Study and Development of a Technology for Manufacture of Special-Purity Calcium Carbonate

The precipitation of CaCO₃ from Ca(NO₃)₂ solutions with gaseous CO₂ and NH₃ was investigated. Different variants of purification of Ca(NO₃)₂ solutions on hydrated aluminum oxide (collector) were considered.     

New Synthetic Methodology and Biologically Active Substances

The η⁵-cyclopentadienyl-η²-propenealkylnickel complexes 4–9 (alkyl  CH₃, CD₃, CH₂SiMe₃, CH₂ CH₃, CH₂ CH₂ CH₃ and CH(CH₃)₂) have been prepared by treating nickelocene (1) with the appropriate organomagnesium halides 2a–2f and propene at ?20 to ?10°C. Temperature dependent ¹H-NMR spectra result from rotation of the propene molecule around the nickel—olefin axis; in the case of 4 and 8, two rotamers a and b can be distinguished below ca. ?60°C. The decomposition pathways for 4 and 8 are discussed.     

分离检测生物活性物质的荧光标记试剂与分子探针及其应用

作者结合自己的研究工作主要评述了用于分离检测氨基化合物（氨基酸、肽、蛋白质和生物胺等）、巯基化合物（谷胱甘肽、半胱氨酸和高半胱氨酸等）及NO等生物活性物质的荧光标记试剂和荧光分子探针的近期进展和应用。除了传统的的OPA、NDA、DNS、FMOC、FITC、NBD-F、AQC、Cy5等在HPLC和CE分离荧光检测应用新进展,还介绍了许多新的荧光分子探针和标记试剂的性能和应用。它们是N－羟基琥珀酰亚胺活性酯荧光标记试剂,6-氧-（N-琥珀酰亚胺乙酸酯）-9-（2'-甲氧羰基）荧光素（SAMF）,1,3,5,7-四甲基-8-苯基-（4'-O-（N-琥珀酰亚胺乙酸酯））-二氟化硼-二吡咯甲烷（TMPAB-Osu,）等和3-碘乙酰胺苯嵌蒽酮荧光探针及MCY5、DSTCY、DCDSTCY和DCTCY等花菁类近红外荧光探针等。     

化学拆分的新方法研究

主要介绍了近年来发展起来的两种化学拆分新方法,包括拆分和组合拆分;并简要论述了化学拆分中的手性识别现象,以及化学拆分方法在手性药物制备中的应用。     

Electrochemical and Chemical Syntheses of Trifluoromethylating Reagents and Trifluoromethyl Substituted Compounds

The electroreduction of the halofluoromethanes CF₃Br, CF₂Br₂ and CF₂BrCl has been studied in high‐pressure stainless steel autoclaves at different cathodes [Pt, steel (V2A, V4A), glassy carbon (GC)] and in various solvent‐supporting electrolyte systems (SSE), e.g. DMF/[Bu₄N]Br, NMP/[Bu₄N]BF₄ etc. The reduction potentials for CF₃Br increase from Pt (–1.6 V) < V2A (–1.8 V) < GC (–2.1 V) and are lower for CF₂Br₂ and CF₂BrCl suggesting a reductive cleavage of C‐X bonds as the first step. CF₂Br₂ and CF₂BrCl show a two‐step reduction in accord with the C–X bond energies (C–F > C–Cl > C–Br) and the “Perfluoro‐effect”. The electrolysis of CF₃Br in different SSE‐systems with sacrificial zinc or cadmium anodes has been reinvestigated with our experimental set‐up to elucidate the influence of the experimental conditions on the type and ratio of the products. The observed products CF₃MBr·42L and (CF₃)₂M·42L (M = Zn, Cd; L = DMF or AN) are the same as in the previous investigations, but are obtained in different ratios, as a rule caused by a parallel chemical corrosion of the respective anodes. By using aluminium as sacrificial anode no CF₃Al compounds are formed. The CF₃ species generated by electroreduction of CF₃Br react with the solvents via hydrogen abstraction and formation of CF₃H. The current yield with respect to the dissolution of the Al anode reaches 120 % indicating a considerable chemical corrosion in addition to the anodic oxidation. This result enabled a one‐pot trifluoromethylation reaction of NMP as organic carbonyl substrate and solvent with CF₃Br and aluminium powder (ratio 3 : 2) at higher temperatures (> 70 °C). The complete reaction of CF₃Br to give CF₃H and 1‐methyl‐2‐trifluoromethyl‐4,5‐dihydropyrrol allowed the isolation of the latter by vacuum condensation and distillation in 45 % yield, rel. to the CF₃Br used. Gallium and indium were also applied as sacrificial anodes in combination with CF₃Br as substrate. In both cases, anodic current yields of about 280 % indicated an extreme chemical corrosion together with cathodic metal depositions corresponding to the cathodic current yield. These deposits – in contrast to those of Zn and Cd – do not react with CF₃Br in Grignard‐type conversions to CF₃Ga and CF₃In compounds. So, the observed products (CF₃)_nMBr_3–n·L (M = Ga, In; n 1‐3; L = DMF, NMP) are obviously formed by chemical corrosion of the electro‐activated anodes. Finally, electrochemical and chemical trifluoromethylations were successfully carried out, using R₃SiCl (R = Me, Vi, Ph), Me₃M′Cl (M′ = Ge, Sn) and aluminium anodes or Al‐powder. The products were characterized either after isolation or in the product solutions by NMR‐spectroscopic investigations.     

