The high boiling point of ethanol (78.2 degree Celcius)
compared to dimethyl ether (−23.6degree Celcius ), though both having the same molecular formula C2H6O, is due to Hydrogen bonding.
Hydrogen bonding is observed when H atom is attached to more electronegative N, F or O atom.
Ethanol molecules are associated due to hydrogen bonding. This results in higher boiling point.
However, hydrogen bonding is not possible in dimethyl ether.