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the microscale laboratory Running a Microscale Organic Chemistry Lab with Limited Resources Robert G. Sllberman SUNY at Cortland Cortland, NY 13045
Cortland College r m t l y made the switch to a mimseale organic chemistry laboratory program despite the potential baniem below. The organic chemistry course at Cortland has four, 18-student lab sections, each of which meets for three hours a week New York State d o e not allow a breakage fee to be c h ~ dOne . faculty member is responsible for all.labs, and no teachinrr a~siaantsan= available Therefore, in addition to the f&ar problem of start up costs (for new equip ment and glassware)manpower constraintsexist. The strategies that were developed to solve these problems may prove helpful to others contemplating a switch to mimscale organic chemistry labs. Shared Kits
Aside h m new instrumentation. the ereatest exDense in changing to a microscale lab is purcKasing glaiware kits. These costs were minimized bv wine a shared kit wlicy Since lab sections do not mee~concu&ently,the same 18 kits are used for each lab with each kit being used by students in different sections. Each kit is labeled with the name and the lab section of students using the kit, and each student is responsible for keeping the kit clean and restocked if glassware is broken. The Five-Mlnute Rule
The responsibility for the kit extends five minutes into the next ciaas. students begin each lab by checkmg their kits. Missing items or problems reported tn the instructor during the first five minutes of the class are the responsibility of the last person to use the kit. Problems that occur aRer the first five minutes are the responsibility of the student using the kit for that lab period. Because there are no breakaee fees. there is little incentive to restock a kit with glaeaw&e liberated from a neighbor's kit. If an item is broken, students merely need to request a replacement. Small stocks of glassware are kept in the lab for this purpose. The shared kit system has been used for three years and the highest glassware breakage cost for all sections during a single year was $143. The worst breakage problems occur when students attempt to take hot glassware out ofthe drying ovens with tongs. This problem was solved by replacing the tongs with cotton gloves that have small dots of polymer on the palms to act as no-slip grippers. The gloves cost a few dollars at any hardware or large discount store. Mlnlmally Stocked Drawers
In addition to the shared kits each student is issued a lab drawer, but the drawer contains only a few items (a thermometer, watch glass, a few small test tubes, two small beakers, a porcelain plate, a centrifuge tube and a few small screw cap vials). The drawer gives students a reasonably secure place to keep their work, but the cost of A140
Joumal of Chemical Education
ARDENP. ZIPP SUNY-Conland c0~land~Ny13045
stocking drawers is small. Any glassware that is broken is simply replaced on request. Since the contents of a drawer can be assessed at a glance, check-in and check-out of an entire class takes only a few minutes. Communal Glassware
The lab also has a communal glassware supply. The most frequently needed items; filter flasks, small Erlenmeyer flasks, crystallizing dishes, funnels, etc. are simply set on the shelves for students to use as needed. After students finish using an item they are obligated to clean it and put it back for the next person's use. Anyone who has been in a student lab can clearly visualize all the glassware being randomly distributed around the room in a short time. This tendency to increase the *entropy"of the lab can be kept under control with the judicious use of a reward system. Grade Equivalent Points
It is essential to keep the glassware, kits, and other lab materials clean and organized, because each kit and piece of glassware may be used by several different individuals during any given week. l b encourage this, a reward system of grade-equivalent points (GEPS) ( 1 ) is used. Students earn three erade-eauivalent mints each lab oeriod if the assigned kir is complete, cle& and dry at tge end of the lab period. GEPS are awarded only if the task is completed properly. Eighteen gradeequivalent points equals an "A" lab remrt . made. - . althoueh this number is arbitrarv. The other clean up chores, such as replacing glaeaware on shelves and general lab clean up, are assigned to small teams.If the team's job has been done satisfactorily everyone in the team gets three GEPS, while if it is unsatisfactory, no GEPS are awarded. An instructor never has to Dressure students to clean UD. Since GEPS have a wsitive k e c t on lab grades, studenis pressure each other. At the end of each lab ~ e r i o dthe instrudor makes a five-minute "inspection to> to award GEPS. The small increase in bookkee~ineneeded to k e e ~track of GEPS is a welcome trade-off fora clean, neat lai. Achart of GEPS earned each week. wsted in the lab. Drovides the necessarv feedback to keep &dent perform&ce of cleanup tasks at"a high level.
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Prepared Laboratory Notebooks
Since only one instructor is assigned to the labs, a system was designed to cut down the time spent grading lab reports. The length of the reports was substantially decreased by asking students to write a set of directions in their laboratory notebooks prior to lab. Their directions are based on those in the lab textbook. but should be annotated and restated version of the text, not just a simple copy of text material. Students come to lab with useful and meaningful lab notebooks, but without textbooks. As the students do the lab they keep detailed research style notebooks, entering data and changes in procedure as they do the ex~eriment.The advantaees of this aDDmach have been &scussed by Piekering (2L In essence most of the information that would be contained in a lab report is now contained in a lab notebook. At the end of the semester the notebooks are collected and
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graded. The notebook grade, which is a substantial part of the lab made. is based on format. claritx observations, and allows for comple&nes~.The advance studknt short, easily graded lab reports.
