Mary G. Chisholm Behrend College ~ennsylvaniaState University Erie. 16510
Organic Chemistry Laboratory A realistic view of problem-solving
The general and widespread dissatisfaction with conventional oreanic lahoratorv courses has produced a regular flow of acicles in the literature for a number of years (i-6), manv of which describe new ventures in the teaching of undergraduate level courses. There has been remarkable uniformity in both the type of course taught and the reaction of students and instructors alike to the experience the course afforded. Little comment has been made, however, on the consequences of some of the more obvious pitfalls of teaching a problem-centered course, or on the relevance of prohle~-solvingas applied in a general way to the total educational process. The ohjectives of such a course evolve about a now familiar theme: (1)to teach the student independence in the lahoratory by introducing prohlem-orientated topics a t the outset. This accomplishes the abandoning of "cookbook" experiments, the need to use the chemical literature and hopefully the development of creative thought ability; (2) to expose the student to modern instrumentation so that he appreciates its essential role in modern chemistry; (3)to structure the course with maximum flexibility so that the requirements of the course may he fulfilled in a manner selected by the student; (4) to master the essential techniques necessary for any degree of proficiency in a modern chemistry lahoratory. Encouraged by the universal enthusiasm of these reports, we decided to embark upon a similar course for our introductory organic laboratory for chemistry majors. Although ostensibly for majors, with the declining popularity of chemistry as a career, i t was filled mostly with students in premed, biochemistry, biology, and those taking a science option with a chemistry bias. We deliberately undertook a problem not embarked upon by many of the previous authors: Manv were teaching- a erouD - .of chemistrvorientated students, some with previous experience in the oreanic lahoratorv 12. 7.8). . . Our students were sophomores, had not had any previous organic lahoratory, and were academically rather immature and, we judged, a t a particularly susceptible point in their education t o be exposed to prohlem-solving for the first time. The result, as anticipated, was overwhelming enthusiasm by all involved in the course. The advantages of such a course have been fully discussed elsewhere (2, 7), and need no further elaboration. We were aware of the obvious disadvantages such as the excessive time requirement by instructors and enthusiastic students, the heavy use of instruments which could lead to breakdown and costly repairs, the necessity of having the laboratory monitored five days a week, and the problem of too high a studentlinstructor ratio. We should Iike to report the problems we encountered that we had not anticipated. Most of the articles in this Journal report almost exclusively of the success of such courses, emphasizing the positive aspects (1, 3, 5). We feel that for anyone attempting to embark on a course of this type, for which there is no standard text,' a discussion of the problems encountered
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1 A book available in the UK (9) goes a long way towards filling this gap; otherwise Krubsack's teat (lo) is the best alternative for introducing the problem-solving approach.
offers a more realistic view of what is involved in teaching an organic lahoratory course in this manner. Course Structure Time
A minimum of eight hours a week was required over a ten-week period. The lahoratory was open on a continuous basis, which amounted to three full days and two half days a week. Content Two sets of syntheses were required, selected so as to include a given list of basic techniques (distillation, chromatograph;, crystallization, etc.). (i)Three compounds were prepared, each from the same starting material selected by the student, and samples of known purity were submitted to the instructor. (2) A three-step multistage synthesis was performed, starting from an aromatic compound, selected by the student. The final product was submitted and the intermediate products were inspected before the next step was undertaken. Each student had a different starting material. Instruction and demonstration of techniques were available on request, some on film. Before any experiment was started, a student was required to make a literature search and submit his selection to the instructor for approval. No unauthorized experiments were permitted. There was no text for the course. Three unknowns were solved using chemical, physical, and instrumental methods. Derivative samples were submitted for inspection. ~
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Notebooks A full renort of all work. both positive and necative was required. Discussion and evaluation of results were made an essential ineredient of the notebook and the student was referred to the chemical literature, particularly this Journal. to see how a reDort should he written. A second working notebook was encouraged, to use while actually working a t the bench, but most students used their report notebook.
