Topic 34: Reactions of carboxylic acids

34.1What does “derivative” mean in this context?
 
34.2Besides the obvious acid/base reaction, what do all the reactions of carboxylic acids have common?
 
34.3Why might it be very important to do the reaction of a carboxylic acid with thionyl chloride in a fume hood?
 
34.4Generally, in mechanisms we are not allowed to use Cl− as a base. Why is that? Why is it allowed here?
 
34.5The acid-catalyzed formation of an ester from a carboxylic acid is a famous reaction. Propose a viable mechanism for this reaction, labeling each of the steps one of: proton transfer, nucleophilic addition, or loss of a leaving group.
 
34.6What is DCC?
 
34.7What problem does DCC solve in the formation of amides from carboxylic acids?
 
34.8Propose a viable mechanism for this reaction, again labeling each step one (and only one) of: proton transfer, nucleophilic addition, or loss of leaving group.
 

Topic 35: Reactions of esters and amides

35.1The mechanism of the acid-catalyzed hydrolysis of an ester is (must be!) exactly the reverse of mechanism you gave in #6, above. Can you write that without looking at the mechanism you wrote in #5? Use your answer there to check.
 
35.2Esters can also be hydrolyzed using aqueous NaOH. This is a much simpler mechanism. Write it, labeling each step one of: proton transfer, nucleophilic addition, or loss of leaving group.
 
35.3What makes this reaction irreversible?
 
35.4Amides are especially stable and require “strenuous” conditions to hydrolyze. What does strenuous mean in this context? Why are these very harsh conditions required?
 
35.5The mechanism your author gives for the hydrolysis of an amide in Section 22.13 is not supported by experimental evidence. This is because Step [2] is not just less likely than the reverse of Step [1], it is 1020 times less likely (due to the enormous difference in pKa between water and ammonia). The mechanism proposed by the experimentalists cleverly involves a water molecule, which first just hydrogen bonds, but then gets involved in a rearrangement that is just a very subtle change in atomic positions. Do you see what is happening in that third step? How does this simple involvement of water avoid the issue presented in that second step of your book‘s mechanism? Cool, huh?
 

Topic 36: Reactions of nitriles

36.1Identify the reagents used to convert nitriles to (a) carboxylic acids, (b) aldehydes, and (c) amines.
 
36.2What makes nitriles especially handy, synthetically speaking?
 
15 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)