运用实验解疑效果好

化学教学中若能多运用实验解决某些有争议性的疑团,能收到较好的效果,增强教学的说理性,培养学生的思维能力和实际动手能力,从而提高教学效率。     

中学化学实验教学改革及其反思

从4个方面反思中学化学实验教学改革,指出中学化学实验教学改革的基本思路是:如何更好地发挥教材中各类实验在中学化学教学的作用,从而实现中学化学教学目标;验证是化学实验的最根本功能,实验的验证性与实验在情感领域和能力、方法领域的功能并不矛盾,而是实现这些领域的功能的基础;实验教学若能从学生出发,引发学生的想法并加以验证,则能有效地发挥教材中的各类实验在化学教学中的作用,提高中学化学教学质量.     

论笔试型化学实验试题的评价和教学导向功能

将笔试型化学实验试题的命题“重心前移”及注意考查实验的细节能有效测试和评价学生的实验能力及科学素养,从而发挥实验试题关注实验、注重过程的教学导向功能。     

有机化学实验短视频辅助实验课堂教学研究

以正溴丁烷的制备实验为教学案例,对有机化学实验短视频辅助实验课堂教学模式进行了探索。该种教学模式能有效地激发学生的学习兴趣,促进学生对实验内容的理解和掌握,改善课堂教学效果。     

高校研究生辅助分析化学实验教学的探索与实践*

研究生实验助教在本科实验教学中发挥着重要的作用。分析化学实验课程教学团队本着以“学生为本”的教学理念,逐步构建起一套研究生助教规范化体系,使得研究生助教辅助教学和实验管理的工作更为科学且高效。同时,阐述了此项工作对提升实验课教学质量及培养研究生综合素质能力的积极意义, 期望能为高校本科实验教学的改革创新和研究生的培养提供有益借鉴。     

结合常年学生科技活动进行开放式的实验教学

建立常年学生科技活动小组进行实验教学,不仅能为部分学生提供一个科研和实验的平台,而且能为有关专业的所有学生提供一个开放式实验的教学基地。它比一般的科技活动模式具有更好的教学效果,值得在大中学校里推广。     

基于IrYdium Chemistry Lab的可视化教学设计——以“盐类的水解”为例

利用虚拟化学实验软件IrYdium Chemistry Lab为基本工具，探讨其在“盐类的水解”一节进行可视化教学设计的具体方法和教学应用价值。说明基于虚拟化学实验的可视化教学设计，能兼顾表达思维可视化过程和结果，有利于强化学生的学科理解能力。     

顺应时代发展,创新农药化学课程教学

顺应时代发展对农药化学教学的要求,依据现代教学论的基本原则,对农药化学课程教学进行了课堂教学-学生实验-生产实践"三位一体"的改革与实践,形成了理论学习-实验-理论学习-实践-理论学习的良性教学模式。实践表明,该模式能全面有效地提高学生创新能力和综合素质。     

介绍一种发光的氨喷泉实验

化学教学中的演示实验不仅能说明重要的化学原理,而且能激发学生的兴趣和好奇心。本文介绍的演示实验由两部分组成,即氨喷泉和化学发光实验。利用氨喷泉的虹吸作用,可以把这两个实验组合起来而成为一种发光的氨喷泉实验。实验装置 (如图所示)。通过“T”型管把一个倒置的圆底烧瓶和混合后能产生化学发光的两种溶液(溶液A和溶液B)连在一起。当少量的     

自制专用试管夹做对比实验

在实验中,我们自制了双夹和三夹,在教学中使用既能使对比实验的可比性增大又能节省宝贵的时间,效果较好。     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.