The invention relates to a continuously operated process for the
purification by distillation of the 1,2-propylene glycol formed as
by-product in the synthesis of propylene oxide, wherein the mixture
formed in the synthesis which contains the 1,2-propylene glycol is
separated in a dividing wall column into low-, intermediate- and
high-boiling fractions and the 1,2-propylene glycol is taken off as
intermediate boiler at the side offtake of the column.