Reactions of Ethers
Ethers (R-O-R’) are compounds formed by replacing hydrogen atoms of an alcohol (R-OH compound) or a phenol (C6H5OH) by an aryl/ acyl group (functional group after removing single hydrogen from an aromatic ring). In this section, reaction, preparation and behavior of ethers are discussed in the context of organic chemistry.
Epoxides
Epoxides are a special class of cyclic ethers which are an important functional group in organic chemistry and generate reactive centers due to their unusual high reactivity. Due to their high reactivity, epoxides are considered to be toxic and mutagenic.
Williamson Ether Synthesis
An organic reaction in which an organohalide and a deprotonated alcohol forms ether is known as Williamson ether synthesis. Alexander Williamson developed the Williamson ether synthesis in 1850. The formation of ether in this synthesis is an SN2 reaction.
Why Substituents Activate or Deactivate a Benzene Ring ?
A substituent present on the benzene ring determines the position of the incoming group and also activates or deactivates ring towards second substitution. Thus the group already present on the ring decides the rate of reaction involving further substitution.
The substitutents which enhance the rate of second substitution with respect to benzene are called activating substituents,while those which decrease the rate of second substitution with respect to benzene are deactivating substituents.
In general o-and p-directing substituents are activating substituents, whereas m-directing substituents are deactivating substituents.
Activating group
The o-and p- directing groups possess one or more lone pair of electrons on their key atoms.The lone pair of electrons interacts with the π-electron system of the ring and gives rise to several resonance structure.
The o- and p-directing group increases the electron density in the ring and thus makes the monosubstituted derivative more susceptible to further electrophilic attack.
Hence the incoming electrophile attacks on o- and p position and occupies these positions on the ring.
Ex: -NH2, -OH, OR etc....,
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