Reactivity III: An Advanced Course in Integrated Organic, Inorganic

Feb 8, 2017 - Gaps in coverage by existing online problems were supplemented by additional questions contributed to the online homework system by an i...
0 downloads 8 Views 409KB Size
Download PDF
Article pubs.acs.org/jchemeduc

Reactivity III: An Advanced Course in Integrated Organic, Inorganic, and Biochemistry Chris P. Schaller,* Kate J. Graham, and Henry V. Jakubowski Chemistry Department, College of Saint Benedict | Saint John’s University, Ardolf Science Center, 37 South College Avenue, St. Joseph, Minnesota 56374, United States S Supporting Information *

ABSTRACT: Reactivity III is a new course that presents chemical reactions from the domains of organic, inorganic, and biochemistry that are not readily categorized by electrophile−nucleophile interactions. Many of these reactions involve the transfer of a single electron, in either an intermolecular fashion in the case of oxidation/reduction reactions or an intramolecular fashion in the case of photochemical events. Others, such as pericyclic reactions, involve movement of electron pairs but lack obvious acid/ base analogies and build on an understanding of photochemistry.

KEYWORDS: Second-Year Undergraduate, Biochemistry, Inorganic Chemistry, Organic Chemistry, Analogies / Transfer, Bioinorganic Chemistry, Oxidation / Reduction, Photochemistry

■

INTRODUCTION

Despite a history of separation in the classroom, these topics have things in common. Transition metal and main group redox reactions, radicals, and basic photochemical processes such as absorbance and fluorescence all involve single electron events, in contrast to the electrophile/nucleophile reactions of standard organic chemistry. Other reactions, in turn, are related to this set despite the fact that they involve pairs of electrons. Organic oxidations and reductions can still be discussed in terms of oxidation states but mechanistically hark back to 1,2eliminations and carbonyl additions, respectively. Reactions under orbital control have something in common with electrophilic additions of alkenes, but the phenomenon of photochemical control ties them also to a discussion of photochemistry. All of these topics may form an interesting body of material together; this idea is the thesis of an advanced course in reactivity, Reactivity III. Care was taken in the design of Reactivity III to develop story lines that would serve as a rationale for the study of these topics. For example, students look at some examples of redoxactive transition metals in biology in the first class as a way of introducing the idea of reduction potentials. Later, they go through a discussion of the ozone cycle and the formation of smog as an introduction to photochemistry. The importance of narrative in teaching science has been described previously.11 Despite concerns that spending time on developing context

A few years ago, a speaker at a national meeting wryly commented on his laboratory’s exploration of electrochemistry, radicals, photochemistry, pericyclic reactions, and transition metal catalysis: “These are all of the things that organic chemists are afraid of.”1 The reaction of the audience confirmed the truth in that assessment. There may be many reasons for discomfort with these topics. One reason is certainly a lack of practice with these reactions. However, although these reactions are understandable and predictable, they often fall outside the patterns of nucleophiles and electrophiles that are common to a wide range of organic reactions. These exceptional reactions, even though they are taught in all organic chemistry courses, do not fit those more common rules, and so they can be difficult to categorize and assimilate into a wider knowledge base.2 From the perspective of an introductory course in organic chemistry, it is not clear where these subjects belong. Radical reactions may be covered relatively early in an organic chemistry textbook,3,4 toward the end,5 or somewhere in between,6,7 because the topic has little relation to other material in the course. Electrochemistry and transition metal catalysts belong in entirely different coursesgeneral chemistry and inorganic chemistryso that information is stored in different “silos”, introducing the difficulty of transferring knowledge across contexts.8 Recently, organic chemistry textbooks have begun including some organotransition metal chemistry, signaling an interest in breaking down these barriers.9,10 © 2017 American Chemical Society and Division of Chemical Education, Inc.

