Physical Properties of Ethers

Ethers are polar molecules: an ether's dipole moment is the vector sum of its two polar C-O bonds, with a further contribution from oxygen's two lone pairs -- diethyl ether, for instance, has a dipole moment of 1.18 D. Because ethers lack an -OH group capable of intermolecular hydrogen bonding with each other, their boiling points are only SLIGHTLY higher than alkanes of comparable molar mass, and considerably LOWER than alcohols of comparable molar mass (Table 11.5 compares n-heptane, 1-methoxypentane and hexan-1-ol, all around molar mass 100, boiling at 371 K, 373 K and 430 K respectively). However, the ether oxygen's lone pairs CAN hydrogen-bond with water's -OH, so ethers remain appreciably miscible with water; the same lone pairs let …