Hydrochloric Acid → 5,5-Bis(3,5-difluorophenyl)-2,4-imidazolidinedione

Participants

Reaction Conditions

Reaction Steps

A mixture of 3,3',5,5'-tetrafluorobezophenone (358 g, 1.41 mol), potassium cyanide (137.5 g, 2.11 mol), ammonium carbonate (406 g, 4.22 mol) and ethanol (3.5 L) was heated at 115° C. for 16 h in a stirred 2 gal pressure reactor. After chilling to relieve the pressure, the reactor was opened and the mixture was poured into 8 L of water in a 22-L flask equipped with a mechanical stirrer. The mixture was acidified (pH 2.0) using concentrated hydrochloric acid (~1 L) (Note 1) and the resulting precipitate was collected by filtration, washed with water, and pressed dry. The crude material was recrystallized from ethanol (~6 L) to provide 399.5 g (87%) of 5,5-di(3,5-difluorophenyl)-2,4-imidazolidinedione (Note 2): mp 271°-274° C.; MS m/z 324 (M+); 1H NMR (DMSO-d6) δ9.50 (s, 2); 7.42-6.90 (m, 6); IR (KBr) 3265, 3160, 3060, 1762, 1710 cm-1.

Provenance & Evidence