Received: July 7, 2016 Revised: January 13, 2017 Published: February 8, 2017 289

DOI: 10.1021/acs.jchemed.6b00503 J. Chem. Educ. 2017, 94, 289−295

Journal of Chemical Education

Article

sphere mechanisms of electron transfer are not typically covered in general chemistries, but these concepts are introduced in Reactivity III, in keeping with the mechanistic theme of this sequence of courses. The transition metalmediated reduction of dioxygen and dinitrogen, important in both biochemistry and chemical industry, is used as a springboard into radical reactions. Some examples of oxidation/reduction coverage, such as the Nernst equation, are omitted from Reactivity III but presented in Macroscopic Chemical Analysis. Students taking both courses concurrently encounter initial concepts of oxidation/ reduction early in the semester in Reactivity III and see a more sophisticated mathematical treatment toward the end of the semester in Macroscopic Chemical Analysis. The intent is that majors can build a deeper understanding of this material if their perspective is limited to one aspect of the topic at a time.20 A second section of the course extends the single-electron theme to a unit on photochemistry. The close relationship between photochemistry and electrochemistry has long been an important topic in inorganic chemistry courses; examples are drawn from both solid-state materials21 and organometallics.22 In Reactivity III, the importance of this topic is further emphasized by looking at the atmospheric phenomena of ozone and smog; environmental issues are an excellent vehicle for chemistry content.23,24 A discussion of some recent studies in photoredox catalysis provides a unifying thread that ties electrochemistry and photochemistry together,25 and photosynthesis provides a classic example of a similar concept from biochemistry. A unit on reactions controlled by orbital symmetry, including cycloadditions and electrocyclic reactions, is developed at the level of a second-year undergraduate organic chemistry course.26 These reactions are well-established in organic chemistry, but some debate has arisen when translating the principles of orbital symmetry to transition metal-mediated reactions.27,28 In Reactivity III, organic cycoadditions are contrasted with the [2 + 2] cycloaddition and cycloreversion of olefin metathesis which, although formally forbidden thermally, nevertheless demonstrate low activation barriers.29,30 Rearrangements to electron-deficient centers have also been linked previously to pericyclic reactions,31 and although that treatment is not typical it has been used as a loose narrative connection to the final topic in this course. Because this is the first course in the Reactivity I−III series to be directed solely at chemistry and biochemistry majors, special attention is paid to exposing students to some of the studies beneath the lessons. For example, in the unit on oxidative phosphorylation, a series of studies is presented that were aimed at understanding why Rieske clusters have higher reduction potentials than other iron clusters.32−35 Students see recent developments, finding motivation in the application of course material to real research.36 Among other topics, they see developments of SOMO catalysis37 and the extension to photoredox catalysis38 in the context of imine and enamine chemistry and then return to further applications of photocatalysis in cycloadditions after discussing reactions under orbital control.39,40 In addition, students can also glimpse the historical development of some topics so that they can understand how scientists approach the unknown. For instance, in a discussion of olefin metathesis, students see some of the reasoning used by Chauvin in elucidating the mechanism of the reaction,41 as well as early contributions from Schrock42 and Grubbs43 toward catalyst development. The importance of this

may be a distraction from key concepts, storytelling seems to promote retention of material learned during class time.12

■

CHEM 315: REACTIVITY III

Context within a New Chemistry Curriculum

Reactivity III is part of a curriculum developed with the aim of building stronger connections between traditionally separate domains within chemistry, with strong lines of narrative to draw students into the material.13 After an introductory course in chemical structure and properties,14 students take a first reactivity class in organic carbonyl reactions, coordination compounds, and the mechanism and regulation of metabolic pathways (Reactivity I).15 A second course in reactivity deals with substitution reactions in alkyl halides and coordination complexes, transition metal organometallics, and the reactions of alkenes and aromatics with electrophiles (Reactivity II).16 Another main branch of chemistry is developed in two courses, Chem 255: Macroscopic Chemical Analysis, and Chem 318: Microscopic Chemical Analysis, which focus on quantitative approaches to measuring and modeling chemical phenomena.13 Chemistry and biochemistry majors typically take Reactivity III after Chem 251: Reactivity II and concurrently with Macroscopic Chemical Analysis; this arrangement allows greater scheduling flexibility as the majority of students at CSB/SJU spend a semester abroad. Overview of Course Content

A list of topics in Reactivity III is provided in Table 1. Although the use of reduction potentials in transition metal and main Table 1. Topics in Chem 315: Reactivity III topic

class periodsa

Introduction to reduction potentials Activity series and Hess’ Law Outer and inner sphere reactions Balancing reactions Organic and biochemical redox Reduction of oxygen and nitrogen Magnetism and EPR Radical reactions Oxidative phosphorylation Photochemistry and atmospheric chemistry Photoredox catalysis Photosynthesis Cycloadditions and pericyclics Olefin metathesis Rearrangements

1 2 1 1 1 2 1 4 4 3 2 2 3 1 1

a

85 min periods: 29 total, with tests and quizzes included during this time.

group redox chemistry is a standard topic in general chemistry courses, the coverage in Reactivity III has a different emphasis. Bioinorganic chemistry is introduced as a way to provide context for the ideas of electron transfer and reduction potentials, and oxidative phosphorylation is developed as a case study. Spending time to develop context for chemistry concepts has been shown to promote retention of material.17 Bioinorganic chemistry seems like an obvious opportunity to build context and draw in students who may also be interested in biology, but it is covered in less than one-third of foundationlevel inorganic chemistry classes18 and just over one-half of indepth courses in inorganic chemistry.19 Inner-sphere and outer290

DOI: 10.1021/acs.jchemed.6b00503 J. Chem. Educ. 2017, 94, 289−295

Journal of Chemical Education

Article

approach has been highlighted in other areas, such as in studying the rates of electron transfer reactions.44 As in previous courses, there is material that does not get very much coverage in Reactivity III. For example, Reactivity III has less focus on organic chemistry than do Reactivity I and II. One topic that receives less attention is organic synthesis. Students do “road map” problems in which they practice reagent recognition and product prediction in the context of a total synthesis45 but do not perform retrosynthetic analyses as they might in an organic chemistry course. Retrosynthesis is taught in an in-depth course, instead.

