Article pubs.acs.org/jchemeduc
Comparing Carbonyl Chemistry in Comprehensive Introductory Organic Chemistry Textbooks Donna J. Nelson,*,† Ravi Kumar,†,‡ and Saravanan Ramasamy† †
Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma 73019, United States Department of Chemistry, Chaudhary Bansi Lal University, Bhiwani, Haryana, India
‡
S Supporting Information *
ABSTRACT: Learning the chemistry of compounds containing carbonyl groups is difficult for undergraduate students partly because of a convolution of multiple possible reaction sites, competitive reactions taking place at those sites, different criteria needed to discern between the mechanisms of these reactions, and no straightforward selection method applicable to all. Factual inaccuracies in some recently used comprehensive introductory organic chemistry textbooks can distract and confuse students. Student interest, combined with some inconsistencies, prompted a systematic comparison of these textbooks, enabling some suggestions for improvement. Students also selected a preferred order of presentation in which carbonyl chemistry should appear for optimal learning: carboxylic acids, aldehydes, ketones, carboxylic acid derivatives, α,β-unsaturated carbonyls, and carbonyl compounds that undergo enol chemistry. This ordering is generally based on a combination of (1) grouping according to the purpose of the functional group, (2) increasing complexity of reactions with a nucleophile, and (3) decreasing carbonyl compound reactivity. In order to facilitate solving carbonyl chemistry problems and understanding these competing factors, information about the reactions is presented in three forms: a text discussion, a Summary Sheet, and a Decision Tree. The recommendations are consistent, descriptive, and pedagogically useful, and they should remedy many discrepancies. KEYWORDS: Second-Year Undergraduate Students, Curriculum, Organic Chemistry, Misconceptions/Discrepant Events, Textbooks/Reference Books, Aldehydes/Ketones, Carboxylic Acids, Mechanisms of Reactions
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INTRODUCTION Reactions of carbonyl compounds and organic chemistry generally are pertinent to many scientific fields, such as petroleum chemistry,1 environmental chemistry,2 biochemistry,3 and medical professions.4 Chemistry at a carbonyl group, or at a molecular site that is activated by a carbonyl group, is the basis of many important reactions in organic chemistry. Numerous different classes of organic compounds contain the CO functionality, such as aldehydes, ketones, carboxylic acids, and carboxylic acid derivatives, to name just a few. Many recently used comprehensive introductory organic chemistry textbooks5−21 contain multiple chapters covering such classes of carbonyl compounds. This massive amount of carbonyl chemistry can constitute almost half of the chapters covered in a second semester introductory undergraduate organic chemistry course. Learning the reactions of carbonyl compounds with nucleophiles or bases is convoluted by having multiple reaction sites and possible cross reactions.22 For example, carbonyl compounds have four different potential sites of reactivity with anions, as represented by the arrows in Figure 1. There is also one reaction site for complexation with cations and other electrophiles at the carbonyl oxygen. Furthermore, in many of © XXXX American Chemical Society and Division of Chemical Education, Inc.
Figure 1. Four possible sites of attack upon carbonyl compounds by base or nucleophile.
the reactions with a nucleophile, the carbonyl oxygen can be protonated or not, and the nucleophile or base can be neutral or anionic. The many reaction permutations increase the topic complexity and student confusion, as students simultaneously learn reactions and their mechanisms.23,24 It has been reported that, in attempts to resolve these difficulties, undergraduate organic chemistry students often consult alternate sources of information in addition to the course-adopted textbook as a way to clarify difficult concepts
A
DOI: 10.1021/ed500421j J. Chem. Educ. XXXX, XXX, XXX−XXX
B
CRC
Roberts Jones/Bartlett
Smith, M. B.
Loudon Fox
Cengage Cengage Macmillan McGraw Hill
Brown Hornback Vollhardt Smith, J. G.
