Maurice J. Nugent'
Tulane University New Orleans, Louisiana 70118
I
Organic Chemistry Laboratory A non-traditional approach
In previous years the organic chemistry laboratory a t Tulane University had been organized in a traditional way. A laboratory text was selected on the basis of the scope of the techniques covered. All students were assigned laboratory periods, and all students were required to complete certain selected experiments according to a schedule. nTost of the faculty felt that such an approach was not completely satisfactory. The most serious criticism was that after completing the laboratory and when put into a new situation even good students wrre not able to perform routine crystallizations, distillations, or spectral identifications. Students had not learned how to use an experiment to attack a cbcmical problem and student criticism of the course was increasing. Last year a problem-solving approach was initiated. The entering student u7as given two unknowns, one single component and the other a mixture. Also he was given a card with a structural formula with the name of a compound whose synthesis had been previously published. Nine different syntheses werc distributed among 162 students. Typically a synthesis was a three or four-step preparation taken from Organic Synthesis or from other organic literature which could readily be located by using Chemical Abstracts. During the first semester the student's tasks were: (1) to identify both unknowns by using any means available, infrared, nmr, derivatives, analytical data, etc.; and (2) to write up in detail an acceptable synthetic scheme for the preparation of 5 or 10 g of material described on his card. Afterward the student would be required to use his synthetic scheme in preparing his compound. Student collaboration in the literature search was not discouraged. The initial reaction of most students was disbelief. The t e x t b o ~ kwhich ,~ showed how to perform various manipulations and gave a thorough discussion of spectroscopic methods, provided few details on the proper sequence of steps in identifying an unknown. The highly regimented structure of the traditional chemical laboratorv had disappeared. .. 1 The author is gratefol to B. Neff, L. L h m e r , M. F. Winkler, A. Kukade, H. F. Yeh, W. R. Thorn, S. H. Lu, M. Chattha and especially to Michael V. Keenan and Clay Frederick who contributed much toward the success of this laboratory. P n s ~ oD., , AND JOHNSON, C., "Organic Structure Det,ermination," Prentice-Hall, Inc., Englewood ClitTs, New Jersey, 1969. a The laboratory was not orowded at any time during the first semester. Some crowding did occur for the final few days of the second semester. One of these instruments wss purchased with funds donated to Tulane University by E. I. DuPant de Nemours and Company. 'Some students described the lsboratory as "unorganized." The teaching sssistants, the library, and the stockroom facilities were necessarily highly organized; the students were not.
The laboratory was opened from 1 P.M. to 5 P.M. daily and all students were allowed to use the 30 station laboratory on any day.a For one hour prior to each laboratory session a lecture and discussion of various manipulations, separation, and purification techniques was held. After students had submitted a sample they were given analytical data. If the sample was pure (as determined by melting point, spectroscopic, or chromatographic methods) the correct analysis was provided to the student. If the sample was impure, the student did not receive the correct analytical data. Two Perkin-Elmer, Model 700 Infrared Spectrometers4 were made available to the students. Sixty megacycle nmr data were obtained by a technician for any sample which a student wished to submit. Students were penalized for wrong answers in order to encourage careful examination of the evidence. Upon request, authentic comparison samples were furnished to the students. All of the students completed this qualitative organic laboratory, and only 14% of the entire class failed to identify t,he single unknown and a t least one component of the mixture. I n the first semester, two 1-hr lectures describing chemical literature searches were given. Only a few students failed to complete their searches and to find acceptable procedures which could be carried out with chemicals stocked in the organic laboratory. The second semester began wibh a series of 1-hr lectures about the experimental techniques involved in each of the syntheses. The laboratory was opened from S A.M. to 5 P.M. each day. Students were given only enough starting material for the amount of product they had been requested to synthesize, and there were penalties for getting refills. Reactions could be carried out at any time, including overnight periods. Only 7y0 of the students failed to cornpletc the second semester course. Partial credit was allowed when students failed to get products and instead turned in precursors. Student preparations were graded according to purity and to alesser extent, on yield. Overall response to the laboratory was favorable. The faculty members of the organic division enthusiastically endorsed the program. An unanticipated economic benefit was the large reduction in the chemical cost per student. Student polling of the course showed no detectable unfavorable response.Vn fact many students were elated and proud of their revelation that their organic laboratory was considered difficult, challenging, and relevant by friends at other universities. The associate dean of the college noted that there had been no student complaints concerning organic chemistry during the academic year. Volume 49, Number 7, July 1972 / 491
This unstructured approach to organic laboratory instruction malics large demands on faculty and librai.~ p~rsonnel. A reference library of Sadtler infrared and nmr spectra is most useful. The Program cannot succeed for large studcnt enrollments without dedicated and competent teaching assistants. Moreover, the program does not expose students to a large variety of experimental techniques, and it will not serve for those instructors who feel that such exposure is necessary.
492
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Journol o f Chemical Education
This unstructured approach is not new, nor did it originate a t Tulane University. It has been used in some form at several small colleges where enrollments were easily handled by individual faculty members. Such a laboratory method is not restricted to organic and at Tulane plans are now formulated t~ extend this problem-oriented approach to a freshman course for non-science majors.
