Attracting the New Generation of Chemistry Majors to Synthetic Chemistry without Using Pheromones A Research-Based, Group to Multistep Syntheses . Approach .. at the College Sophomore Level Donna S. Amenta James Madison University, Harrisonburg, VA22807 John A. Mosbo
University of Central Arkansas, Conway, AR 72035 In the second semester of our sophomore chemistry majors' Integrated InorganidCrganic Laboratory course1 we have developed an approach that works very effectively. The focal point of the course is group multistep synthetic problems. The syntheses are based on departmental research efforts and include the involvement of upper-level undergraduate chemistry students as peer mentors. At the end of the course there are oral presentations in meeting format and the submission ofjournal-format group papers. The direct and intangible benefits to our students and the department have far exceeded our expectations. When we began thinking about modifying our traditional second-semester sophomore-level laboratory course, one of our motivations was to introduce some advanced synthetic techniques. Our department does not offer an upper-level laboratory that stresses synthetic techniques. Our staffing situation precludes offering such a course, but even if that were to change, it is not clear that we would choose to offer one. We feel that an upper-level course likely would be taken only by our ACS-track students, that an additional requiremen; would detract from their research efforts, and that teaching advanced techniques at the sophomore level provides students with some-necessary tools before they begin research. Another motivation was to change students' perceptions about synthetic chemistry and the tools used by synthetic chemists. Prior to initiating the changes we describe here, few students were interested in working on synthetic research projects, and they held some peculiar ideas about instrumentation. For example, they viewed IR as an instrument primarily built for spectroscopists and NMR as almost strictly within the purview of analytical chemistry, rather than as critical tools for synthetic practitioners. We also wanted to provide students with an idea of the kinds of thinking involved in a research problem, especially to students who did not traditionally opt for a research exuerience. We have a number of maiors who complete a cimbined chemistry and business Gogram, go to medical and urofessional schools. attend graduate schools in areas other than chemistry, oo teach g h i g h schools after graduating. Most of these students do not complete an ACS-track major because of other curricular demands. 'Course orereauisites are first-semester soohomore-leveloroanic chem stry ;no labora~ory.Coreq~snes are sedond-semesterorian c an0 a sophomore-level inorgan c coJrse. Tne laboralory s ndependenl an0 does not necessarl y para le the seqLences of echre
topics. 'Prior to 1992-1993 we introduced the two nuclei in opposite order. We feel there are advantages to introducing interpretation of NMR spectra using 13C.
We, therefore, began constructing a course that would maintain an emphasis on syntheses, introduce some advanced synthetic and purification techniques, make greater use of instrumentation and reinforce spectroscopic interpretation, be based on use of primary literature, provide students with more independence than they had been experiencing, and not further tax departmental resources. With about 25 students in lab and limited equipment for advanced techniques, we felt it would be difiicult to have each student use all of the techniques we wanted to introduce. Therefore, we looked for ways to have fewer students use certain equipment, and for them to show and describe it to the other students. We thought it would be good for each student to have his or her own project, but rejected that as impractical. We decided to reduce the number of simultaneous syntheses and accompanying problems by having groups of students do a particular synthesis. Initially this decision bothered us because it was based on expediency rather than pedagogy. After having used this approach for five years, however, we believe it has turned out to be better than individual projects. Background
The foundations for the group projects are laid carefully during the first semester and the early part of the second. In the first semester students are introduced to classic synthetic, separation and purification techniques. Throughout the semester, spectroscopy is emphasized heavily Students are introduced to W-Vis and GC-MS, but our primary focus is on FT-IR and FT-NMR. FT-IR is intrcduced in the second week of the first semester, and FT-NMRin the sixth (13C1and 11th ('HI weeks.' From the time of introduction, students are expected to use FT-IR and FT-NMR techniques routinely in virtually all subsequent exercises. In addition to these hands-on experiences, we concentrate heavily on spectral interpretation. Concomitantly, we attempt to build individual organizational and communication skills. In addition to frequent evaluations of notebooks, we require journal-format papers. The first one includes only introductory and experimental sections. The second also includes a results and discussion section and is based on a synthesis that leads to multiple products. The second semester begins with a multistep synthesis. The students prepare, purify, and characterize femcene, then use their product to obtain acetylferrocene. All students individually perform these experiments that are completed by the sixth week of the semester. Volume 71 Number 8 August 1994
661
Group Projects
The Groups
The group projects are introduced during the fourth week of the semester, when we announce the memberships of the groups. This overlaps with the students' spectroscopic studies of ferrocene and acetylferrocene but gets them started thinking about the idea of a group project. The groups are selected carefully. Experience has taught us that each group should include students of diverse talents (cognitive and manipulative). Adiversity of laboratory skills, general personalities, and motivations among members of the group is better than a homogeneous composition. Each group consists of four or five students, depending on course enrollment. A group of four works slightly better than one of five. We designate one member of the group as a contact person. The students are told that this person is not necessarilv the -m u p - leader. but someone we tend to run into frequ&ly, can contact if necessary, and who, in turn,is responsible for contacting the other members. In fact, we try to select a person who we believe also has the requisite skills to help the m - up . stay organized and on target. Peer Mentors
