联反应、羰基化反应、氧化反应及加氢反应等方面的应用研究进展,同时对其发展方向与应用前景进行了展望.     

Glaser反应研究新进展

Glaser偶联反应是合成二炔化合物的重要反应,广泛应用于有机合成、材料化学等领域.介绍了近年来Glaser偶联反应中溶剂、氧化剂、底物等领域的研究新进展,指出Glaser偶联反应在不断加深其各方面绿色化研究的同时,多功能团底物的Glaser偶联反应与不对称的Glaser偶联反应也值得关注.     

伯醇的脱羟甲基反应的研究进展

伯醇来源广泛且廉价易得,是生产各种化学品,如农用化学品、食品添加剂、香料和药物等的重要化工原料.伯醇的脱羟甲基反应是一种利用伯醇制备少一个碳原子的碳氢化合物的方法,在生物质降解和药物合成等方面有着广泛的应用,引起了有机化学家的关注.根据反应类型综述了伯醇的脱羟甲基反应的发展,根据反应特点分为四个部分综述:过渡金属催化脱羟甲基转化为甲烷和水的反应、过渡金属催化脱羟甲基转化为一氧化碳和氢气的反应、过渡金属催化脱羟甲基转化为甲醛的反应、无过渡金属脱羟甲基转化为甲酸和水的反应.主要从反应体系、适用范围、反应机理等方面阐述了伯醇的脱羟甲基反应的研究进展.     

温度和时间对有机合成反应影响的探讨

根据物理化学和有机合成原理,从动力学、热力学、反应机理及溶解度等各方面详细分析了反应温度和反应时间对有机合成反应的影响。通过这些分析,可以让同学们更好地在合成反应课程的学习中掌握和分析反应温度和反应时间对反应的影响。     

化学反应在发射光谱分析上的应用(Ⅱ)——同时测定岩石中W、Mo等十一个痕量元素

在发射光谱分析中应用化学反应的方法,能改善分析检出限和分析精度,在纯物质中杂质元素分析和矿物原料中痕量元素分析方面得到了相当多的应用。对反应机理、反应条件和反应剂的选择等方面作了一定的研究。在矿物原料分析中,常用的化学反应有氯化反应、碘化反应、氟化反应和硫化反应。其中以氯化反应最为有效,应用也较为广泛。本文报导了利用CuCl、NH_4Cl为反应剂,同时测定岩石土壤中W、Sn、Mo.Pb、Bi、Cd、Ga、Ge、In、Tl、Zn等十一个痕量元素的试验结果。1.反应剂混合物的选择     

廉价过渡金属催化烯烃异构反应研究进展

过渡金属催化的烯烃异构反应在有机化合物合成、日用化学品合成、原料油应用和天然产物合成中都有着举足轻重的作用。廉价过渡金属由于其在资源、价格、后处理等方面的优势,日益受到研究者的重视。本文主要综述了近几十年来廉价过渡金属铁、钴、镍在催化烯烃异构反应方面的研究进展,详细阐述了不同的催化体系在催化活性、反应选择性、底物适用性及反应机理方面的特点。虽然目前的催化体系已经表现出优异的性能与应用价值,但在烯烃异构的立体选择性、区域选择性机制等方面,仍然需要更深入的研究。     

N-酰基吡唑类化合物的制备及其在合成中的应用

N-酰基吡唑类化合物作为酰化试剂逐步引起了广泛关注,对其制备以及在醇解,氨解,格氏反应,瑞福尔马斯基反应等方面的用途做了探讨.     

国内光催化研究进展简述

分1975~1985, 1985~1995和1995~2012三个时期简要介绍了国内光催化研究进展, 主要侧重于光催化材料及其改性、应用和反应机理方面的研究进展, 并指出了当前光催化领域存在的一些重要问题和未来的发展趋势, 涉及到光解水、CO₂还原、环境净化和选择性有机合成等方面.     

