Why is Chapter 1 not a “general chemistry review” chapter?
Why does resonance appear in Chapter 1?
Why are protic and aprotic solvents introduced in Chapter 2?
Why is Molecular Orbital Theory presented separately from Valence Bond Theory in Chapter 3?
In Chapter 4, why are conformers covered before constitutional isomers?
How can/should I treat nomenclature?
Why are chirality and configurational isomers introduced before reactions?
Why is curved arrow notation for reactions introduced in Chapter 6 in the context of proton transfer reactions?
Why are reaction free energy diagrams introduced in Chapter 6 in the context of proton transfer reactions?
How much should I emphasize free energy diagrams and charge stability in Chapter 6?
Can I skip Chapter 7 (An Overview of the Most Common Elementary Steps), because the topics will be revisited later in the book in the context of the reactions where they apply?
Why are the orbital pictures of the common elementary steps presented in Interchapter C?
Why are multistep mechanisms introduced in the context of SN1 and E1 reactions in Chapter 8?
Why is Chapter 9 devoted only to the SN1/SN2/E1/E2 competition?
Is it important to emphasize reversibility and kinetic vs. thermodynamic control in Chapters 9?
Why are nucleophilic substitution and elimination reactions introduced before electrophilic addition reactions or nucleophilic addition reactions?
Why are strategies for multistep synthesis introduced in Chapters 10 and 11, and not earlier?
Why are the nucleophilic substitution & elimination that are useful for synthesis introduced in two chapters (Chapters 10 and 11) instead of one?
Why is mass spectrometry (Chapter 15) introduced before IR, UV-vis, and NMR spectroscopy?
Can the structure determination chapters (Chapters 15-17) be moved earlier?
Why are nucleophilic addition reactions presented in two chapters (Chapters 18 and 19)? Similarly, why are nucleophilic addition-elimination reactions presented in two separate chapters (Chapters 22 and 23)?
Why are a carbon reactions not presented in their own chapter?
Why are the reactions that form organometallic reagents presented in Chapter 20?
Why are the Diels-Alder, syn dihydroxylation, and oxidative cleavage reactions introduced in their own chapter (Chapter 26) instead of alongside electrophilic addition reactions (Chapters 12 and 13)?
Why are radical reactions presented at the end of the book (Chapter 27)?
How can I get my students to perform their best with synthesis? Taking advantage of the appendices.
With the Karty textbook, can I teach all of carbonyl chemistry in the first semester?
With the Karty textbook, can I teach alkene/alkyne chemistry in its entirety (including Diels-Alder and oxidative cleavage reactions) in first semester?
Why is Chapter 1 not a “general chemistry review” chapter?
General chemistry review topics are spread throughout the first six chapters of my book to provide a better transition from general chemistry to organic chemistry. Students tend not to have retained as much general chemistry as we want or need them to have retained, in which case a general chemistry review chapter, which marches rapidly through several topics, ends up leaving students behind. Moreover, even if a student is quite capable with general chemistry topics, it does not necessarily mean that the student is able to apply those concepts to organic molecules, which are larger and more complex than molecules students encounter in general chemistry.
By spreading general chemistry topics throughout the first six chapters, my textbook allows students more time to spend on a particular topic before moving on to the next. Once a general chemistry topic is reviewed, students then see how it applies to organic chemistry, in ways beyond what they would have seen in general chemistry. For example, in Section 1.5, students quickly review the rules for drawing Lewis structures of small molecules. Then, in Section 1.6, students learn how to complete Lewis structures for large, complex organic molecules. As another example, in Section 6.4, students review Gibbs free energy and energy diagrams, and then in Section 6.6, students learn how to use free energy diagrams and charge stability to predict relative strengths of acids and bases.
Why does resonance appear in Chapter 1?
Resonance appears in Chapter 1 to give students as much practice with predicting molecular stability and drawing curved arrows as possible before they are held accountable for working with reactions and mechanisms. Practicing with resonance helps students understand and make predictions about key aspects of molecular stability, a major factor that dictates the outcome of a chemical reaction. Students also draw curved arrows when drawing resonance structures, the same curved arrows that are used in drawing mechanisms. Students are typically quite ready for working with resonance in Chapter 1 because it is it is a review topic from general chemistry and a straightforward extension of Lewis structures. When the introduction of resonance is instead delayed until the context of p bonds and conjugation, students have less time to gain mastery of resonance and curved arrow notation before starting reactions and mechanisms, thus compromising the learning of reactions and mechanisms.
Why are protic and aprotic solvents introduced in Chapter 2?
Traditionally, protic and aprotic solvents are introduced in the context of the competition between SN1, SN2, E1, and E2 reactions, to demonstrate the way solvent effects can impact the outcome of that competition. When students learn a new concept like this in the context of predicting the outcome of a reaction, students tend to focus on just the reaction, not the understanding of the next concept. In such cases, the understanding of solvent effects falls by the wayside. With my textbook introducing protic and aprotic solvents in Chapter 2, students learn the concept in the context of a topic that is already familiar to them from general chemistry: solubility. Not only does this make it more comfortable for students to focus on understanding protic and aprotic solvents when they first learn the topic, but students will see it a second time when they later learn about the SN1/SN2/E1/E2 competition. This makes it more manageable for students to focus on the SN1/SN2/E1/E2 competition then.
Why is Molecular Orbital Theory presented separately from Valence Bond Theory in Chapter 3?
In many textbooks, molecular orbital theory and valence bond theory are presented together and rapidly, often in a general chemistry review chapter. As a result, students tend to come away with substantial confusion as to what actually distinguishes the two theories, and what the advantages and disadvantages are to each. In my textbook, Chapter 3 is devoted entirely to these two theories. Chapter 3 first develops valence bond theory, applying it toward the structure and stability of common small molecules. Then, those ideas are revisited from the perspective of molecular orbital theory. This helps students to better distinguish one theory from the other, and to better come away with the notion that valence bond theory is simpler, at the expense of having significant limitations.
Moreover, molecular orbital theory is presented entirely in a “Deeper Look” section. All “Deeper Look” sections are devoted to topics that are more challenging or more quantitative. Therefore, instructors can teach as much or little molecular orbital theory as they see fit for their students, without worrying about being bitten later on by skipping its coverage.
In Chapter 4, why are conformers covered before constitutional isomers?
The main reason is for students to come away with a better understanding of why some molecules that might initially appear to be different, such as the ones below, are in fact not constitutional isomers. We can show students how to make this conclusion from a process we give them, but it helps even more so to show students that they are in fact the same molecule through single bond rotations.
That having been said, an instructor who wishes to teach constitutional isomers before conformers can do so seamlessly, simply by teaching Sections 4.10 – 4.13 before Sections 4.1 – 4.9. In fact, some users of the textbook already teach in this rearranged order.
How much time should I spend on Chapters 1-4, and what are the major things I should make sure my students know from those chapters?
Other organic chemistry textbooks devote their first chapter to reviewing general chemistry, speeding through the highlights of what students ought to have retained from their general chemistry course. I take a different approach in my book. Instead, I spread the bulk of these general chemistry review topics over the first four chapters—chapters that are devoted to various aspects of molecular structure and stability. Therefore, in many instances throughout these chapters, students will review familiar material from general chemistry and will almost immediately apply it to a new organic chemistry topic. There are at least three advantages to this: (1) students better see organic chemistry as an extension of topics from general chemistry, rather than being distinct from general chemistry, so the transition to organic chemistry is more seamless; (2) because the review topics are split up, they can be covered more extensively, if necessary, without the instructor or students feeling bogged down in a lengthy rehash of general chemistry; and (3) students can better hit the ground running at the outset of the course, delving into organic chemistry topics earlier.
