Microscale and Miniscale Organic Chemistry Laboratory Experiments, 2nd Edition

To the Student

The Importance of Laboratory Work
Why perform organic chemistry laboratory work? It is because discoveries in this very important field are often made in the laboratory. There is no substitute for proving or disproving a new idea by direct experimentation. Even so, not all great discoveries are planned. For example, Dr. George Papanicolaou discovered what is now known as the Pap smear to test for cervical cancer while he was researching something quite different-the role of chromosomes in determining gender. This serendipitous and thrilling discovery was made in a laboratory setting. Dr. "Pap" was an experienced laboratory worker and was a keen enough observer to take advantage of this accidental discovery.

Not all chemistry students ultimately become researchers looking for new scientific discoveries. Many pursue careers in the health professions. Still others pursue careers outside of science and outside of the laboratory. It is very important for society's leaders to be knowledgeable and appreciative of the importance of laboratory science. By encouraging an open, creative scientific atmosphere, new discoveries can be made that continue to benefit society as they have done so remarkably in the past 200 years. Recent advances in lifestyle worldwide are traceable directly to hard work of scientists in many disciplines, which are largely due to experimental work. For chemists, this work takes place mainly in the laboratory. The discoveries of Teflon, penicillin, malaria vaccine, birth control pills, aspirin, and AZT were directly attributable to laboratory work. James Watson and Sir Francis Crick deciphered the genetic code only after the necessary clues were made available from laboratory experiments. Forty years after elucidation of the code, the characterization of the entire set of human genes is being uncovered. Highly specialized experimental laboratory techniques have been essential to reveal the required information.

Students and Laboratory Work
As important as laboratory work has been for society, all organic chemistry students deserve a taste of experimental work in a required laboratory curriculum. Certainly, some students in your class will become scientists and even research scientists, but many others will not. Is it really necessary to have a laboratory curriculum for every introductory organic chemistry course?

Past students offer the best insights into this question. These students have entered all walks of life. Many remember the laboratory as the reason they got through courses in organic chemistry. The laboratory helps to bring meaning to the equations and reactions. Seeing a yellow organic solid helps a student appreciate the relationship between structure and spectroscopy. Solving the structure of an unknown compound through experimentation gives a student a feeling for how scientific discovery can work. Learning in the laboratory is a combination of many factors: careful planning and understanding of what is to be done and why, carrying out the plan, making insightful observations, and completing work by drawing relevant conclusions and answering questions. Learning by doing is a crucial aspect of learning about science in the view of former students. Your laboratory experience may help you to gain employment while you are in college or after you graduate. Employers need employees who are knowledgeable about laboratory methodology and who are skilled in the use of analytical instrumentation. Laboratory experiences are prerequisites for students seeking graduate education in the sciences.

Organic Laboratory over the Years
As important as laboratory work has been, the nature of the laboratory has evolved to reflect developments in the field and health, safety, and economic considerations. Forty to fifty years ago, organic experiments were performed on a larger scale than today. Corks were used to join most pieces of glassware. Today, standard-taper glassware or glassware with plastic screw tops is used to facilitate assembly and operation. These convenient joints facilitate and lessen time required for assembly. Today, smaller quantities of chemicals are commonly used. These changes have lowered costs of chemicals since smaller amounts are required. Using smaller quantities of chemicals helps to reduce odors and quantities of organic vapors in the laboratory. Formerly, everyone in the building knew when the organic lab was in session because odors were detectable throughout the building. Today, it is hard to know if organic labs are in session or not.

The nature of experiments has also changed. Chief among changes has been the application of spectroscopic analysis, particularly infrared and nuclear magnetic resonance spectroscopy. There are now more sophisticated ways to verify what you have made in the laboratory.

Why Use this Book?
You will be guided in doing numerous exercises to learn basic laboratory techniques. Focusing on each technique will build your confidence when applying the techniques in later experiments. Several of your experiments are discovery-based and you will solve the structures of unknown compounds. In addition, you will build and expand on learning practicalities and applications not provided by coverage in the lecture course.