A Microscale Purification and QualitativeSpectroscopic Examination of Cw (Buckminsterfullerene) An Experiment Suitable for Undergraduate Organic Laboratofy Courses
The Micmscale Lab Report
Because most of the traditional information called for in the lab report already has been entered in the lab notebook, it need not be repeated in a lab report, so a short report is written on a 5 8 index card. Atypical report has a n equation for the reaction, significant observations, and datasuch as melting or boiling points, and can be prepared quickly and easily by students during the last 10 minutes of the class. The reports are ready to hand in as students leave for the day, so that lab reports are never late! These reports are much less timeconsuming to grade, resulting in a tremendous time saving for the instructor faced with grading 70-80 lab reports a week. The essential information is written only once in the lab notebook, and lab reports are simply a summary of the completed work.
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Shorter Lab Experiments
One oftbe trademarks of a traditional organic chemistry lab is a frantic scramble to finish the lab in the allotted time frame. A typical 3-h lab often seems to be planned so that an average student can finish the lab in 3 l/Z b. Students may begin the lab by watching a solution reflux for an hour. but invariablv end the lab bv rushine to finish the final sLps in a pmce&re just as class eudsr~ecausemicmscale labs typically require less reaction time, lab experiments are shorter, but this often leads to a tendency to do many more experiments during a term. It seems more sensible to plan a lab that an average student can complete in 2 lD h. The 30-min leeway allows students some time to think about what they are doing, recover from a mistake, prepare their minoscale lab report and, of course, leave the lab on time. The lab becomes a much less stressful place for both the instructor and the student. Students are more likely to leave the lab with a feeling of success and accomplishment. The lab atmosphere is more relaxed, and some students may begin to see the fascination that lab work holds for most chemists. The strateeies above have ~ m v e dsuccessful at Cortland and dowedous to modernize the organic laboratory proeram and imomve the lab atmosohere. both ohvsicallv and socially It L o u r hope that they will be usifil for r h e r s who plan to change their organic chemistry laboratory programs.
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LiteraturnCited 1.HcUer. R E J. C. S. T 197S.8.231. M.J. C 9 T.Is80 19, 190.
2. Picks*.
' Author to w h m correspondence should be addressed. me crude soot should be handled with care because potentially toxic aromatic byproducts may be present. If an HPLC is available, the actual ratio can be determined. We used a 25 cm x 4.6 mm Du Pont Zorbax 5 Silica Gel column with hexane as eluent. Flow rate was 0.75 mL /min with UV deteaion at 260 nm. The fullereneselute in order of increasing molecular weight.
James F. ~arecek'and Scott D. Kuduk
State University of New York Stony Brook, NY 11794
Since their first preparation in 1985 (1,2),interest has continued unabated in the family of closed cages of carbon atoms known as fullerenes. One of the difficultiesin working with these compounds is obtaining macroscopic a simple amounts of pure materials. This article and inexpensive purification procedure, which can be used in an undergraduate organiclaboratory course, for isolating the most common member of the family, Cm fullerene. The purification is based on a recent report by Scrivens and 'Jbur (3)that uses activated carbon as the separation medium. If instrumentation is available, IR, UV,and 13CNMR spectra can be conveniently obtained. Crude fullerene-containing graphitic soot can be prepared by methods previously described in this Journal (4, 5) or can be purchased fmm a number of sources (Texas Fullerenes, Strem, etc.).' The crude soot usually contains about 5% fullerenes by weight. If an ultrasonic cleaning bath is available, the fullerenes can be extracted conveniently by suspending the soot in toluene (1 g I50 mL) and sonicating at mom temperature for an hour. The mixture is filtered under reduced pressure through a pad of Celite and the solid washed with toluene. The burgundy-colored fdtrate is evaporated to dryness on a rotary evaporator at 40 "C leaving a black solid. If a sonicator is not available, the soot can be placed in an extraction thimble and extracted with toluene in a Soxhlet apparatus for 3-4 h. Evaporation of the toluene affords the crude fullerene mixtll?~
The solid obtained (usually 30-40 mglg of crude soot) is washed bv swirling twice with ether ( 5 mLI 20 me: of solid) to remove any grease and ether soluble hydrocaTbon side pmduds. The solid is finally dried under reduced pressure to remove residual ether. The fullerene mixture at this point usually contains 8590% Csowith the remainder being mostly C,o and traces of higher fullerenes. The actual composition depends on the source of the sooL3Astock solution can be prepared for 20 students by dissolving the crude extract in toluene (30 mg/ 10 mL).The solution is stable for at least several weeks if stored in the dark. The separation of Cm from the other fullerenes may be conveniently done using a 5 314411. disposable glass Pasteur pipet as a column. A plug of cotton is placed in the bottom and covered with a thin layer of sand. The column is packed with a slurry prepared fmm 0.2 g of Silica Gel 60 (flash silica) and 0.1 g of activated carbon in toluene. This eives a 2.5 x 0.5-em column bed. Norit A activated carbon from several different sources gave good results. About 0.5 mLofthestmk fullerenesolution (1-2 meofcrude extract) is applied to the column, and the solvencis drained to the top of the bed. The column is then eluted with toluene.
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Volume 71 Number 6 June 1994