Cengage
Pearson
Bruice
McMurry
1 7
Wiley Pearson
Klein Wade
5 3
1
8
5 2 6 4
7
2 5 4 2 11 9
Current Edition
2009 2004
2010
2012
2009 2006 2011 2013
2013
2012 2010
2012 2004 2010 2006 2013 2013
Pub. Year
4 2
5
5
5 3 5 6
3
3 4
7 4 4 8 5 4
No. of Chapters
RCHO
R2CO RCOHal
RCOOR
RCOX (RCO)2O
RCONR2
β-C
1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 9 1 2 3 4 5 6 7 9 1 2 3 4 5 6 7 9 1 2 3 4 5 6 7 9 1 2b 2b 4 5 6 7 9 Reversed aldehyde and ketone 1 3 2 4 5 6 7 9 1 3 2 4 5 6 7 9 Presented aldehydes and ketones later 1 7 6 2 3 4 5 8 Presented α-H abstraction, β-attack, or both earlier 1 2 3 5 6 7 8 9 1 2b 2b 5 6 7 8 4 1 2 3 6 7 8 9 5 1 3b 3b 6 7 8 9 2 Reversed aldehydes and ketones; presented β-attack and α-H abstraction earlier 1 4 3 6 7 8 9 5 Carboxylic acids and β position attack are not in recommended order 3 2 1 4 5 6 7 9 Carboxylic acid derivatives and other groups are not in recommended order 1 3 2 7 6 4 5 9 1 3b 3b 7 8 5 6 9
RCOOH
8 2
8
2
4 9 4 5
9
8 8
9 9 8 8 8 8 8
α-H
mostly C
C
C
C mostly mostly C
LUMO
C C
C mostly mostly C C mostly
Arrow Points at CO LUMOa
20 21
19
18
14 15 16 17
13
11 12
5 6 7 8 9 10
Ref
LUMO = lowest unoccupied molecular orbital. In this column “mostly” indicates that the mechanism arrow points at the CO LUMO in most instances, “C” indicates that the arrow points at the carbon of CO from any direction, and “LUMO” indicates that the arrow always points at the CO LUMO. bAldehyde and ketone functional groups are presented together and not separately, therefore the same order number is used.
a
Textbooks
Publisher
Student-preferred presentation order Clayden Oxford Univ Eğe Houghton Mifflin Jones Norton Sorrell Univ Science Solomons Wiley Carey McGraw Hill
Senior Author
Presentation Ordering of Site of Attack by Nu− or B− upon Carbonyl Compounds
Table 1. Carbonyl Reaction Presentation in Introductory Organic Chemistry Textbooks
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and/or supplement the weak points of a text.24a Such convenient sources can offer a student alternative explanations that better fit his or her learning style.23,24a The need for a fact-based and straightforward presentation in general chemistry, in undergraduate organic chemistry, and in graduate level organic chemistry textbooks has been suggested24 for facilitating student learning. This is especially important in organic chemistry because some organic chemistry textbooks have very long service lives (over ten years5) before new editions are released. For example, the first edition of Clayden5 was published in 2001, and the second edition was published 11 years later in 2012. The importance of being consistent and reducing confusion in introductory organic chemistry textbooks has also been discussed.24 The convoluted nature of carbonyl chemistry increases the critical nature of the selection, order, grouping, and comparison of reactions in organic chemistry textbooks.5−21 Its presentation should reinforce, rather than contradict, the actual reactivities of carbonyl compounds. Therefore, we (a) examined comprehensive introductory organic chemistry textbooks for carbonyl reaction ordering, factual accuracy, and terminology, (b) compared and tabulated their carbonyl reaction ordering versus the above three ordering criteria, and (c) evaluated the texts using this data-driven approach in order to help identify optimal and practical characteristics for covering carbonyl chemistry.
chemistry. Additional information about these results is available in the Supporting Information.
