Boiling points of alcohols are than those of alkanes, haloalkanes or ethers of comparable molecular masses. This is due to the formation of very stable intermolecular hydrogen bonding(bonding with other molecules of the same or different species). because of the presence of electronegative Oxygen atom and –OH group. So due to the intermolecular hydrogen bonding, many similar molecules join due to the formation of these strong bonds. As a result of which, a large amount of energy is required to break these bonds.
Intermolecular Hydrogen bonding in ROH, where R is an alkyl group.
If we see ethers(ROR’), we will find that ethers have much low boiling points as compared to the isomeric alcohols. Unlike alcohols, as we saw earlier, the ethers are not associated by any sort of intermolecular Hydrogen bonding due to the absence of Hydrogen atom with the electronegative Oxygen atom which was present in case of alcohols(-OH).
No H atom is associated with Oxygen atom, so no intermolecular hydrogen bonding observed.
The inter-particle forces existing there are weak dipole-dipole forces.
Due to all these reasons, ethers have low boiling point as compared to their isomeric alcohols.
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