Topic 38: Reactions of enols and enolates with molecular bromine, chlorine, and iodine

38.1Molecular bromine (Br2) reacts with double bonds. What is the mechanism of that reaction?
 
38.2In the presence of a trace of acid, ketones and aldehydes establish an equilibrium between keto and enol forms that usually involves a very small percentage of enol. How does this explain the acid-catalyzed reaction of Br2 with ketones and aldehydes?
 
38.3What are two uses of α-bromoketones?
 
38.4What is initial product of reaction of I2 with a ketone in the presence of base?
 
38.5What is the limitation of this reaction?
 
38.6When can this limitation work for us to do something useful?
 

Topic 39: Reactions of enolates with alkyl bromides: direct alkylation

39.1What is the most common strong nonnucleophilic base used to irreversibly deprotonate a ketone?
 
39.2Why is the reaction of an enolate with an alkyl bromide generally carried out at −78 C?
 
39.3Does this procedure produce the kinetic product or the thermodynamic product?
 
39.4How would we go about finding the original journal article for a reaction such as the following that you read about in a book and want to know more about? [Hint: Have you used SciFinder?]

 
39.5What are two major issues in trying to alkylate ketones using enolates? How does the use of 1,3-dicarbonyl compounds address at least one of these issues?
 
39.6What are the structures of the 1,3-dicarbonyl compounds 2,4-pentanedione, ethyl 3-oxobutanoate, and diethyl malonate?
 
39.7Why is sodium ethoxide (NaOEt) a suitable base for the irreversible deprotonation and alkylation of 1,3-dicarbonyl compounds?
 
39.8After alkylation of ethyl 3-oxobutanoate with benzyl chloride, aqueous NaOH is added, the reaction is stirred for a while, then acidified with HCl and heated. What happens? What is the structure of the aromatic compound produced in this reaction?
 
14 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)