Industrial Synthesis Bimolecular Dehydration of Alcohols

Show how the following ethers might be synthesized using (1) alkoxymercuration-demercuration and (2) the Williamson synthesis. (When one of these methods cannot be used for the given ether, point out why it will not work.) 

Alkoxymercuration adds the —OR group of the alcohol to the more substituted carbon atom of the C=C double bond. 

The least expensive method for synthesizing simple symmetrical ethers is the acid-catalyzed bimolecular dehydration, discussed in Section 11-IOB. Unimolecular dehydration (to give an alkene) competes with bimolecular dehydration. To form an ether, the alcohol must have an unhindered primary alkyl group, and the temperature must be kept low. If the alcohol is hindered or the temperature is too high, the delicate balance between substitution and elimination shifts in favor of elimination, and very little ether is formed. Bimolecular dehydration is used in industry to make symmetrical ethers from primary alcohols. Because the dehydration is so limited in its scope, it finds little use in the laboratory synthesis of ethers. 

If the conditions are carefully controlled, bimolecular dehydration is a cheap synthesis of diethyl ether. In fact, this is the industrial method used to produce millions of gallons of diethyl ether each year. 

Bimolecular dehydration of alcohols is generally a poor synthetic method. 

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