Complex IV (cytochrome c oxidase) revisits a problem from earlier in the course: the need to exploit the highly positive reduction potential of molecular oxygen without releasing reactive oxygen species in the cell. This unit includes possible pathways by which protons could be transported counter to the direction of electron flow.60,61 Comparatively little time is spent on complex V (ATP synthase), which enters the picture after the electron transport chain.62

■

IMPLEMENTATION

Faculty Participants

Specific Example of Course Coverage: Nitrogen Reduction

Previous courses in the Structure and Reactivity series were developed and taught by cohorts of instructors representing a breadth of training.8−11 This approach facilitated coverage of material from multiple traditional domains of chemistry. Reactivity III involved a smaller number of students compared to Reactivity I or II, so only one or two sections were offered in a semester, but cooperation between faculty was still a crucial part of course development and delivery. Reactivity III has been taught by an organometallic chemist with a background in physical organic methods, an organic chemist with training in natural products isolation, a physical biochemist with expertise in kinetics, and a medicinal chemist. All of these participants prepared varying amounts of materials for the course. An inorganic chemist, who has not yet taught the course, also contributed significantly to course preparation. It was essential for these participants to share their work and to be willing to approach their peers for help.

Nitrogen reduction is examined in the context of biological nitrogen fixation, the Haber-Bosch process, and model studies used to investigate both. The subject is covered after oxidation/ reduction chemistry and a brief introduction to radicals. Students are first introduced to the Haber−Bosch process, including the temperature dependence of the equilibrium constant and a possible mechanism of reaction, which is presented by analogy with organometallic reactions from Reactivity II. After looking into the structure of the FeMo cofactor,46 different possible mechanisms for biological nitrogen fixation are developed, including one that involves protonation only at nitrogen and one that invokes iron hydride complexes.47,48 Model studies focus on the relative rarity of dinitrogen complexes and the need for highly reduced metal centers to exploit weak π-donation in the ligand/substrate.49−51 IR and 15 N NMR spectroscopy are introduced as probes of nitrogen reduction upon binding,52 and the use of carbon monoxide as a surrogate for dinitrogen is illustrated.53 Students also see electrochemical studies of model complexes, including the dependence of reduction potential on the protonation state of the complex.54

Pedagogy

Reactivity III employed a blended approach to learning.63 Students were expected to finish readings on the material outside of class. In the classroom, instructors highlighted key points on the topic of the day before directing teams of students to work on a series of questions in a workbook. Instructors circulated among teams, engaging individual students, and stopped to address the entire class at intermediate points and again at the end of the class period. The class was scheduled for fifty-five min class periods meeting three times weekly or, more recently, for eighty-five min class periods meeting twice weekly. Periodically, written quizzes or tests were used to check student progress. Most recently, these included 15 min quizzes once per week and 45 min tests once per month. A number of supporting materials proved helpful. A workbook for daily use was developed in-house (see Supporting Information for sample pages). Some of the content was drawn from materials previously used in organic, inorganic, and biochemistry courses, but the majority was written from scratch. Frequently, narratives in the workbook were drawn from either recent or classic primary literature in an effort to engage students with the process of science. Although a custom-published textbook was initially used to support selected topics, the majority of readings were drawn from sources such as Chemwiki64 as well as an in-house online textbook.65 Other technological supports included a commercially available online homework system, requiring that students purchase a passcode.66 Online homework can stimulate student learning by promoting regular practice.67 These questions vary in sophistication. Some are multiple choice; some require matching items in one column with items in another; and some require students to draw a compound, such as a reaction

Second Example of Course Coverage: Oxidative Phosphorylation

Oxidative phosphorylation is covered after students have developed an understanding of oxidation/reduction and radical chemistry. The section is organized around the different complexes within the oxidative phosphorylation supercomplex. Starting with respiratory complex I (NADH−quinone oxidoreductase) and complex II (succinate−quinone oxidoreductase), students look at the structure and properties of electron carriers such as FeS clusters, heme, and ubiquinone.55 The roles of flexible one- or two-electron carriers such as FAD and FMN are highlighted, and the importance of tuning reduction potentials along the electron transport chain is investigated here and in the other complexes. The latter topic is especially important and is analogous to the widely recognized influence of microenvironment on pKa values, with resulting consequences in biochemical function.56 Calculations of the energy involved in the NADH reduction of oxygen, compared to some individual steps in the electron transport chain, underscore the importance of a multistep pathway. Coupling of electron transport to proton pumping is also discussed.57 A section on complex III (coenzyme Q-cytochrome c oxidoreductase) includes the importance of the Q loop in increasing efficiency of proton pumping. In addition, investigations of the high reduction potential of Rieske FeS clusters are used as a case study of the scientific process.32−35 Students also look into possible mechanisms through which mobile electron carriers reach their targets.58,59 291

DOI: 10.1021/acs.jchemed.6b00503 J. Chem. Educ. 2017, 94, 289−295

Journal of Chemical Education

Article

product or a mechanistic intermediate, whereas others require students to add curved arrows to intermediates in anticipation of the next reaction step. There are a number of tutor exercises that lead students interactively through the basics of new topics. Gaps in coverage by existing online problems were supplemented by additional questions contributed to the online homework system by an instructor; over one hundred new problems were coded for Reactivity III. An instant response tool was also used in the classroom to assess retention of material from the previous class period.68 For the most part, however, none of these questions obviate the role of questions on paper, a more flexible medium that allows more nuanced evaluation of student work.

