Abstract Halogen exchange of 1, 2, 4, 5-tetrachlorobenzene with spray-dried potassium fluoride has been found to proceed smoothly using 1, 3-dimethyl-2-imidazol-idinone as a solvent at 300 C in a pressure reactor to give 2, 4, 5-tri-fluorochlorobenzene without any rearrangement.
