对铁钉锈蚀条件的再探究

通过对课本中"铁钉锈蚀条件的探究"的案例分析,从反应物、生成物、定性和定量等角度改进设计了该实验,在对问题的再探究中引导学生自主设计、自主实验、自主评价,形成科学探究的方法和能力。     

新课程背景下化学科学探究活动的设计和评价

本文研究新课程背景下科学探究活动的设计和评价,探索网络环境下,“空气污染的成因与防治”科学探究活动的实施。通过创设“问题情境、任务驱动、自主探究、解释与结论、协作与交流、反思与评价”六个教学环节实施科学探究活动。并对科学探究活动作过程性、综合性、发展性、多元化的评价,有利于激发学生科学探究的兴趣,培养学生科学探究意识、协作精神、创新精神和实践能力,提高学生信息素养和科学探究能力。     

安徽省农村初中化学实验教学现状的调查与思考

新课程将化学实验、科学探究作为化学课程改革的突破口,以培养学生的主动性和创新意识,提高学生的科学素养。自从新课程实施以来,农村中学化学实验教学情况如何,笔者通过对安徽省部分农村初中化学实验教学情况进行调查,探研问题存在的原因,并提出改进农村化学实验教学的几点建议。     

以深度的科学探究促进初中生高阶思维能力发展*——以“酸和碱的中和反应”为例

针对学生在学习“酸和碱的中和反应”中普遍存在的“被动接受具体知识、缺失开展真实科学探究的思路、机械记忆中和反应规律、缺乏批判质疑精神及高阶思维能力不足”等倾向问题,设置了驱动性问题链协助学生搭建“情境问题”与“真实的科学探究”间的思路桥梁,在深度的科学探究中发展学生的发散性思维、有序思维、多角度分析问题、设计创造思维、逻辑严密的推理及评价反思等高阶思维能力。课堂教学中营造轻松、舒适的交流讨论环境,有益于学生之间碰撞出思维的火花、激发出创造的灵感。课堂观察表明,深度科学探究教学的实施,有效提升了学生的高阶思维能力及解决问题的能力。     

更新观念重新审视新课程——管窥100年诺贝尔化学奖的感悟

化学新课程倡导以宽泛的化学知识为载体,在教师与学生、学生与学生以及学校与社会的相互合作情境中,引导学生体验科学探究过程,在探究中体验科学的本质、科学精神和科学态度,学习科学研究的基本方法,在科学探究中学会学习。新课程自实施以来,许多教育工作者从教育哲学、社会学和教育史学层面予以了充分肯定,笔者拟从100年诺贝尔化学奖的视角探讨新课程的理念问题及其意义。     

通过实验探究激发和培养学生的创造力

以课本中的电解水实验和草酸与高锰酸钾反应的实验为基础,同时基于碱式碳酸铜与甲酸反应实验中遇到的实际问题,设置科学问题,开展实验探究,重视实验探究的过程,让学生体验通过科学研究解决科学问题的全过程,激发学生的潜质,培养学生的创造力。     

“暖宝宝使用前后主要成分的探究”教学实录

记录“暖宝宝使用前后主要成分探究”的一节教学评比课,在引导学生利用所学知识解决实际问题的过程中让学生体验科学探究的乐趣和艰难,让学生在实验中获得科学探究的过程体验和价值体验。     

与科学探究相匹配的化学教学内容选择研究

培养学生的科学探究能力,已经成为当代化学课程与教学改革的核心要求。围绕科学探究进行化学教学内容的选择、创设一个有利于进行科学探究的情景是当前迫切需要解决的问题。本文从增强学生对化学学科内容的理解能力、有助于理解科学家是如何研究自然界的、培养调查能力和科学思维等方面讨论了选择化学教学内容的原则。     

对3套高中化学必修模块教材中科学探究栏目的思考

通过对“人教版”、“鲁科版”及“苏教版”高中化学必修模块教材中科学探究栏目进行统计后发现,3个版本教材所设计的探究活动都以实验的、局部的、学生个体的探究为主;要求学生完成的探究要素以“进行实验、收集证据”较多,对“提出问题、猜想与假设、制定计划”的要求较少。笔者认为,教师在教学过程中应注意培养学生的问题意识,提高提问的技能;鼓励学生大胆猜想,科学制定计划;促进学生反思与合作学习。     

促进学生“科学探究与创新意识”素养的发展*——以“氢氧化亚铁的制备”为例

以“氢氧化亚铁的制备”教学设计为例,通过开展专题课,引导学生深入探究氢氧化亚铁制备实验的设计与改进,重点关注学生“科学探究与创新意识”素养水平的发展,并基于具体的测评数据进行反馈评价。     

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%.     

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.     

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.     

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%).     

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.     

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.     

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.     

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.