Abstract
The addition of β-propiolactone to an acetone solution of anhydrous aluminum chloride containing small amount of zinc chloride at 40 to 45°C resulted in an exothermal ring-opening reaction of β-propiolactone. When 2 moles of β-propiolactone was added to 1 mole of aluminium chloride and then 1 mole of water was added to the mixture, the yield was over 93% with good reproducibility and high selectivity to β-propiolactone.
The presence of acetic acid or acetic anhydride did not deactivate this catalyst system. It was affected by addition of water to a smaller extent than conventional catalysts of aluminum chloride-acetone system. In order to investigate the higher selectivity obtained, the structure of the catalyst was studied mainly by using IR- spectroscopy. The result indicated that this catalyst was probably the aluminum salt of β-chloropropionic acid which was coordinated with solvent molecules. The high selectivity of this catalyst system was discussed in terms of the structure of the catalyst.