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RESULTS AND DISCUSSION The ordering and content of material pertaining to carbonyl compounds across 175−21 comprehensive introductory organic chemistry textbooks are compared in Table 1. Results are shown in Table 1. Textbooks examined vary in the number of chapters devoted to carbonyl chemistry (Table 1), e.g., one text8 has eight chapters, one text5 has seven, one text17 has six, five texts9,14,16,18,19 have five, five texts6,7,10,12,20 use four chapters, three texts11,13,15 use three, and one text21 has two chapters (Table 1). Variations in ordering, grouping, selection, and carbonyl reaction comparison are found across the texts.5−21 All but one textbook had errors in appropriately pointing the mechanism arrow depicting nucleophilic attack at the carbonyl LUMO (lowest unoccupied molecular orbital). Some texts had factual errors, such as (A) nucleophilic attack at the carbonyl carbon of carboxylic acids with OH still intact17 and (B) not pointing the arrow at the LUMO of the carbonyl π bond.5−12,14−21 These may be well-meaning attempts to simplify the material, but they could nevertheless (1) confuse students learning to draw reaction mechanisms or (2) leave them feeling ill-prepared25b for questions on the role of the carbonyl antibonding orbital in standardized tests, such as ACS standardized exams in organic chemistry.25c The use of unnecessary terminology can confuse students, so if different terms are used for identical concepts, it must be explicitly stated that they are equivalent; this is not done currently. Furthermore, recent changes in terminology have not been adopted uniformly across the textbooks. For example, the term “conjugative effect” is still used in one text,21 while it has been replaced with “resonance effect” in the others; although both are technically correct, it could again lead to confusion if students consult multiple textbooks.
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METHODOLOGY For comparison and thoroughness, a copy of each known comprehensive, introductory, two-semester organic chemistry textbook was assembled that was in use when the project began. There were 15 commonly used textbooks (Clayden,5 Jones,7 Sorrell,8 Solomons,9 Carey,10 Klein,11 Wade,12 Bruice,13 Brown,14 Hornback,15 Vollhardt,16 J. G. Smith,17 McMurry,18 M. B. Smith,19 and Loudon20), and two additional recently used ones (Eğe6 and Fox21), both of which were very popular while they were available, were added (Table 1). Textbooks were obtained from publishers and compared, details of which are listed in the left columns (senior author, publisher, edition, and year) of Table 1. Several groups of undergraduate students, who recently had completed Organic Chemistry I and II, and were enrolled in research courses from 2011 through 2013, collected data on the organization and characteristics of the textbook material on carbonyl compounds, and helped to formulate the recommendations discussed herein. Additional information about (1) consulting alternative instructional material and (2) the benefit of devices developed to facilitate learning carbonyl chemistry (a Summary Sheet and a Decision Tree, which are presented below) has been obtained from surveys and discussions with the above and other undergraduates over a period of time.25a A majority of students surveyed indicated that they consulted other textbooks and alternative instructional materials frequently. Some students indicated that they used other textbooks extensively. They also indicated that carbonyl chemistry seems convoluted due to multiple reaction sites in carbonyl compounds and possible cross reactions. All surveyed students preferred carbonyl chemistry to be presented in an order starting with compounds undergoing the simplest mechanisms and lowest reactivity, and transitioning to increasing complexity and greatest reactivity. Students preferred a Decision Tree over a Summary Sheet or written explanations for helping one to learn carbonyl
Presentation Ordering
Presentation ordering in a text can effortlessly reinforce the order of reactivity of the above carbonyl compound reaction sites. The reactivity of different carbonyl compounds and the reaction mechanism complexity of each could be recalled merely by recalling the order in which the material was presented. In Table 1, the characteristics of the carbonyl chemistry contained in each text are listed, and the texts are arranged according to their agreement with the ordering recommended and identified as most desirable by students. Ordering Used by Textbooks Examined Herein
Most currently used texts use unexplained common organizational techniques, but only sparsely applied to a couple of carbonyl functional groups. The remaining carbonyl groups are then frequently presented in an inconsistent order. Examples of these are detailed below. Abstraction of a proton from a carboxylic acid (Figure 1, position 1) appears first.5−18,20,21 It is placed in the acids and bases section of most texts, which seems logical considering the functionality of the carboxylic acid. Aldehyde and ketone reactions (Figure 1, position 2) are presented after carboxylic acids, but before carboxylic acid derivatives,5−12,14−21 which is reasonable because it follows a logical order based on reaction mechanism complexity. Aldehydes are presented most often before ketones,5−10,14−16 which fits the concept of presenting carbonyls in order of C
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Figure 2. Summary Sheet showing (a) conditions needed in order for the reaction to deviate from attack at the carbonyl carbon and (b) reaction site decision criteria.
