Ethylene glycol (HOCH2CH2OH), the major substance in antifreeze, has a normal boiling point of 198oC. By comparison,

Question:

Ethylene glycol (HOCH2CH2OH), the major substance in antifreeze, has a normal boiling point of 198oC. By comparison, ethyl alcohol (CH3CH2OH) boils at 78oC at atmospheric pressure. Ethylene glycol dimethyl ether (CH3OCH2CH2OCH3) has a normal boiling point of 83 oC, and ethyl methyl ether (CH3CH2OCH3) has a normal boiling point of 11 oC.
(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?