■

COURSE OUTCOMES As in other courses from the CSB/SJU curriculum, Reactivity III has been assessed through a combination of grade data, standardized test questions, and choice of major. The percentage of students receiving a grade of D, F, or W (% DFW) provides a rough index of the students’ experience in the course; the results suggest that Reactivity III is a very manageable course (Table 2). A lower %DFW rate in Reactivity

Figure 1. Distribution of difficulty indices of questions selected for Chem 315 final exam compared to a complete ACS exam, based on national pool. On this scale, 0−20% is hardest and 81−100% is easiest.

difficulty index 56%) with a randomly selected ACS exam (average difficulty index 54%). It is difficult to compare results on exam questions taken in one contexta complete ACS examwith results on isolated questions taken out of that context. Nevertheless, student performance on the Chem 315 exam questions appears to be slightly higher than performance on the selected questions nationally (Table 3). Historically, students at CSB/SJU have

Table 2. Comparative Average Student Outcomes and Percentages of Students with Grades of D, F, or W course, academic yeara Org Chem II, 2005−2012 Inorganic/Biochem, 2005−2012 Reactivity III, 2013d Reactivity III, 2014e Reactivity III, 2015e Reactivity III, 2016e

students, N c

100 24c 38 42 54 42

ASOb

W, %

DFW, %

2.62 2.93 3.32 2.89 2.78 3.08

3.5 1.2 0.0 2.4 0.0 0.0

8.9 3.6 0.0 2.4 0.0 0.0

Table 3. Comparison of Average Difficulty Index on ACS Exam Questions in Chem 315 to Nationally Normed Data average difficulty index, ACS exam questions

a

Academic year refers to the end of academic year; i.e., 2005 = academic year 2004−2005. bAverage student outcome (ASO) in the class on a 4.0 scale. cAverage number per year during period reported. d Spring section only. eFall and spring sections.

academic year

Chem 315 dataa

national datab

2013 2014 2015 2016

60 59 61 67

56 56 56 56

a

The difficulty index is the fraction of students with the correct answer to a question. bThe average of difficulty indices of all questions used, based on national norms.

III than that observed in Organic Chemistry II might be expected in a class composed of chemistry and biochemistry majors, who are committed to seeing the course through. However, the %DFW rate appears to be even lower than in previous biochemistry and inorganic chemistry classes. Average student outcome (ASO), the mean grade earned in the class on a 4.0 scale, was comparable to the previous eightyear average in upper-division biochemistry and inorganic chemistry, except for abnormally high grades during the inaugural offering. This initial spike was subsequently corrected by revising the relative number of points based on homework vs testing. A difference in means test (two-tailed t test) suggests that the mean is also the same as that observed in Organic Chemistry II, although that result may change after larger numbers of students have taken Chem 315. The final exam for Reactivity III included forty-nine questions drawn from ACS exams in organic, inorganic, general, and biochemistry. These questions were delivered in an online format with the help of the ACS Exams Institute. An attempt was made not only to select questions that fit the content of Chem 315 but to select a distribution of difficulty levels similar to that of an ACS exam (Figure 1). The difficulty indexthat is, the percent of students answering a particular question correctly in national pool data provided by ACSwas used to compare the Chem 315 exam questions (average

performed above average on ACS subject exams, so this result probably does not reflect a distinct advantage of Chem 315 over traditional courses in organic, inorganic, and biochemistry. Instead, it illustrates that significant deviation from an orthodox delivery of the chemistry curriculum need not sacrifice mastery of standard content. In addition to these questions, twenty-one final exam questions were written in-house to assess topics for which corresponding questions were not found in ACS exams. These questions were important for developing a fuller understanding of student comprehension and also helped replicate a more typical seventy-question ACS exam experience but do not allow direct comparison to students nationally. Further measures indicate the impact of the entire curriculum on students, rather than the specific results of Chem 315. The first two cohorts of chemistry majors to complete the new curriculum were assigned by a coin toss to take either the Major Field Achievement Test (MFAT) or the Diagnostic of Undergraduate Chemistry Knowledge (DUCK) exam. Although the overall mean on these tests was high, at approximately the 70th national percentile, CSB/SJU students 292

DOI: 10.1021/acs.jchemed.6b00503 J. Chem. Educ. 2017, 94, 289−295

Journal of Chemical Education

Article

aspects of the new curriculum. Majors were already able to take some of the current in-depth courses, offered as special topics courses, during AY 2011 and afterward. Subsequently, there was an additional increase in majors after the formal rollout of the new curriculum. Causes other than curricular change could explain an increase in the number of majors. An increasing number of enrolled undergraduates could be responsible, for example. However, CSB/SJU has tried to become more selective in the past decade, leading to a slight decrease in the size of the incoming class, although total numbers of students served by the chemistry department have remained constant. A comparison to national trends would be useful, but ACS-CPT appears to have discontinued its reports on these numbers in 2009.69 CSB/SJU Admissions has not increased its priority on recruiting chemistry students over this period, but the chemistry department was awarded a grant for ten annual chemistry or biochemistry scholarships shortly after the curricular change was implemented; the first scholars graduated in 2016, one year after the first cohort to complete the new curriculum.70 It is expected that these scholarships have increased the number of chemistry and biochemistry majors, but awardees are drawn from a pool of accepted students already earmarked to receive some kind of college scholarship, so the degree to which this individual scholarship has impacted overall numbers is not clear. Anecdotally, some of the students who accepted the scholarship have stated that they did so because of the curriculum. Turnover in faculty is another possible reason for increasing numbers of majors. The department has had seven retirements of tenured faculty members (out of a previous total of 13) over the last ten years; these members have been replaced by four tenure-track people and a number of adjunct faculty. New instructors may bring an increased level of enthusiasm that attracts students. On the other hand, adjunct faculty tend to turn over rapidly; the department has had 16 in the past ten years (compared to eight in the previous ten), most of whom go on to permanent teaching positions elsewhere. Thus, the net effect of personnel changes is difficult to assess.