Interpretation of inorganic arsenic metabolism in humans in the light of observations made in vitro and in vivo in the rat

The toxicity of inorganic trivalent arsenic for living organisms is reduced by in vivo methylation of the element. In man, this biotransformation leads to the synthesis of monomethylarsonic (MMA) and dimethylarsinic (DMA) acids, which are efficiently eliminated in urine along with the unchanged form (As_i). In order to document the methylation process in humans, the kinetics of As_i, MMA and DMA elimination were studied in volunteers given a single dose of one of these three arsenicals or repeated doses of As_i. The arsenic methylation efficiency was also assessed in subjects acutely intoxicated with arsenic trioxide (As₂O₃) and in patients with liver diseases. Several observations in humans can be explained by the properties of the enzymic systems involved in the methylation process which we have characterized in vitro and in vivo in rats as follows: (1) production of As_i metabolites is catalyzed by an enzymic system whose activity is highest in liver cytosol; (2) different enzymic activities, using the same methyl group donor (S-adenosylmethionine), lead to the production of mono- and di-methylated derivatives which are excreted in urine as MMA and DMA; (3) dimethylating activity is highly sensitive to inhibition by excess of inorganic arsenic; (4) reduced glutathione concentration in liver moderates the arsenic methylation process through several mechanisms, e.g. stimulation of the first methylation reaction leading to MMA, facilitation of As_i uptake by hepatocytes, stimulation of the biliary excretion of the element, reduction of pentavalent forms before methylation, and protection of a reducing environment in the cells necessary to maintain the activity of the enzymic systems.     

Reactions in droplets in microfluidic channels

Fundamental and applied research in chemistry and biology benefits from opportunities provided by droplet-based microfluidic systems. These systems enable the miniaturization of reactions by compartmentalizing reactions in droplets of femoliter to microliter volumes. Compartmentalization in droplets provides rapid mixing of reagents, control of the timing of reactions on timescales from milliseconds to months, control of interfacial properties, and the ability to synthesize and transport solid reagents and products. Droplet-based microfluidics can help to enhance and accelerate chemical and biochemical screening, protein crystallization, enzymatic kinetics, and assays. Moreover, the control provided by droplets in microfluidic devices can lead to new scientific methods and insights.     

Recent Advances in Analytical Methodology for in vivo Electrochemistry in Mammals

Electrochemistry is one of the most advanced techniques for monitoring neurochemical activities in the living brain because electrochemical approaches bear the advantageous features of high spatial and temporal resolutions, which facilitate its tremendous potential in investigating the highly spatially heterogeneous brain system and the fast dynamics of neurochemical activities. On the other hand, since brain is the most complicated organ in the sense of its numerous kinds of neurochemical species, high selectivity is always required for any analytical methods that approach the brain. In this review, we will discuss various electrochemical methodologies to achieve selective detection of neurochemicals in mammalian brain and the strategies developed mainly by our group towards selective monitoring of both electrochemically active and inactive neurochemicals. At the end, we will discuss possible solutions towards brain mapping of neurochemical species and combination of neurochemical detection strategy with electrophysiology as the direction of future development of electroanalysis in living brain.     

Advances in passive sampling in environmental studies

Passive sampling is based on the phenomenon of mass transport due to the difference between chemical potentials of analytes in a given environmental compartment and the collection medium inside a dosimeter. The subsequent laboratory procedure (i.e. extraction, identification and determination of analytes) is the same as in the case of classic sampling techniques.Passive sampling techniques are characterized by simplicity with regard to the dosimeter's construction as well as its maintenance. Therefore, they find ever increasing application in the field of environmental research and analytics. When choosing a passive sampling method, one should not forget that some passive samplers require the time-consuming calibration step before being used in the field.Novel solutions and modifications of existing sampler designs have been presented. Practical application of passive dosimetry in environmental analytics, including sampling of water, soil, air and other atypical media are discussed. Some aspects of calibration methods in passive dosimetry are also described. The latest trends in the application of passive sampling are highlighted.     

青蒿素研究进展

青蒿素是目前治疗疟疾的特效药。本文对自青蒿素发现以来的最新研究进展进行了比较详尽的综述。内容包括: 青蒿素的发现及历史, 青蒿素的来源, 青蒿素的全合成,青蒿素的生物合成, 青蒿素衍生物以及植物组织培养生产青蒿素。     