One upper class chemistry major also is assigned to each group as a "peer mentor." Most are unpaid volunteers. Usually the only paid peer mentor is the one who also is responsible for getting equipment and reagents together for the lab. Mentor assignments are made according to the students'interests andlor experiences with the project syntheses or with specialized techniques required by it. We meet reeularlv with the mentors to review and discuss where their group is with respect to the overall project, and to helo identifv potential oroblems (both technical and w r sonnei). The &tors heip reduce the load for the faculty during the lab period, but it is critical that the faculty be immediately available and involved. This concept of peer mentoring developed over several years out of necessity. In the first year, 20 students were distributed among five groups with two faculty. We found it difficult to keep up with what each group was doing while also introducing new laboratory techniques; consequently, in the second year we asked for some help. TWO upper-class students worked with us on a limited basis by teaching some of the techniques. We continued to be the immediate supervisors of all the groups. In the third year, three upper-class students helped, and one of them was put in charge of supervising a group, while we supervised the remaining three groups. This peer mentoring worked so well that we have continued it.
-
The Group Syntheses
Proiects are selected to introduce a varietv of technique; Each group has at least one step that iniludes use of a glove bag, as well as assembling glassware and completing a reaction under an inert atmosphere. Other techniaues. such as use of airless (Schlenk)elassware. continuou; liquid-liquid extraction, Soxhlet &traction; vacuum distillation. 31P and lg5PtNMR. GC/FT-IR, etc.. are not performed by every group, but all the students have the opportunity to see them used. These techniques also are deicribed in detail in the oral presentations-given at the end of the course. In the first year, foiu of the five projects were classic multistep syntheses (e.g., insect pheromones, luminescent compounds, anesthetics, etc.), such as can be found in this Journal and organic laboratory texts. This was not effective. Students lost enthusiasm in mid-synthesis. The pizazz of making a "relevant" compound did not last. The 662
Journal of Chemical Education
problems were too well defined, and the procedures and outcomes too rigidly structured. The fifth project, however, was to prepare a com~oundthat was an intermediate for a synthesis ;hat we were carrying out in our research laboratory. Although we adhered to the same overall structure for this as for the others, we had to make frequent changes in procedures, especially regarding isoladon and purification, because it was not a "canned synthesis. We were concerned about thisinitially, because we thought the students might become confused and frustrated. To our surprise, the element.9 of the unknown and discovery with attendant possible contribution to the progress oi a research project were stimulating and motivating. Not knowing whether it was the students or the projects, in the second year we undertook three research-related problems and two standard svntheses. Aeain. we found that. in eeneral, the research-oriented proYble& maintained ktuzent interest and built enthusiasm better than the other two. For the past three years we have continued our emphasis on research svntheses. with mod results. When we sav to the students that we &e notlsure how to proceed with a purification, they often think we are hiding something from them. When they discover that we really do not know, it becomes a challenge to them. Thevget excited about the problem and almost-become obsessedwith finding a solution. As the students become more excited about their projects, they want to spend time working in lab other than their scheduled laboratory period. We increasingly allow them unsupervised time for low-risk activitie~.~ Getfing Started and the Remainder of the Semester
The approximate timetable for the project portion of the second semester is given in the table. This section details activities delineated there. The projects begin in earnest during the second week (fifth week of the semester). Each group is given a two-tothree paragraph description of the multistep synthetic problem and a brief overview of the relevance of the problem to an active research problem in the department. These descriptions contain few, if any structures, and no equations. They are intended to provide only enough information to get the students started with a focused literature sear& The search begins with the CRC Handbwk. Merck Indm, and the ~ l d h c catalog h to help the students determine formulas of starting materials, reagents, andlor products given in the overview. Each group is then guided in searching selected indexes of ChemicalAbstracts. We have found that this part of the literature search must he limited and well-focused, due in part to the fact that the formal course in chemical literature at JMU usually is taken later, during the junior year. This focused search minimally includes the index guide, formula indexes, and abstract issues of Chemical Abstmcts, as well as the primary literature. We give the students a range of ~ h e m i c ~d b s t k c t volumes s to begin their search. This is necessary so as to avoid taking large amounts of time, because JMU does not have collec~ tive indexes past the ninth. For example, a group may be given a 10-yeartime frame to search formula indexes for a key paper. The searches also are constructed so that the orimarv articles are in ioumals available at JMU. and ;hey a& supervised caref;lly by the faculty and peer kentors to helo rwide the students to their kev Daoercs, . . with minimal f&&ration. The groups are asked to get together before the next lab period to sort through what thev have found in the literatke and to think ab&t how the overall synthesis fits together. With the help of the faculty, the peer mentor leads her or his group in a discussion of the results of the literature search and helps in the development of a total synthetic
" ..