Because the first four chapters have extended coverage of a number of general chemistry topics, you can feel comfortable spending less time on several of those topics in class, or even requiring students to review them on their own outside of class. Well before the course begins, I encourage you to identify the specific topics/sections to cover only lightly in class or exclude from class time entirely. You will appreciate the time saved to devote to other topics later on. In my case, I spend roughly three weeks on Chapters 1-4, which I view as a week saved.
By the same token, there are topics/sections in the first four chapters on which I strongly recommend spending a good amount of time in class. These are topics that students either don’t learn well in general chemistry, are very important foundations for later material, or both. Here I have listed these sections, and I have provided rationale.
1.6. Strategies for Success: Drawing Lewis Dot Structures
QuicklyStudents are generally good at using the stepwise protocol for
drawing Lewis structures of small, inorganic molecules. Organic
molecules, however, are often much larger and are more structurally
complex, rendering that stepwise protocol ineffective. Section 1.6
gets students accustomed to applying common bonding scenarios to
organic molecules (e.g., four bonds to C, three bonds and a lone pair
to N, etc.), so working with organic molecules is far less
intimidating.1.9. Assigning Electrons to Atoms in Molecules: Formal
ChargeFormal charge is vastly important in organic chemistry, especially in
mechanisms where formal charges are located on different atoms from
one step to the next. Students learn formal charge in general
chemistry, but often don’t retain it because they memorized the
equation to calculate formal charge. In Section 1.9, formal charge is
taught in a way that is more intuitive, asking students to compare
the number of electrons assigned to an atom in a molecule to the
number of electrons the isolated atom has. Thus, students better
retain their ability to calculate formal charge.1.10. Resonance Theory; 1.11. Strategies for Success: Drawing
All Resonance StructuresResonance is typically covered in general chemistry, but I have yet
to see a student entering organic chemistry already having mastery of
the topic. At best, students have a vague recollection of what
resonance structures are and what a resonance hybrid is. At the same
time, resonance is vital to understanding aspects of molecular
structure and chemical reactivity.Section 1.10 provides the principles of resonance theory, and Section
1.11 gives students the tools to draw resonance structures. In
Section 1.11, in particular, students are taught to look for one of
four basic features appearing in a Lewis structure, to then add the
appropriate curved arrows based on that feature, and finally to
follow the curved arrows they drew to arrive at the next resonance
structure. Teaching students to draw resonance structures by first
identifying one of these four features has been very effective in my
teaching.More than just serving as a model to understand molecular structure
and chemical reactivity, aspects of resonance prepare students
extremely well for working with mechanisms. The curved arrow notation
that students work with in Section 1.11 is precisely the same curved
arrow notation used in reaction mechanisms. Moreover, when drawing
resonance structures, atoms can gain and lose octets, and formal
charges “hop” from one atom to another, in much the same way we see
these things happen in mechanisms. Working with mechanisms,
therefore, does a great job identifying deficiencies students have
with formal charges and octets. Some textbooks delay an in-depth
treatment of resonance until after conjugation has been taught, but
because resonance provides such a good preparation for mechanisms, I
strongly believe that delaying resonance like this does students a
great disservice. To the contrary, the earlier resonance is presented
and the more frequently it is revisited, the better experience
students will have throughout the course.1.12. Shorthand Notations
One reason to spend time on this section is that line structures are
new to most students. Moreover, line structures demand students to be
proficient with octets and formal charges, so, like resonance, line
structures do a great job identifying deficiencies in these areas.Along those lines, I strongly recommend heavily emphasizing to your
students to become intimately familiar with the bonding scenarios in
Table 1-5. The earlier that students can instantly associate an
atom’s formal charge with the number of bonds and lone pairs the atom
has, the more competent and confident students will be.1.13. An Overview of Organic Compounds: Functional
GroupsStudents of course need to know functional groups because functional
groups dictate physical and chemical behavior and are the basis for
nomenclature. It is important for students to begin to learn certain
functional groups and their corresponding compound classes here for a
couple reasons: (1) Interchapter A, the first unit on nomenclature,
appears immediately after Chapter 1; and (2) students begin to
associate functional groups with physical properties in Chapter 2 and
with chemical properties (acid strength) in Chapter 6.2.3. Strategies for Success: The Molecular Modeling
KitI am a strong believer in model kits, telling students that model
kits can do a lot of the hard work for them. This is especially true
when students work with conformations and chair flips (Chapter 4) and
stereochemistry (Chapter 5). But I also learned the hard way that
it’s insufficient to just tell students that model kits are helpful;
students must be shown. Without me bringing model kits into the
classroom, my students would convince themselves that model kits are
too time consuming to be worth it. My students would constantly look
for shortcuts to avoid model kits, to my students’ detriment. But
once I started bringing model kits into the classroom, even to carry
out simple exercises like the ones described in Section 2.3, I
started to get close to 100% buy-in by students, and this pays
dividends down the road.2.7. Solubility
Students generally approach this topic from the standpoint of “like
dissolves like.” In truth, students can probably solve most
solubility problems without going any deeper than this. But it is
quite worthwhile to spend time on Section 2.7 in class, specifically
delving into the role that solvation plays in dissolving ionic
compounds. Beyond its application to solubility, solvation can have a
major impact on chemical reactions, especially SN1, SN2, E1 and E2
reactions (Chapter 9). In my experience, students deal much better
delving into solvation for the first time here—in a familiar context
of solubility—than in the throes of dealing with the SN1/SN2/E1/E2
competition.2.8. Strategies for Success: Ranking Boiling Points and
Solubilities of Structurally Similar CompoundsEarlier in this chapter, students reviewed how to rationalize
relative boiling points and solubilities by examining just one type
of intermolecular interaction. Section 2.8 asks students to recognize
all types of intermolecular interactions that are present, and then
to evaluate their relative importance. In so doing, this section does
a good job identifying deficiencies students might have with
identifying and assessing the relative importance of intermolecular
interactions.2.9. Protic and Aprotic Solvents
Other textbooks typically introduce the topic of protic and aprotic
solvents for the first time in the context of the SN1/SN2/E1/E2
competition (Chapter 9 in my book), and you could consider delaying
Section 2.9 until then, but I strongly recommend against doing so.
