The marked increase in propylene oxide production was promoted by the availability of ethylene chlorohydrin plants, which became unprofitable in the 1960s. After only minor modifications, propylene oxide could be manufactured in these units.

Analogous to ethylene oxide, propene is reacted at 35-50 °C at 2-3 bar in reaction columns with an aqueous chlorine solution in which HCl and HOCl are in equilibrium. The resulting 4-6% mixture of α- and β-chlorohydrin (ratio 9:1) is dehydrochlorinated - without intermediate separation - at 25 °C with an excess of alkali, e. g., 10% lime water or dilute sodium hydroxide solution from NaCl electrolysis:

The propylene oxide is then rapidly driven out of the reaction mixture (to avoid hydration) by directly applying steam and then purified by distillation. The selectivity is 87-90% (based on C₃H₆). Main byproducts are 1,2-dichloropropane (selectivity 6-9%) and bischloro (selectivity 1-3 %).

As the total chlorine losses are in the form of economically nonutilirable CaCl₂ or NaCl solutions, work has been conducted oxidation systems. Instead of the inorganic oxidking agent HOCl. oreanic comoounds have been selected to transfer the O from the beginning to find chlorine-recycle or chlorine-free to propene.