glycol (glĪˈkōl) [key], dihydric alcohol in which the two
hydroxyl groups are bonded to different carbon atoms; the
general formula for a glycol is (CH2) n (OH)2. The most
important glycol is the simplest, ethylene glycol, or
1,2-ethanediol, CH2OHCH2OH, a slightly sweet-tasting, somewhat
viscous liquid that is miscible with water. Because of its low
volatility (b.p. 197°C) and low corrosive activity, it is widely
used in mixtures of automobile antifreeze. Ethylene glycol can
be esterified to form polyesters, e.g., Dacron, and can be
nitrated to form an explosive used in mining. It is prepared
commercially by oxidation of ethylene at high temperature over a
silver oxide catalyst, followed by acid-catalyzed hydrolysis of
the ethylene oxide that is formed. Cellosolves (e.g., methyl
cellosolve, CH3OCH2CH2OH) are monoether derivatives of ethylene
glycol. They are excellent solvents, having solvent properties
of both ethers and alcohols; they have other uses as well.
Polyethylene glycol (PEG) is used to thicken sha