Vibronic coupling in molecules and in solids

We utilize the experience gained in our previous studies on the "chemistry of vibronic coupling" in simple homonuclear and heteronuclear molecules to begin assembling theoretical guidelines for the construction of potentially superconducting solids exhibiting large electron-phonon coupling. For this purpose we analyze similarities between vibronic coupling in isolated molecules and in extended solids. In particular, we study vibronic coupling along the antisymmetric stretch coordinate (Q(as)) in linear symmetric AAA molecules, and along the optical phonon "pairing" mode coordinate (Q(opt)) in corresponding one-dimensional [A]( infinity ) chains built of equidistant A atoms. This is done for a broad range of chemical elements (A). The following similarities between vibronic coupling in molecules and phonon coupling in solids emerge from our calculations: 1) The HOMO/LUMO electronic energy gap in an AAA molecule increases along Q(as), and the highest occupied crystal orbital/lowest unoccupied crystal orbital gap in [A]( infinity ) chain increases along Q(opt). 2) The maximum vibronic instability is invariably obtained for a half-filled, singly occupied molecular orbital in AAA molecules, and for a corresponding half-filled band in [A]( infinity ) chains. 3) The vibronic stability of an AAA molecule increases with a decrease of the AA bond length, as does the vibronic stability of [A]( infinity ) chains (external pressure may lead to a reversal of a Peierls distortion). 4) The high degree of s-p mixing and ionic/covalent forbidden curve crossing dramatically enhance the vibronic instability of both AAA molecules and [A]( infinity ) chains. We also introduce one quantitative relationship: The parameter log(R) (where R is molar refractivity, a parameter used by Herzfeld to prescribe the conditions for the metallization of the elements) correlates with a parameter f(AA) (defined as twice the electronegativity of A, divided by the equilibrium AA bond length), used by two of us previously to describe vibronic coupling in AAA molecules for a broad range of elements (A=halogen, H, or an alkali metal). We hope to illustrate that key chemical aspects of vibronic coupling in simple molecules may thus be profitably transferred to corresponding materials in the solid state.     

Trends in Structural Polymer Science in Industry

Plastics production has grown rapidly in the past 30 years. The versatility of plastics which is not exceeded by any other class of materials, guarantees that polymers will continue to be very important in the future. However, at present a distinct change is taking place in polymer research and development. While in the pioneering days of plastics new polymer properties were determined by the choice of suitable monomers, today the commercialization of polymers from new monomers is restricted to a few specialities with a rather modest production volume. On the other hand, the number of new polymers derived from old monomers is increasing very rapidly. The development of highly selective catalysts and advances in reactor technology have provided the means for producing new tailor-made polymers. The same is true regarding new polymer blends and alloys based on old polymers: blending immiscible polymers yields materials with property profiles superior to the features of the individual components. Using selected examples, this paper will discuss trends, possibilities and challenges for structural polymer research in industry. © 1997 John Wiley & Sons, Ltd.     

Recent progress in nitroxide-mediated polymerizations in miniemulsion

Recent developments in nitroxide-mediated polymerizations conducted in emulsion and miniemulsion have advanced the field across a range of both experimental and theoretical fronts. This article reviews progress in bicomponent initiating systems (including use of camphorsulfonic acid to enhance rate), unimolecular initiating systems, miniemulsions not requiring the use of volatile costabilizers, polymerization of acrylates, mathematical modeling and simulation, and theoretical understanding with regards to issues such as compartmentalization, preservation of polymer chain livingness, the role of aqueous phase kinetics and phase partitioning. These topics are discussed and analyzed to present an integrated portrait of the current status of nitroxide-mediated polymerizations in emulsion/miniemulsion and to identify the most pressing concerns, issues, and opportunities. To cite this article: M.F. Cunningham, C. R. Chimie 6 (2003).     

Recent Advances in in situ multi-spectroelectrochemistry

To consider the past, present and future of in situ spectroelectrochemistry, a review on the recent state of modern spectroelectrochemistry and trends in the development of spectroelectrochemcial techniques is presented for the combined application of different in situ spectroelectrochemcial methods like ESR spectroelectrochemistry, NMR spectroelectrochemistry, Raman spectroelectrochemistry or IR spectroelectrochemistry to electrode systems. Starting with a discussion of the first steps in spectroelectrochemistry in the past, the main part of this review is focused on the advantages of the combined application of spectroelectrochemical techniques in the analysis of electrode reactions. The spectroelectrochemical methods are demonstrated to be successful in electrode reactions both for solid structures like polymers or carbon nanotubes and for molecular structures like fullerenes and oligothiophenes. The final outlook is attributed to future developments in spectroelectrochemistry.