Aryl diazonium salts are a class of important synthons in the field of organic synthesis due to their versatile reactivity and easy availability. Despite the widespread use of the denitrogenation-type cross-coupling, reduction, and azo-coupling reactions of aryl diazonium salts, the cycloaddition reactions of aryl diazonium salts have long been neglected. Noteworthy is that recent renaissance in this type of reactions has open powerful access to a diverse array of N-heterocycles. This minireview summarizes the latest development and applications of cycloaddition reactions of aryl diazonium salts as well as their new opportunity in organic synthesis.
In order to implement President Xi's speech on the national conference of ideological and political work in universities, and build a collaborative education mode of ideological and political theory course in the same direction with all kinds of courses, the important practice about utilizing the classroom teaching to educate students has been investigated. In this paper, an example of instructional design about integrating the intellectual education and moral education in the introduction section of inorganic chemistry is discussed, including the setup of learning goal, the selection and presentation of teaching content and development of teaching activities.
Based on the self-built online open course and internet teaching resources, the online and offline mixed teaching mode were carried out in physical chemistry laboratory. The "problem-based and student-centered" teaching processes were designed to carry out the inquiry learning and process evaluation. The students' abilities were trained stage by stage before, during and after class to improve their autonomous learning ability, comprehensive ability and innovation ability. The results achieved provide valuable experience for the exploration of online and offline mixed experimental teaching mode.
Nowadays the course of medical organic chemistry experiments has many problems, such as unitary content, traditional teaching mode, limited hours, and the inadequate attention to the course. In this paper, a blended teaching mode of medical organic chemistry laboratory was introduced. The construction includes the change of teaching methods, the enrichment of teaching contents, the introduction of virtual simulation experiments, and the improvement of evaluation system. It is found that the blended teaching mode could better develops students' innovative thinking abilities, and offers effective basis for education reform. At the same time, it offers an opportunity for students to learn anytime and anywhere.
Taking the synthesis of coumarin-3-carboxylic acid as an example, we propose shifting the traditional lab training style from following directions to finishing a project. The results show that, the transition prominently improves the students' interest in organic chemistry and their motivation to explore theoretical knowledge. On the other hand, it enables students to prepare themselves for participating in scientific research.
A series of innovative teaching practice are carried out from the aspects of thought updating, content optimizing, method improving, means updating, integration strengthening and penetration enhancing, under the guidance of the teaching thoughts of "student-centered, and focusing on the cultivation of students' interest and ability, especially the ability of sustainable development and innovation". The practice aims at the key points and difficult problems in the teaching and the weaknesses in the learning of polymer chemistry, based on the analysis of students' learning situation. Good teaching results and a series of innovative teaching accomplishment have been achieved, and the course has been constructed into a provincial first-class course.
Following the philosophy of "student-centered and improving basic scientific literacy", the contents and teaching forms of the laboratory course were redesigned, and the teaching resources such as the laboratory courseware, the experimental procedure video, the virtual simulation experiment, the test question bank and expanded reading materials were constructed. Blended online/offline teaching practice was carried out for 92 classes through the Super Star Learning platform. The reform has greatly stimulated the enthusiasm and initiative of students, imperceptibly improved students' scientific literacy and achieved good teaching effects. It also provides a useful reference for the teaching reform of related laboratory courses.
Through the three-dimensional curriculum system in which the teaching materials and the in-house built MOOC platform complement each other, the learning channel is expanded. Through content guidance and task driven, the "three-dimensional integration" online and offline hybrid teaching mode effectively promotes students' autonomous learning. The teaching content and teaching schedule design can be adjusted in real time according to the feedback of students' learning effect. Through the association between teaching objectives and learning activities, we can strengthen students' autonomy and participation in the teaching process, and use process evaluation to stimulate students' internal driving force in learning, so as to help students regulate the learning process and promote deep learning.
This paper analyzes and compares the structure of cubic diamond and hexagonal diamond, and emphasizes the structural differences between cubic crystal and hexagonal crystal. The template of tetrahedral four coordination and tetrahedral four coordination coupling with linear two coordination crystal structure is established based on the diamond structure, and employed to analyze the material with similar structure.