The SN1/SN2/E1/E2 competition is not only unfamiliar to students, but
is also really challenging for many. Therefore, when students are
learning how to deal with the SN1/SN2/E1/E2 competition in Chapter 9,
it is better to invoke protic and aprotic solvents as a review rather
than as an entirely new concept. By contrast, here in Section 2.9,
students learn about protic and aprotic solvents in the familiar
context of solubility.3.1 – 3.8. Atomic and Molecular Orbitals; Hybridization;
Valence Bond Theory; Orbital Pictures and Orbital Energy
DiagramsI tend to slow down a bit on these sections to cover them in good
depth, for a couple reasons. (1) My students don’t tend to retain
much of this material from general chemistry; and (2) it helps
prepare students for conjugation and aromaticity in Chapter 14 and
UV-vis spectroscopy in Chapter 15. To save time, however, you can
consider shortening most of the topics in these sections without
compromising material that comes later in the book. The exception is
Section 3.4 on hybridization. I would make sure to cover that section
to good depth because of the frequency with which hybridization is
used to explain important aspects of reactions throughout the book.3.9. Bond Rotation about Single and Double Bonds: Cis and
Trans ConfigurationsThe idea that single bonds rotation but double bonds do not is
relatively straightforward, but I spend time in class on this topic
for two reasons. (1) It’s a nice transition into a major topic of
Chapter 4—conformers. (2) Discerning which double bonds have
available cis/trans configurations is more challenging to students
than we might guess. Therefore, I have found that taking students
through the exercise of determining whether a double bond has
cis/trans configurations highlights deficiencies that students might
have with manipulating molecules in three dimensions.3.11. Hybridization, Bond Characteristics, and Effective
ElectronegativityThese topics have important implications in chemical reactivity,
especially regarding acid strengths (terminal alkynes) and
heterolytic bond dissociation to produce carbocations (SN1 and E1
reactions). You could consider delaying this topic until Chapter 6,
where effective electronegativity is applied to acid strengths, but I
recommend against doing so. In Chapter 6, students will need to focus
on curved arrow notation, acid-base equilibria, reaction coordinate
diagrams, and charge stability, so it is better there to invoke
effective electronegativity as review than as a new concept.4.1-4.9. Conformational Analysis, Ring Strain, and Chair Flips
These sections are all rather standard, and I slow down to cover them
in good depth. To save time, however, I gloss over Section 4.4
(Conformers: Cyclic Alkanes and Ring Strain) in class, quickly
mentioning the results of Table 4-1 and highlighting the fact that 6-
membered rings are strain free, 5- and 7-membered rings have mild
strain, and 3- and 4-membered rings are highly strained. I leave the
detailed
relationship between ring strain and heat of combustion for out-of-
class exercises. I also save time in class by glossing over Sections
4.5 (Conformers: The Most Stable Conformations of Cyclohexane,
Cyclopentane, Cyclobutane, and Cyclopropane) and 4.6 (Conformers:
Cyclopentane, Cyclohexane, Pseudorotation, and Chair Flips), slowing
down in Section 4.5 just to cover cyclohexane’s chair conformation,
and slowing down in Section 4.6 to cover the basics of cyclohexane
chair flips.I also take time in class to go through the exercise from Section
4.7. Strategies for Success: Drawing Chair Conformations of
Cyclohexane. I demonstrate once how to draw an accurate chair
conformation, and then tell students that they must practice that
exercise repeatedly. I also take this opportunity in class to show
students a few ways of drawing a chair conformation inaccurately—e.g,
equatorial bonds that should point left are drawn pointing right, and
vice versa; and bonds that are not clearly axial or equatorial.4.10. Strategies for Success: Molecular Model Kits and Chair Flips
I emphasize this section heavily in class, as this is where model
kits become really useful for students. Without model kits, students
try to make associations of the sort “if I see X, and Y takes place,
then I should draw Z.” It’s a form of memorization. But with model
kits, students build the model based on what they see drawn,
manipulate the model including chair flips, make their assessments
based on sterics, and then use the resulting model as a guide to draw
the result. When model kits are used in this way, students are more
accurate in their answers, and they come away with a better feel for
the chemistry at play. Getting student buy-in to use model kits
regularly like this, however, is partly an outcome of the earlier
emphasis I place on model kits from Sections 2.3 and 3.10.4.11. Constitutional Isomerism: Identifying Constitutional Isomers
Even though my students dealt with constitution isomers in general
chemistry, I spend significant time on this material in class because
most of my students don’t have a sufficient grasp connectivity when
they enter the course. Yet being able to recognize differences in
connectivity is important for later topics, such as identifying
stereocenters and dealing with regiochemistry.4.12. Constitutional Isomers: Index of Hydrogen Deficiency (Degree of Unsaturation)
This material is new to most students, and is a standard topic.
However, I present it differently in my book than in other books.
Other books coach students to use a formula to calculate the IHD of a
given formula. My book asks students to quickly sketch a molecule
saturated molecule with the same number of non-hydrogen atoms given
in the formula, and compare the number of hydrogen in the given
formula to the number of hydrogen atoms in the saturated molecule.
This takes a few seconds longer than plugging numbers into a formula,
but students remember this process better than a formula they try to
commit to memory, so their answers are more accurate. That being
said, my book does present the 2n + 2 result for saturated
hydrocarbons, and it also gives students two in-chapter problems
(4.23 and 4.24) for students to determine how that results changes
with each added N, O and F atom.4.13. Strategies for Success: Drawing All Constitutional Isomers of a Given Formula
I spend time in class to teach this strategy, bringing students
through at least one example. Although drawing all constitutional
isomers may not be a vital task in itself, the protocol helps
students learn connectivity more deeply when they must consider the
next isomer to draw, and when they compare an isomer they just drew
to other isomers they previously drew. This exercise also helps
identify deficiencies that can pose problems for students later on;
students who struggle with drawing all isomers of a given formula
will more likely struggle with mechanisms, where it is important to
keep track of bonds broken and formed.
How can/should I treat nomenclature?
Nomenclature is divided into five interchapters (Interchapters A, B, C, E, and F) to give instructors flexibility as to how and when to teach the material. In my case, the only nomenclature I teach in class is Interchapter C, which deals with stereochemical configurations. I assign the other four nomenclature interchapters for self study. My students are held accountable, however, for all nomenclature material on exams.
To ensure that my students are actually working on the nomenclature I don’t cover in class, I assign copious nomenclature problems in Smartwork. I assign a large number of nomenclature problems there, even though I don’t cover the material in class, because of how straightforward nomenclature is to master: encounter a new rule, learn the rule, apply the rule, then repeat. The critical part here is applying the new rule, which the Smartwork problems enable my students to do.
I require my students to work through the nomenclature interchapters roughly where they appear in the book: following Chapters 1, 3, 5, 7, and 9. Therefore, my students complete all of nomenclature in the first semester. Another effective way to cover nomenclature is to save Interchapters E and F for second semester, so that students stay fresh with nomenclature throughout the entire year. Covering nomenclature in this way remains effective because Interchapters E and F deal with alcohols, amines, ketones, aldehydes, and carboxylic acids and their derivatives—compound classes whose reactions are principally covered in the second half of the textbook.
Why are chirality and configurational isomers introduced before reactions?
Some textbooks introduce chirality and configurational isomers after the first organic reactions and mechanisms have been introduced. When a new concept is introduced in the context of reactions, students tend to focus on the outcome of the reaction rather on understanding the new concept. In my textbook, I begin to introduce reactions and mechanisms in Chapters 6 and 7, thus allowing students to focus entirely on chirality and configurational isomers in Chapter 5, without distraction. This gives students at least two chapters’ worth of time to master chirality and configurational isomers before learning about stereochemistry of reactions in Chapter 8.
Why is curved arrow notation for reactions introduced in Chapter 6 in the context of proton transfer reactions?
Some textbooks introduce curved arrow notation for reactions in the context of organic reactions that are new to students, such as alkene additions. In such cases, students will already have their hands full with learning about electrophiles and carbocation intermediates, and their focus on understanding curved arrow notation will be compromised. In my textbook, curved arrow notation for reactions is introduced in the context of proton transfer reactions, which are already familiar to students from general chemistry. Students will already be familiar with acids and bases, and the bonding changes that occur in these reactions, thus allowing students to focus more wholly on curved arrow notation.
Why are reaction free energy diagrams introduced in Chapter 6 in the context of proton transfer reactions?
Some textbooks introduce reaction free energy diagrams in the context of organic reactions that are new to students, such as alkene additions. In such cases, students will already have their hands full with learning about electrophiles and carbocation intermediates, and their focus on understanding how to construct or interpret free energy diagrams will be compromised. In my textbook, reaction free energy diagrams are introduced in the context of proton transfer reactions, which are already familiar to students from general chemistry. Students will already be familiar with acids and bases, and the bonding changes that occur in these reactions, thus allowing students to focus more wholly on understanding reaction free energy diagrams.
How much should I emphasize free energy diagrams and charge stability in Chapter 6?
Chapter 6 deals with the introduction of mechanisms, thermodynamics, and charge stability in the context of proton transfers. Section 6.1 reminds students what a proton transfer is and introduces curved arrow notation as a means by which to keep track of bonds breaking and forming. I don’t spend much time on this section in class because students are familiar with acid-base reactions from general chemistry, and the curved arrow notation presented here is the same that students learned in the context of resonance in Chapter 1.
Section 6.2 deals with equilibria pertaining to proton transfer reactions. I only touch on the highlights of this material in class because much it is review from general chemistry. I do spend some significant class time on Section 6.2b (Predicting the Outcome of a Proton Transfer Reaction Using pKa Values) because it is a task that students must apply frequently throughout the rest of the course. I will also present a quick example from Section 6.2d (Le Châtelier’s Principle, pH, and Percent Dissociation) so students can later tackle the material in the biomolecules sections (Sections 6.9 and 6.10) dealing with ionization states of amino acids and electrophoresis.
