大学无机化学中“原电池”的启发探究式教学实践*

介绍了大学无机化学课堂中“原电池”部分的教学实践。通过启发-探究式教学模式,启发学生把常见的氧化还原反应,经过不断的设问和探究,最终设计成原电池,实现了通过原电池装置来证实氧化还原反应发生了电子传递的教学目的。学生在教师的启发下探究、分析、推导、创新和修正,使学生清晰地认识到知识的前后逻辑关系,对氧化还原反应概念、原电池装置有更深刻的理解,培养了学生的科学辩证思维能力。     

基于学生问题驱动的化学概念教学——以高中化学“电解质”为例

以小组合作为学习方式,由学生提出的学习问题驱动化学概念教学,通过对学生课前自主预习中提出的问题进行归纳、分类研究,以此为基础设计平行性、模块化、渐进式的教学任务来突破教学重、难点,并在课堂上运用互动课堂反馈系统及时测查学生的学习效果。教学结束后发放量表,调查学生对问题驱动教学过程的评价,并对化学概念课型中提升学生自主提问意识的教学理念与实践方法进行讨论。     

“电离与离子反应”的单元教学设计与实施*——食盐精制:从微观角度看粗盐中可溶性杂质的去除

在“食盐精制:从微观角度看粗盐中可溶性杂质的去除”的单元教学中,通过初识粗盐中的杂质、微观角度看氯化钠、微观角度看粗盐溶液、微观角度认识除杂方法、设计除杂方案并实施等活动,促进学生理解与应用电离、离子反应等核心概念,引领学生解决真实问题,形成解决除杂实验问题的基本思路,实现能力素养的发展。经过多轮次教学改进,结合教学实践及其教学效果抽提出“聚焦核心概念和学生必做实验,实现认识能力的进阶与实际问题解决过程高度融合”“通过学科实践及实验探究,建立宏观、微观、符号关联,突出证据推理,构建思维模型”“通过持续性评价活动,外显学生的前概念,促进概念转变,形成化学学科思维方式”等教学策略。     

中学生对“溶液”概念理解的可视化表征及启示

学生概念理解的可视化表征可以通过学生的作图来展示,分析图示可以获取学生概念理解的更加深入的信息。梳理了国内外有关中学生对“溶液”概念理解的研究,集中对学生的作图进行分析,呈现了中学生对“溶液”概念理解的可视化表征。针对作图发现的学生概念理解的结果,提出了促进中学生“溶液”概念理解的教学启示。     

化学数字化实验影响学生概念改变的实证研究

选取"离子反应"知识作为研究内容,开展了相关化学数字化实验的教学实践,通过二段式测验工具、SOLO分类法的量化分析,来检测化学数字化实验对学生概念改变的影响。结果显示,化学数字化实验能够在一定程度上促进学生的概念改变。     

电解质概念教学中存在的问题及解决对策

通过对学生访谈和作业反馈情况来看,学生对电解质概念的内涵和外延存在不同程度的曲解。通过对教材概念的呈现方式、教学过程和学习方式的反思后提出：电解质概念的教学不宜利用导电实验引入,不宜用导电性作为判断依据;相关练习未能澄清概念关键点;电解质概念教学让学生感受到了过多挫败感,而非成就感。最后提出电解质概念教学应强化本质特征,突出电离特性,促进概念理解。     

初中化学计算教学初探

化学计算是中学化学教学的重要内容之一,通过化学计算教学可以使学生从质和量的观点来加深对有关概念、原理、物质性质及其变化规律的理解。同时对发展学生的分析归纳、数学思维能力和创造思维能力,也起着促进作用。     

高职医用化学项目化教学的探讨

通过分析目前医用化学教学中存在的主要问题,提出了项目化教学的概念,使学生在完成项目任务的过程中,提高学生自主学习兴趣,培养学生各方面的能力,更好地提高学生的专业知识和实际操作技能,从而实现高职教育培养高素质技能型专门人才的目标。     

初中化学概念形成与教学策略

化学基本概念的学习往往成为初中学生成绩的分化点,在教学中帮助学生克服这一学习障碍,体现新课程所强调的过程、方法、情感等的教学理念是亟待解决的课题,本文通过对概念结构以及概念形成的细化分析,探讨了概念教学中培养学生掌握与应用概念的能力以及降低概念理解难度的途径。     

以核心概念为统领设计化学教学

以核心概念为统领设计教学,是把居于学科中心、具有迁移价值的核心概念作为学生需要持久理解的教学目标,通过核心概念统整有关事实和概念,使得学生能够在更高的认知层面上理解某些概念,为他们的终身发展提供支持。阐述了核心概念的特性与价值,并探讨了如何以核心概念为统领设计化学教学。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.