functional groups, (b) degree of reaction mechanism complexity, and (c) reactivity of the carbonyl functional group. Criterion c was used as much as possible because students indicated that having the presentation ordering in the text parallel the order of reactivity of the carbonyl compound reaction sites would help them recall the latter. However, the presentation order proposed herein is not based merely on carbonyl functional group reactivity. Carboxylic acid reaction (Figure 1, position 1) should typically be the first carbonyl compound presented because it will be put in the acids and bases section, which comes near the beginning of most texts,5−18,20,21 and it is logical because the most reactive site of a carboxylic acid with an anion is its acidic proton (pKa = 4.8).26 Because reaction mechanisms of aldehydes and ketones with nucleophiles are simpler than those of carboxylic acid derivatives, aldehyde and ketone reactions preferably should precede the latter. The mechanistic simplicity of nucleophilic attack at an aldehyde or ketone logically supports this reaction being the default carbonyl reaction, so other carbonyl compounds with more complex reaction mechanisms will be considered as deviations from this default reaction. Aldehydes and ketones are generally more reactive than some carboxylic acid derivatives (esters and amides), but less reactive than others (acid halides and anhydrides). Presenting aldehyde and ketone reactions (Figure 1, position 2) after carboxylic acids and before carboxylic acid derivatives is reasonable because this follows a logical order based on
decreasing reactivity as much as possible. However, other relationships are also found: ketones are discussed before aldehydes,11−13,18−20 aldehydes and ketones are presented together,15,17,21 and aldehydes and ketones are also presented after all carboxylic acid derivatives.13 When reactions of two functional groups are presented together in a text, the two groups are given the same presentation order number (e.g., two 2’s for Carey,5 two 3’s for J. G. Smith,17 two 3’s for Fox21) in order to compare easily with other texts; therefore, these three texts do not order aldehydes and ketones relative to each other. Although reactivity ordering could be applied to the presentation order of the remaining carbonyl functional groups, this is not done in most currently used texts.5−12,14−21 Carboxylic acid derivatives (Figure 1, position 2) generally appear in order of decreasing reactivity,5−19 but this is not the case for Louden20 or Fox,21 who discuss carboxylic acid esters and amides before acid halides and anhydrides, although the latter are more reactive than the former. Ordering with respect to decreasing reactivity is not usually applied to β attack in α,β-unsaturated carbonyls or to abstraction of an α-proton.6−12,14,16,18−21 Attack is presented at the β-carbon before α-proton abstraction.5,13,15,17 Rationale for the Recommended Order of Presentation
We brainstormed with students in order to determine characteristics that make the material easiest for them to understand and learn. Multiple factors were identified: (a) grouping compounds according to the purpose of their D
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carbonyl reaction mechanism complexity. Mastering simpler reaction mechanisms first prepares a student to learn the more complex ones. Reaction at position 2 is simplest and involves attack of a nucleophile at a ketone or aldehyde carbonyl carbon, which occurs unless there is a more reactive site such as a carboxylic acid proton, a carbonyl bearing a good leaving group such as halide (Hal) or acetate, an α,β-unsaturation, or a proton α to a carbonyl. Reactions of carboxylic acid derivatives should come after aldehydes and ketones. They should be presented as a set due to their similar reaction mechanisms, and be discussed in decreasing order of reactivity toward nucleophiles. This suggests matching presentation order with reactivity order when considering the other carbonyl compounds as well. Thus, carbonyl compounds other than carboxylic acids, aldehydes, and ketones (carboxylic acid derivatives, α,β-unsaturated carbonyl compounds, and carbonyl compounds undergoing α-proton abstraction) can be presented in decreasing order of their relative reactivities. Attack by a soft base at the β position in α,β-unsaturated carbonyls (Figure 1, position 3) occurs more rapidly compared to α-proton abstraction, so the former is recommended to precede the latter. α-Proton abstraction (Figure 1, position 4) with a soft base theoretically can occur whenever there is an αproton, but not generally selectively in competition with attack at the β-carbon of an α,β-unsaturated carbonyl. A soft nucleophile attacks the β-carbon preferably over abstraction of an α-proton, and both are favored over nucleophilic attack at the carbonyl carbon.27 Therefore, the proposed order here does not merely reflect the reactivity of different compounds. It also considers (1) grouping compounds that have functionalities with a similar purpose (carboxylic acids in the acids and bases section) and (2) the complexity of the reaction mechanism (aldehydes and ketones versus carboxylic acid derivatives).
