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In organic chemistry an enol ether is an alkene with an alkoxy substituent. (2025). 9780199270293, Oxford University Press. ISBN 9780199270293 The general structure is R2C=CR-OR where R = H, alkyl or aryl. A common subfamily of enol ethers are vinyl ethers, with the formula ROCH=CH2. Important enol ethers include the reagent 3,4-dihydropyran and the monomers methyl vinyl ether and ethyl vinyl ether.
The reactivity of enol ethers is highly dependent on the presence of substituents alpha to oxygen. The vinyl ethers are susceptible to polymerization to give . They also react readily with in the thiol-ene reaction to form . This makes enol ether-functionalized monomers ideal for polymerization with thiol-based monomers to form thiol-ene networks.
Some vinyl ethers find some use as inhalation anesthetics. Enol ethers bearing α substituents do not polymerize readily. They are mainly of academic interest, e.g. as intermediates in the synthesis of more complex molecules.
The acid-catalyzed addition of hydrogen peroxide to vinyl ethers gives the hydroperoxide:
Nazi Germany used vinyl ether mixtures as rocket propellants during WWII, because their hypergolic combustion with a mixture of nitric acid and is relatively insensitive to temperature.
Vinyl ethers can be prepared by reaction of acetylene and alcohols in presence of a base.
Although enol ethers can be considered the ether of the corresponding , they are not prepared by alkylation of enolates. Some enol ethers are prepared from saturated ethers by elimination reactions.
The enzyme chorismate mutase catalyzes the Claisen rearrangement of the enol ether called Chorismic acid to Prephenic acid, an intermediate in the biosynthesis of phenylalanine and tyrosine.
Batyl alcohol and related glycyl ethers are susceptible to dehydrogenation catalyzed to give the vinyl ethers called :
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