Question

Ethylene glycol (HOCH₂CH₂OH), the major substance in antifreeze, has a normal boiling point of 198 °C. By comparison, ethyl alcohol (CH₃CH₂OH) boils at 78 °C at atmospheric pressure. Ethylene glycol dimethyl ether (CH₃OCH₂CH₂OCH₃) has a normal boiling point of 83 °C, and ethyl methyl ether (CH₃CH₂OCH₃) has a normal boiling point of 11 °C. (a) Explain why replacement of a hydrogen on the oxygen by a CH₃ group generally results in a lower boiling point. (b) What are the major factors responsible for the difference in boiling points of the two ethers?