Timetable for Group Project
Week of Week of Project Semester
Activitya Groups, contact people, and mentors assigned;project concept and general calendar described. Syntheses assgnea: herature searches begun. Pnor lo nen lab, groups meet to consider bterature Bndmgs, reactm sequence for overall synthesis, and specifics for first step of synthesis, including purification. Reaction seauence for overall svnthesis equipment an0 s~pplyrequest sheet with anacned apparat-s sketcn ana proceo.re for forst step comp eled: pre imlnary group timetable developed. (Theseries discussing specifics,completing equipment and supply sheets,and modifying timetables is repeated each of the subsequentweeks.) Syntheses begun (depending upon project. a given group may have multiple set-upsof the same reaction). From this point through remainder of project period, group members frequently come in at times other than scheduledlab hours to stop reactions and/or begin preliminary work-upssuch as rotary evaporations. Initially, they are encouraged m come in at least as pairs. Isolation and purification of pmduct from first step begun Products characterized spectroscopically and physically Major portion of experimental work wntinued. Experimental work continued;oral report discussed generally. Faculty meet with each group for preliminary discussion ofgroup organization, and conceplualizationof individual transparencies fororal report Complete laboratory work. Faculty meet with each gmup. Information for each transparency has been drawn on paper by the students. Each student in group informally discusses what wiil be said about each transparency Major correclions, revisions, and suggestions made by the faculty, Clean uo. ~a% G u p rehearsespresentatnon with bnal transparencnes. Only mrnor changes suggested by taculfy
Oral presentations; formal paper, gmup notebook.. and arouD. arades handed in. BAni~ifies undertaken outside schedule laboratoty times am shown in italics. experimental work also is bsing accomplished during these weeks.
-
scheme. At this point, chemical structures and equations are formulated for each synthetic step, and literature yields for each step are identified. The groups also are informed of the amount of final product they are attempting to prepare. This serves as the reference from which they determine the approximate scales of the synthetic steps
via a retmsynthetic approach. The groups then focus on the f i s t step in detail. This includes an in-depth discussion of both the chemistry involved and the procedures to be used. During the course of these discussions, quantities of reagents, solvents and starting materials are considered, as well as the specific design of the apparatus to be used. The students then list the types and quantities of reagents, solvents, and equipment on an "Equipment and Supply Request Sheet," which is turned in. They also provide a sketch of the equipment setup with a written procedure that includes appropriate quantities and attach it to the request sheet. Each week the groups must submit a sheet for the following week. We fmd them invaluable in making certain that necessary materials and apparatuses are available to the students when they need them. More importantly, the processes involved in assembling the information for the sheet help the students organize their thoughts with regard to what they are goingto do, how they are going to do it. and what thev need to accom~lishit. This also ~nicklv leads them to recognize that thkre are certain lab tasks (e.g., rotary evaporations, spectroscopic, and physical characterizations of products) which, if accomplished outside scheduled laboratory period^,^ allow them to complete their work more efficiently. They also become adept at identifying who is going to do what and when, and each adopts a sense of responsibility to his or her group. In the ninth week of the project we encourage the students to think seriously about their oral presentations. We have a general discussion of the organization and make appointments for each group to meet with us prior to the next laboratory period. Ground rules for the presentations include each member having approximately an equal role. For example, in a typical format one student introduces the problem and later summarizes the overall results, and each of the other students presents the reaction, product characterization, and literature mechanism for one step of the synthetic scheme. The total time allowed per group is 20 minutes. During the individual group appointments we help them to think through a general organization of introduction, body, and conclusion. Once established, they work on the details of what belongs in the body for their specific synthesis and how that can be broken down so that it can be accomplished easily by a number of presenters. We spend time discussine the ouantitv of material that is aoorooriate for a single transparency and address the issue of how many transparencies are appropriate for a 20-min presentation. By the 10th week of the projects the students are strongly encouraged to have the experimental portion near completion, and to be finishing up their spectroscopic characterizations. Between the 10th and l l t h project lab periods we meet with each group for a preliminary "runthrough" of their oral presentation. The students show us on oaoer what thev olan to out onto transoarencies. and they describe wha
