Using Green Chemistry Principles As a Framework To Incorporate

Article pubs.acs.org/jchemeduc

Using Green Chemistry Principles As a Framework To Incorporate Research into the Organic Laboratory Curriculum Nancy E. Lee,* Rich Gurney, and Leonard Soltzberg Department of Chemistry and Physics, Simmons College, Boston, Massachusetts 02115, United States S Supporting Information *

ABSTRACT: Despite the accepted pedagogical value of integrating research into the laboratory curriculum, this approach has not been widely adopted. The activation barrier to this change is high, especially in organic chemistry, where a large number of students are required to take this course, special glassware or setups may be needed, and dangerous chemicals and safety are of special concern. At Simmons College, the organic laboratory curriculum has been revamped by incorporating faculty research on asymmetric reduction of ketones in solvent-free conditions using polylactic acid derivatives. This paper describes the methods for converting from traditional expository laboratories to research-integrated laboratories by incorporating green chemistry principles in the greening of synthetic reactions. Results and assessment of student learning and attitudes are reported. KEYWORDS: First-Year Undergraduate/General, Second-Year Undergraduate, Laboratory Instruction, Curriculum, Organic Chemistry, Hands-On Learning/Manipulatives, Aldehydes/Ketones, Green Chemistry, Student-Centered Learning, Synthesis

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t is now understood that research-integrated laboratories are more effective in teaching students the process of scientific discovery than the traditional expository experiments.1 Numerous articles have appeared describing methods of incorporating research into the undergraduate curriculum from first year to fourth year projects.2 Despite the accepted pedagogical value of a research-integrated laboratory curriculum, this paradigm has not been widely adopted. The activation barrier to this change is high, especially in organic chemistry, which typically involves a large number of students taking the course as a requirement and may involve special glassware, setups, and dangerous chemicals. Other barriers may include the faculty time commitment for implementing such a change, the cost for the transformation, and convincing faculty colleagues of the value of research-integrated laboratories. Simmons College, with an undergraduate student body of about 1,900 women and graduating 15−20 chemistry and biochemistry majors a year, was among these institutions teaching laboratories the traditional way in 2003. Students had long been required to do a year-long fourth-year independent research project with a thesis. However, there was a disconnect between how laboratory skills were taught during their first three years and what students needed to undertake during their capstone fourth year research. Missing from the expository lab experiments was student experience with higher-order cognitive skills, such as planning an investigation, inference, and evaluation of the work. © XXXX American Chemical Society and Division of Chemical Education, Inc.

IDENTIFYING RESEARCH PROJECTS FOR CURRICULAR INTEGRATION

A difficult challenge was identifying projects suitable for multiple sections of first-year students who were novices in the laboratory. (Students take Organic Chemistry I in the second semester of their first year.) An important factor in lowering the activation barrier for switching to a research-based laboratory was the adoption of green chemistry principles as the framework for integration of faculty research into the laboratory curriculum. The choice of research projects and all associated laboratory work were guided by the 12 principles,3 including atom economy, prevention of waste, using benign renewable substances, and generating easily degradable products. Sustainability and saving the environment are causes with which students strongly identify. Students become engaged and excited about the “greening” process and enthusiastically participate in the research. Questions in identifying projects that were “doable”, relevant for first-year novices and rooted in the principles of green chemistry were as follows: • Is there any starting material or target compound for a research project that needs to be synthesized in large quantity for an existing purpose in another course or research laboratory? Principle 1 • Is there a reaction that can be improved in terms of yield? Have varying conditions, such as reflux duration,

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dx.doi.org/10.1021/ed300283y | J. Chem. Educ. XXXX, XXX, XXX−XXX

Goals

Missing Research Skills

Goals

−Applying techniques learned from Organic I in solving unknowns or purifying mixtures. −Deciding what data to gather to solve unknowns. Being able to interpret the data. −Deciding scale and method to prepare reagents as needed. −Keeping an accurate research notebook. −Finding published procedures. −Following a literature procedure. −Adapting a procedure to scale a reaction. −Collaborating as team, sharing data and information.

Missing Research Skills

−Locating information on safety, hazards, waste disposal, contamination issues, purchasing chemicals, and scaling reactions. −Deciding when to use distillation, extraction, column chromatography, recrystallization, GC, and TLC. −Using TLC to analyze unknown mixture: choosing developing solvent and visualization techniques; extension to column chromatography. −Application of recrystallization to purify unknown solid mixture; choosing solvent.

