新课程背景下高中化学课外实验活动的实践与思考

在强调开放性实验探究的新课程改革实践过程中,设计开展了“原电池”为主题的课题式课外合作探究实验、“金属与稀硫酸反应”实验的定量化验证及“南京景观水体手持仪器现场监测应用”等一系列课外实验活动,初步建立起了高中化学课外实验活动的校本课程机制,培养了学生化学实验素养和可持续学习研究能力。     

比较教学法在仪器分析实验教学中的应用

仪器分析实验是化学及相关专业的重要实验课程。结合课程特点和培养目标,提出了将比较教学法融入课堂的教学方法,指出了意义和作用,介绍了教学中开展比较教学的实践与应用。该方法加强了学生对仪器功能特点的掌握,激发其实验兴趣和创新精神,学生的认知能力在比较过程中不断建构、丰富、提高和发展,取得了较好的效果。     

翻转课堂模式在有机化学实验教学中的探索与实践

针对当前有机化学实验课程存在重讲授轻实验、重验证轻探究、重结果轻过程等弊端,学生积极性和主动性受抑制等问题,我们将翻转课堂模式应用于有机化学实验的教学中进行探索和实践。改变课前和课中学习方式,课前通过信息技术手段完成知识传授过程,课中师生研讨完成知识内化过程,将教学模式从"以教为主"转变为"以学为主",提高了学生的学习积极性、课堂参与度,培养了学生的自主学习、团队协作、表达交流等能力。我们发现翻转课堂模式下,学生在实验操作失败率、实验产物收率、实验报告质量、理论考试成绩等实验课程综合能力上获得提高,有机化学实验课程教学质量得到进一步提升。     

虚拟实验在初三化学实验教学中的实践与应用

正1利用虚拟实验突破课堂实验教学由于时间空间的限制,亲自动手进行探究实验成了学生的一种奢望,虚拟实验则给课堂带来新尝试。比如在一氧化碳还原氧化铁的实验教学中,教师利用问题引导学生在电子触摸屏上利用拟真仪器设计实验装置,进而处理产物检验、尾气处理、操作顺序等问题,不断完善实验过程,培养学生的科学探究能力。又比如在气体制取复习课上,教师在虚拟实验室上展示有关药品和仪器,让学生拖动仪器连接装置和变动装置以满足不同的实验需求,从而帮助学生深化理解实验原理,突破实验复习课。     

基于应用目标的多维度实验教学培养方案与实施——以色谱实验为例

面向研究生的仪器分析实验课程如何从教学方式、教学内容上进行改革,提高教学质量,南开大学中心实验室进行了有益的尝试。以色谱分析实验为例,通过在线课程拓展学生理论学习的时空域;丰富实验内容与分组实验相结合,提升了学生的学习热情,加强了学生实际操作的训练;以科研工作为驱动力的研究型实验课程安排更加契合学生的实际需求,增强了学生的主动学习意识,培养了学生的实际工作能力。教学实践表明,课程改革收到了较好的效果。新的教学模式提高了学生的实践能力,对新的仪器方法学习有助于其科研创新工作的开展。     

地方院校无机化学实验课程学习情况调查与分析

对学生学习现状的准确把握是促进课程改革,提升教学质量的基础。通过本次调查统计了学生对无机化学实验课程学习的基本情况,包括学习兴趣、学习目标、预习方式、预习效果、实验操作及学习效果,总结了学生在该课程学习中的主要问题和诉求,通过数据分析提出了实施无机化学实验课程有效教学的改进措施。     

充分利用《化学与生活》模块的活动性栏目转变学生学习方式的一些尝试

《普通高中化学课程标准(实验)》明确指出“转变学生的学习方式是课程改革的基本要求。教师要更新教学观念,在教学中引导学生进行自主学习、探究学习和合作学习,帮助学生形成终身学习的意识和能力。”针对《化学与生活》选修模块中“活动.探究”、“动手空间”、“角色扮演”、“学以致用”等活动性栏目功能和特点的不同,在教学中采取了不同的教学策略,促进了学生的自主学习、探究学习及合作学习。     

仪器分析课程教学与实验改革

结合应用化学专业学生的学习特点,对仪器分析课程教学与实验过程进行了改革尝试。     

基于虚拟实验室的仪器分析课程教学改革

在问卷调查的基础上,针对仪器分析课程教学中存在的问题,构建了原子吸收光谱虚等系列虚拟实验室,并与真实实验环境和操作相互补充,从理论、实验、实训3方面进行教学改革,旨在实现教学过程中真正的互动及培养学生的实践创新能力。     

仪器分析发展史在大学教学中的应用探讨

在大学仪器分析教学过程中 ,通过讲授仪器分析发展史 ,培养学生的创新能力 ,激发学生学习该课程的热情 ,使学生能更好地掌握基础原理与实验技能。介绍了仪器分析发展史在本科教学中的几种讲授方式     

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.     

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.     

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.     

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.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.