After the discovery in the year 1886, Molisch's reaction used to be applied as a powerful tool to differentiate carbohydrates and glycosides qualitatively from other materials. A brief review is given herein on the discovery, reaction mechanism and application of Molisch's reaction. Perspectives are also given on the potential applications of Molisch's reaction.
Ion transference number is an important parameter of physical chemistry, and its measurement is the basic content in physical chemistry laboratory. Based on the measurement of ion transference number in "Basic Physical Chemistry Laboratory", combined with measurements of the electromotive force, a new experiment was designed for measuring the transference number of copper ion and sulfate ion in solution, and the ion transference numbers obtained are basically consistent with the values in the literature. We attempt to use the laboratory skills that college students already mastered in physical chemistry laboratory and integrate the knowledge of electrochemistry to design and explore a new method for measuring ion transference by the electromotive force method. The students' comprehensive ability can be improved to solve problems.
In this paper, the experimental process including fabrication, characterization and electrochemical measurements of the composites is believed to be helpful for students to understand the connections between the knowledge of the fundamental chemistry, enhance laboratory skills and improve the innovation mind and comprehensive capability. In addition, students could also be aware of the electrochemical energy-storage frontiers, stimulating their research interest and scientific research ability. Hence, this experiment is appropriate for the comprehensive chemical laboratory curriculum of junior students majored in chemistry and applied chemistry.
This study introduced a comprehensive experiment of green polymer chemistry. Phenylacetylene was polymerized by using organic rhodium complex as the catalyst in the aqueous solution. The molecular structure and photothermal properties of phenylacetylene (PPA) were characterized by fouriter transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), ultraviolet-visible spectrophotometer (UV-Vis), fluorescence spectrometer and thermogravimetric analyzer. Furthermore, this designed experiment is easy to operate and can use the solvent as a variable factor to inspire students to think actively. The experimental content covers the knowledge points of polymer chemistry, applied spectroscopy and polymer instrumental analysis and characterization. The implementation of this experiment can not only improve the students' comprehensive ability to use professional knowledge, but also cultivate the students' systematic scientific research thinking and environmental protection awareness.
Thermodynamics tells that solid state reactions will not stop until they complete, and will not be affected even when a small amount of solvent is used. Here, we report that solid MgCl2·6H2O and solid NH4Cl react to produce NH4Cl×MgCl2·6H2O in half an hour at room temperature, with the help of a little water that just submerges the solids. This experiment will introduce the concept of less solvent solid state reactions and their applications in green chemical processes, and it can also make the student know how to freeze a reaction to fit to the ex situ kinetic studies.
The digital reform of textbook is an inevitable trend in the "Internet Plus" age and the relevant explorations have been widely carried out throughout the world. It's a new idea for Xiamen University to develop a "dynamic" textbook library for chemistry experiments. This paper mainly introduces a detailed consideration for "dynamic" textbook library and an overall design of its implementation. The aim is to provide reference experience for the construction of chemistry laboratory textbooks.
Based on the concept of integration of science and education, the scientific research project "Nano-ZnO Pigment Thermal Control Coating" is transformed into an experiment in materials chemistry laboratory for undergraduates. Nano-ZnO prepared by organic amine-assisted hydrothermal method is used as the pigment, and the thermal control coating is obtained by the blade coating method. The experiment has the aerospace and defense background and covered chemistry, materials and energy disciplines which exhibited novelty, practicality and operability. Students can obtain basic scientific research training from the synthesis method and characterization technology of pigment powder, coating preparation and optical performance testing. It is conducive to cultivate students' home country feelings, laboratory skills, exploration and innovation ability, deepen the theoretical knowledge and stimulate students' interest in scientific research.