Skills of determining physical properties, performing functional group tests, solubility tests. Spectroscopy methods: operation, application, interpretation, logical reasoning, gathering data, analyzing data. Ability to put data together to logically deduce structure. Synthesis: introduction to green chemistry. Synthesis: unknown determination. Alternative heating methods, green chemistry, macromolecules, coordination chemistry. Application of organic chemistry to materials science, drug discovery, current topics in organic chemistry.

Exploration of Functional Groups, Separation of Liquids Separation of Solids AnalysisPurity Determination Purification of Solids AnalysisPurity Determination Separation Analysis - Purity Determination Reactivity Exploration Separation Pharmaceutical Research, microscale

Solving 2 unknowns A Green Microwave Oxidation The Aldol Condensation of Unknowns Microwave Synthesis of Tetraphenylporphyrin Gold Monolayer Lab/Combinatorial Chemistry Lab

Functional Group Reactivity Distillation Extraction TLC Recrystallization Melting Point Column Chromatography Gas Chromatography Synthesis Chiral Resolution Natural Product Isolation Old Laboratories in Organic II

Old Laboratories in Organic I

Table 1. Goals for Old Expository Experiments in Organic I and II and Missing Research Skills

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Part 3Assessment Weeks, 12−13

Assess student learning gains and compare to previous years.

Characterizing outcome of chemical reaction. Isolating and purifying product from reaction mixture. Characterizing final pure product.

Planning and performing a chemical reaction.

Part 2Synthetic Methods: Accomplishing a Grignard Reaction and Oxidation, Weeks 5−11

Goals Safety in organic laboratory. Learning how to gather information about a chemical. Keeping a laboratory notebook. Searching literature for a specific molecule. Purifying an alkyl halide and determining purity.

Part 1Fundamental Techniques, Weeks 1−4

Weeks

−Summarize data and write formal lab report. −Evaluate techniques and protocols. −Lab Practical: demonstrate proficiency for operating GC, rotary evaporator, IR, 13C NMR; set up distillation; perform TLC analysis. −Written laboratory exam to assess ability to plan an investigation, infer and evaluate. −Evaluate research integration experience.

−Scale from literature and write detailed procedure to synthesize 3 g of crude alcohol. −Calculate amount of reagent(s) and prepare solutions/reagents. −Perform Grignard reaction and learn how to monitor reaction by mini-workup and TLC. −Learn to find optimal conditions for running TLC for target compounds. −Isolate product by extraction. −Characterize crude product by TLC, IR, 13CNMR. −Purify product and characterize pure product by IR, TLC, 13CNMR.

−Compile chemical inventory for all chemicals to be used during semester and rank chemicals according to a “Greeness scale.” −Find MSDS, physical properties, catalog information, ordering, quantity in stockroom, and supplier information. −Learn to use SciFinder to locate procedure. −Learn to use Wiki and keep a research notebook. −Purify alkyl halide by distillation and determine purity by GC.

Description of Tasks

Table 2. New Research-Integrated Laboratory Curriculum Organic Chemistry I Project: Synthesize a Commercially Unavailable Ketone in Pure Form

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missing pieces as possible. The goal for Organic Chemistry I, as shown in Table 2, was for each student group to synthesize a commercially unavailable ketone in pure form. This would involve purifying the starting material, performing a Grignard reaction to give an alcohol, and then oxidizing the alcohol to the ketone. For Organic Chemistry II, the goal was for students to identify these ketones, perform the reductions with and without PLA chiral derivatives, and compare the results (see Table 3). The overall research objectives were to find whether the substitution on the aryl group mattered in the reduction and to determine which chiral derivatives worked best for the reduction.

temperature, or concentration, been studied? Principles 2, 6 • Is there a reaction that can be “greened” by reducing waste, using alternative catalysis methods, switching to greener solvents, or improving separation/purification methods? Principles 5, 8, 9. Through these questions, two projects were identified: finding green methods for asymmetric reduction of a ketone using polylactic acid (PLA) derivatives and optimizing the synthesis of a monomer to be used for making a green polymer, poly(vinyl benzyl thymine) (pVBT). These projects embody green principles, such as reactions that proceed at ambient temperature and pressure, and do not require an inert atmosphere, utilize reagents from renewable sources, and employ solvent-free reaction conditions. The implementation of one project, asymmetric reduction with PLA, in the first-year organic chemistry curriculum, how it has evolved, and evaluation of these efforts is described.