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Grading A student who completed the course, submitted the samnles. identified the unknowns. and produced a legible notebook would achieve a C, regardless of the quaiity of the samnles or the identitv of the unknowns. A student who managed to escape a little outside the confines of his immediate coal of makine a -~ r o d u c.t .hv . identifvina . - side roducts, verifying a mechanism, or making additional products, could qualify for a higher grade. A student could achieve an A by proving that he had learned something of the spirit of research and prohlem-solving. If a student wished to spend the whole term on one or possibly two experiments he could do this with the approval of the instructor, after discussing how he could best fulfill the course requirements and an appropriate modification of the grading system. The value of negative results was stressed. There were 12 students in the class, supervised by one instructor, not always the same person. A Beckman IR18A, DB-G and a Bendix 2300 gas chromatograph were available. One visit to a nearby nmr spectrometer was made, where students had the opportunity to have their samples run for them.
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Volume 52, Number 11, November 1975 / 739
Realism in the Laboratory
The problems we encountered can be grouped into four broad categories: (1) those.relating to the selection of projects made by the student; (2) those that were a direct result of the large variation in the ability of the students; (3) the presentation and treatment of laboratory notebooks and renorts:. and (4) the use of instruments. By far the'&eatest problem we found was that of trying to surreptitiously guide students into making good choices of experiment, especially for their first project, when they had little idea of what mieht be involved when thev read a set of instructions in the library. There is no point in forbidding a student's selected experiment because it is dangerous, uninstructive, or some other reason, after he has been told he may choose his own, because this, to the student, is a failure by the instructor to keep his side of the hargain in the course. I t seemed that every student chose something potentially lethal for his first experiment: hromine, thionyl chloride (alkyl halide preparation), concentrated nitric-sulfuric acid mixtures, large quantities of ether; so the decision rested with the instructors as to how much courage we had, and whether the experiment was instructive. Also their lack of experience tended to make them short cut the selection orocedure where thev could and if their friend had done something which had been satisfactory, they would try to repeat i t themselves, failing to appreciate that, for example, primary, secondary and tertiary alcohols may behave very differently under the same reaction conditions. Foolish choices could, of course, be vetoed when the experiment was submitted for approval, but we preferred to discuss modification to the original suggestion rather than to give the student an outright "no," telling him to return with something more suitable. This leads directly to the second problem as it was inevitably the weaker students who made the poor selections. We also found that, without any guidance, the better students chose the easier starting materials and the poorer students chose the more exotic ones which in most cases were harder. The appeal of a big molecule containing several features (e.g., cyclic, unsaturated, two functional groups) seemed to lure the weaker student into difficulties. Thus when a reaction went astray, producing a stubborn black tar, the glamorous starting material suddenly lost its appeal, and the student's limited ahility to transport classroom material into the lahoratory resulted in his heing illequipped to respond to the challenge. The weaker students were also more eager to bv-pass the librarv commitment or to borrow some easy information from a-friend. One text ( 1 0 was used more than most because it provided standard procedures in an easily usable form. Next year we are thinking of making i t less available (by request from the instructor) as students learned less about the use of the literature than we had hoped. One result of the limited selection procedure was that nobody chose to do a Friedel Crafts reaction, a Grignard reaction or a metal hydride reduction, although these reactions had been extensively discussed in class and were all rather suitable, for various reasons, for problem-solving a t the introductory level. However many students insisted on performing various oxidation reactions, even after the laboratory smelled of valeric acid for several days. Another major problem we encountered was the quality of the laboratory notehooks. Although we explained their purpose many times, it became increasingly clear to us that sophomores are not sufficiently mature to appreciate that a notebook is the only positive means they have for being evaluated in the course. Our criteria for giving an A grade were carefully spelled out: A student must prove that he has learned something of the spirit of research and problem solving.. . . The contents of a notehook are the only means we know for finding this out. A comment on the final student evaluation summarized their feelings. In answer to the
