Cleavage of diphenylether with boron trifluoride under supercritical conditions

Diphenylether (DPE) was efficiently hydrolyzed into phenol (up to 58 mol%), using Lewis acids, such as boron trifluoride (BF3) and Ni(BF4)2, in supercritical water (SCW) at 380 °C. The side-reactions were insignificant, and BF3 was found to be nearly twice as effective, than HBF4 under the same conditions. Cleavage of DPE in supercritical organic solvents, such as 2,2,2-trifluoroethanol and trifluoroacetic acid, with BF3 at 250 °C, was less successful and accompanied by Friedel-Crafts side-reactions. However, >25 mol% of DPE was cleaved to phenyl trifluoroacetate in supercritical trifluoroacetic acid with equimolar BF3 at 250 °C/1 h.