Topic 10: Electron-Donating and electron-withdrawing groups

10.1What is the difference between inductive and resonance effects?
 
10.2What is the most electron donating group discussed in this section?
 
10.3What is the most electron withdrawing group discussed in this section?
 
10.4How does the 3D structure of aniline provide strong evidence that for the NH2 group at least, resonance effects win out over inductive effects? (See Wikipedia for aniline, 3D model (JSmol) - Interactive image in the information box on the right.)
 
10.5The 1H nmr signal for benzene comes at δ 7.2. The ortho- and para-hydrogens in anisole appear at δ 6.9. What does this tell you?
 
10.6Why are NO2 and SO3OH such strong electron-withdrawing groups?
 

Topic 11: Electrophilic aromatic substitution of substituted benzenes

11.1Why are electrophilic aromatic substitution reactions accelerated by electron-donating groups already on the benzene ring?
 
11.2How could this cause serious problems specifically for Friedel-Crafts alkylation?
 
11.3How does the same reasoning also lead to the observed preference of electron-donating groups for ortho/para- vs. meta-regioselectivity in electrophilic aromatic substitutions?
 
11.4Why are electrophilic aromatic substitution reactions slowed down by electron-withdrawing groups already on the benzene ring? Explain using the comparison of two reaction coordinate diagrams, including all resonance contributors for the intermediate in each case.)
 
11.5What is the mechanistic explanation for why all meta directors are electron withdrawing?
 
11.6What makes halogens different from all other deactivators in terms of the observed patterns of electrophilic substitution?
 
11.7What makes halogens totally different from other deactivators in terms of electronics?
 
11.8How does your author finesse this issue?
 
11.9What do other authors say about this?
 
11.10What do you think is the best explanation for why halogens slow down electrophilic aromatic substitutions but still direct the incoming electrophile to the ortho and para positions?
 
11.11Why doesn‘t OH also do this? [Hint: The answer to this question has something to do with orbital size.]
 
11.12Why should it not be surprising that aniline cannot be a substrate for any Friedel-Crafts reaction?
 
11.13Why should it be surprising that aniline is an ortho-para director in the case of nitration or sulfonation? [Recall the conditions of the reaction.]
 
19 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)