previously fared strongly compared to their peers (Table 4). A difference in means test (two-tailed t test) indicates that the Table 4. Overall Performance by Fourth-Year Students on Comprehensive Chemistry Exams national percentile score testa,b,c

academic year

students, Ne

high

low

mean

MFAT

2004−2014 2015 2016 2015 2016

164 13 12 13 12

99 93 99 97 99

16 31 38 14 35

79 76 67 60 72

DUCKd a

Major Field Achievement Test (MFAT). bDiagnostic of Undergraduate Chemistry Knowledge (DUCK). cStudents randomly assigned MFAT or DUCK. dNo baseline data available. eBiochemistry majors may choose to take a test in either chemistry or biology.

average MFAT scores remained the same before and after the curriculum change. Again, that result may be revised after larger numbers of students have taken Chem 315. Even a modest change in performance may simply reflect the trade-off in coverage of materials. For example, the foundationlevel inorganic chemistry curriculum based on reactivity trends with a focus on transition metals provides little coverage of main group and descriptive chemistry. Furthermore, a move away from uniform in-depth requirements toward more flexibility in course selection has allowed students to focus on their areas of interest but may leave each student with gaps in other topics. A further measure of the impact of this curriculum can be seen in the numbers of students choosing to major in chemistry or biochemistry (Table 5). Although the choice of a major is Table 5. Distribution of Chemistry and Biochemistry Majors Graduated by Year major

AY 1995− 2014a

AY 2015b

AY 2016

AY 2017c

AY 2018c

Chem, N Biochem, N

13 7

27 16

23 12

23 20

24 15

■

CONCLUSIONS A third course has been developed that covers integrated reactivity in organic, inorganic, and biochemistry. This course is complementary to those previously reported because it is not based on the standard pattern of acid/base or electrophile/ nucleophile interactions.10,11 A theme of single electron reactions is extended from electrochemistry to photochemistry and other reactions that defy simple electrophile/nucleophile descriptions are also included. Overall, students display strong proficiency in these topics. Strikingly, the introduction of this new Structure, Reactivity, and Quantitation curriculum has coincided with an increase in the number of majors in chemistry and biochemistry. Although this change in major enrollment cannot be attributed to the curricular change, it serves as an indicator that dramatic revision of the chemistry curriculum can be undertaken without fear of driving away students.

a

Average per year during this period. bFirst cohort to graduate from new curriculum. cProjected, based on estimated 10% attrition after declaration of major in second year.

more strongly linked to experiences in the first year, most students declare their major while taking Reactivity III, and so a negative experience in the course might lead students to drop out of the major. In fact, the number of students graduating each year with either a chemistry or a biochemistry major has nearly doubled since the introduction of the new curriculum, and current trajectories show that trend continuing in the next two years. Readers of previous papers in this series may note that this increase was gradual; there was a smaller increase in AY 2012.14 However, this curriculum did not come out of nowhere. The first semester of general chemistry already resembled the current Structure and Properties course by the fall of 2009. Organic chemistry students were already getting September exposure to NMR spectroscopy and autumn exposure to carbonyl chemistry before 2000; transition metal organometallics began to appear in the course in the early 2000s. These latter changes were later incorporated into different

■

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available on the ACS Publications website at DOI: 10.1021/acs.jchemed.6b00503. 293

