Cyclohexyl ethyl ether

The organosilane reduction of ketones in the presence of alcohols provides an excellent route to unsymmetrical ethers. The reaction of cyclohexanone with ethanol and Et3SiH/TFA gives cyclohexyl ethyl ether in good yield.327,328 The... 

Cyclohexyl ethyl ether [TMSI-catalyzed ketone-unsymmetrical ether reduction], 124... 

A-3. Outline a scheme for the preparation of cyclohexyl ethyl ether using the Williamson method. 

Answer VII-c is an unsymmetrical aliphatic etlicr (I -methyl cyclohexyl ethyl ether). 

Iodide and bromide ions are good nucleophiles but weak bases, so they are more likely to substitute by the Sn2 mechanism than to eliminate by the E2 mechanism. Mechanism 14-1 shows how bromide ion cleaves the protonated ether by displacing an alcohol. In most cases, the alcohol reacts further with HBr to give the alkyl bromide (see Section 11-7). The reaction of cyclohexyl ethyl ether with HBr is an example of this displacement. The cyclohexanol produced by the cleavage reacts further with HBr, and the final products are ethyl bromide and bromocyclohexane. 

Because all nucleophiles are also bases, nucleophilic substitution and base-promoted /3-elimmation are competing reactions. The ethoxide ion, for example, is both a nucleophile and a base. With bromocyclohexane, it reacts as a nucleophile (pathway shown in red) to give ethoxycyclohexane (cyclohexyl ethyl ether) and as a base (pathway shown in blue) to give cyclohexene and ethanol ... 

When one of the substituents is a ring, as in 4.23, another method is common. This could be named as cyclohexyl ethyl ether, but can also be described as ethoxycyclohexane. One rather special class of ethers is the epoxides, or oxiranes, such as 4.24 and 4.25. There are two methods by which they can be named—the first refers to the alkene from which they are generally synthesized plus the word oxide. Thus, 4.24 is ethene oxide and 4.25 cyclohexene oxide. Alternatively, the molecule may be named as an alkane, and then the word epoxy, and the location of the three-membered ring added. In this case, the names would be ethane epoxide and cyclohexane-l,2-epoxide. 

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