Topic 46: Ethers - Reactions of ethers with strong acid

46.1How is the reaction of ethers with HCl similar to the reaction of an alcohol with HCl?
 
46.2Why does the reaction of an ether with HCl consume two moles of HCl for every mole of ether?
 
46.3The reaction of an epoxide with water-free HBr in CHCl3 takes only seconds, while the reaction of an acyclic ether with HBr can take days. For example, from a report of 1930, relating to the reaction of n-butyl ether with HBr:

The flasks containing these mixtures were closed with tight-fitting stoppers held in place by wire and covered with collodion. After standing for ten days at room temperature, the liquids were refluxed for three and one-half hours in a water-bath, and the layers which were formed were separated.

The question is: Why the big difference?
 
46.4What happens differently if an epoxide is opened with HBr added as a dilute aqueous solution?
 
46.5Why would H2SO4 in water be a better choice than HBr in water, if you want to form a 1,2-diol from an epoxide?
 
46.6What do we mean when we say that an epoxide opening is stereospecific?
 
46.7What do we mean when we say that an epoxide opening is regioselective?
 
46.8What happens if EtOH is used instead of H2O as the solvent in the reaction of an epoxide under acidic conditions?
 

Topic 47: Epoxides - Reactions of epoxides with anionic nucleophiles

47.1Acyclic ethers, such as ethyl ether, do not react at all with anionic nucleophiles. Epoxides do. Why the big difference?
 
47.2What is the mechanism of the reaction of 1,2-epoxycyclohexane with NaOMe? With NaCN?
 
47.3What other reactions of 1,2-epoxycyclohexane with anionic nucleophiles can you imagine might work?
 
47.4What is the stereoselectivity of the reaction between 1,2-epoxy-1-methylcyclohexane and NaCN?
 
47.5What is the regioselectivity of the reaction between 1,2-epoxy-1-methylcyclohexane and NaCN?
 
13 questions
364 questions for Organic I

364 Questions for Organic I

Dearest Student. This web page is a set of questions I call Detailed Intended Learning Outcomes For Organic Chemistry (Part I). 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 247 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)