aldehydes and ketones. Ordering the latter carbonyl functional groups according to their reactivities is simplified by a Summary Sheet (Figure 2) and by a Decision Tree (Figure 3); these compare and clarify the characteristics of deviations from the default reaction without considering the complexity of the reaction mechanisms.
Devices That Visualize the Reactivity Order of Carbonyl Compounds
Figure 3. Decision Tree showing reaction site decision criteria.
Two devices were developed that visualize the ordering of carbonyl compound reactivity, and these can be used in conjunction with the typical written description of the reactivity order of carbonyls. Attack of a nucleophile at a carbonyl carbon leads to addition in aldehydes and ketones and to substitution in carboxylic acid derivatives with good leaving groups. A source of confusion for students can be that the site of attack in reactions of carbonyl compounds can range from positions 1 through 4 (Figure 1) depending upon reaction conditions and structural features of the substrate. Another way to facilitate grasping reaction site selectivity criteria by simplifying it is to consider attack at the carbonyl carbon (Figure 1, position 2) as the default reaction due to simplicity of its mechanism and attack at positions 1, 3, and 4 to be deviations from the default. Therefore, the reaction of carboxylic acid derivatives, attack at the β position of an α,βunsaturated carbonyl, and deprotonation of an α-H can each be considered as a deviation from the default reaction. This simplifies predicting which reaction will occur because one merely must determine whether a characteristic that will cause deviation is present. Deviation from the default reaction can be described in the written part of the text, but it can also be presented in the form of supplementary devices that enable visualizing the reactivity ordering of carbonyl compounds other than the default
Summary Sheet (Figure 2)
A Summary Sheet details conditions that switch the site of attack away from the carbonyl carbon, which is considered the default reaction site. One alternative is deprotonation of a carboxylic acid under basic conditions, while attack at the carbonyl carbon is possible under acidic conditions.26 A carboxylic acid has pKa = 4.8, so even a weak base should deprotonate it rather than attack at the carbonyl. A somewhat similar situation exists for an amide with an amidic proton, but an amide has a pKa of approximately 15.0 and needs a much stronger base to be deprotonated. A second way to deviate from the default reaction is to favor the selective abstraction of an α-proton of an aldehyde, ketone, ester, or amide under strongly basic conditions by a means such as increasing the anion bulkiness. A nucleophile with a low charge concentration (a soft base) attacks at the β position of an α,β-unsaturated carbonyl derivative and constitutes a third deviation from the default reaction, while a nucleophile with a high charge concentration (a hard base) attacks the carbonyl carbon. Decision Tree (Figure 3)
A Decision Tree helps to weigh and apply characteristics that switch the reaction mechanism away from the default attack at the carbonyl group. To decide whether a nucleophile will attack E
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the carbonyl carbon or deviate from this default reaction, a stepwise method can be adopted (Figure 3). First, if a carboxylic acid or an amide is the substrate, then deprotonation at N or O will take place under basic conditions. If this criterion is not met, then the presence of a “soft” nucleophile with low charge density will lead to attack at the β position in α,β-unsaturated aldehydes and ketones. However, if the reaction involves a “hard” nucleophile, then it will proceed via attack at CO, the default reaction. If the reaction uses a strong base, it will abstract an α-proton from an aldehyde, ketone, carboxylic ester, or N-dialkylated amide rather than attack the carbonyl carbon. An α-proton abstraction from a carboxylic acid will not occur in the presence of the COOH acidic proton, so OH is not a possible substituent attached to CO here. Students indicated that having such figures and summaries in textbooks would be a simple, effective, and concise way to present and compare this extensive information, which is otherwise typically spread throughout the text. These recommendations for improvement result from student opinions, the textbook analysis herein, and years of organic chemistry teaching experience.