DOI: 10.1021/acs.jchemed.6b00503 J. Chem. Educ. 2017, 94, 289−295

Journal of Chemical Education

■

Article

A. Chemical Structure and Properties: A Modified Atoms-First, OneSemester Introductory Chemistry Course. J. Chem. Educ. 2015, 92 (2), 237−246. (15) Schaller, C. P.; Graham, K. J.; Johnson, B. J.; Jones, T. N.; McIntee, E. J. Reactivity I: A Foundation-Level Course for Both Majors and Nonmajors in Integrated Organic, Inorganic, and Biochemistry. J. Chem. Educ. 2015, 92 (12), 2067−2073. (16) Schaller, C. P.; Graham, K. J.; McIntee, E. J.; Jones, T. N.; Johnson, B. J. Reactivity II: A Second Foundation-Level Course in Integrated Organic, Inorganic, and Biochemistry. J. Chem. Educ. 2016, 93 (8), 1383−1390. (17) Lowery Bretz, S. Novak’s Theory of Education: Human Constructivism and Meaningful Learning. J. Chem. Educ. 2001, 78 (8), 1107−1116. (18) Raker, J. R.; Reisner, B. A.; Smith, S. R.; Stewart, J. L.; Crane, J. L.; Pesterfield, L.; Sobel, S. G. Foundation Coursework in Undergraduate Inorganic Chemistry: Results from a National Survey of Inorganic Chemistry Faculty. J. Chem. Educ. 2015, 92 (6), 973−979. (19) Raker, J. R.; Reisner, B. A.; Smith, S. R.; Stewart, J. L.; Crane, J. L.; Pesterfield, L.; Sobel, S. G. In-Depth Coursework in Undergraduate Inorganic Chemistry: Results from a National Survey of Inorganic Chemistry Faculty. J. Chem. Educ. 2015, 92 (6), 980−985. (20) Johnstone, A. H. The Development of Chemistry Teaching. J. Chem. Educ. 1993, 70 (9), 701−705. (21) Ellis, A. B. Excited-State Processes of Relevance to Photoelectrochemistry. J. Chem. Educ. 1983, 60 (4), 332−335. (22) Tyler, D. R. Organometallic Photochemistry: Basic Principles and Applications to Materials Chemistry. J. Chem. Educ. 1997, 74 (6), 668−672. (23) Bunce, N. Introduction to Environmental Chemistry, 1st ed.; Wuerz: Winnipeg, MB, Canada, 1993. (24) Baird, C.; Cann, M. Environmental Chemistry, 5th ed.; W. H. Freeman and Company: New York, 2012. (25) Tucker, J. W.; Stephenson, C. R. J. Shining Light on Photoredox Catalysis: Theory and Synthetic Applications. J. Org. Chem. 2012, 77 (4), 1617−1622. (26) Jones, M., Jr.; Fleming, S. A. Organic Chemistry, 5th ed.; W. W. Norton & Company: New York, 2014; pp 1153−1202. (27) Corey, E. J.; Sarshar, S.; Azimioara, M. D.; Newbold, R. C.; Noe, M. C. X-ray Crystal and NMR Structure of a Highly Reactive Bidentate 1,2-Diamine-OsO4 Complex, Formally a 20-Electron Outer Valence Shell Species. Mechanistic Implications for the 1,2-DiamineAccelerated Dihydroxylation of Olefins by OsO4. J. Am. Chem. Soc. 1996, 118 (33), 7851−7852. (28) DelMonte, A. J.; Haller, J.; Houk, K. N.; Sharpless, K. B.; Singleton, D. A.; Strassner, T.; Thomas, A. A. Experimental and Theoretical Kinetic Isotope Effects for Asymmetric Dihydroxylation. Evidence Supporting a Rate-Limiting “(3 + 2)” Cycloaddition. J. Am. Chem. Soc. 1997, 119 (41), 9907−9908. (29) Folga, E.; Ziegler, T. Density Functional Study on Molybdacyclobutane and its Role in Olefin Metathesis. Organometallics 1993, 12 (2), 325−337. (30) Monteyne, K.; Ziegler, T. The [2 + 2] Addition of Ethylene to Metal−Ligand Multiple Bonds: A Density Functional Study of Mo(E)OCl2. Organometallics 1998, 17 (26), 5901−5907. (31) Hornback, J. A. Organic Chemistry, 2nd ed.; Thomson Brooks/ Cole: Belmont, CA, 2006; pp 994−1001. (32) Zu, Y.; Couture, M. M.-J.; Kolling, D. R. J.; Crofts, A. R.; Eltis, L. D.; Fee, J. E.; Hirst, J. Reduction Potentials of Rieske Clusters: Importance of the Coupling between Oxidation State and Histidine Protonation State. Biochemistry 2003, 42 (42), 12400−12408. (33) Zu, Y.; Fee, J. E.; Hirst, J. Breaking and Re-Forming the Disulfide Bond at the High-Potential, Respiratory-Type Rieske [2Fe2S] Center of Thermus thermophilus: Characterization of the Sulfhydryl State by Protein-Film Voltammetry. Biochemistry 2002, 41 (47), 14054−14065. (34) Leggate, E.; Hirst, J. Roles of the Disulfide Bond and Adjacent Residues in Determining the Reduction Potentials and Stabilities of

Sample pages from the Reactivity III workbook, with accompanying notes from the daily schedule for the class; sample assessment data; and information on accessing electronic or hardcopies of the workbook (PDF, DOCX)

AUTHOR INFORMATION

Corresponding Author

*(C.P.S.) E-mail: [email protected]. ORCID

Chris P. Schaller: 0000-0003-0763-0446 Kate J. Graham: 0000-0002-2301-0557 Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS This material is based upon work supported by the National Science Foundation under Grant 1043566. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. The authors wish to thank Brian Johnson and Ed McIntee for their contributions to the course, as well as Nicholas Jones for his help with assessment.