分光光度法测定化学试剂中痕量钙

在pH10.4的NH3 NH4Cl介质中,Ca2+与DBC 偶氮氯膦生成1∶1蓝色络合物.络合物的最大吸收波长位于624nm,方法的表观摩尔吸光系数ε624nm=3.82×104L·mol-1·cm-1,钙量在0～25μg/25mL范围内遵守比尔定律.本法用于化学试剂KCl,NaCl及NaNO3中痕量钙的测定,得到了满意的结果.     

神经网络方法用于分辨3种化学物质

神经网络方法用于分辨３种化学物质冯伟,胡上序（浙江大学化工系,杭州,３１００２７）关键词模式分类,神经网络,模拟退火,遗传算法,传感器阵列传感器阵列技术是利用传感器阵列所提供的交叉敏和模式识别及微机处理技术,来提高传感器的选择性和传感器的测量精度［１...     

Developing a QSPR Model of Organic Carbon Normalized Sorption Coefficients of Perfluorinated and Polyfluoroalkyl Substances

Perfluorinated and polyfluoroalkyl substances (PFASs) are known for their long-distance migration, bioaccumulation, and toxicity. The transport of PFASs in the environment has been a source of increasing concerned. The organic carbon normalized sorption coefficient (K_oc) is an important parameter from which to understand the distribution behavior of organic matter between solid and liquid phases. Currently, the theoretical prediction research on log K_oc of PFASs is extremely limited. The existing models have limitations such as restricted application fields and unsatisfactory prediction results for some substances. In this study, a quantitative structure–property relationship (QSPR) model was established to predict the log K_oc of PFASs, and the potential mechanism affecting the distribution of PFASs between two phases from the perspective of molecular structure was analyzed. The developed model had sufficient goodness of fit and robustness, satisfying the model application requirements. The molecular weight (MW) related to the hydrophobicity of the compound; lowest unoccupied molecular orbital energy (E_LUMO) and maximum average local ionization energy on the molecular surface (ALIE_max), both related to electrostatic properties; and the dipole moment (μ), related to the polarity of the compound; are the key structural variables that affect the distribution behavior of PFASs. This study carried out a standardized modeling process, and the model dataset covered a comprehensive variety of PFASs. The model can be used to predict the log K_oc of conventional and emerging PFASs effectively, filling the data gap of the log K_oc of uncommon PFASs. The explanation of the mechanism of the model has proven to be of great value for understanding the distribution behavior and migration trends of PFASs between sediment/soil and water, and for estimating the potential environmental risks generated by PFASs.     

方剂的化学成分及药效物质

方剂是中医临床用药的主要形式,是中医理论整体观和辨证施治的最佳体现,在整个中医药体系中占有举足轻重的地位;由于化学成分不清楚,作用机理不明确,方剂的国际化在很大程度上受到了限制。方剂的化学成分和药效物质研究是中医药现代化研究的两个重要组成部分。近年来,多种生物技术和分析化学方法为方剂化学成分和药效物质研究提供了新的方法和技术。本文在总结方剂化学成分和药效物质基础研究现状的基础上,提出了进一步深入研究的基本思路。     

Chemical Aspects of Bioisosteric Substances: Thienyl- and Pyridinyl-Phosphinic Acids

Abstract

Substitution of the carboxyl-group (-COOH) in substances of biological interest by the phosphinic acid group (-PH(O)OH) leads to “bioisosteric” compounds [1,2]. This concept is of great importance for the pharmaceutical and biochemical investigation as many of those biomimic compounds show remarkable biological activities.     

基于本体分类法的化学键迷思概念转变研究*

基于概念本体分类模型,以化学键相关内容为载体,详细阐述化学概念本体分类模型的内涵,以及在化学迷思概念转变中的应用。同时,从本体论的视角讨论本体分类法可作为化学概念教学的新的补充。     

Metal Chemical Vapor Deposition: Design and Synthesis of New Source Reagents for Osmium Thin Films

Treatment of β-diketone ligands, such as hfacH (hexafluoroacetylacetone) or tmhdH (2,2-dimethyl-3,5-heptanedione), with binary metal carbonyls Ru3(CO)12 or Os3(CO)12 in a stainless steel autoclave at elevated temperature afforded the corresponding mononuclear Ru or Os complexes 1, 2 and 3 in good yields. A second type of mononuclear Os CVD source reagent 4 has also been obtained from a reaction of Os3(CO)12 with 3 eq. of iodine under CO atmosphere. These four Ru and Os CVD source complexes are all relatively stable and highly volatile; thus, they can be utilized for depositing the respective metal thin-films with overall quality comparable or better than those deposited using the commercially available source reagents. The surface morphology, the purity and the crystallinity were identified by SEM micrograph, X-ray photoelectron spectroscopy, conductivity measurement and powder XRD, respectively. Possible reaction mechanisms leading to the formation of the metal deposit are presented.     