Figure 4. Arrow is positioned correctly in order to depict the lone pair of the nucleophile occupying the carbonyl antibonding orbital17 (p 880). However, this reaction does not take place as drawn because the carboxylic acid proton is more reactive with anions than the carbonyl carbon is.
However, such attack at the carbonyl of COOH by a nucleophile will not happen because the proton of COOH is more reactive than the carbonyl carbon, especially in reactions with anionic nucleophiles (Nu:−).28 Use of Color in the Textbook
Using colorful images in a textbook can be more appealing to the eye and might seem to be merely a matter of taste. However, when used in excess, illogically, or without explanation, color can be a mere distraction; it can hinder recognizing the primary teaching objective and learning the desired material.29 Using multiple colors in a single heading and unnecessary shading in reaction mechanism steps containing an embedded step name do not appear to convey any important message, and colored boxes in reaction mechanisms divert attention from the main mechanistic points11 (e.g., pp 922− 954). Similarly, highlighted comment boxes used in reaction mechanisms13 are reported by students to be distracting. Students found selection of colors5 to be inappropriate because using red for all reactions does not distinguish different mechanistic steps. Different colors are used without the selection of colors designating different steps or components of a reaction.19
Using Appropriate Arrows To Show Attack at the Carbonyl
The concept of breaking a carbonyl π bond by populating its antibonding orbital is not addressed in most current introductory organic chemistry textbooks.5−12,14−21 This misses a convenient instructional opportunity because students may not understand the molecular orbital changes involved in breaking such a bond. This concept could be conveyed easily by depicting a lone pair of electrons moving to occupy the antibonding orbital of the carbonyl π bond. In order to show this process most accurately, the arrow depicting attack of a nucleophile upon a carbonyl group should, therefore, point at the region of space defined by the corresponding π* orbital. The carbonyl π* orbital occupies the region of space that is (1) above and below the plane formed by the carbonyl carbon and the two atoms singly bonded to it and (2) on the back of the carbonyl functionality, opposite to oxygen. However, it was found that most textbooks point the arrow at the carbonyl carbon from arbitrary angles. Although pointing each arrow correctly at the region of space occupied by the π* orbital13 may be more costly for publishers, doing this is necessary in order to preserve the factual accuracy of the presented material and better serve a student. An exception might be made when depicting attack at cyclic carbonyls where it would be necessary for the arrow to cross a C−C bond in order to show the nucleophile lone pair, which populates the π* orbital. Avoiding this by having the arrow point at the carbonyl carbon from the side and exocyclically may, therefore, be acceptable in cyclic carbonyls due to problems with arrows overlapping bonds and difficulties with typesetting. However, the downside to this is that it could set an example for students to use a wrong angle of attack at carbonyls generally, which could create misperceptions for acyclic carbonyl compounds.
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CONCLUSION Comparing 15 currently available5,7−20 and two recently used6,21 comprehensive introductory organic chemistry textbooks reveals that their carbonyl chemistry presentations differ in a number of ways. Optimal factors in ordering the presentation of carbonyl compounds were identified: (a) introduce carboxylic acids in the acids and bases section, (b) select attack at the carboxyl carbon to be the default reaction based on the degree of reaction mechanism simplicity, and (c) order the remaining reactions based on the reactivity of the carbonyl compound reactive position. If no relationship between presentation ordering versus mechanism complexity or carbonyl reactivity is conveyed, the approach to carbonyl compound reaction mechanisms seems unsystematic. In order to help a student avoid confusion in predicting the site of nucleophilic attack, a Summary Sheet and a Decision Tree showing reaction site selectivity criteria were presented. These guides facilitate analyzing and understanding nucleophilic reactions of carbonyl compounds. Arrow-pushing has long been an integral part of organic chemistry5−21 and should be used to convey directionality in attack, which is directly tied to the influence of orbital overlap and population of the π* orbital upon nucleophilic attack at C in carbonyl reactions with nucleophiles.
