Nucleoside Chemistry and Flash Chromatography: An Integrated Approach to Teaching an Organic Chemistry Laboratory

We report here the development of an integrated approach to teaching an organic chemistry laboratory. The laboratory exercise focused on the syntheses of two modified nucleosides and used the syntheses as a vehicle to teach organic chemistry from the point of view of how science is done in the real world. The project not only taught advanced organic bench techniques, but also drew heavily from the basics of molecular biology. The laboratory exercise was taken from the work accomplished in an industrial research laboratory and introduced during the spring semester of 1998. Each three person group was provided with a file containing the relevant literature and given the task of completing the synthesis and purification in a three week period. The groups were encouraged to handle the science and chemistry in a manner similar to a research group in an industrial or academic setting. Each group presented their results in a written paper and an oral presentation.     

Characterizing the Gel to Liquid Crystal Transition in Lipid-Bilayer Model Systems

A laboratory exercise that introduces differential scanning calorimetry (DSC) is presented. In order to connect this basic physical chemistry technique with an application in the biological sciences, students investigated the thermodynamic properties of lipid-bilayer model compounds. DSC was used to characterize the gel-to-liquid-crystal transition for three phosphatidylcholines of varying acyl chain length. The laboratory exercise is suitable only for students with some background in physical chemistry and biochemistry.     

Determination of Arsenic in Drinking Water by Graphite Furnace Atomic Absorption Spectroscopy. An Undergraduate Instrumental Analysis Laboratory

A laboratory exercise, the analysis of arsenic in drinking water by graphite furnace atomic absorption spectroscopy (GFAA), is presented for use in an undergraduate instrumental methods course. The purpose of this GFAA exercise is to expose students to a practical and commonly used application, to provide students with hands-on experience with the instrument, and to reinforce concepts taught in the classroom. Students safely analyze a real-world sample containing an analyte in the parts-per-billion concentration range.     

Purification of Three Spectral Isoforms of Recombinant Fluorescent Protein from Insect Bioreactors Infected with Recombinant Baculovirus

Recombinant peptides and proteins have a wide range of applications, especially in medicine and biomedical research. Methods to rapidly and inexpensively manufacture recombinant proteins are needed to realize the full potential of proteins in medicine and to broaden their applications. A one-semester-length laboratory exercise is reported here demonstrating the use of the insect bioreactor system to create recombinant proteins. These laboratory exercises are suitable for students majoring in biochemistry or biotechnology and can be used to teach students basic biochemistry laboratory techniques including bacterial transformation, plasmid DNA isolation, insect cell culture, production of recombinant virus, use of recombinant viruses to deliver transgenes to a living organism, protein isolation by precipitation and chromatography, and protein quantification and protein characterization by electrophoresis and western blotting. The techniques acquired can also be used as the basis for related independent research projects in the second semester.     

Applications of benchtop NMR in the organic chemistry instructional laboratory

The instructional organic chemistry laboratory has been substantially improved through the implementation of benchtop NMR analysis. When used in conjunction with unknown reaction components in multi-outcome experiments, NMR analysis transforms the laboratory exercise into an investigative inquiry wherein students elucidate structures for their products and thereby deduce their unknown reaction components. This analytical approach closely models the research laboratory and is a valuable preparatory tool for undergraduate researchers. Three newly developed multi-outcome experiments based upon the Diels–Alder cycloaddition, the synthesis of carboxylic amides, and the Friedel-Crafts alkylation are herein described to illustrate the utility of benchtop NMR analysis in the instructional laboratory.     

An Investigation of Electrolyte Solutions Using a Simple Conductivity Apparatus

A student laboratory exercise in qualitative analysis has been developed to address student misconceptions associated with electrolyte and nonelectrolyte solutions. This exercise uses a previously reported, inexpensive, home-built conductivity meter to identify acid solutions. An additional short preparatory exercise provides students the opportunity to classify known solutions as strong, weak, or nonelectrolytes and gives students experience using a conductivity meter. These activities have been used successfully with both high school and introductory college chemistry students.     