Synthesis and Chemical Constitution of Diphenoxyphosphoryl Derivatives and Phosphonium Salts as Coupling Reagents for Peptide Segment Condensation

The reactions of diphenoxyphosphoryl chloride ((PhO) 2 P(O)Cl) and different chlorophosphonium salts ([R 3 PCl]X, R = (CH 3 ) 2 N, pyrrolidine, X = PF 6 m , BF 4 m ), respectively, with 7-aza-1-hydroxybenzotriazole (HOAt), 1-hydroxybenzotriazole (HOBt), hydroximinomalonitrile (HOxDCO), and ethyl hydroximinocyanoacetate (HOxO) are described. The structures of the new compounds, which are useful coupling reagents for epimerization-free peptide segment condensation, are discussed on the basis of their 1 H, 13 C, 31 P NMR, and IR spectra. The reactions of (PhO) 2 P(O)Cl lead to mixtures of O - and N -phosphorylated isomers of varying ratios. Contrary, reactions of chlorophosphonium salts yield exclusively one isomer.     

面向分析化学教学的数理统计软件的开发和应用

针对分析化学教材中统计数值表不够全面、抽象难懂的不足,开发了基于Matlab和Android平台的数理统计软件。该软件具有简洁的界面、直观的图像和自然的人机交互等优点,提供数理统计应用中的概率计算和统计检验所需的临界值,分布类型包括正态分布、t分布、X²分布和F分布。该软件旨在辅助分析化学师生提高解题效率,从而将学习重点集中在数理统计知识的深入理解和结果的合理阐释;也为此后专业统计软件的使用提供平稳过渡。本文介绍了该软件的主要特点,结合例题详细说明了软件的使用方法。     

Flow Technology for the Genesis and Use of (Highly) Reactive Organometallic Reagents

In the field of organic synthesis, the advent of flow chemistry and flow microreactor technology represented a tremendous novelty in the way of thinking and performing chemical reactions, opening the doors to poorly explored or even impossible transformations using batch methods. In this Concept article, we would like to highlight the impact of flow chemistry for exploiting highly reactive organometallic reagents, and how, alongside the well-known advantages concerning safety, scalability, and productivity, flow chemistry makes possible processes that are impossible to control by using the traditional batch approach.     

Phytoalexins,Chemical Defense Substances of Higher Plants?

Phytoalexins are defense substances with antimicrobial properties which are produced by plants after infection. They include various groups of natural substances (e.g. isoflavonoids, terpenoids, polyacetylenes and dihydrophenanthrenes). Induction of phytoalexin formation can be caused not only by living microorganisms but also by products of microbial origin (elicitors) or by stress treatment (cold, UV light). The elicitor from the mycelial walls of the fungus Phytophthora megasperma var. sojae (Pms) is a β-1,3-glucan with branches at C-6. In some cases the basic features of the biosynthesis of the phytoalexins are known. The activity of the enzymes involved in phytoalexin biosynthesis is increased by the action of the elicitor on plant tissues. The ability of some microorganisms to chemically modify the phytoalexins may be related to their pathogenicity. The role of phytoalexins as defense substances is not yet fully clear.     

Polyaromatic Scavenger Reagents (PAHSR): A New Methodology for Rapid Purification in Solution-Phase Combinatorial Synthesis

A new method of purification of solution-phase combinatorial libraries has been developed. Development of a chemically inert polyaromatic anchor with a reactive "scavenger reagent" (PAHSR) allows unreacted reagents and impurities to be removed from a reaction by absorption of the PAHSR to charcoal and simple filtration.     

Interrogating Plant-Microbe Interactions with Chemical Tools: Click Chemistry Reagents for Metabolic Labeling and Activity-Based Probes

Continued expansion of the chemical biology toolbox presents many new and diverse opportunities to interrogate the fundamental molecular mechanisms driving complex plant–microbe interactions. This review will examine metabolic labeling with click chemistry reagents and activity-based probes for investigating the impacts of plant-associated microbes on plant growth, metabolism, and immune responses. While the majority of the studies reviewed here used chemical biology approaches to examine the effects of pathogens on plants, chemical biology will also be invaluable in future efforts to investigate mutualistic associations between beneficial microbes and their plant hosts.     

Chemical Shift Reference for MASSCP-13C NMR Studies of Reagents Immobilized on Silica Gel

Abstract

This report demonstrates that immobilized trimethylsilane is an appropriate reference standard for MASSCP-¹³C NMR studies of reagents immobilized on silica gel. An example is presented which shows that the immobilized trimethylsilane exhibits many of the advantages as a reference for these solid samples as does tetramethylsilane for liquid samples. It is further shown that pure solids may interact with an immobilized phase and produce significant spectral changes and thus are not appropriate as reference standards.