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IMPLEMENTATION AND LOGISTICS

Staffing

These research-based laboratories were successfully implemented with class sizes of 50−80 students divided into three to six laboratory sections capped at 16 students per section. Trial and error showed it was important for all lab sections to be taught by full-time faculty, not part-time adjuncts, so that the participating faculty members were physically on campus beyond the lab times, were communicating frequently, and could be flexible with the lab syllabus; indeed, changes were made to the syllabus in response to laboratory outcomes during the semester, as shown in the Supporting Information. As research questions arose in the lab, additional techniques could be introduced. It was also desirable to have two student teaching assistants (TAs) in the lab to guide and train groups carrying out different aspects of the research. One student was designated as the “Instrument TA”, whose job was to prepare instruments for use and to train other students in their operation. The second TA was available for routine student questions, as the lab instructor was often busy consulting with each group about their research progress. It is hard to envision implementing this approach with large section sizes and only graduate teaching assistants to staff them.

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DEVELOPING A RESEARCH PROJECT FOR CURRICULAR INTEGRATION At the time of the laboratory curriculum overhaul, a number of students were working on a green chemistry research project nicknamed “Trash to Treasure”, the depolymerization of poly(lactic acid) (PLA) from waste cups back to the monomeric lactic acid.4 Lactic acid is chiral, and ways to use it in an asymmetric reaction were being studied, thus merging the two fields in a “green asymmetric” project as shown in the graphical abstract and Supporting Information. It was decided to study the asymmetric reduction of ketones in solvent-free conditions with PLA derivatives as chiral agents. Solvent-free reduction of ketones has been published,5 but the effect of a chiral agent on the reduction had not been studied. After identifying a research project, it was necessary to plan, develop, implement, and assess this new method of instruction. The key question here was what concepts, techniques, and methods are fundamental to the course objectives? Table 1 (columns 1 and 2) shows the answer to this question based on the goals of each old expository experiment. Organic I is heavily technique-oriented, and students are expected to apply these techniques in Organic II in solving unknowns, performing syntheses, and purifying mixtures. Table 1 also shows, in column 3, what was needed for research but missing from the traditional curriculum. It emerged that students were being taught each technique in a compartmentalized fashion by following recipes but did not know how to apply these techniques outside of that particular experiment. What was glaringly missing was the decisionmaking process, for example, how to decide what purification or analysis method should be used. This had been clear when, in the second semester, students needed to identify unknowns; they did not know where to start without specific instructions. The curriculum was also missing skills for locating information on safety, hazards, waste disposal, and synthesis procedures. Once literature procedures were found, students did not know how to follow them because they were written for experienced chemists, not novices. Students could not deviate from these procedures in terms of scale or substitution of reagents. Another key deficiency was the lack of teamwork, sharing of data, and working together to solve problems. The chosen research topic was then mapped onto the Table 1 laboratory curriculum, incorporating as many techniques and

Pre-Lab Lectures

It was also critical to have one common prelaboratory lecture so that all lab sections heard the same lecture. Each week’s prelaboratory lecture was based on the technique needed for the week ahead. After a technique had been introduced, each student wrote a summary of the purpose of the technique and a general procedure to follow in the future. Throughout the semester, students built their own e-portfolios of organic techniques and stored them in individual Wikis within a larger course Wiki. Students referred to these e-portfolios frequently during the subsequent semester in Organic Chemistry II. No Lab Manuals or Lab Setup

An important learning gain was achieved by eliminating lab manuals as well as prepared solutions and reagents. In traditional laboratories, a setup person prepared the reagents and solutions. Students did not get experience in figuring out how much of a reagent was needed without unnecessary waste or how to prepare the material; these are daily decisions most chemists make. In the research-integrated lab, each group brought their own set of procedures that included preparation of reagents. Students had access to the list of stockroom chemicals so that they could determine if a reagent they needed could be prepared. This gave them the opportunity to make decisions D


Lab Practical: demonstrate proficiency for operating instruments and solving unknowns. Demonstrate practical proficiency in operating IR and NMR and be able to deduce structure using proton, carbon NMR spectra. Demonstrate ability to perform synthetic procedure from literature procedure.