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Journal of Chemical Education
question, "State two things you particularly disliked about the course!' was the word. "notebooks." One obvious result of this feeling was that students rarely did themselves justice when writing un or discussine their neeative results. They either mot;! up the experim&tal detazs laboriously, saying how many times something was repeated, omitting the results and discussion, or they ignored the repeated attempts completely hoping that we would not find out about their misfortunes. We were unable to convince them that an unsuccessful experiment could earn an A. The last general prohlem we faced was that of coping with the student attitude to instrumentation. We knew that we would encounter higher costs due to wear and tear and we knew that the students' enthusiasm would lead them to the instruments with every gum, residue, and tar they made, possibly with expensive results. We found a way of unblocking syringe^,^ several students learned how tedious it can he to polish sodium chloride windows, and our cost of chart paper rose by 350%, but there were no disasters. The students enjoyed this opportunity more than anything else in the course and although purists may argue that "black boxes" do not teach chemistry, the instruments do serve to kindle enormous enthusiasm, and we feel very strongly that, particularly in a laboratory course, students should do what they enjoy hecause they will learn more. Nobody enjoyed column or thin-layer chromatography. Since mastery of the technique was a requirement of the course everybody attempted some kind of separation and obviously found the method tedious compared to the glamor of the instrument room. By the time students were ready to undertake the task of identifying their unknowns, their technique and thought processes were so vastly superior to those of any previous class. that most of them took far less time than we anticipated. One student managed to correctly identify his unknowns in a week and ohviouslv thought - that the last Dart of the course was rather a bore. Evaluation
We (students and instructors) all emerged from this course worn out and happy that something had been accomplished. We now believe that the sophomore year is not the best time to expose a student to problem-solving for the first time. Academic maturity is no criterion for determining the suitability of a class to problem-solving, open laboratow courses. This non-traditional annroach has been successfuily used with nonmajors in science subjects (12) and even a t the high school level (13, 14) which indicates that i t is not a method restricted to highly motivated, comoetent maiors. Problem-solvine. and de-. exoerimentation. . cision-making reach far outside the confines of a chemistry lahoratory, so, as educators, we are obligated to expose the student to the opportunity to learn how to deal with such situations as early as possible. The chemistry laboratory happens to be a particularly good place to start, where problem-solving - in its broadest sense 115) can be tackled. More rigorous guide-lines are required than we gave, to help students overcome the bewilderment of the first weeks. After reading reports in this Journal we started out thinking that most people had an overrated opinion of their students and we were convinced that we had a class of below average ability, but a t the conclusion of the course we decided that provided the motivation and enthusiasm were there, a mediocre student could perform well above his normal level. What of future laboratory courses? If the students enjoy a course, the instructor enjoys a course, the students feel
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After soaking in a cleaning solution, Micro Laboratory Cleaning Solution, supplied by the International Products Corporation, Trenton, N.J.,for up to 5 days, all blocked syringes worked normally again.
that they have learned more than they would in a conventional course and no serious accidents occur, these surely are the ingredients of a successful course. We shall try again. Acknowledgment
I wish to thank Dr. David Spalding and the students of Chemistry 36 at Behrend C o k e , whose enthusiasm and patience made this course possible. Literature Clted (1) Silberman, R., and MeConndl, J., J. CHEM. EDUC., 46.267 (1968). (2) Fife. W. K., J. CHEM. EDUC.. (5.416 (1968).
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U,(Jullc24, ~M. J.. J.~CHEM.~ EDUC.. ~ 49,491t (1972).. (6) Gumtone, r. D.. Chsm Bn't., 8.553 (1972). (7) Bobbitt, J. M.. aad H u w , S. J.. J. CHEM. EDUC..51.5€ (1974). (8) Ncckan,D. C., J.CHEM. EDUC..47,7M(I970). (9) to^^. F. D.. sharp. J. T., and smith. D. M.. "*n~ ~ t m d ~ ~covnein f o r y P..&cal OrgnnicChemistry," Methum, London, 1970. (w K ~ U ~A. ~ .C , ~- , ~ ~ ~ organic ~ ~ ichemistry." m ~ ~ t myn a ~ and ~ncon,~nc..naton, 1973. 3rd Ed., Low, Vogel, A, Textbmk of Plaetid Ogaaie cmsn aad co., ond don, 1956. (12) Snyder. C. H.. Hubingar, H.,and Cole, 5. S. J. CIiEM.EbUC.,51.56(1374). (13) Tomlinson,M. J.,Educ. Chem., 11.51 (1974). (14) MeCuire. J.. and Jahmtone, A..Educ. Chom.. 11.50 (1974). (15) Tomlin8on.M. J..Edur. Chom.. 11.40(1974). (5) ~
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Volume 52. Number 11. November 1975 / 741