■

REFERENCES

(1) Yoon, T. P. Organic Synthesis Using Visible Light Catalysis. Presented at the 241st National Meeting of the American Chemical Society, Anaheim, CA, March 27−31, 2011; Paper ORGN 632. (2) Nosofsky, R. M.; Palmeri, T. J.; McKinley, S. C. Rule-PlusException Model of Classification Learning. Psych. Rev. 1994, 101 (1), 53−79. (3) McMurry, J. E. Organic Chemistry, 6th ed.; Thomson Brooks/ Cole: Belmont, CA, 2004; pp 316−342. (4) Brown, W. H.; Foote, C. S.; Iverson, B. L.; Anslyn, E. V.; Novak, B. M. Organic Chemistry, 6th ed.; Brooks/Cole Cengage: Belmont, CA, 2012; pp 296−330. (5) Karty, J. M. Organic Chemistry: Principles and Mechanisms, 1st ed.; W. W. Norton: New York, 2014; pp 1199−1244. (6) Solomons, T. W. G.; Fryhle, C. B.; Snyder, S. A. Organic Chemistry, 11th ed.; Wiley: Hoboken, NJ, 2013; pp 457−497. (7) Ege, S. Organic Chemistry: Structure and Reactivity, 4th ed.; Houghton Mifflin: New York, 1999; pp 804−838. (8) Murray, J. L.; Atkinson, E. J. O.; Gilbert, B. D.; Kruchten, A. E. A Novel Interdisciplinary Science Experience for Undergraduates Across Introductory Biology, Chemistry, and Physics Courses. J. Coll. Sci. Teach. 2014, 43, 46. (9) Bruice, P. Y. Organic Chemistry, 8th ed.; Pearson: Upper Saddle River, NJ, 2016; pp 508−531. (10) Clayden, J.; Greeves, N.; Warren, S.; Wothers, P. Organic Chemistry, 1st ed.; Oxford: New York, 2001; pp 1331−1344. (11) Hobbs, L.; Davis, R. Narrative Pedagogies in Science, Mathematics and Technology. Res. Sci. Educ. 2013, 43 (3), 1289− 1305. (12) Arya, D. J.; Maul, A. The Role of the Scientific Discovery Narrative in Middle School Science Education: An Experimental Study. J. Educ. Psych. 2012, 104 (4), 1022−1032. (13) Schaller, C. P.; Graham, K. J.; Johnson, B. J.; Fazal, M. A.; Jones, T. N.; McIntee, E. J.; Jakubowski, H. V. Developing and Implementing a Reorganized Undergraduate Chemistry Curriculum Based on the Foundational Chemistry Topics of Structure, Reactivity, and Quantitation. J. Chem. Educ. 2014, 91 (3), 321−328. (14) Schaller, C. P.; Graham, K. J.; Johnson, B. J.; Jakubowski, H. V.; McKenna, A. G.; McIntee, E. J.; Jones, T. N.; Fazal, M. A.; Peterson, A. 294

DOI: 10.1021/acs.jchemed.6b00503 J. Chem. Educ. 2017, 94, 289−295

Journal of Chemical Education

Article

Respiratory-Type Rieske Clusters. Biochemistry 2005, 44 (18), 7048− 7058. (35) Brown, E. N.; Friemann, R.; Karlsson, A.; Parales, J. V.; Couture, M. J.-M.; Eltis, L. D.; Ramaswamy, S. Determining Rieske Cluster Reduction Potentials. JBIC, J. Biol. Inorg. Chem. 2008, 13 (8), 1301− 1313. (36) Shea, K. M.; Gorin, D. J.; Buck, M. E. Literature-Based Problems for Introductory Organic Chemistry Quizzes and Exams. J. Chem. Educ. 2016, 93 (5), 886−890. (37) Beeson, T. D.; Mastracchio, A.; Hong, J.-B.; Ashton, K.; MacMillan, D. W. C. Enantioselective Organocatalysis Using SOMO Activation. Science 2007, 316 (5824), 582−585. (38) Nicewicz, D. A.; MacMillan, D. W. C. Enantioselective Organocatalysis Using SOMO Activation. Science 2008, 322 (5898), 77−80. (39) Lin, S.; Ischay, M. A.; Fry, C. G.; Yoon, T. P. Radical Cation Diels-Alder Cycloadditions by Visible Light Photocatalysis. J. Am. Chem. Soc. 2011, 133 (48), 19350−19353. (40) Lu, Z.; Yoon, T. Visible Light Photocatalysis of [2 + 2] Styrene Cycloadditions by Energy Transfer. Angew. Chem., Int. Ed. 2012, 51 (41), 10329−10332. (41) Chauvin, Y. Olefin Metathesis: The Early Days (Nobel Lecture). Angew. Chem., Int. Ed. 2006, 45 (23), 3740−3747. (42) Schrock, R. R. Multiple Metal−Carbon Bonds for Catalytic Metathesis Reactions (Nobel Lecture). Angew. Chem., Int. Ed. 2006, 45 (23), 3748−3759. (43) Grubbs, R. H. Olefin-Metathesis Catalysts for the Preparation of Molecules and Materials (Nobel Lecture). Angew. Chem., Int. Ed. 2006, 45 (23), 3760−3765. (44) Di Giacomo, F. A Short Account of RRKM Theory of Unimolecular Reactions and of Marcus Theory of Electron Transfer in a Historical Perspective. J. Chem. Educ. 2015, 92 (5), 476−481. (45) Schaller, C. P.; Graham, K. J.; Jones, T. N. Synthesis Road Map Problems in Organic Chemistry. J. Chem. Educ. 2014, 91 (12), 2142− 2145. (46) Einsle, O.; Tezcan, F. A.; Andrade, S.; Schmid, B.; Yoshida, M.; Howard, J. B.; Rees, D. C. Nitrogenase MoFe-Protein at 1.16 Å Resolution: A Central Ligand in the FeMo-Cofactor. Science 2002, 297 (5587), 1696−1700. (47) Kästner, J.; Blöchl, P. E. Ammonia Production at the FeMo Cofactor of Nitrogenase: Results from Density Functional Theory. J. Am. Chem. Soc. 2007, 129 (10), 2998−3006. (48) Hoffman, B. M.; Lukoyanov, D.; Yang, Z. Y.; Dean, D. R.; Seefeldt, L. C. Mechanism of Nitrogen Fixation by Nitrogenase: The Next Stage. Chem. Rev. 2014, 114 (8), 4041−62. (49) MacKay, B. A.; Fryzuk, M. D. Dinitrogen Coordination Chemistry: On the Biomimetic Borderlands. Chem. Rev. 2004, 104 (2), 385−402. (50) Bart, S. C.; Lobkovsky, E.; Chirik, P. J. Preparation and Molecular and Electronic Structures of Iron(0) Dinitrogen and Silane Complexes and Their Application to Catalytic Hydrogenation and Hydrosilation. J. Am. Chem. Soc. 2004, 126 (42), 13794−13807. (51) Creutz, S. E.; Peters, J. C. Catalytic Reduction of N2 to NH3 by an Fe−N2 Complex Featuring a C-Atom Anchor. J. Am. Chem. Soc. 2014, 136 (3), 1105−1115. (52) Avenier, P.; Taoufik, M.; Lesage, A.; Solans-Monfort, X.; Baudouin, A.; de Mallmann, A.; Veyre, L.; Basset, J.-M.; Eisenstein, O.; Emsley, L.; Quadrelli, E. A. Dinitrogen Dissociation on an Isolated Surface Tantalum Atom. Science 2007, 317 (5841), 1056−1060. (53) Sellmann, D.; Sutter, J. In Quest of Competitive Catalysts for Nitrogenases and Other Metal Sulfur Enzymes. Acc. Chem. Res. 1997, 30 (11), 460−469. (54) Sellmann, D.; Utz, J.; Blum, N.; Heinemann, F. W. On the Function of Nitrogenase FeMo Cofactors and Competitive Catalysts: Chemical Principles, Structural Blue-prints, and the Relevance of Iron Sulfur Complexes for N2 Fixation. Coord. Chem. Rev. 1999, 190 (1), 607−627. (55) Efremov, R. G.; Baradaran, R.; Sazanov, L. A. The architecture of respiratory complex I. Nature 2010, 465 (7297), 441−445.