and provided practice in making reagents. All such work was done in accord with the principles of green chemistry. Spectroscopy concepts and theory were covered in the course lecture, but operational skills, techniques, and interpretation were learned in the lab for the characterization of research-based compounds. Collaborative Research Teams

In Organic Chemistry I, groups of two or three students were assigned to one of twelve different target ketones for synthesis. There were at least two groups working on each ketone. This scheme provided a check on reproducibility but, more importantly, encouraged collaboration among groups from different lab sections via research group Wikis within the larger course Wiki. The first group of the week posted their results on their research group Wiki so that the next group would not repeat that work but would use that group’s findings to try something else. By sharing data, groups who collaborated got more done than groups who did not. If a team was dysfunctional, it showed in their lack of progress. To make sure that a group was not spinning its wheels, faculty monitored progress carefully. The student-synthesized ketones from Organic Chemistry I were originally intended to serve as the unknowns for Organic Chemistry II; however, this original research plan was overly ambitious. Rather than forging ahead with the oxidation of the isolated alcohol products from the Grignard reaction in Organic Chemistry I, students instead focused on greening the synthesis of the alcohol and fully characterizing the product via additional methods. In Organic Chemistry II, teams were given an unknown from the stockroom, some pure and some not, without any procedures or directions. They were required to perform at least one chemical test to confirm or eliminate functional groups. For each chemical they were about to use, an MSDS sheet was required, as well as a plan for how to dispose the chemicals after the test. If purity of the unknown was questionable, students had to decide on the best method for determining purity and for purification. The unknowns distributed were all ketones to tie into the reduction research. After deducing the structure of the ketone, students performed a reduction without chiral derivatives as their control. Once comfortable with the control procedure, they repeated the reduction in the presence of lactic acid, ethyl lactate, or partially digested PLA. To see if chiral reduction had taken place, their alcohols were analyzed in a GC equipped with a chiral column and compared against racemic alcohols.

Assess student learning gains and compare to previous years.

Plan how to monitor the progress of the reaction, how to workup crude product, isolate product from reaction mixture. Purify and characterize product. Repeat reduction with a chiral agent. Obtain % ee of alcohol from chiral reduction. Summarize data and write report. Summarize data and write lab report.

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ASSESSMENT

Assessment of Student Outcomes

Students were assessed in various ways. For each technique a student learned, a written summary was evaluated and a quiz was given. A final written laboratory report was required for each reaction run and unknown identified. A written exam and a practical exam were given in which proficiency in the operation of GC, IR, rotary evaporator, and proton and carbon NMR were demonstrated. Also, proficiency in fractional distillation, extraction, preparing solutions, thin-layer chromatography, the use of a laboratory notebook to record observations, and locating safety information from an MSDS were demonstrated. Some results of the assessment are shown in Figure 1. (Quantitative assessment results from subsequent years are given in the Supporting Information.) The bars labeled “Post

Part 3Assessment Weeks 12−13

Part 2Reductions Weeks 5−11

Description of Tasks

Research/plan/execute functional group test; learn how to operate NMR for proton and carbon spectra. Use NMR, IR, functional group tests to deduce the structure of unknown. Plan and perform a chemical reaction.

Determining structure of unknowns. Running reduction of unknown ketone with and without chiral agent. Purifying, characterizing and determining % ee.

Goals Weeks

Part 1Structure Determination of Unknown Weeks 1−4

Table 3. Organic Chemistry II Project: Identify an unknown ketone, perform reduction with and without chiral agents, and compare these results


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Student performance in the lecture part of the course was also examined for any changes due to their laboratory experience. Figure 2 shows student performance by topic on the ACS 2004 standardized exam, administered from 2005 to 2009. Although there was no change in how the lecture was taught during these years, there was marked improvement in the percentage of students getting the right answers in 2009 for ten of the sixteen topics. It is interesting that the Diels−Alder chemistry question (enclosed in green), which was not covered due to lack of time, showed a substantial improvement. Apparently 15−20% of students guessed the correct answer out of four multiple-choice answers in 2005 to 2008. However in 2009, when students did the research-integrated laboratories, there was a jump to almost 40% of students getting this question correct. This outcome was attributed to improvement in the students’ critical thinking skills gained from their research-integrated experiences. Although some improvement could be due to differences in the student cohorts, a principal concern was that important learning not be sacrificed in the pursuit of the higher-level benefits of research-integrated laboratories. The data do not suggest any such loss.

