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Chemical Properties of Ether

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Ethers are relatively inert compounds; however, under specific conditions they do undergo the following types of reactions :

Reactions of Ethers Involving the Oxygen Atom

Ethers behave as Lewis bases because of the presence of two lone pairs on oxygen atom and thus dissolve in cold concentrated acids to form stable oxonium salts.

Formation of oxonium salts from ether

Also, being lewis bases, ethers form coordinate compounds, known as etherates, with lewis acids such as BF3, AlCl3, Grignard reagents etc.

Formation of boron trifuoride etherate

Electrophilic Substitution Reaction

The alkoxy group (-OR) is ortho para directing and activates the aromatic ring towards electrophilic substitution reaction in the same way as in phenol. Ethers, however, are less reactive than phenols towards electrophilic substitution reaction.

Resonance structure of ether

Reactions Involving Alkyl Group; and Cleavage C-O

The alkyl group of ether is also responsible for many reactions. The most common one is the action of air and light on ethers that results in the formation of peroxides. The C-O bond in ethers does not get cleaved easily, and hence, the reactions involving the cleavage of C-O bond take place under drastic conditions.


We are done with the conceptual part. We will study the reactions from next page onwards.

Questions

Question : Explain why ortho-nitrophenol is more acidic than ortho-methoxyphenol?

Answer : In o-nitrophenol, because of -R and -I-effect of -NO2 group, electron density on oxygen in O-H bond decreases that causes O-H bond to break easily.

-I-effect in o-nitrophenol

-I-effect in o-nitrophenol

-R-effect in o-nitrophenol

-R effect in o-nitrophenol

In contrast, due to +R-effect of the OCH3 group, the electron density on oxygen in the O-H bond increases ;therefore, the release of proton becomes difficult.

+R-effect in o-methoxyphenol

+R-effect in o-methoxy phenol

Hence, o-nitrophenol is more acidic than o-methoxyphenol.

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