氯气和氨酸钾的制备微型化实验研究

氯气和氯酸钾的制备及性质实验是师范院校化学专业无机化学实验的重要内容。按教材[1]进行实验,药品用量大,实验成本高,废弃物多,污染严重。     

适合学生探究氯气性质的微型实验装置

氯气的制备及其化学性质的研究是高中化学课程中的重要部分。然而,氯气的毒性和危害是学生亲自进行氯气制备和性质实验的最大障碍。本文运用微型实验的思想对氯气的制备和性质实验装置进行了精心设计,大大降低了氯气的危害程度,达到了能让学生安全操作的水平;同时,该套实验装置也同样适用于其他有毒气体的制备和性质研究。     

利用针管进行氯气有关性质实验的研究

新课程背景下的化学实验更应突出绿色化、微型化、定量化、探究性和趣味性,在进行氯气性质实验时,为了解决氯气的污染问题,体现无(低)毒、低污染原则,利用针管进行氯气溶解性实验、氯水漂白性实验、氢气在氯气中燃烧实验,实验现象明显,操作简便,很好地发挥了实验的教育功能。     

新课标下的氯气漂白性质的实验改进

为解决氯气漂白性质实验的繁琐和环境污染等问题,对该实验的装置、材料、演示方法进行了探讨,设计了在密闭的装置里进行实验的新方案,取得了良好的实验效果。     

基于自封袋和塑料点滴板的氯气性质实验设计

通过运用自封袋和塑料点滴板等微型装置设计实验,并选用浓度较稀的盐酸和次氯酸钠溶液反应来制取氯气,采用滤纸来扩大性质实验中溶液的接触面积,可以很好地完成氯气的氧化性、氯气与碱反应、氯水的漂白性以及氯离子的检验等实验。该微型实验设计绿色环保,操作简便。     

钠在氯气中燃烧实验的改进

指出了现行高中化学教材中钠在氯气中燃烧实验的不足,详细介绍了改进后的实验装置及其实验方法,简化了氯气制备及其实验过程,保障了整个实验在封闭体系内进行,解决了钠在氯气中燃烧实验严重污染环境问题,从而培养了学生的环保意识。     

12-钨硅酸制备的微型实验研究

12-钨硅酸制备是大学教材《无机化学实验》中的常规实验。该实验为验证型实验，探究性和综合性不足，实验药品用量大，安全性低。从《化学类专业本科教学质量国家标准》出发，考虑实验设计性、综合性和安全性，对该实验进行了改进，包括无机物的制备、结构表征和性能测定。微型实验和单因素实验探讨Si∶W₁₂配比、温度和时间等对乙醚萃取法制备12-钨硅酸的影响；用紫外和红外光谱表征产品结构；用电化学工作站测定产品的电化学性质。通过实验，引导学生掌握科学系统的研究方法，加深绿色化学理念，进一步理解结构-性能的密切关系，了解杂多酸在科研领域中的应用，培养学生的综合实验能力和创新能力，为后续进行毕业论文和从事科研工作打下基础。     

二氧化硫性质实验改进

二氧化硫具有酸性氧化物的通性、还原性、氧化性和漂白性,这些性质在新课讲授中都要通过实验验证,因为二氧化硫以及相关药品有毒,实验过程中很容易造成教室环境污染,影响学生的身体健康,鉴于此,我对二氧化硫性质实验进行了改进,取得了很好的效果.     

微型实验“氯气的制备与性质”在高三复习中的应用

微型实验“氯气的制备与性质”试剂用量少,有害气体排放少,实验目的达成率高,是教材编写、试题命制及学生课外活动青睐的实验素材之一。高三一轮复习中,该实验的恰当引入可以提升复习效率,实现知识、能力的双重提升。1实验方案的选择和改进     

改进氯气实验,降低空气中毒气含量的探索

为了降低化学实验中排放到实验室空气中毒气的含量,使有关这方面的演示实验,能改为同学自己操作的分组实验,以增强我们的感性认识和实验能力,我选择了卤族中氯气性质的有关实验,加以改进,将原来由集气瓶收集氯气的方法,改为用18×180(实际容量为32ml)的试管进行收集,在相同的实验室条件下,获得了相同的实验效果。经我多次反复测定,改进后实验室空气中氯气实际含量平均为0.32ppm,小于允许浓度1ppm,因此使这一重要的基础实验直接由学生分组进行成为可能,对增加和加强分组实验,有普遍意义。     

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%.     

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.     

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.     

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.     

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.     

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.     

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.     

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.