(56) Pace, C. N.; Grimsley, G. R.; Scholtz, J. M. Protein Ionizable Groups: pK values and Their Contribution to Protein Stability and Solubility. J. Biol. Chem. 2009, 284 (20), 13285−13290. (57) Berrisford, J. M.; Sazanov, L. A. Structural Basis for the Mechanism of Respiratory Complex I. J. Biol. Chem. 2009, 284 (43), 29773−29783. (58) Hochman, J.; Ferguson-Miller, S.; Schindler, M. Mobility in the Mitochondrial Electron Transport Chain. Biochemistry 1985, 24 (10), 2509−2516. (59) Lenaz, G.; Genova, M. L. Kinetics of Integrated Electron Transfer in the Mitochondrial Respiratory Chain: Random Collisions vs. Solid State Electron Channeling. Am. J. Physiol. Cell Physiol. 2007, 292 (4), C1221−C1239. (60) Wikström, M. Proton Translocation by Cytochrome c Oxidase: A Rejoinder to Recent Criticism. Biochemistry 2000, 39 (13), 3515− 3519. (61) Brändén, G.; Gennis, R. B.; Brzezinski, P. Transmembrane Proton Translocation by Cytochrome c Oxidase. Biochim. Biophys. Acta, Bioenerg. 2006, 1757 (8), 1052−1063. (62) Dimroth, P. Operation of the F0Motor of the ATP-Synthase. Biochim. Biophys. Acta, Bioenerg. 2000, 1458 (2−3), 374−386. (63) Woods, D. R. Problem-Oriented Learning, Problem-Based Learning, Problem-Based Synthesis, Process Oriented Guided Inquiry Learning, Peer-Led Team Learning, Model-Eliciting Activities, and Project-Based Learning: What is Best for You? Ind. Eng. Chem. Res. 2014, 53 (13), 5337−5354. (64) Larsen, D., Ed. ChemWiki: The Dynamic Chemistry Hypertext. http://chemwiki.ucdavis.edu (accessed 22 Nov, 2016). (65) Schaller, C. P. Structure and Reactivity in Organic, Biological and Inorganic Chemistry. http://employees.csbsju.edu/cschaller/ ROBI2.htm (accessed 22 Nov, 2016). (66) OWL, Version 2, Cengage Learning. http://www.cengage.com/ owlv2 (accessed 22 Nov, 2016). (67) Parker, L. L.; Loudon, G. M. Case Study Using Online Homework in Undergraduate Organic Chemistry: Results and Student Attitudes. J. Chem. Educ. 2013, 90 (1), 37−44. (68) Socrative, MasteryConnect. http://www.socrative.com (accessed 22 Nov, 2016). (69) American Chemical Society - Committee on Professional Training. Annual Reports of Earned Bachelor’s Degrees in Chemistry. https://www.acs.org/content/acs/en/about/governance/committees/ training/reports/degreesreport.html (accessed 22 Nov, 2016). (70) National Science Foundation. Award Abstract #1059730, Future Chemists Scholarships and Supports. https://www.nsf.gov/ awardsearch/showAward?AWD_ID=1059730 (accessed 22 Nov, 2016).

295

DOI: 10.1021/acs.jchemed.6b00503 J. Chem. Educ. 2017, 94, 289−295