Cryo-polymerization is a newly developed polymerization technique. Its polymerization temperature is below the freezing point of the medium and the polymerization locus is indeed the liquid microphase (about 10%, volume percent) embedded in the frozen bulk. Due to the low polymerization temperature as well as the highly concentrated monomer in the polymerization locus, cryo-polymerization facilitates the preparation of (ultra) high molecular weight polymers. In this experiment, the cryo-polymerization of acrylamide and acrylic acid is performed separately, the molecular weight of the obtained polymer is modulated by varying polymerization parameters and determined by the dilute solution viscometry method. This experiment can prompt students to grasp the primary principle to control molecular weight of radical polymerization, utilize Mayo equation flexibility and learn some laboratory skills through watching out the experimental details, leading to acquisition of the ability to design experiment.
Myoglobin is not only easily available, but also an inherent complex between protein and porphyrin ligand. Therefore, non-covalent complex of myoglobin was selected as the research model for teaching experiment to lead the senior students to practice the direct screening strategy of enzyme inhibitors by electrospray multistage mass spectrometry. Through comparing the effects of different sample preparation conditions on the MS determination of the complex, including organic solvent content and pH, students will understand the importance of sample preparation for MS analysis and grasp how to use MS/MS technology to achieve online qualitative analysis of functional small molecule ligands. The experiment here has been used for a few years as one of the teaching experiments in "comprehensive chemical biology experiments" course for undergraduates majoring in chemical biology at our college. With continuous teaching practice and optimization of the experiment, some good teaching effects have been achieved.
A comprehensive chemistry experiment is recommended for the preparation of a self-healing supramolecular elastomer. In this experiment, the preparation method, structure characterization and the self-healing property of the polymeric complexes were mainly included. Through this experiment, students can master the characteristics of supramolecular interactions and their application in the field of preparing self-healing materials. This experiment helps broaden students' chemical vision, and plays an important role in cultivating students' innovative ability and comprehensive application ability of knowledge.
First, p-phenetidine and acetic acid were used as starting materials, and then acetic anhydride was added through nucleophilic substitution reaction to obtain phenacetin. The structure was identified by 1H-NMR. The components of compound aspirin were analyzed by thin layer chromatography and high performance liquid chromatography, and then the relations and differences between the two chromatography techniques were discussed. This experiment covers the experimental skills such as reflux, centrifugation, recrystallization, NMR, thin layer chromatography and high performance liquid chromatography, and can help the undergraduates improve their analytical abilities.
Taking Chaozhou Gongfu tea culture as the background, based on the traditional brewing technology of Gongfu tea, the antioxidant activity of tea soup was used as the evaluation index to explore the optimization conditions of brewing technology of Gongfu tea. The content of the experiment includes a series of learning tasks, such as literature research, experimental scheme design, experimental operation, data processing and essay writing. The results of practical teaching show that the integration of traditional tea culture into experimental teaching is easy to stimulate students' interest in learning and transfer cultural genes. To guide students to put forward problems from the source of cultural life, to analyze and solve problems with scientific methods will help students to be familiar with the scientific process and develop correct habits of scientific thinking. At the same time, students in practical activities will touch on multiple disciplines and multiple laboratory skills training, which can comprehensively improve students' comprehensive quality and achieve the goal of curriculum education.
Chemical equilibrium is an important teaching content of physical chemistry course. In this paper, the existence, uniqueness and stability of chemical equilibrium state are discussed systematically and comprehensively for reference in chemistry equilibrium teaching.
The disconnection approach is applied to teaching of polymer chemistry. The disconnection strategy for usual polymer synthesis problem is proposed, the rules are summarized, and the usual polymer synthesis problem is categorized. These approaches made it easier for the students to handle polymer synthesis problems, to learn the method and have the ability to learn. Accordingly, a new classification of polymerization reactions is suggested, which classifies polymerization reactions into three categories by occurring between functional groups, via opening of double bonds, and by opening of rings. It is also summarized that the disconnections in polymer synthesis are usually made between the units along the main chain, between the main chain and the side groups, between the main chain and the branches, and between the main chain and the end groups, and at the position of the functional groups or the heteroatoms.
