Question

Ethanol, CH₃CH₂OH, boils at 78.4 ᵒC, whereas dimethyl ether, CH₃OCH₃ boils at -23.7 ᵒC. Explain why the boiling point of ether is so much lower than that of ethanol.  

Answer 1

With the same number of carbon atoms , alcohols have much higher boiling point than ethers.

This is because of hydrogen bonding in alcohols. On other hand, ethers do not exhibit hydogen bonding.

Hydrogen bonding is an electrostatic attraction between hydrogen atom which is attached highly electronegative atom like F,N,O of one molecule and nearby highly electronegative atom of another molecule.

Ex: H-O--H , F-H---F, N-H---N

The hydrogen atom attached to oxygen of one alcohol molecule forms hydrogen bonding with oxygen atom of another alcohol.

So, more temperature is required to seperate these two molecules thus rises the boiling point.

Therefore, alcohols have higher boiling point than ethers with the same number of carbon atoms.

Hence, CH₃CH₂OH has much higher boiling point than CH₃OCH₃.