The functional group in ethers (-O-) is comparatively inert with respect to the -OH functional group in alcohols and phenols even though the oxygen atom in each of the groups has two lone pairs of electrones. Therefore, ethers are not easily attacked by alkalies, dilute mineral acids, PCl5, metallic sodium etc. under ordinary conditions. But they undergo chemical reactions under specific conditions.
1. Cleavage of C-O bond in ethers
The cleavage of C-O bond in ethers takes palce under drastic conditions with excess of hydrogen halides. The reaction of dialkyl ether gives two alkyl halide molecules.
R-O-R + 2HX -------------> 2RX + H2O
Alkyl aryl ethers are cleaved at the alkyl-oxygen bond. The reaction yields phenol and alkyl halide.
Ethers with two different alkyl groups are also cleaved in the same manner.
R-O-R' + H-X ------------> R-X + R'-OH
The order of reactivity of hydrogen halides is as follows: HI > HBr > HCl.
1. Reaction with HI
2. Reaction with H2SO4
3. Formation of Peroxides
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