Tricresyl Phosphate: Cresol and Phosphorus Oxychloride over Magnesium Chloride

Tricresyl phosphate is a phosphate ester used as a plasticiser for PVC. Wilson's process (US 2,960,524, 1960) heats a phenol with phosphorus oxychloride and a little magnesium chloride, which keeps the mixture fluid: first at 110 °C, then up to 200 °C under a partial vacuum until hydrogen chloride stops coming off. It is neutralised with soda and vacuum-distilled; the patent's yield was 96 %. Here cresol alone is used (the patent's example mixed phenol and cresol), so the amounts are our arithmetic. The picture: our diagram.