Gene Hiegel
and Robert Belloli
California State College Fullerton, California 92631
Independent Synthesis Projects in the Organic Chemistry Laboratory
Because of the limited time available for senior research, it is imperative that the student should already have been introduced to the type of thinking and planning that characterizes chemical research before being assigned a senior research problem. At California State College, Fullerton, where faculty-direct,ed senior research is required of all chemistry majors, independent synthesis projects in the sophomore organic chemistry laboratory course have been found to provide a valuable and realistic introduction to the library, the chemical literature, and laboratory experiment planning early in the undergraduate chemist.ry curriculum. Before the individual synt,hesis projects are assigned, the students become acquainted with the library and it,s chemistry holdings through the cooperation of the College science librarian.' Each student then either chooses or is assigned a different two-st,ep organic synt,hesis, and he must find in the chemical literature suitable procedures to carry out the reactions. After the procedures are approved and chemicals in t,he necessary quantit,ies and any special equipment are gathered, the student begins the laboratory ~ ~ o r kOn . completion of the projects, each student gives an oral presentation of his results to other members of the class. Procedure
Early in t,he second semester, one laboratory period (3 hr) is set aside to acquaint the students wit,h the
chemistry collection of our library. In the library our College science librarian gives a lecture on the history of chemical publicat,ions, and following t,he distribution of a list of bibliographical sources in organic chemistry, she leads a discussion on t,he contents and usefulness of the works listed, during which representat,ive volumes are passed around for the students' inspection. Included in this list are such works as chemical dict,ionaries, encyclopedias, handbooks, history books, language dictionaries, Beilstein, chemical and biological abstracts, and current avareness publications (Index Chemicus, Chemical Titles). After this session, a brief tour of the book, journal, abstract, and reference sections of the library is conducted. Back in the laboratory, the instructor continues with a discussion directed toward the literature search to be carried out in connect,ionwith the synthesis projects assigned later. This discussion concentrates on the use of those library mat,erials which will be most useful, e.g.,
Organic Syntheses, Organic Reactions, Chemical Abstracts, etc. The projects consist of two-step organic syntheses involving reactions of a type not already encountered in the regular schedule of experiments that all students perform. These syntheses are changed each year. The student,^ are asked to return two weeks after the syntheses are assigned with suitable procedures and a list of chemicals and special equipment needed. Each student has a well-equipped locker which includes a Icontes Kem-Kit, a magnetic stirrer, an oil bath with heater, and a variable transformer. A suitable procedure could be obtained from a literature reference to the synthesis of the exact compound or by adaptation of the synthesis of an analogous compound, e.g., met,hyl instead of ethyl ester, 5-membered ring inst,ead of 6-membered ring. In eit,her case the procedure will have to be adjust,ed in consideration of the fact that not only must 10 g of t,he first compound be turned in but also sufficient quantity remain to allow the preparation of 10 g of the second compound. Alt,hough any synthetic route for which the student has found references is theoretically allowable, approval of the synthesis is based on feasibility (amount of difficulty and time required), safety, and availability of chemicals and equipment. When the procedure is approved, the students are asked to t,urn in to the chemical stoclcroom containers labelled to indicate t,he type and amount of each chemical required. A considerable amount of time is saved and confusion avoided both for the students and storeroom by having labelled flasks turned in several periods before the lab work is initiated. The students are allotted the last five periods of the semester to do the actual laboratory ~ ~ o associated rk with their projects. This includes carrying out the reactions and purifying and identifying both products before turning them in to the instructor. Some representative examples of the syntheses assigned are shown.
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The students learn that not all experiments are divisible into 3-hr time periods since many reactions and procedures require much longer times. They also learn that a detailed set of directions for a synthesis or experiment is no guarantee that everything will work as described, an impression that they might have from doing laboratory manual experiments. Throughout the performance of the syntheses the students keep a research style record of the laboratory work. On the last day of laboratory each student gives a brief oral presentation describing his syntheses to the class with the methods he chose, experimental problems encountered, and reasons for overall success or failure. Concluding a year of organic laboratory with experiments of this nature proved to be a satisfying and
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Journal o f Chemical Education
rewarding experience for both students and faculty. A good library introduction from the somewhat disimilar viewpoints of the science librarian and the lab instructor, practical library practice in a realistic situation using most aspects of literature seaching, and actual experiment planning including devising procedures, gathering chemicals and equipment, and organizing lab time were obtained by the student. The students are exposed to a variety of reactions, techniques, and equipment such as Soxhlet extractors, mechanical stirrers, vacuum pumps, and compressed gases, which due to time and equipment limitations they could not otherwise experience. Interest in the progam is evidenced by the fact that the students' response during and after the experiments is enthusiastic despite the large number of hours invested in the library and laboratory outside the normal lab time allotted. I n grading, emphasis is placed on the student's imagination and effort in attacking the synthesis since the syntheses were not of equal difficulty and many were not completed due to lack of time or student errors. In the future we plan to give library assignments before the syntheses are assigned, to insure a more thorough familiarity with certain aspects of the literature, and plan to expand the laboratory time from five to seven or eight periods. Part of the success of this program is attributable, among other things, to the relatively small number of students per laboratory, all of whom are chemistry majors, and to the fact that these laboratories are supervised exclusively by our regular full-time faculty.