Section 6.3 (Thermodynamics and Gibbs Free Energy), too, is largely a review of material students would have seen in general chemistry, but there are two key things that I make sure to get across in class. One is the association between higher free energy and less stability. The other is the meaning of the reaction coordinate. I spend significant class time on the reaction coordinate because, even though students in general chemistry see it appear as the label of the horizontal axis in free energy diagrams, students entering organic chemistry largely find the term mysterious and struggle to articulate what it actually means. Other textbooks take the reaction coordinate for granted, assuming that students know what it is and how to work with it, but my book does not; it is important for students to work comfortably with the reaction coordinate, especially as it pertains to identifying key features of a free energy diagram (such as intermediates) and applying the Hammond postulate.
Section 6.4 (Strategies for Success: Functional Groups and Acidity) is relatively straightforward, but it is a very important section. It applies for the first time the idea that functional groups dictate chemical reactivity, so it reinforces the need for students to recognize various functional groups. Thus, this section helps diagnose issues that students have with identifying functional groups. Section 6.4 also is the place where I tell students I need them to commit the pKa values for the following types of acids to memory: H2SO4; HCl, H3O+ and protonated alcohols; carboxylic acids; phenols; NH4+ and protonated amines; ketones and aldehydes; terminal alkynes; H2; NH3 and amines; alkenes and benzenes; alkanes and ethers. I ask students to know these pKa values so students are equipped to handle proton transfer steps as part of larger mechanisms later on. These pKa values are used regularly to justify when such a proton transfer makes sense, and whether it is reversible or irreversible.
Sections 6.5 and 6.6 develop the idea of charge stability using relative acid strengths. I devote about one-and-a-half class periods to this material because of how useful charge stability is in understanding mechanisms. Students need to be able to determine the relative stability of a charged species on the basis of its structure.
As part of teaching Sections 6.5 and 6.6, I heavily emphasize free energy diagrams (see, for example, Figures 6-6, 6-7, and 6-8). By associating the lower pKa with the more downhill or less uphill deprotonation, students gain a much better feel for the role that charge stability plays in acid strengths. Thus, these free energy diagrams become a powerful tool for students to use when they need to predict relative acid strengths on the basis of molecular structure. Students first write out the complete deprotonation reactions involving each acid. Then students locate the vertical position of each set of reactants on the basis charge stability, and do the same for each set of products. Finally, students add curves to connect each set of reactants to the corresponding products, after which students can simply “read off” the relative acid strengths by noting the order of the curves from least downhill or most uphill (weakest acid) to least uphill or most downhill (strongest acid).
The benefits of using free energy diagrams as a tool for predicting relative acid strengths is most apparent when students need to predict the order of numerous acids at once. Section 6.7 (Strategies for Success: Ranking Acid and Base Strengths—The Relative Importance of Effects on Charge) brings students through an example of ranking four acids, culminating in the free energy diagram in Figure 6-14.
I don’t spend a lot of class time on Section 6.8 (Strategies for Success: Determining Relative Contributions by Resonance Structures), but I do make sure to cover the basics and present at least one example. The material in this section is essentially just an application of charge stability toward a concept that students learned in Chapter 1: the lowest energy resonance structure has the greatest contribution to the hybrid. Thus, I principally use Section 6.8 as a means by which to reinforce what students just learned in Chapter 6 pertaining to predicting the relative stability of charged species.
Can I skip Chapter 7 (An Overview of the Most Common Elementary Steps), because the topics will be revisited later in the book in the context of the reactions where they apply?
Although it might be tempting to skip Chapter 7 for that reason, Chapter 7 is important to cover/teach, for two main reasons.
First, Chapter 7 allows students to focus on learning key aspects of elementary steps and curved arrow notation before being held accountable for predicting products of reactions with multistep mechanisms. In other textbooks, where elementary steps are introduced alongside reactions with multistep mechanisms, students’ focus is pulled toward predicting the overall products, at the expense of understanding mechanisms. This is a major cause for memorization. With Chapter 7, students can focus on elementary steps in what is essentially a risk-free environment.
Second, messaging. As experts, we know that mechanisms simplify organic chemistry. We tell students that this simplicity comes from a small number of elementary steps appearing over and over in hundreds of seemingly different reactions. Students are being asked to take this on faith when we tell it to them at the outset, before they can see what those elementary steps actually are, or how simple each step is. With all of these common elementary steps shown together, upfront, students can gain assurance that the various elementary steps are straightforward and manageable. And knowing that all of the reactions mechanisms encountered through Chapter 25 will be constructed from the same 10 elementary steps, students can come away with the belief that elementary steps and mechanisms actually do simplify organic chemistry, even before they see the first multistep mechanism. Students come away with the belief that spending time on elementary steps and mechanisms is worthwhile.
Why are the orbital pictures of the common elementary steps presented in Interchapter C?
There are two main reasons. One is to allow instructors to tailor the teaching of frontier molecular orbital theory to their own students. With the orbital pictures of the common elementary steps presented in an interchapter, an instructor can teach as much or as little as they see fit, without having to worry about main topics later in the book relying on material that was skipped.
The second reason is to show frontier molecular orbital theory more holistically. In other textbooks, the HOMO-LUMO interactions are shown only for a few elementary steps, such as SN2 and nucleophilic addition. Moreover, those pictures tend to be tied to specific functional groups, isolated from orbital pictures of other elementary steps. My textbook, by contrast, presents the frontier molecular orbital picture of all ten common elementary steps together in Interchapter C, including E2 steps and carbocation rearrangements. Thus, students can see how frontier molecular orbital theory is applied in similar ways to different elementary steps, and they can come away with a better appreciation of the power of frontier molecular orbital theory.
Why are multistep mechanisms introduced in the context of SN1 and E1 reactions in Chapter 8?
Once the 10 common elementary steps have been covered in Chapter 7, any of a variety of multistep mechanisms can be introduced. My textbook proceeds to introduce SN1 and E1 reactions as the first multistep mechanisms. With these reactions, we can teach students how stereochemistry and reaction kinetics are used to justify a proposed mechanism. We can also teach students how to reasonably incorporate proton transfer and carbocation rearrangements into fundamental mechanisms. Other multistep mechanisms, such as additions to alkenes or additions to carbonyl compounds, do not lend themselves to teaching all of these ideas.
Why is Chapter 9 devoted only to the SN1/SN2/E1/E2 competition?
In other organic chemistry textbooks, some combination of SN1, SN2, E1 and E2 mechanisms are introduced in the same chapter that also deals with predicting the outcome of the competition involving those reactions. In my textbook, dealing with the competition among these reactions is separated from the material that deals with aspects of their mechanisms. The SN2 and E2 mechanisms are presented as elementary steps in Chapter 7, and the SN1 and E1 mechanisms are introduced in Chapter 8. Then, Chapter 9 is devoted entirely to the competition among the SN1, SN2, E1 and E2 reactions. The main thrust for organizing the material this way is to combat memorization and to reinforce the value of mechanisms.
Students by and large enter organic chemistry convinced that the most important aspect of the course is predicting products of reactions and, furthermore, that the reactions must be committed to memory in order to predict products. For these students, it can be detrimental to deal with the SN1/SN2/E1/E2 competition in the same chapter the mechanisms are introduced because of how strong the pull is toward predicting products; it plays into the hands of students’ misconceptions. By contrast, with the SN1/SN2/E1/E2 competition limited to Chapter 9 only, aspects of the mechanisms for these reactions take center stage in Chapters 7 and 8. Thus, students come away from Chapters 7 and 8 with a greater value of the insights that mechanisms offer toward understanding reactions, and that mechanisms are worthwhile. This sets an important precedent for learning reactions throughout the rest of the book.
