化学平衡制图软件HYDRA/MEDUSA在大学化学教学中的应用

介绍化学平衡制图软件HYDRA/MEDUSA的基本功能与特点。结合大学化学课程在化学平衡教学方面的内容,分别给出了沉淀-溶解平衡、酸碱平衡、配位平衡与氧化还原平衡的应用实例,充分显示了该软件有利于学习大学化学课程中复杂的平衡计算,帮助认识各化学形态之间的化学反应和控制条件,也为涉及到化学平衡体系计算与形态分布的化学研究提供帮助。     

以热力学为主线的无机化学反应原理教学内容再思考

针对大学无机化学教材虽讲授热力学初步原理但应用不足的实际情况,以化学反应过程Gibbs自由能变化?r Gm?为主线,处理以离子反应为特征的沉淀溶解平衡、氧化还原平衡、酸碱平衡及配位平衡,使学生从热力学角度理解和认识“化学平衡”,克服以化学反应速率动力学引入和描述“化学平衡”导致的弊端,实现对“化学平衡”本质认识及在以离子反应为特征反应体系中的应用,期待构建热力学主线下的无机化学反应原理教学内容。     

从科学概念本体和发展史视角对化学平衡相关问题的分析

中学化学教学中关于化学平衡的认识存在多种误区,本文先从科学概念本体的视角系统考察了化学平衡的相关概念,对各种认识误区进行了分析,明确了原有分析化学平衡问题的视角的缺陷;再从科学概念发展史的视角探讨了化学平衡问题的分析方法,确立了符合热力学基本规律的更科学、更实用的化学平衡问题的分析工具——平衡常数;最后明确了基于平衡常数的化学平衡的相关认识及其基于平衡常数的平衡观构建的重要价值,可促进教师更加科学地认识化学平衡问题,关注并在教学中落实化学平衡常数的教学价值,为中学化学中四大平衡的教学提供借鉴和参考。     

强碱滴定弱酸的信息化教学软件及其教学实践*

基于酸碱滴定中的离子平衡现行教学中存在的问题,研发了一款以强碱滴定弱酸为例的离子平衡知识学习与习题检验的软件工具。该软件以可视化的技术,用曲线、柱状图等形式展示滴定过程中的动态变化,便于学生从滴定过程中的离子反应、图像和数据中获取信息并进行推理,从而认知酸碱滴定中的离子平衡的内在原理。该软件不仅能用于离子平衡中各概念的教学,也能为相关习题课的讲解创设必要的教学情境。     

化学平衡的稳定条件

化学平衡的稳定条件张世民（湖南大学化学化工系长沙４１００１２）关键词化学，平衡，稳定性本文讨论了化学平衡的稳定条件，特别是理想气体化学平衡的稳定条件，并指出理想气体恒温恒压化学反应和恒温恒容化学反应的平衡都是稳定的。我们知道，恒温恒压或恒温恒容化学反...     

化学形态分析软件CHEMSPEC及其应用

放射性核素在地质层中的吸附和迁移行为与其所处的化学形态密切相关．为了预测在处置库受损情况下放射性核素的时间和空间分布,需要建立化学形态分析与水力学计算相耦合的数学模型及计算软件．为此,我们编写了化学形态分析软件CHEMSPEC．本文在简要介绍该软件的原理和程序结构后,着重介绍该程序为防止质量平衡方程组迭代求解过程的发散所采取的措施,提出用“预报－校正法”处理沉淀－溶解平衡的算法,以及用“冻结”和“解冻”氧化态的策略处理包含氧化还原反应和沉淀反应的化学平衡的计算．本文用4个典型例子说明CHEMSPE在现阶段能解决些什么问题．最后讨论了存在的问题和尚待完成的工作．     

对化学平衡教学中一些问题的理性思考

深刻认识化学平衡移动原理和反应程度,审视化学平衡常数大小、平衡转化率变化、平衡移动方向与反应程度之间的关系和正逆反应速率相对大小与平衡移动的关系。平衡是否移动就看能否减弱刚变化的因素。反应限度与反应程度不同。     

信号流图在氧化还原反应平衡系统建模与计算中的应用

利用信号流图集成了化学平衡基本物理量之间的关系,为获取化学平衡计算公式提供便利.举例说明了氧化还原反应平衡系统信号流图模型的建模和利用信号流图模型求解平衡浓度的过程.     

Visual MINTEQ软件在大学化学教学中的应用

介绍了水文地球化学软件Visual MINTEQ的基本功能和特点,并结合大学化学课程中化学平衡章节的教学内容,举例说明了该软件在缓冲溶液pH计算、酸碱滴定过程模拟、配合物分布曲线绘制以及沉淀溶解平衡预测等应用实例中的使用方法.Visual MINTEQ程序在大学化学课堂中的应用不仅丰富了教学形式,还加强了学生对相关理论知识的理解和掌握,从而为其创新实践能力及科学研究方法的培养奠定了良好的基础.     