Figure 1. Percent correct from the same exam taken by Organic I students who had expository laboratories [2008, red] versus researchintegrated laboratories [2009, before (light blue) and after the semester (dark blue)].

2008” show learning gains from the old expository laboratory for each of the techniques taught in 2008. The 2009 results are for students who experienced the new research-integrated laboratories for the first time. These students took the same exam as the 2008 cohort, both at the beginning of the semester (“Pre 2009”) and at the end of the semester (“Post 2009”). In every technique, except for recrystallization, the learning gain was greater for students who did the research-integrated laboratories. (Recrystallization was not covered that semester because the work dealt only with liquids.) TLC, a technique that students had difficulty with in the past, showed a huge gain in 2009. Also noteworthy under the topic of enantiomers is that, in 2008, students did an expository lab separating a racemic mixture using a chiral resolving agent. In 2009, students did not do a lab explicitly dealing with resolution of enantiomers; instead, stereochemistry was implicitly included through research integration, and the learning gain for enantiomeric resolution was much greater in 2009. This achievement was attributed to the fact that students understood the ultimate goal of their research on asymmetric reduction and were able to apply their knowledge about chirality.

Assessment of Student Attitudes

Students were asked to evaluate their experience in researchintegrated laboratories. Detailed results from 2008, 2009, and 2010 are given in the Supporting Information. The majority of students responded favorably to the research-integrated experience. Most students felt the Wiki was useful in communicating to other groups the results of their research and a good place to store their techniques for future use. An overwhelming number of students felt that they learned valuable skills that would help them in future laboratory courses. Not surprisingly, the 2009 students, who had a full year of research-integrated laboratories, felt more confident in their laboratory skills, instrument operation, and interpreting spectra compared with the 2008 cohort, who only had one semester of research-integrated laboratories. Another interesting finding was that more students in 2009 were confident in their decision to pursue a career in research and more students that had been

Figure 2. Percentage of Organic Chemistry II students correctly answering questions on various 2004 ACS Standardized Exam topics. F



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student-generated procedure was not suitable. Some students were initially frustrated by such situations. However, experiencing the process of doing research was evidently more instructive and rewarding than following a set of instructions. Although students did not reach the stated research objective, the research-integrated laboratories provided many initial findings that the students later pursued. In fact, many students chose to continue this research in their third year in their spare time and then chose it as their fourth-year thesis topic. The technical findings from this research have been published elsewhere.6 It was naive to believe that an army of research assistants could be trained that would quickly obtain publishable results. It was found that some student results were questionable and needed to be repeated, for example, reportedly pure substances that were not pure, yields that included impurities, or omission of important pieces of data from lab reports. The process was improved in each successive year by noting such deficiencies and then incorporating changes. Although the quality and quantity of research results did not meet initial expectations, the measured student learning gains and affirmative student response far exceeded expectations.

undecided in major felt likely to change their major to chemistry or biochemistry. These results were further reflected in strongly positive freeform student comments, such as this typical response (others are given in the Supporting Information): I was in Organic Chemistry I before research integration so I know firsthand how beneficial research integration is to understanding organic chemistry. Because I relied so heavily on procedures that were given to me, I never understood what I was doing or why anything was happening. All lab taught me was that I was good at reading directions. Organic Chemistry IIresearch integrated lab forced me to understand reactions, problem solve and work as a team. It may seem surprising initially that no student comments focused explicitly on green chemistry. Within this researchintegrated environment, greening is taught as a continual process rather than a target or a destination. The principles of green chemistry are woven throughout the structure of the research program from the choice of topic to the techniques employed and from the original plan to modifications of the plan based upon opportunities encountered. Green chemistry becomes integral to a student’s thinking about the work of an organic chemist. The absence of student comments on green chemistry may suggest that the research integration method can be successful in habituating students to green chemistry so that they are not thinking of green chemistry as separate or optional. “Green” is now standard chemistry.

