The tertiary glycols are known as _pinacones_ and are formed on the
reduction of ketones with sodium amalgam.
The glycols are somewhat thick liquids, of high boiling point, the
pinacones only being crystalline solids; they are readily soluble in
water and alcohol, but are insoluble in ether. By the action of
dehydrating agents they are converted into aldehydes or ketones. In
their general behaviour towards oxidizing agents the primary glycols
behave very similarly to the ordinary primary alcohols (q.v.), but the
secondary and tertiary glycols break down, yielding compounds with a
smaller carbon content.
Ethylene glycol, C2H4(OH)2, was first prepared by A. Wurtz (_Ann.
chim._, 1859 [3], 55, p. 400) from ethylene dibromide and silver
acetate. It is a somewhat pleasant smelling liquid, boiling at 197
deg. to 197.5 deg. C. and having a specific gravity of 1.125 (0 deg.).
On fusion with solid potash at 250 deg. C. it completely decomposes,
giving potassium oxalate and hydrogen,