Factual Errors in Nucleophilic Attack at Carbonyl Compounds
Attack by an anion at the carboxylic acid carbonyl group (instead of attack to abstract the acidic carboxylic acid proton) is depicted in one text 17 (Figure 4). This drawing communicates that attack at the carbonyl carbon of COOH by Nu:− is favored over carboxylic acid proton abstraction. F
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(21) Fox, M. A.; Whitesell, J. K. Organic Chemistry, 3rd ed.; Jones and Bartlett Publishers: Sudbury, MA, 2004. (22) (a) Private communication from: Carroll, H.; Robinson, C.; Nguyen, T.; Pham, U.; Maddox, T.; Hovell, V.; Fusco, A.; Bayaa, D.; Clevenger, S.; Phan, A. (b) Refer to Supporting Information for survey results. (23) Lingenfelter, K. Prescription from House MD: Confessions of a Science Groupie; 241st National Meeting of the American Chemical Society, Anaheim, CA, March 27, 2011. (24) (a) Nelson, D. J.; Brammer, C. N. Toward Consistent Terminology for Cyclohexane Conformers in Introductory Organic Chemistry. J. Chem. Educ. 2011, 88 (3), 292−294. (b) Adams, D. L. Toward the Consistent Use of Regiochemical and Stereochemical Terms in Introductory Organic Chemistry. J. Chem. Educ. 1992, 69 (6), 451−452. (c) Vitz, E. Redox Redux: Recommendations for Improving Textbooks and IUPAC Definitions. J. Chem. Educ. 2002, 79 (3), 397−400. (d) Suidan, L.; Badenhoop, J. K.; Glendening, E. D.; Weinhold, F. Common Textbook and Teaching Misrepresentations of Lewis Structures. J. Chem. Educ. 1995, 72 (7), 583−586. (e) Refer to Supporting Information for survey results. (25) (a) Nelson, D. J. Devices to Clarify Reaction Site Selection by Nucleophiles and Bases in Carbonyl Compounds; 216th ACS National Meeting, Boston, MA, ORGN 212, Aug 23, 1998. (b) Private communication from: Hasting, W.; Jin, L.; Carroll, H.; Robinson, C.; Nguyen, T.; Pham, U.; Maddox, T.; Hovell, V.; Fusco, A.; Bayaa, D.; Clevenger, S.; Phan, A. (c) ACS standardized exam. http:// chemexams.chem.iastate.edu/ (accessed January, 2012). (26) Smith, M. B.; March, J. March’s Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 6th ed.; John Wiley & Sons, Inc.: Hoboken, NJ, 2007; pp 329−331. (27) (a) Posner, G. H. An Introduction to Synthesis Using Organocopper Reagents; John Wiley & Sons, Inc: New York, NY, 1980; p 8. (b) Kabashima, H.; Katou, T.; Hattori, H. Conjugate Addition of Methanol to 3-Buten-2-one Over Solid Base Catalysis. Appl. Catal., A 2001, 214, 121−124. (c) Negishi, E. Organometallics in Organic Synthesis; John Wiley & Sons, Toronto, 1980; Vol. 1, Chapter 4. (d) Akita, M.; Matsuoka, K.; Asami, K.; Yasuda, H.; Nakamura, A. Selective Carbometallation of α,β-Unsaturated Carbonyl Compounds and Substituted Oxacyclopropanes with Zirconium-Diene Complexes. J. Organomet. Chem. 1987, 327, 193−209. (28) Personal communication. Niwayama, S., Department of Chemistry, Texas Tech University, TX, 2011. (29) Simons, D. J. Selective Attention Test (video). Viscog Productions; 1999. www.viscog.com (accessed December, 2011).
ASSOCIATED CONTENT
S Supporting Information *
Results of the survey, methodology, and printable Figures 2 and 3. This material is available via the Internet at http://pubs.acs. org.
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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