Another important reason for organizing the SN1/SN2/E1/E2 material this way comes from the ability to bring some key tools for working with multistep mechanisms to the forefront. In Chapter 8, students are taught how the stereochemistry and kinetics of reactions are rationalized from the mechanism. Furthermore, Chapter 8 introduces very useful rules of thumb for multistep mechanisms, such as how to reasonably incorporate proton transfers and carbocation rearrangements into multistep mechanisms. These concepts, if presented alongside predicting the major products of the SN1/SN2/E1/E2 competition, often become buried and tend to be overlooked by students.
Finally, dedicating chapter 9 to the SN1/SN2/E1/E2 competition more effectively promotes the process students are taught to predict the outcome. The process that students are taught asks students to consider the various factors that control the reactions rates: type of substrate, nucleophile/base strength and concentration, leaving group ability, solvent, and heat. If instead the mechanisms of the reactions—and various aspects such as stereochemistry and kinetics—are introduced in the same chapter that such a process is also presented, students too often become overwhelmed. Rather than commit to learning and applying that process, students tend to look for shortcuts to memorize.
To recap, I have devoted Chapter 9 entirely to the competition among the SN1/SN2/E1/E2 competition to promote learning and understanding, and to deter students from memorizing. Students can focus on aspects of the mechanisms in Chapters 7 and 8 before being accountable for predicting the major products of the competition in Chapter 9.
Is it important to emphasize reversibility and kinetic vs. thermodynamic control in Chapters 9?
Section 9.12 (Kinetic Control, Thermodynamic Control, and Reversibility) is located toward the end of Chapter 9, and you might be tempted to skip it or gloss over it. The material in that section is important, however, because it helps students build proper tools for predicting the major products of competing reactions—one of the most challenging tasks students face in organic chemistry. Students first face this challenge in Chapter 9 when they must determine the predominant mechanism in the SN1/SN2/E1/E2 competition, but they must also face this task with other competing reactions throughout the book, such as: competing elimination reactions (Zaitsev’s rule), competing reactions involving electrophilic addition steps (Markovnikov’s rule and o/p- vs. m-directors), competing deprotonations at carbons (kinetic vs. thermodynamic enolates), and nucleophilic addition to a carbonyl group competing with conjugate addition or enolate formation. Because students are routinely tasked with these kinds of competitions, I make sure to give significant emphasis to Section 9.12 in class, and I strongly recommend that you do as well.
One of the most important concepts from Section 9.12 to get across to students is that the outcome of a competing set of reactions can differ depending on whether the competition takes place under kinetic control or thermodynamic control. Students must therefore know whether they should try to determine the outcome on the basis of reaction rates or product stabilities. Without knowing that these two types of control exist for competing reactions, students have a tendency to limit their considerations only toward reaction rates.
Students are then taught how reversibility is linked to the type of control under which a competition takes place: a reversible competition effectively equilibrates the products, so the major product is the one that is most stable; in an irreversible competition, the products, once formed, are there to stay, so the one that accumulates the fastest is the major product. In short, a reversible competition tends to take place under thermodynamic control, whereas an irreversible competition tends to take place under kinetic control.
Finally, a critical piece to implementing this tool for predicting the outcome of a competition is to determine whether the competition takes place reversibly or irreversibly. Students are shown that this depends principally on how energetically stable the products are relative to the reactants, and the free energy diagram is a very helpful visual aid to get this point across.
Students will be far more successful predicting the products of competing reactions when they can reliably determine whether the competition is reversible or irreversible, and then apply that knowledge toward establishing kinetic or thermodynamic control. Training students to evaluate free energy diagrams to establish reversibility goas a long way toward helping students along these lines. Conversely, students who are not proficient doing these kinds of things tend to rely predominantly on memorization, a tactic that we know is destructive.
Why are nucleophilic substitution and elimination reactions introduced before electrophilic addition reactions or nucleophilic addition reactions?
Nucleophilic substitution and elimination reactions are relatively self-contained, and their mechanisms remain simple throughout their discussion. These reactions, furthermore, do not require students to wrestle with thermodynamic control versus kinetic control. By contrast, electrophilic addition reactions and nucleophilic addition reactions begin rather straightforwardly, but they both ramp up in complexity quite quickly. Consider electrophilic addition reactions to alkenes and alkynes, where some textbooks introduce electrophilic addition reactions. The addition of a Brønsted acid is a simple two-step mechanism, with no leaving groups. Soon after, however, reactions that proceed through a bromonium ion intermediate are introduced, where the opening of the ring occurs with SN2-type stereospecificity and with regiochemistry governed by steric hindrance and charge stability reminiscent of carbocations. The mechanisms rapidly become complex, too, particularly with oxidative cleavage reactions and hydroboration-oxidation reactions. Similarly, nucleophilic addition reaction mechanisms start out rather simple, but they become complex rather quickly, too. Acetal formation, for example, is a 7-step mechanism. Moreover, both electrophilic addition and nucleophilic addition reactions tend to include the competition between 1,2-addition and 1,4-addition, which requires students to wrestle with thermodynamic versus kinetic control.
Why are strategies for multistep synthesis introduced in Chapters 10 and 11, and not earlier?
The main reason is to prevent students from memorizing reactions. In other textbooks, expectations for students to solve multistep syntheses begin earlier, when students are still at the outset of learning mechanisms. Student focus is shifted away from mechanisms and onto net reactions, and when this is done too early, students fail to develop sufficient skills with or true buy-in for mechanisms. It is then quite challenging to get students back on the path of learning mechanisms when the next reactions are introduced; students instead tend to stick with memorizing reactions.
With strategies for multistep mechanisms in my book delayed a few chapters, until Chapters 10 and 11, students have a few more chapters to develop their skills in mechanisms, and more importantly, to see how mechanisms simplify organic chemistry. Thus, students develop a firm buy-in for mechanisms. So, when we later return to learning more reactions, it is much easier for students to transition back to focusing on mechanisms instead of memorization.
Delaying the introduction of strategies for multistep synthesis a few chapters does not mean that students’ skills in solving multistep syntheses are compromised. Quite the contrary, a better mastery of mechanisms helps students master synthesis problems, particularly because understanding mechanisms helps students more successfully choose the right reactions to accomplish desired transformations. Literature supports this idea. What it means instead is that we instructors simply need to slightly delay the expectations we place on students to solve complex synthesis problems. But with that slight delay, we can ultimately place high levels of expectations for synthesis on students, even higher than with other textbooks.
Why are the nucleophilic substitution & elimination that are useful for synthesis introduced in two chapters (Chapters 10 and 11) instead of one?
The answer is scaffolding. The introduction of strategies for multistep synthesis places new and significant demands on students, especially on the ways that they must think about reactions and what they accomplish. With these ramped-up demands on students, it is important to keep the synthesis problems simple at the outset. Chapter 10 keeps those synthesis problems simple by dealing only with syntheses that keep the carbon structure unchanged; solving these synthesis problems thus requires only functional group transformations, the topic of Chapter 10. Then, the demands are ramped up even more in Chapter 11, where the syntheses require changes to the carbon structure. Chapter 11 therefore deals with reactions that form carbon-carbon bonds, and it also introduces retrosynthetic analysis as a tool for students to mentally disconnect those carbon-carbon bonds as they think backward.
Can I move aspects of Chapter 13 (the first chapter devoted to synthesis strategies) earlier? How early can/should I move multistep synthesis?
The biggest reason I wrote this textbook was to facilitate students learning and understanding the material rather than memorizing it. Organizing the reactions according to mechanism goes a long way toward reaching that goal, because students can see patterns emerge they otherwise wouldn’t see. In a similar vein, it also helps quite a bit to remove distractions from the early reaction chapters, when students are first learning reactions and mechanisms. That is why, for example, nomenclature and physical properties are dealt with elsewhere, giving students more time to focus on each topic at hand. It is also why I placed the first chapter on synthesis strategies, Chapter 13, where it is. By that point, students will have been through four chapters dealing with mechanisms and predicting products of reactions—Chapters 9-12—so a student’s foundation working with mechanisms will be solid before shifting gears in a big way to deal with synthesis strategies.