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CONCLUSIONS Identifying a framework (in the present case, green chemistry) for research integration in the laboratory curriculum facilitates the process by guiding faculty thinking about possible projects and curricular synergies. This framework also helps students understand the research context and promotes their buy-in. There is even a budgetary dividend from adopting researchintegrated laboratories with green principles. Because faculty research is integrated into the course, the instructional budget helps support the research; money is saved through decreased chemical waste and wages spent on lab preparation. Nonetheless, switching to a research-integrated laboratory curriculum is challenging, as discussed above. Despite the drawbacks, the documented learning gains suggest that the multifaceted benefits of a research-integrated laboratory curriculum far outweigh the difficulties encountered. Another benefit is that students discover in their first year if research is something they want to pursue. This allows students to plan ahead and take better advantage of their remaining years in college. This jumpstart also gives students an advantage in applying for other research activities. Before the adoption of the research-integrated curriculum, none of the second-year students had been able to obtain summer REUs (Research Experience for Undergraduates program). Over the ensuing four years, at least one or two second-year students have secured REUs each summer, and the overall number of students getting REUs has increased. With the success of research-integration into organic chemistry, research-integrated laboratories are now offered in other subdisciplines, and graduating students often have been involved with three to five different research projects. Equally important, if research is not for a student, she finds out early and can explore other career directions. An added benefit from early student exposure to research is recruiting students to join research laboratories. The student population of organic chemistry includes, of course, biology and physics majors in addition to chemistry and biochemistry majors. Indeed, the research integration program included laboratory courses in the Biology and Physics Departments, as well as in Chemistry; the general research skills obtained in these courses cross-fertilize and reinforce each other, especially

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LESSONS LEARNED The initial goals for both semesters were, in retrospect, overly ambitious. In Organic I, most students were able to finish up to the alcohol stage after the Grignard reaction but did not have time for analysis after purification or for oxidizing the alcohol. In Organic II, the identification of unknowns went smoothly, but the reductions did not run as expected. There were huge variations in the amount of time required to perform the reduction, depending on the assigned ketone. Some reactions went to completion, but many did not. Many teams spent the rest of semester finding the best way to purify the racemic alcohol. Once pure racemic alcohols were obtained, each alcohol required method development on the chiral GC column. It first seemed that the number of reactions run by the students had been minimal compared to traditional laboratories, where a student might perform five or six different reactions. However, considering the fact that students did everything themselves, including searching the primary literature using SciFinder, finding MSDSs on all chemicals, adapting a literature procedure to their target molecule, deciding what scale to run the reaction, finding appropriate glassware, making all necessary solutions, monitoring the reaction, working up the reaction, purifying the reaction mixture, analyzing the product, and characterizing the productall guided by the principles of green chemistrya huge amount of learning was encompassed. Traditional laboratories could be completed in one lab period because much time had been put into refining them to work FOR the students, not BY the students, thus short-circuiting the realworld laboratory process. Because the instructor knew the expected outcome, students needed only to ask an instructor when they encountered problems. In contrast, researchintegrated laboratories forced students to solve real problems, for example, when an instrument was not working properly or a G



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for students who end up taking multiple research-integrated courses. A dramatic increase occurred in students interested in doing research; 14 out of 54 second-year students joined a research lab in 2011! Not only was student interest in research high, but those who went through research-integrated laboratories achieved better “lab sense”, laboratory skills, confidence, independence, and realistic expectations of research, even as second-year students. Before the researchintegrated curriculum, it was not feasible to allow many secondyear students to participate in faculty research. Now, routinely, a group of second-year students, headed by an upper-division student, carry out research together. The upper-division students take the leadership role played by postdocs in a research university setting. This graduate school model of mentoring gives research continuity typically not possible in an undergraduate setting, as students graduate and third-year students take their place. This program provides a model by which other institutions can explore a research-integrated laboratory curriculum and reap the benefits inherent in this approach to laboratory education.

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ASSOCIATED CONTENT

* Supporting Information S

Polylactic acid/asymmetric reduction research project schema; student assessment of research-integrated laboratory experience; free-form student comments on research-integrated laboratory experience; quantitative assessment of learning gains; lab syllabi for Organic Chemistry I; evolution of a research-integrated lab syllabus (compare with item 5); lab syllabi for Organic Chemistry II; handouts on laboratory techniques. This material is available via the Internet at http:// pubs.acs.org.

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AUTHOR INFORMATION

Corresponding Author

*N. E. Lee. E-mail: [email protected]. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS We thank the organic chemistry students who have participated in these research-integrated laboratories. We also thank the W. M. Keck Foundation, the Camille and Henry Dreyfus Foundation, and the Simmons College Presidential Fund for Faculty Excellence for financial support of this program. We thank the reviewers for their careful reading and constructive suggestions.

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REFERENCES

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Using Green Chemistry Principles As a Framework To Incorporate

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