Physical Properties of Ethers

概要

An ether molecule has a net dipole moment due to the polarity of C–O bonds. Subsequently, boiling points of ethers are lower than those of alcohols of comparable molecular weight and slightly higher than those of hydrocarbons of comparable molecular weight (Table 1).

Ethers can act as hydrogen bond acceptors, making them more water-soluble than hydrocarbons, but since ethers cannot act as hydrogen bond donors, they are much less soluble in water than alcohols. Ethers are considered good solvents because of their ability to form hydrogen bonds with other molecules, combined with the London Dispersion forces between the alkyl groups bonded to oxygen. Ethers have high volatility and can quickly evaporate during the isolation of reaction products.

Table 1. Comparison of Boiling Points of Ethers, Alcohols, and Hydrocarbons

Name	Structural Formula	Molecular weight (g/mol)	bp (°C)
Dimethyl ether		46	−25
Ethanol		46	78
Propane		44	−42
Diethyl ether		74	35
1-Butanol		74	118
Pentane		72	36