12. Alcohols, Ethers, Epoxides and Thiols

Propose a mechanism for each of the following reactions:

b.

Heating an alcohol with sulfuric acid is a good way to prepare a symmetrical ether such as diethyl ether.

b. How would you synthesize ethyl propyl ether?

Propose a mechanism for each of the following reactions:

a.

Heating an alcohol with sulfuric acid is a good way to prepare a symmetrical ether such as diethyl ether.

a. Explain why it is not a good way to prepare an unsymmetrical ether such as ethyl propyl ether.

Which of the following ethers would be obtained in greatest yield directly from alcohols?

Explain why the acid-catalyzed condensation is a poor method for the synthesis of an unsymmetrical ether such as ethyl methyl ether, CH₃CH₂-O-CH₃.

Which of the following ethers can be formed in good yield by condensation of the corresponding alcohols? For those that cannot be formed by condensation, suggest an alternative method that will work.

(a) dibutyl ether

(b) ethyl n-propyl ether

(c) di-sec-butyl ether

1,4-Dioxane is made commercially by the acid-catalyzed condensation of an alcohol.

(a) Show what alcohol will undergo condensation, with loss of water, to give 1,4-dioxane.

(b) Propose a mechanism for this reaction.

Contrast the mechanisms of the two preceding reactions, the dehydration and condensation of ethanol.

Explain why bimolecular condensation is a poor method for making unsymmetrical ethers such as ethyl methyl ether.

Propose a mechanism for the acid-catalyzed condensation of n-propyl alcohol to n-propyl ether, as shown above. When the temperature is allowed to rise too high, propene is formed. Propose a mechanism for the formation of propene, and explain why it is favored at higher temperatures.