I feel that it is very important for students to have such a solid foundation working with mechanisms before dealing with synthesis strategies because of the danger that synthesis has in promoting memorization. Students by and large enter the course already convinced that they must commit a large number of reactions to memory, and asking students too early to develop quick recall of reactions that carry out specific changes to a molecule—a must for organic synthesis—can have the effect of devaluing mechanisms. Why should students spend time studying mechanisms if they believe their primary goal is to excel at synthesis? The location of Chapter 13 for synthesis strategies strikes a good balance: It comes after students have spent four chapters developing buy-in for mechanisms, so there is little risk of students ignoring mechanisms down the road, but it’s still early enough that students don’t lose sight of how the reactions they’ve learned can be applied.
That being said, some instructors will want students to work with significant aspects of synthesis prior to Chapter 13. One way to do so is to assign the end-of-chapter problems denoted “SYN,” which begin in Chapter 9. Prior to Chapter 13, these SYN problems have students deal with relatively simple, low-level aspects of synthesis—things students can deal with comfortably without specifically having learned some of the strategies presented in Chapter 13. Students might be asked for the reactant or the reactions conditions necessary to carry out a one-step synthesis. These kinds of problems help develop the mindset for more complex aspects of synthesis students will soon face.
Perhaps you want to take this a bit further, having students deal with multistep synthesis prior to Chapter 13. If so, you should feel comfortable teaching parts of Chapter 13 earlier. However, I would recommend not moving the material earlier than immediately after Chapter 10. Otherwise, you would run the risk of undermining the value of learning mechanisms, and you would also run the risk of students not having learned reactions that are suitable to demonstrate a particular synthesis strategy.
If you do decide to teach some of the Chapter 13 strategies earlier, be sure that the examples showing how to apply the strategies incorporate only the reactions that have been taught. For example, consider the following if you decide to move some strategies from Chapter 13 to immediately after Chapter 10:
Section 13.1. Writing the Reactions of an Organic Synthesis
Avoid Equations 13-4, 13-5, 13-9Section 13.4b. Synthetic Traps and Regiochemistry
Avoid Equations 13-19, 13-20, 13-21, 13-22, 13-23, 13-24, 13-29, 13-
30Section 13.5. Choice of the Solvent
Avoid Equations 13-31, 13-32, 13-33Section 13.6. Considerations of Stereochemistry in Synthesis
Avoid Equations 13-44, 13-45, 13-46, 13-47, 13-48, 13-49Section 13.7. Strategies for Success: Improving Your Proficiency with Solving Multistep Syntheses
The example given incorporates the addition of Br2 across a C=C
double bond, so you will need to construct an example that
incorporates only reactions from Chapters 9 and 10.Section 13.8b. Green Chemistry
Avoid Equations 13-50, 13-51, 13-53, 13-54, 13-55
Why is mass spectrometry (Chapter 15) introduced before IR, UV-vis, and NMR spectroscopy?
The main reason is because of what a mass spectrum affords us, which is a molecular formula. Chapters 16 and 17 introduce spectroscopy, and solving the structure of a molecule from IR, UV-vis, or NMR spectra rely on having a molecular formula at our disposal. That said, you can teach Chapters 15-17 in any order you see fit. If Chapter 15 is delayed until after Chapter 16 or 17, you will just need to avoid assigning end-of-chapter Integrated Problems in Chapter 16 or 17 that rely on interpreting information from a mass spectrum.
Can the structure determination chapters (Chapters 15-17) be moved earlier?
Yes, and in fact some users of my textbook already do this. It works because Chapters 15-17 are self-contained. In some textbooks organized according to functional group, introductory aspects of spectroscopy are presented in a self-contained chapter or two, but important aspects tied to certain functional groups are reserved for separate chapters on those functional groups. In my textbook, those aspects that are tied to certain functional groups are also included in the self-contained structure determination chapters.
If you move Chapters 15-17 earlier, I recommend not moving them any earlier than Chapter 4, because Chapters 4 deals with conformers and constitutional isomers—concepts that students should have under their belts when solving spectroscopy problems. Additionally, if you move those chapters earlier, you might also consider moving Chapter 14 earlier, which deals with conjugation and aromaticity. Understanding conjugation and aromaticity is not absolutely critical to solving spectroscopy problems, but it can help.
Why are nucleophilic addition reactions presented in two chapters (Chapters 18 and 19)? Similarly, why are nucleophilic addition-elimination reactions presented in two separate chapters (Chapters 22 and 23)?
The answer is scaffolding. In Chapters 18 and 22, the reactions that are taught are ones in which a reagent that is added is already strongly nucleophilic. Thus, the mechanism for the nucleophilic addition or nucleophilic addition-elimination reaction is kept rather short and simple. As such, we can maintain focus and emphasis on just the fundamental mechanism throughout Chapters 18 and 22. Then, in Chapters 19 and 23, we ramp up the complexity of the mechanisms when the reagents that are added are only weakly nucleophilic or non-nucleophilic. Complexity is introduced when the reaction is acid- or base-catalyzed, and when the number of steps in the mechanism is substantially greater.
Why are a carbon reactions not presented in their own chapter?
In other textbooks, a carbon reactions are presented in their own chapter, typically after short chapters on nucleophilic addition and nucleophilic addition-elimination reactions of carbonyl compounds (ketones/aldehydes, and carboxylic acids and their derivatives). My book instead distributes a carbon reactions over four chapters, in the context of the mechanisms that are actually taking place: a-halogenation and a-alkylation reactions are presented in Chapters 10 and 11 because they have SN2 mechanisms; aldol addition reactions are introduced in Chapter 19 because they have base-catalyzed nucleophilic addition mechanisms; and Claisen condensation reactions are introduced in Chapter 23 because they have irreversible base-promoted nucleophilic addition-elimination mechanisms.
When other textbooks present a carbon reactions late in their own chapter, it puts these reactions on a pedestal, in which case students will have the unfortunate tendency of treating these reactions as somehow being different than other ones they have encountered. I say this is unfortunate because, if students see reactions sharing the same mechanism as being different, mechanisms will fail to simplify organic chemistry for these students. By contrast, in my textbook, by introducing each type of a carbon reaction alongside other reactions that share the same mechanism, it reinforces the power of mechanisms to simplify organic chemistry. As one user of my textbook said: For the first time, my students actually ‘got’ aldol reactions.
Why are the reactions that form organometallic reagents presented in Chapter 20?
In my textbook, Section 11.2 is the first time students see the use of an organometallic reagent in a new organic reactions, in the context of opening epoxide rings with Grignard or alkyllithium reagents. Why not introduce how to synthesize those organometallic reagents concurrently, instead of waiting until Section 20.6? After all, making a Grignard reagent or an alkyllithium reagent from an alkyl halide is really simple, at least on paper! The answer is to prevent the learning curve for solving multistep synthesis problems from becoming too steep. Chapter 11 is the tail end of students being introduced to basic strategies for solving multistep synthesis problems, and students will already be challenged with syntheses that call for changes to the carbon structure. By allowing students to use organometallic reagents as starting materials, one variable for these synthesis problems is removed. And for many students, that one variable could be the difference between the synthesis problem being straightforward or not, especially at a time when multistep synthesis problems are still a new challenge.
That having been said, you can easily move the organometallic reagent formation reactions in Section 20.6 earlier as you see fit. You can teach those reactions alongside the epoxide-opening reactions in Section 11.2, or when students see these reagents again in the context of Grignard/alkyllithium reactions involving ketones and aldehydes in Section 18.4.
