Topic 5: Benzene

5.1What is a Kekulé structure?
 
5.2How do we pronounce Kekulé?
 
5.3What does a double-headed arrow mean, and why don‘t we just use two arrows, one going to the right, and one going to the left, to describe resonance contributors?
 
5.4Why is it incorrect to every say that one resonance contributor is “more stable” than another resonance contributor?
 
5.5Draw three valid Lewis structures that are consistent with the formula C6H6, but can be ruled out based on experimental evidence?
 
5.6One of Prof. Hanson‘s pet peeves is that people should never ever use curved arrows to show resonance. Why do you think this bothers him so much?
 
5.7After reading the IUPAC Rule 93.35, comment on whether it is ever appropriate to refer to or ask for the IUPAC name for a compound. That is, why do the authors of this preamble write, To force the naming of all compounds into the Procrustean bed of one set of rules would not serve the needs of general communication?
 
5.8What are the IUPAC-preferred names that do not have “benzene” in them of three monosubstituted benzenes?
 
5.9What do ortho, meta, and para refer to? When (and only when) are they useful in names? When might their use be appropriate outside of actually naming compounds?
 
5.10What is the difference in meaning between phenol, phenyl, and benzyl?
 

Topic 6: Aromaticity, the Hückel (4n + 2) rule, and molecular orbital theory

6.1What is a chemical “species”? (How is that different than a “compound”?)
 
6.2Read the IUPAC Gold Book definition of the Hückle rule . What are the key elements a structure has to have to be said to “obey” the Hückel (4n + 2) rule (and thus likely represent an “aromatic” species)?
 
6.3When do you count electrons in lone pairs on oxygen or nitrogen when those atoms are in rings being considered as possibly aromatic?
 
6.4Why can we read “anti-aromatic” as “hypothetical only — never going to happen.”
 
6.5What is the significance of the terms atomic orbital, MO, HOMO, LUMO, σ (sigma), π (pi), ѱ (psi), bonding, nonbonding, antibonding, and degenerate in the context of aromaticity?
 
6.6The essential success of Hückel‘s simple mathematical analysis was that in aromatic systems there tends to be a deep π orbital below pairs of degenerate orbitals. How does that lead to the 4n + 2 rule?
 
6.7What does “antiaromatic” look like on an MO diagram?
 
17 questions
472 questions for Organic II

472 Questions for Organic II

Dearest Student. This web page is a set of questions I call Detailed Intended Learning Outcomes For Organic Chemistry (Part II). Some time ago I asked myself, "Bob, what do you think are the key questions that you hope students will be able to answer after taking Chemistry 248 at St. Olaf College?" So here you have them. Some are very simple; some require more thought. All are good questions to be thinking about as you read, discuss, and master the practical aspects of organic chemistry. They are discussion starters and review tips. There are no answers here (though there are some clues). The questions are here to help you focus on what's important (to me, at least!) and organize your learning process. The questions are grouped into topics. Bite-size chunks. Take them a few at a time. Don't feast on them all at one sitting!

(preliminary version 2021.01.15 feeback: Bob Hanson)