The Big Freeze: Water and the Scientific Process

In recent years there has been increasing movement toward laboratory exercises that are inquiry-based, requiring students to assume more active roles in the learning process. A laboratory experiment was developed in this light, framed around a simple question, “Which freezes faster, hot water or cold water?” The experiment was used at the beginning of the general chemistry year-long course sequence and served as an introduction to the scientific process. Students were each asked to develop a hypothesis and then design a simple experiment to determine which freezes faster, hot water or cold water, using small cold baths to freeze the water. A strength of this experiment is that students not only design and perform the experiments, but at the end they evaluate each other’s methods.     

Qualitative Analysis of Herbs by Gas Chromatography/Mass Spectrometry (GC/MS). An Undergraduate Instrumental Analysis Laboratory Exercise

A laboratory exercise to be used in an undergraduate instrumental methods course is presented for the qualitative analysis of interesting real-world herbal extracts. The objective of this experiment is to familiarize students with a modern experimental method gas chromatography/mass spectrometry (GC/MS).     

A New Laboratory Experiment Based on a Chemical Transformation of Santonin: Synthesis of Santonic Acid

In this paper we describe a new comprehensive laboratory experiment based on a chemical transformation of santonin. The experiment is designed as a puzzle-solving exercise for advanced undergraduate organic chemistry courses and consists of the structure elucidation of santonic acid, the product obtained by the action of strong alkalis on santonin. An enquiry-based approach helps the students achieve this goal by combining their knowledge of organic chemistry and spectroscopy together with mechanistic thinking.     

A Colorful Investigation of a Diprotic Acid: A General Chemistry Laboratory Exercise

A general chemistry laboratory experiment that can be completed in a single laboratory period is described that familiarizes students with the acid—base chemistry of a diprotic acid and with the use of visible spectroscopy to determine species concentrations. This experiment is a modified version of a previously described laboratory exercise developed for an upper-division quantitative analysis course. Students work in teams and as a class to generate different ionization states of various highly absorbing dyes. Both spectroscopic and potentiometric (pH) data is collected using LabWorks II stations, but other inexpensive pH meters and visible spectrometers (e.g., Spec 20s) are suitable. A spreadsheet template is used to determine the percent composition of various ionization states of a diprotic acid and to determine the pK_a values. Besides introducing students to fundamental tools and key chemical concepts, this laboratory is also inexpensive to operate and utilizes nontoxic, colorful solutions.     

A LABORATORY INVESTIGATION OF TWO ULTRAVIOLET SPECTRORADIOMETERS

Abstract— Spectral measurements of the solar UV irradiance at the earth's surface depend critically on the characteristics of the spectroradiometers and the procedures used in their calibration. Two UV spectroradiometers were subjected to a series of laboratory tests to investigate which factors were most significant in limiting the reliability of the absolute irradiance measurements. Three independent standards of spectral irradiance were scanned by both instruments under a range of bench conditions. The results were consistent to within about 3%, most of the uncertainty being due to scattered light in the laboratory. An UV laser was used to determine the slit function of each spectrometer and the influence of internal stray light. Significant departures from the ideal cosine and azimuth responses were measured by a xenon lamp. Both spectroradiometers were kept indoors throughout the experiments. The relevance of these laboratory results is discussed with respect to the task of measuring solar UV radiation in the field.     

Evolution of catalytic function

An RNA-based evolution system was constructed in the laboratory and used to develop RNA enzymes with novel catalytic function. By controlling the nature of the catalytic task that the molecules must perform in order to survive, it is possible to direct the evolving population toward the expression of some desired catalytic behavior. More recently, this system has been coupled to an in vitro translation procedure, raising the possibility of evolving protein enzymes in the laboratory to produce novel proteins with desired catalytic properties. The aim of this line of research is to reduce darwinian evolution, the fundamental process of biology, to a laboratory procedure that can be made to operate in the service of organic synthesis.     