Why are the Diels-Alder, syn dihydroxylation, and oxidative cleavage reactions introduced in their own chapter (Chapter 26) instead of alongside electrophilic addition reactions (Chapters 12 and 13)?
The main reason is that a key step in these reactions is different from the elementary steps introduced in Chapter 7. The 10 elementary steps in Chapter 7 are used to construct the mechanisms for all reactions introduced in my textbook through Chapter 25. Then, the Diels-Alder, syn dihydroxylation, and oxidative cleavage reactions in Chapter 26 invoke [4+2] cycloaddition steps. More than simply having different curved arrow notation from the elementary steps in Chapter 7, this new elementary step also carries with it specific new rules for stereochemistry and regiochemistry, which bring additional challenges.
The second reason applies principally to oxidative cleavage reactions. These reactions depend on students having experience with conditions that are oxidative or reductive, and the different outcomes of each. Notably, in the oxidative cleavage reaction with KMnO4 or in an ozonolysis reaction with oxidative workup, students need to know how an initial aldehyde that is produced would be oxidized to a carboxylic acid, whereas ketones are left alone. Students don’t gain a feel for these oxidations of aldehydes (and the lack of oxidation of ketones) until Chapter 20.
In some other textbooks that are organized by functional group, the reactions that I introduce in Chapter 26 are instead introduced in an alkene chapter. The stereochemistry and regiochemistry rules for Diels-Alder reactions are a tall order for a lot of students, to the point of becoming overwhelming. Moreover, that would place oxidative cleavage reactions before the treatment of the oxidation of ketones/aldehydes. The danger is that this essentially asks students to memorize such outcomes, rather than relying on any intuition they might otherwise gain from previous chapters.
Why are radical reactions presented at the end of the book (Chapter 27)?
First and foremost, it is because radical reactions proceed by mechanisms that are different from most mechanisms that students encounter in undergraduate organic chemistry. The curved arrow notation for these radical mechanisms is different, and some radical reactions are also distinguished by proceeding through chain reaction mechanisms. By delaying radical reactions until the end (Chapter 27), it allows us to build a complete story of reactions proceeding through closed-shell mechanisms, without chain-reaction mechanisms, before changing gears quite dramatically. The benefit from this kind of continued focus is that it reinforces a student’s buy-in for mechanisms simplifying organic chemistry. If instead we have a dramatic change in gears much earlier in the course, like we see in other textbooks, it can substantially take away from a student’s trust about the simplifying nature of mechanisms.
The second main reason is that delaying radical reactions to the end reduces student mistakes, particularly when it comes to curved arrows. When students learn single-barbed curved arrow notation alongside double-barbed curved arrow notation, as in other textbooks, they too often end up using the two types of curved arrows interchangeably. By contrast, when students first encounter single-barbed curved arrow notation in Chapter 27 in my textbook, they have no opportunity for mistakenly using single-barbed curved arrow notation in the first 26 chapters.
How can I get my students to perform their best with synthesis? Taking advantage of the appendices.
Students often have to shift gears in significant ways when they begin to learn organic synthesis. Rather than focusing on the incremental changes brought about by elementary steps, students must focus on the big differences between the overall reactants and products. Rather than think in the forward direction, students must think retrosynthetically. And students are often called upon to work through trial and error, due to the open-endedness of synthesis design. To help students navigate this shifting of gears, I have included some key features in my textbook.
One really helpful feature is the collection of all the reactions in the book in Appendices C and D. Appendix C is a single table that contains all the reactions that alter the carbon skeleton. Appendix D contains all the functional group transformations, organized into tables according to the compound class that is produced. Organizing the reaction in the appendices like this is immensely useful when students are just beginning to learn retrosynthesis. When a student tackles a synthesis problem, they initially focus on the target and ask questions like “what reaction will produce an alcohol?” or “what reaction will produce an amide?” or “what reaction will form a C-C bond involving an C?” By answering these questions, students have candidates they can implement in their synthesis design, and arrive at precursors. Students then shift their focus to those precursors and ask similar questions. And with the tables organized the way they are in Appendices C and D, students can quickly find the answers to these kinds of questions. To answer the first question, for example, students would turn to Table 3 in Appendix D. To answer the second question, students would turn to Table 9 in Appendix D. And to answer the third question, students would turn to Appendix C.
Having students use Appendices C and D like this is really helpful, first of all, because it minimizes frustration when students are looking for the right reaction to carry out a specific task. Retrosynthetic analysis is immediately awkward for many students because of the requirements to think in the reverse direction. Any substantial frustration added on top can be the tipping point for students to abandon retrosynthetic analysis altogether. Second, using Appendices C and D like this can help students prioritize how they spend time studying. Each time a student goes to one of these appendices to find a reaction to carry out a specific task, it’s a message that (1) the reaction is useful, and (2) the student had difficulty recalling it when it mattered. Thus, the reactions for which a student uses Appendices C and D the most are the reactions that students ought to study the most.
Another really helpful feature of the book I use to help students master synthesis is Section 13.7, Strategies for Success: Improving Your Proficiency with Solving Multistep Syntheses. This section teaches students to design their own synthesis problems and then trade with a study partner to solve those syntheses. Of course solving those syntheses gives students additional practice applying the principles of retrosynthetic analysis and finding the appropriate reactions to carry out the necessary transformations. But in addition, a very helpful part of this exercise is students designing their own syntheses. To do so, a student must begin with a functional group embedded within a carbon structure of the student’s choosing, assigning that molecule as their starting material. Then the student decides what transformations to carry out, keeping track of the necessary reaction for each transformation. After a handful of transformations, the student’s final product becomes the target of the synthesis. This exercise designing a synthesis is quite helpful because, to choose each transformation, a student must ask questions like “What reaction can I carry out on an alkene?” or “What reaction can I carry out on a nitrile?” These kinds of questions test a students’ familiarity with the reactions that a functional group can undergo. If a student struggles to come up with more than two or three answers, then two things should happen. (1) The student should be directed to Appendix B: Characteristic Reactivities of Particular Compound Classes. There, students can find the functional group of interest and quickly see what kinds of transformations can be carried out on it. References are provided to the specific sections where each transformation is discussed. Similar to what I described above, this helps to avoid student frustration, which prevents students from abandoning this important exercise. (2) Also, similar to what I described above, each time a student turns to Appendix B to come up with various transformations to carry out, the student should keep note of it as guidance for which reactions deserve more of their attention when studying.
Even though Appendices B, C, and D have been in the textbook since the first edition, I started incorporating them into the classroom directly just this year. My students were performing solidly with multistep synthesis problems before last year. But when I began to incorporate those appendices into the classroom, my students began to perform even better. I will continue to show students how to make use of these appendices in the years to come.
With the Karty textbook, can I teach all of carbonyl chemistry in the first semester?