The kinetic features of the nitration reaction of aromatic compounds were discussed. The structure dependence of the rate-determining step and therefore the rate equation is derived. Based on these discussions, the influential factors of nitration reaction are analyzed and the reaction conditions are optimized. For addition of dehydration agent, the possible mechanism is proposed based on which this rate equation and optimal conditions are discussed. This can be used as a good case for case-study for application of the principle of physical chemistry in organic chemistry so as to deepen the students' understanding of condition optimization.
The law of contradiction, the dialectical relationship between the dynamic and the static state, and that between the whole and the part were used to solve the qualitative problems of fluid flow. The problems include the variations of friction loss, static pressure and flowrates in simple and complicated pipelines. The teaching practice showed that solving the above problems by philosophy principles has the characteristics of clear principles, accurate and quick judgement, and could enhance the students' dialectical ability. This method was approved and received by the greater part of the students.
Inductive and deductive methods are important for organic chemistry learning. The effects of hydroxyl and methoxy groups on carboxylic acid acidity in several systems are analyzed. The influence of hydrogen bonding on carboxylic acid acidity varies in different systems.
The hcp and ccp are the two main structures that most metals adopt. The tetrahedral holes and octahedral holes in these structures are commonly difficult for students to grasp. In this paper, we focus on the arrangement of the holes in the close-packed structures. This is also very helpful in learning ionic crystals.
The kinetic differential equations of reaction systems were introduced. By using the fourth-order Runge-Kunta numerical integration method and Visual Basic 6, a general kinetic simulation software was obtained. The relations between the concentrations of every component with time at a fixed temperature were directly calculated. The teaching practices on physical chemistry and other courses shown that this software could directly display the relationships between the concentrations of every component of the reaction system and the influencing factors such as time and temperature, which would be helpful for students to grasp the laws of reaction kinetics and the knowledge points of the courses.
Generally, the bigger π bond order of conjugated olefins is corresponding to the shorter bond length. However, some π bond orders of naphthalene calculated by the Hückel molecular orbitals (HMO) method do not match the experimentally measured bond lengths, thus many students questioned the accuracy of the computed results using the HMO method. In this work, we employed ab initio Hartree-Fock (HF) method and suggested a revised HMO method with correction factor to recalculate and provide more reasonable π bond orders of naphthalene. By comparing the results calculated by the semi-empirical HMO and HF methods, this article can make the students understand origin of the computational error by using HMO method.
The basic functions and features of Visual MINTEQ, a software for chemical equilibrium modeling, are presented in this paper. Some examples were given to illustrate the usage and application of this program in college chemistry teaching, including pH calculation of buffer solution, acid-base titration simulation, chemical species distribution curve plotting and precipitation-dissolution equilibrium prediction. It was found that the application of Visual MINTEQ software not only enriches the form of classroom teaching, but also improves the students' understanding and mastery of relevant theoretical knowledge, thus establishing a scientific and efficient research method for students' future studying career.
Organic fluorides have been widely applied in various spheres, especially in the medical field. However, due to the distinctive reactivity of fluorine, the introduction of fluorine atom has always been a problem in organic chemistry. As a novel synthetic method developed in recent years, organic electrochemical synthesis has greatly expanded the boundaries of organic reactions, which have enabled the development of many efficient and eco-friendly fluorination methods. In this paper, we will focus on these examples of electro-chemical fluorination, and discuss the possible role of electrochemical methods in the field of fluoro-chemistry.
By reviewing and combing the literatures about Chinese Chemistry Olympiad (referred to as CChO), it was found that the studies on CChO by Chinese scholars are concentrated in five parts, including the analysis of the competition test questions, the strategies of training competition, the competition situation of regional area, the commenting on competitions and the comparative analysis of domestic and international Chemistry Olympiad. The results suggest that the competition test questions and the strategies of training competition are two major hotspots. There are only a few studies on the development in Chemistry Olympiad of regional area. In the researches on the strategies of training competition, Chinese scholars have focused on the cultivation of students' thinking and problem-solving skills and gradually began to pay attention to the students' interest, independent learning, and cooperative learning. As the core literacy of chemistry is proposed, some scholars have successively carried out the studies in the combination of the chemistry education hotspots with Chemistry Olympiad (mainly focus on the test questions and the strategies of training competition).