An Instrumental Analysis Laboratory Using Electrogenerated Chemiluminescence

An undergraduate instrumental analysis laboratory exercise is presented for the characterization of light emission generated using electrochemiluminescence (ECL). ECL involves the electrochemical generation of excited states and as such is a sensitive probe of electrochemical, electron-transfer and energy-transfer processes at electrified interfaces. An objective of this experiment is to have students develop an understanding of the mechanisms and factors affecting ECL. Also, this exercise gives students experience in coupling two powerful analytical techniques: electrochemistry and spectroscopy. With the recent development of ECL technology for use in clinical diagnostics applications, this exercise also facilitates discussions on the importance of basic research and the practical aspects of taking a technology from the bench top to commercial reality.     

Evaluating Experiment with Computation in Physical Chemistry: The Particle-In-A-Box Model with Cyanine Dyes

The results from a classic experiment in the undergraduate physical chemistry laboratory, the particle-in-a-box model for spectroscopic transitions of conjugated dyes, is compared to computational results obtained using a molecular mechanics structural approach and the extended Hückel molecular orbital picture. The goal of this exercise is to help students to think critically about their experimental data and to use comparisons of mathematical and computational models to try to understand departures of an experiment from expectations.     

Incorporation of Phytoremediation Strategies into the Introductory Chemistry Laboratory

An undergraduate laboratory exercise appropriate for introductory chemistry courses at the high school or college level is presented. The objective of the laboratory is to introduce the idea that plants can be used to remove contaminants from the environment–a process called phytoremediation. This laboratory connects the disciplines of chemistry and biology while enabling students to learn the skills of measurement, titration, calculation of molarity of an unknown solution, graphing, and interpretation of data.     

“一定溶质质量分数的氯化钠溶液的配制”项目式教学*——自制洗鼻液

以“盐水洗鼻”中洗鼻液的配制为抓手和主要任务,通过学生将任务拆解成子任务并转化为化学问题,在合作探究、实际操作中,掌握溶质、溶剂及溶质质量分数之间的关系,配制出符合标准的洗鼻液。     

How to increase the service temperature of polystyrene

In this overview we describe more recent attempts to raise that temperature range of polymeric systems containing styrene as the major starting monomer in which an article will loose dimensional stability under specified conditions. A search in the literature, both in journals and patent applications, over the last five years reveals a wealth of possibilities to perform this task. However, only a few of these have reached the commercial status, mostly due to reasons.     

Liquid scintillation measurement of40K for the education on radioactivity

Liquid scintillation counting of⁴⁰K in ordinary potassium propionate is a highly suitable experimental task in the general education on radioactivity. The counting efficiency is about 90%, depending little on the measurement conditions. Potassium propionate is of suitable properties and can be easily obtained commercially or by conversion from other compounds. The result of counting, about 1,700 cpm/g, is highly impressive to many students, indicating the existence of⁴⁰K radioactivity unexpectedly high in the normal nature, and can be used for the exercise of calculating our internal radiation exposure.     

基于绿色化学理念的苯甲醛与安息香的相互转化

为了在基础教学实验中引入绿色化学理念以及强化氧化还原反应操作,本文设计了苯甲醛和安息香的相互转化实验:以苯甲醛为原料经维生素B1催化得到安息香,再用硼氢化钠还原安息香得到二苯乙二醇,二苯乙二醇用新型绿色催化剂NaMnOx氧化回到苯甲醛。通过氢核磁共振(1H NMR)对氧化还原反应的产物结构进行了鉴定,液相色谱分析结果表明氧化反应转化率达到90%以上。通过这一循环转化反应的实现,一方面树立了学生的绿色化学理念,另一方面加强了氧化及还原反应的操作训练,在进一步锻炼学生实验能力的同时,使其对化学反应的认知与评价更加完整。