初中化学“分子和原子”的教学逻辑——基于2011-2018年的文献分析

以2011-2018年19篇有关初中化学“分子和原子”的教学研究文献为研究对象,基于教学观念与策略分析归纳出2种主要的教学逻辑:“证据推理型”和“模型认知型”。从“初步建立微粒观”“发展微粒观”“初步形成微粒观”等3个维度对2种教学逻辑进行归纳和评析,结合教学实践提出了一个新的“模型认知型”的教学逻辑。     

基于数字化实验,落实 “证据推理与模型认知” 学科核心素养——以拓展探究复分解型离子反应发生条件的教学应用为例

本研究利用数字化电导率传感器对离子反应的发生条件实验进行拓展设计,测定常温下,等浓度的CH₃COONH₄溶液分别与蒸馏水、NaCl溶液、HCl、NaOH溶液混合后的电导率变化,以实验的数据和图像为证据,推理部分离子反应的实质和发生条件,促进学生对离子反应内涵的认知,在教学中渗透 “证据推理与模型认知”学科核心素养。本研究是对教材内容的补充和拓展, 为教师进行离子反应的教学实践拓展提供一定参考。     

初中化学“溶解现象”项目式教学*——从海带中提取碘和甘露醇

围绕“海带中碘的检验和提取”和“甘露醇的提取”2个社会生活情境展开,通过流程图的制作、流程问题的探讨、实验的具体操作以及课后拓展研究等4组任务,来完成“溶解现象”章节复习,建构工业流程的认知模型,理解“溶解、溶液、溶解度、结晶”等学科概念,渗透元素观、微粒观、平衡观等学科观念,发展设计探究实验、数据分析与证据推理等学科关键能力。     

从化学学科核心素养到学生学习活动*——基于证据推理与模型认知的“空气”教学

以学生活动为载体,借助表现性评价,有助于学生学科核心素养的形成。根据“表现性评价”和“证据推理与模型认知”的内涵,从“获取推理证据”“基于证据推理”“建立认知模型” “基于模型认知”等4个维度提出表现性评价量规,以 “空气”第1课时教学内容为例,设计表现性任务。介绍了在“空气”第1课时的教学中,教师在课堂上基于表现性评价观测学生课堂表现,并根据学生素养达成情况及时调整教学,展开“教、学、评”一体化的教学过程。     

基于变构学习模型的高中化学“导致悖论”教学设计*

“导致悖论”教学是一种智在创境、妙在引领的教学,其核心理念源自于变构学习模型的悖论思想,给学习者创造一个“肯定→否定→肯定”的反思性学习过程。高中化学教学设计可以通过4种途径分别创设“概念与概念”相悖、“理论与实验”相悖、“理论与理论”相悖和“实验与实验”相悖的悖论情境,最终实现学生新旧概念的更替和高阶思维能力的发展。“导致悖论”教学在实施中要注意精选合适的知识内容,加强学生心理的调控,提供丰富的支撑材料。     

化学实验“三三三”翻转教学模式的探索与实践*

针对当前化学实验翻转课堂教学模式中存在的不足,依托“云班课”,重构了以学生为中心的化学实验“三三三”翻转教学新模式,即将实验教学划分为“三个课堂”:自学课堂、理论课堂和实验课堂等;理论课堂里包含“三个环节”:个人汇报、小组活动和测试点评等;学习效果评判有“三个评价”:自学评价、参与评价和动手评价等。以有机化学实验中“环己烯的合成”为例,采用该新的教学模式开展了教学活动,整个教学过程不仅体现了“以学定教、学生为中心”的教学理念,而且也能发挥出线下传统课堂的优势,实现了将“知识内化”的时间拉长,达到对学生线上自学“知识传授”掌握度的有力检验的目的,更有时间和空间进行课程思政元素的挖掘与融入,完成在知识传播中实现对学生的价值引领。     

基于真实情境的初中化学微项目教学实践与反思*——以“溶液的形成”为例

以“溶液的形成”为例进行微项目教学实践,选择学生熟悉的护手霜为主题情境,巧妙设计了“原料分散”“微观探秘”“辨识活动”“对比实验”“感知乳化”等系列微项目活动,通过情境不断地设置认知冲突,引导学生反思、修正并最终形成更完善的概念,在环环相扣的探究活动中使学生自主建构结构化的知识。通过制作“护手霜”将“溶解”和“乳化”串联,感知溶液,感受乳化,感悟人与自然、社会的和谐、可持续发展。     

高中化学“氧化还原反应的应用”项目式教学——设计过氧化氢使用注意事项标签

以“设计过氧化氢使用注意事项标签”为项目主题,开展高中化学“氧化还原反应的应用”教学。学生通过说明书对比发现问题,完成“探究过氧化氢能否与氧化性物质混用”“探究过氧化氢为何不能与还原性物质混用”“探究过氧化氢起消毒作用原理”等3个主项目任务及“寻找日常生活中常见消毒剂”的拓展任务,完成过氧化氢性质的预测及验证,在探究过程中建构并应用价性模型,形成从化合价角度认识物质氧化性或还原性的思路方法,认识氧化还原反应的重要意义。本教学设计为单课时微项目,学生思维的开放度稍弱,可以适当延长课时。     

基于文献分析的“氧化还原反应”概念教学逻辑

以15篇有关“氧化还原反应”的课例研究文献为研究对象,基于内容分析法归纳出4种主要的教学逻辑：“分类标准直给型”“分类标准批判型”“反应本质揭示型”“知识演绎批判型”。从“知识是什么”“知识是如何被理解的”2个维度对4种教学逻辑进行评析,以反思氧化还原反应教学研究的发展及其局限。     

利用“水文明”变迁彰显学科价值的课堂教学——以“水的净化”为例

以调查问卷的方式,分析了“水的净化”在教学中存在的问题:学生认知层次较浅,难以体会水净化的实践和内涵;教师认知程度不够,难以体会水净化的价值和意义。提出在教学中应融合“水文明”变迁史,通过开展“看、动、做、品”等4个方面的活动,帮助学生全面深入理解水的净化过程,真正体会到化学学科的价值,理解“绿水青山就是金山银山”的意义。     

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%.     

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.     

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.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.