丙烯气相水合反应过程的热力学分析

根据所提出的高压复杂物系化学平衡组成的计算方法，对丙烯气相水合反应进行了热力学分析。计算了反应条件对各反应组分平衡组成的影响。得到了丙烯和水的平衡转化率、异丙醇（ＩＰＡ）及异丙醚（ＩＰＥ）的平衡组成随温度、压力、进料中水／烯比及原料中异丙醇含量的变化规律，确定了该反应体系在热力学上的最优操作条件，为催化剂的筛选提供了依据。     

充满生机和科学机遇的磷化学研究所

简要地综述了第十五届国际磷化学会议的报告内容，介绍了目前磷化学的主要 研究领域，包括不对称合成、配合化学，生物碱化学，药物化学，农业化学等相关 领域的研究动态及新进展。     

Novel arylpyridine‐based 1,3,4‐oxadiazoles: Synthesis,antibacterial, and anti‐inflammatory evaluation

In view of developing novel bioactive compounds, a series of 2‐(5‐[2‐methyl‐6‐arylpyridin‐3‐yl]‐1,3,4‐oxadiazol‐2‐ylthio)‐1‐arylethanones (6a–n) were designed and synthesized in good yield. Novel compounds were evaluated for their antibacterial and anti‐inflammatory activities. All synthesized compounds were screened for their antibacterial activity against Staphylococcus aureus, Bascillus subtilis, Eschericia coli, and Pseudomonas aeruginosa strains. Compounds 6a , 6b , 6c , 6h , and 6i displayed the highest antibacterial activity with minimal inhibitory concentration (MIC) values ranging from 6.25–12.5 μg/mL in comparison with the standard Ciprofloxacin. The results of anti‐inflammatory activity of carrageenan‐induced footpad edema assay indicated that tested compounds exhibited remarkable anti‐inflammatory activity with percentage of inhibition of 63.9–70.1% (potency 96.8–106.20% of indomethacin activity) after 3 hr. Particularly, 6c – e and 6j – l were found to be excellent inhibitors of inflammation, with potential higher than that of the standard, Indomethacin.     

Novel [1,2,4]triazolo[3,4-b][1,3,4]thiadiazine derivatives embedded with benzimidazole moiety as potent antioxidants

Fourteen novel [1,2,4]triazolo[3,4-b][1,3,4]thiadiazine derivatives bearing benzimidazole moiety ( 7a-n ) have been synthesized using the one-pot nitro reductive cyclization method. All the synthesized compounds were confirmed by ¹H nuclear magnetic resonance (¹H NMR), ¹³C NMR, fourier-transform infrared (FT-IR), mass spectrum, and elemental analyses. All the title compounds were subjected to in vitro antioxidant activity. The free radical scavenging activity of the compounds was examined using DPPH, nitric oxide, and superoxide radical scavenging methods. The results demonstrated that compound 3-(2-(3,4-dimethoxyphenyl)-1-propyl-1H-benzo[d]imidazol-5-yl)-6-4-tolyl-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine ( 7c ) was potent in scavenging both DPPH and nitric oxide radical with IC₅₀ values of 13.57 and 18.55 μg/ml when compared to the standard with IC₅₀ values of 23.75 and 23.14 μg/ml, respectively, which was due to the presence of electron-donating groups. The activity was found to decline when electron-donating groups were replaced by electron-withdrawing groups. Moderate scavenging activity was observed for the superoxide radical. Structure activity relationship and physiochemical properties were studied for all the derivatives.     

Dual zinc catalysts for L‐lactide polymerization and reaction of CO2 with cyclohexene oxide

A series of zinc complexes, [ L ^X ZnEt] ( 1–5 ) and [ L ^X Zn ₂ (OAc) ₃ ] (6–9) , associated with NNO‐tridentate Schiff base ligands (2‐(((2‐((cyclohexyl[methyl]amino)methyl)phenyl)imino)methyl)phenolate (CAP) derivatives), were synthesized, and their activity toward ring‐opening polymerization (ROP) of L‐lactide (LA) and the reaction of CO₂ with cyclohexene oxide were also investigated. All of [ L ^X ZnEt] revealed excellent catalytic activity to ring‐opening polymerization (ROP) of LA in the presence of benzyl alcohol. Among them, [ L ^H ZnEt] (1) showed the highest activity with 82% conversation within 45 s. In contrast, [L ^X Zn ₂ (OAc) ₃ ] (6–9) were inactive in ROP of L‐lactide. In addition, all of these Zn complexes demonstrated moderate activity in the reaction of CO₂ with cyclohexene oxide in the presence of Bu₄NCl.     