Will you invent a cure for cancer by using this book? Probably not, but this book may provide you with the tools and enthusiasm to begin a search for a cure. This book will introduce you to experimentation in organic chemistry, laboratory techniques, observational techniques, characterizing the products of a reaction, spectroscopic analysis of structural problems, even kinetics and experimental design. You will form a foundation for further courses that may lead to a career searching for cures to deadly and disabling diseases!

Learning Objectives
Students benefit in many ways from taking the organic laboratory course. Some of the student objectives are to:

• Develop new laboratory skills.
• Build organizational and critical thinking skills by compiling and analyzing data.
• Develop scientific writing and record keeping skills.
• Appreciate the art of experimental design.
• Understand and respect chemicals and conditions for their safe use.
• Use web-based modules as databases and for writing reports.

To the Instructor

Purpose
This book is a comprehensive introductory treatment of the organic chemistry laboratory that was written with several goals in mind: 1) to produce a flexible set of experiments that consists of both microscale and miniscale procedures; 2) to include reasonably safe experiments that offer a discovery-oriented approach; 3) to offer a mix of discovery-based experiments and traditional experiments, emphasizing both organic synthesis and physical organic experiments; 4) to include modern separation and analysis methods; 5) to provide an extensive introduction to spectroscopy whether spectroscopic equipment is available or not; and 6) to minimize cost of waste disposal. The text includes techniques for handling glassware and equipment, safety in the laboratory, -theory of reactions and techniques, applications, and relevant background information. The experiments offer flexibility not only in choice of miniscale or microscale techniques, but also in choice of starting materials and characterization methods. The laboratory curriculum supports the organic lecture and the sequence of topics in the lecture class. Therefore, experiments in this book are based on reactions that are presented in your lecture classes.

Prerequisites
The text is aimed at organic chemistry students who are enrolled in the one-year -sophomore/junior undergraduate courses. These students are usually biology and chemistry majors and students who are majoring in pre-health professional studies. Prerequisites are a good foundation in the principles of chemistry (usually two semesters of general chemistry) and a corequisite or prerequisite of a lecture course in organic chemistry.

Content
The laboratory text is divided into three parts: experimental techniques, which include brief introductory exercises; spectroscopic methods of analysis; and experiments that illustrate many of the reactions introduced in the introductory organic course. It also includes pertinent references to the literature.

Organization
Each experiment includes background information and mechanisms (where relevant), prelab assignment, safety precautions and hazards, experimental setups and procedures, characterization methods, cleanup and disposal, results and conclusions, and postlab assignments. Spectroscopy experiments include numerous problems, in addition to directions for hands-on applications.

Features
Several novel experiments are included in the text, in addition to the traditional experiments normally performed in an organic laboratory course. New experiments include organic qualitative analysis of alkenes, alkynes and alkyl halides, synthesis of pyrroles and imidazoles, and experiments that emphasize experimental design.

Instructor's Manual
An instructor's manual (ISBN 0697-41603-8) is available from McGraw-Hill. This manual includes directions for laboratory preparators, instructor's notes for each experiment, and solutions to problems and prelab and postlab assignments. Additional information for instructors is available on the text web site.

Course Website
The web site http://www.mhhe.com/schoffstall offers supportive backup for the organic laboratory course. It presents updated helpful hints for lab preparators and instructors, typical schedules, sample electronic report forms, sample quiz and exam questions and examples of lab lecture or material for self-paced prelab student preparation, and relevant links to other web sites. On-line assistance is available to instructors via the "Ask the Authors" link on the site.

Acknowledgements
The authors wish to thank Connie Pitman and the many talented students at the University of Colorado at Colorado Springs and at the University of Southern Colorado who contributed greatly to the development of this book. In particular, we thank the following students at the University of Colorado at Colorado Springs for their efforts in testing experiments at various stages of preparation of the text: