“原位”红外光谱追踪反应条件下催化体系的变化

为了观察和监测反应条件下中间产物和催化剂的变化,自行设计并安装了高温高压红外流动池。池体用不锈钢制成,窗口材料为NaCl或CaF₂。它可承受100atm和200℃。整个测量系统包括高压釜、循环泵、红外池等。用Microlab-600型红外分光光度计记录图谱。池内温度和压力与反应釜桐同,可对反应液体、气体或气液混合物进行"原位"追踪。当用铑膦络合物催化剂进行丙烯氢甲酰化反应时,在近于工业反应条件下(t=10O℃,P=17atm,正丁醛溶剂),检测到催化剂母体Rh(acac)(CO)(PPh₃)转化为活性物种RhH(CO)₂(PPh₃)₂;在合成气压力较低时,只转化为RhH(CO)(PPh₃)₃;此活性物种随催化剂失活而消失。催化剂加氧失活后,检测到配位体三苯基膦氧化为氧化三苯基膦,催化剂生成二聚物,丙烯氧化成丙酮,追踪到原料气CO氧化为CO₃的动态过程。本文对"原位"红外光谱实验方法、高温高压红外池作了介绍,并给出有关实验数据和结果。     

“焰色反应”实验的创新设计

针对教材中“焰色反应”实验存在的不足,通过对“焰色反应”原理及条件的分析,进行了4大实验创新设计,获得异彩纷呈的实验现象,充分激发了学生的学习积极性,培养对化学的热爱。本课的创新改进实现了对教材内容的二次开发,充分发掘了化学实验的教育功能,让课堂焕发活力。     

高中有机化学教学中提升核心素养并体味科学价值*——以“乙炔的化学性质”为例

介绍了“乙炔的化学性质”的教学设计思路,展现了如何利用创新实验、丰富素材和问题讨论,帮助学生理解有机物性质和结构之间的关系。主要涉及以下几个环节:(1)通过课前自主预习,从乙炔与乙烯的相似性入手,预测乙炔的性质,了解乙炔的实验室制法;(2)结合2个创新分组实验“基于井穴板的微型化气体连续制备和性质检验装置”“利用真空输液瓶、微型样品瓶和注射器的密闭气体微型反应装置”,教师和学生一起巩固了乙炔的实验室制法,验证了预测的化学性质,丰富了对乙炔性质的感性认知,发现了“乙炔不能使酸性K₂Cr₂O₇溶液褪色”的异常现象;(3)从尝试解释异常现象入手,教师和学生一起从键能、加成比例、聚合后主链结构等多个角度探讨了乙炔与乙烯性质和结构的差异,建立起有机物官能团与性质关系的认知模型;(4)通过尝试利用模型解释2000年诺贝尔化学奖“导电高分子”和2017年度国家自然科学成果一等奖“AIE聚集诱导发光材料” 的结构、性质与应用,教师和学生一起提升了对认知模型的理解建构,感悟了科学研究的乐趣,体会化学科学在促进人类文明发展和社会进步中的重要作用。     

变量控制在实验探究专题教学中的应用与评价*——以“镁+水”反应体系为例

在以“Mg+H₂O”反应体系为核心的实验探究专题教学活动中,通过变量控制的方法设计实验方案,采用常规实验、数字化实验等方式,多层次探究加速“Mg+H₂O”反应速率的原因和控制条件。在有层次的教学活动中递进式发展学生通过变量控制的方法设计实验方案的能力、拓宽对影响化学反应速率因素的认识角度,通过对活动环节的评价,诊断并发展学生的实验探究能力。     

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。     

“离子迁移”实验的改进及其实验条件优化*

针对“离子迁移”实验中实验现象不明显、实验操作难度大的问题。采用将CuSO₄、K₂CrO₄与淀粉加工成热的糊状流体,趁热装入U型管,冷却后变成半固体的方法,解决了上述问题。并采用单因素实验法对淀粉的用量、CuSO₄与K₂CrO₄混合物的用量(CuSO₄与K₂CrO₄物质的量之比为1∶1)以及迁移电压等实验条件进行优化。优化后的实验结果显示,离子迁移后形成的区域颜色与半固体淀粉的颜色差别很大,便于学生远距离识别。该方法操作简单、现象明显,有利于一线教师的教学演示和学生的分组实验。     

以实验和论证为杠杆撬动化学概念深度学习*——以“分子与原子”教学为例

以倡导“理解与批判、联系与构建、迁移与应用”的深度学习为理念,围绕“分子与原子的概念”比较教材与文献的设计思路,调整认知脉络,着力解决“概念学习过程中实验探究少,宏观现象进入微观分析的相关实验不匹配,忽略证据推理、变化观念与平衡思想核心素养”等不足。设计“3种形态的碘与淀粉的反应、H2O2溶液与品红反应、H2O2溶液的分解反应”3组实验,设置学生画分子模型、画H2O2分子分解的微观过程等活动,提炼“物质种类、分子种类、物质性质之间的关系是什么？你从实验中找到哪些证据支持观点？前2个单元的实验,还有哪些可作为论证的依据？”等问题,引发学生充分论证。“实验、活动、问题、论证”环环相扣,促成教学内容的有效结构化,通过化学概念的深度学习实现化学学科核心素养的发展。     

“宏观辨识与微观探析”视域下的初中化学教学*——中和反应

在“宏观辨识与微观探析”视域下进行中和反应教学,首先以常规实验为载体,从宏观视角认识中和反应的外在表现,然后以模型、动画为载体,从微观视角了解中和反应的微观过程,再以数字化实验为载体,从宏观与微观相结合的视角理解中和反应的内在本质,最后联系生产生活实际,体验中和反应的应用价值。这样设计,学生能深刻理解中和反应的本质,增进化学学科理解,培养化学学科核心素养。     

初中化学(科学)启蒙教材中“实验”“插图”“科普知识”的比较分析*

我国大陆和台湾的化学(科学)教材在化学启蒙方面的内容编写有着各自的特点和优势,因此以我国大陆人教版初中《化学》与我国台湾康轩文教版《自然与生活科技》为例,通过问卷调查法与对比分析法,研究化学启蒙阶段的学生对待化学的态度以及海峡两岸教材中“实验”“插图”“科普知识”等3部分内容的设置差异。结果表明:(1)化学实验是启蒙阶段学生对化学感兴趣的起始点,也是初接触时的难点,其中以我国台湾《自然与生活科技》教材中化学实验的探究性及层次性更深;(2)化学启蒙阶段教材中插图的科学性、清晰度以及精美程度对学生学习化学的兴趣和态度有较大影响;(3)化学教材中的模型图实物化有助于学生拨云见日,了解化学的真实模样。     

“实验化学”翻转课堂教学案例设计

针对实验化学课程的特点,探讨了实验化学“课前知识传递,课堂知识内化,课后反思提高”的翻转课堂教学设计。以“硫酸亚铁铵的制备”为实验案例,通过翻转课堂在学习目标、活动主体与教学流程上的教学设计,详细阐述了以学生为中心的教学实施,并全面评价了教学实践。     

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.