Exploring recent developments on 1,2,4-triazole: Synthesis and biological applications

Triazoles are nitrogen-bearing heterocycles. In the last few decades, researchers have focused on fused heterocycles, as they have better pharmacological effect compared to triazoles alone. Among the two isomers of triazole, this article aims to explore the work carried out on 1,2,4-triazole and N-bridged heterocycles derived from 1,2,4-triazole in last 18 years, highlight different synthetic pathways, and present a brief summary of the different biological activities possessed by 1,2,4-triazole derivatives. The information collected in this article is expected to help researchers to discover novel therapeutic agents for better applications in the field of pharmaceutical science.     

Biologically inspired 3Fe4S cluster as structural mimics of FeMoco M-cluster

A 3Fe4S cluster related to M-cluster of Mo-nitrogenase is reported. [K(THF)₅][Fe₃(μ-bdt)₂(μ-PPh₂)(CO)₅] ( 1 ) is synthesized from photo-assisted structural rearrangement of [K(THF)₂][(μ,κ²-bdt)Fe₂(μ-PPh₂)(CO)₅] under visible light irradiation. The molecular structure of 1 consists of a Fe₃ core bearing one dithiolate bridge and the second dithiolate group capping onto the metallic plane. The structural motif of 1 is analogous to that of Mo-participated 3Fe4S unit in M-cluster of Mo-nitrogenase, with the similar Fe-Fe and Fe-S bond distances. Upon protonation in 193 K, a Fe-hydride species ( 1H ) is generated and characterized to possess the bridging hydride group (δ = −12.57 ppm) by ¹H-NMR spectroscopy and DFT calculation. In CH₃CN solution, complex 1 exhibits a reversible reduction and oxidation process at $E_{1/2}^{\mathrm{red}}$ = −1.94 V and $E_{1/2}^{\mathrm{ox}}$ = −0.18 V, respectively, at 273 K. The reduction behavior of 1 in CH₂Cl₂ solution at 243 K displays a slight modification in the presence of trifluoroacetic acid, revealing a moderate anodic potential shift (~50 mV). The current amplitude of the reduction wave is linearly increased with the increasement of acid added, indicative of the catalytic event.     

环戊二烯类有机金属含硫族化学的新进展

本文系统地综述了环戊二烯类有机过渡金属含硫族(S, Se, Te) 化学领域的研究现状和进展。参考文献136 篇。     

化学学科的新视角及其在化学教育中的反映

传统化学以研究变化,关注变化前后的结果而著称。化学与其他学科,特别是生命科学的相互渗透使得化学的动态特征更加突出,化学学科格局也因之发生了变化。因此,化学需要新认识。     

Meeting the sustainable development goals in a tropical climate

This article reflects on the Federation of Asian Chemical Societies (FACS) Citation Award Lecture delivered in the Industrial Technology Research Institute Symposium on CO₂ Utilization and Green Technology during the 18th Asian Chemical Congress held in Taipei, December 12, 2019. Malaysia produces sizable amounts of palm oil and palm kernel oil, with palm fronds and tree trunks as the main waste. At the Malaysia Japan International Institute of Technology, the biomass was decomposed to produce fine chemicals, used as substrate for mushroom growth, and converted to bio-coke for heat energy. A notable difference has been found regarding the emission of greenhouse gases from a natural peat forest and those from the oil palm plantation converted from peatlands, where in the palm plantation, water table is lowered and aerobic processes occurs, resulting in more CO₂ being released compared to CH₄. The introduction of fertilizers to the plantation resulted in more N₂O being released. The team has also pioneered a project to plant temperate vegetables. Cooling pipes (16–18°C with circulating water cooled by chiller) were embedded within each thermal conditioning soil plot. Lettuce and radish, the experimental plants, showed good growth in the thermal conditioning soil due to nitrogen-fixing bacteria, which were destroyed at a higher temperature.     

The Chemistry of Protactinium

Protactinium exhibits an ambivalent chemical behavior. In non-aqueous solutions and in the solid state, both quadrivalent and quinquevalent protactinium has properties which characterize it as a typical actinide element. On the other hand, investigations in aqueous solution show quinquevalent protactinium to be a homologue of niobium and tantalum. It exhibits – except in hydrofluoric acid solutions – a marked tendency to undergo irreversible hydrolysis and condensation reactions, which leads to the situation that tracer amounts (ca. 10^?12 mole/l) and macroscopic amounts (10^?3–10^?6 mole/l) of protactinium often behave differently. Reduction with strong reducing agents gives aqueous solutions of Pa(IV), the properties of which again correspond in general to those of Th(IV) and show no relation to Nb(IV). Our knowledge of the chemical behavior of this rare radioelement has been advanced, in particular, by the production in 1958–1960 of 100 g of pure protactinium – the largest amount so far – from residues of the British production of uranium.