Yes, and here is one way it has been done successfully by our users:
Organic Chemistry I
Chapter 1. Atomic and Molecular Structure
Chapter 2. Three-Dimensional Geometry, Intermolecular Interactions, and Physical Properties
Chapter 3. Valence Bond Theory and Molecular Orbital Theory
Chapter 4. Isomerism 1. Conformers and Constitutional Isomers
Chapter 5. Isomerism 2. Chirality, Enantiomers, and Diastereomers
Chapter 6. The Proton Transfer Reaction: And Introduction to Mechanisms, Equilibria, Free Energy Diagrams, and Charge Stability
Chapter 7. An Overview of the Most Common Elementary Steps
Chapter 8. An Introduction to Multistep Mechanisms: SN1 and E1 Reactions and Their Comparisons to SN2 and E2 Reactions
Chapter 9. Competition Among SN2, SN1, E2, and E1 Reactions
Chapter 18. Nucleophilic Addition to Polar p Bonds 1. Reagents That Are Strongly Nucleophilic
- Skip the following sections: 18.6 & 18.7, Wittig reactions and Wittig reagents; 18.10 – 18.12, organic synthesis
Chapter 19. Nucleophilic Addition to Polar p Bonds 1. Reagents That Are Weakly Nucleophilic or Non-nucleophilic, and Acid and Base Catalysis
- Skip the following sections: 19.5, reductive amination; 19.6, the Wolff-Kishner reduction; 19.13, the Robinson annulation; 19.14, organic synthesis
Chapter 22. Nucleophilic Addition-Elimination Reactions 1. Reagents That Are Strongly Nucleophilic
- Skip the following sections: 22.4, Gabriel synthesis; 22.5, haloform reactions; 21.7, specialized reducing agents
Chapter 23. Nucleophilic Addition-Elimination Reactions 2. Reagents That Are Weakly Nucleophilic or Non-Nucleophilic
- Skip the following sections: 23.4, synthesis of acyl halides; 23.5, the Hell-Vollhard-Zelinsky reaction; 23.6, synthesis of sulfonyl chlorides; 23.8, Baeyer-Villiger oxidations; 23.10, organic synthesis
Chapter 29. Biomolecules 1. An Overview of the Four Major Classes of Biomolecules
- Skip the following sections: 29.15 – 29.19, lipids.
Organic Chemistry II
Chapter 10. Organic Synthesis 1. Nucleophilic Substitution and Elimination Reactions and Functional Group Transformations
Chapter 11. Organic Synthesis 2. Reactions That Alter the Carbon Skeleton, and Designing Multistep Syntheses
Chapter 18. Nucleophilic Addition to Polar p Bonds 1. Reagents That Are Strongly Nucleophilic
- Just these sections that were skipped in first semester: 18.6 & 18.7, Wittig reactions and Wittig reagents; 18.10 – 18.12, organic synthesis
Chapter 19. Nucleophilic Addition to Polar p Bonds 1. Reagents That Are Weakly Nucleophilic or Non-nucleophilic, and Acid and Base Catalysis
- Just these sections that were skipped in first semester: 19.5, reductive amination; 19.6, the Wolff-Kishner reduction; 19.13, the Robinson annulation; 19.14, organic synthesis
Chapter 20. Redox Reactions; Organometallic Reagents and Their Reactions
Chapter 21. Organic Synthesis 3. Intermediate Topics in Synthesis Design
Chapter 22. Nucleophilic Addition-Elimination Reactions 1. Reagents That Are Strongly Nucleophilic
- Just these sections that were skipped in first semester: 22.4, Gabriel synthesis; 22.5, haloform reactions; 21.7, specialized reducing agents
Chapter 23. Nucleophilic Addition-Elimination Reactions 2. Reagents That Are Weakly Nucleophilic or Non-Nucleophilic
- Just these sections that were skipped in first semester: 23.4, synthesis of acyl halides; 23.5, the Hell-Vollhard-Zelinsky reaction; 23.6, synthesis of sulfonyl chlorides; 23.8, Baeyer-Villiger oxidations; 23.10, organic synthesis
Chapter 12. Electrophilic Addition to Nonpolar p Bonds 1. Addition of a Brønsted Acid
Chapter 13. Electrophilic Addition to Nonpolar p Bonds 2. Reactions Involving Cyclic Transition States
Chapter 14. Conjugation and Aromaticity
Chapter 15. Structure Determination 1. Mass Spectrometry
Chapter 16. Structure Determination 2. Infrared Spectroscopy and Ultraviolet-Visible Spectroscopy
Chapter 17. Structure Determination 3. Nuclear Magnetic Resonance Spectroscopy
Chapter 24. Aromatic Substitution 1. Electrophilic Aromatic Substitution on Benzene, and Useful Accompanying Reactions
Chapter 25. Aromatic Substitution 2. Reactions of Substituted Benzenes and Other Rings
Chapter 26. The Diels-Alder Reaction, Syn Dihydroxylation, and Oxidative Cleavage
Chapter 27. Reactions Involving Radicals
Chapter 28. Polymers
By organizing the two-semester sequence in the above way, each semester has a distinct theme. First semester focuses on organic structure and reactivity, with emphasis on reactions in which the nucleophile is an electron-rich atom with a lone pair of electrons. Second semester focuses on organic synthesis and spectroscopy, and also introduces reactions in which the nucleophile is a nonpolar p bond, along with cycloaddition and radical reactions.
With the Karty textbook, can I teach alkene/alkyne chemistry in its entirety (including Diels-Alder and oxidative cleavage reactions) in first semester?
Yes, and here is one way it has been done successfully by our users:
Organic Chemistry I
Chapter 1. Atomic and Molecular Structure
Chapter 2. Three-Dimensional Geometry, Intermolecular Interactions, and Physical Properties
Chapter 3. Valence Bond Theory and Molecular Orbital Theory
Chapter 4. Isomerism 1. Conformers and Constitutional Isomers
Chapter 5. Isomerism 2. Chirality, Enantiomers, and Diastereomers
Chapter 6. The Proton Transfer Reaction: And Introduction to Mechanisms, Equilibria, Free Energy Diagrams, and Charge Stability
Chapter 7. An Overview of the Most Common Elementary Steps
Chapter 8. An Introduction to Multistep Mechanisms: SN1 and E1 Reactions and Their Comparisons to SN2 and E2 Reactions
Chapter 12. Electrophilic Addition to Nonpolar p Bonds 1. Addition of a Brønsted Acid
Chapter 13. Electrophilic Addition to Nonpolar p Bonds 2. Reactions Involving Cyclic Transition States
- Plus Section 20.3. Catalytic Hydrogenation: A Review of Alkene and Alkyne Reductions, Reductions of Other Functional Groups, and Selectrivity
Chapter 14. Conjugation and Aromaticity
Chapter 26. The Diels-Alder Reaction, Syn Dihydroxylation, and Oxidative Cleavage
Chapter 15. Structure Determination 1. Mass Spectrometry
Chapter 16. Structure Determination 2. Infrared Spectroscopy and Ultraviolet-Visible Spectroscopy
Organic Chemistry II
Chapter 9. Competition Among SN2, SN1, E2, and E1 Reactions
Chapter 10. Organic Synthesis 1. Nucleophilic Substitution and Elimination Reactions and Functional Group Transformations
Chapter 11. Organic Synthesis 2. Reactions That Alter the Carbon Skeleton, and Designing Multistep Syntheses
Chapter 17. Structure Determination 3. Nuclear Magnetic Resonance Spectroscopy
Chapter 18. Nucleophilic Addition to Polar p Bonds 1. Reagents That Are Strongly Nucleophilic
Chapter 19. Nucleophilic Addition to Polar p Bonds 1. Reagents That Are Weakly Nucleophilic or Non-nucleophilic, and Acid and Base Catalysis
Chapter 20. Redox Reactions; Organometallic Reagents and Their Reactions
Chapter 21. Organic Synthesis 3. Intermediate Topics in Synthesis Design
Chapter 22. Nucleophilic Addition-Elimination Reactions 1. Reagents That Are Strongly Nucleophilic
Chapter 23. Nucleophilic Addition-Elimination Reactions 2. Reagents That Are Weakly Nucleophilic or Non-Nucleophilic
Chapter 24. Aromatic Substitution 1. Electrophilic Aromatic Substitution on Benzene, and Useful Accompanying Reactions
Chapter 25. Aromatic Substitution 2. Reactions of Substituted Benzenes and Other Rings
Chapter 27. Reactions Involving Radicals
Chapter 28. Polymers
One caveat to rearranging topics in this order is the potential risk for students to memorize aspects of Chapter 26 reactions. Also, in first semester, it might be tempting to jump straight from Chapter 7 to Chapter 12. It can be done effectively, but I would caution against doing so, because Chapter 8 covers important concepts to help students work comfortably with multistep mechanism, including stereochemistry, how to reasonably incorporate proton transfer steps into multistep mechanisms, and how to deal with resonance delocalized intermediates.