Sulfuric Acid → 4-Fluoro-3-(trifluoromethyl)phenol

Participants

Reaction Conditions

Reaction Steps

70 g (0.39 mol) of 4-fluoro-3-trifluoromethylaniline, prepared according to G.C. Finger and colleagues, Journal of Med. Chem., 7, (1964), 572, are added a little at a time, while stirring, to 500 ml of a 2.5 N solution of sulphuric acid heated to a temperature of 65° C. The solution obtained is cooled to 0° C and 27 g of sodium nitrite dissolved in 45 ml of water are added whilst continuing the stirring and ensuring that the temperature does not exceed +5° C. After the end of the addition, the mixture is stirred for a further hour, during which it becomes perfectly clear. Thereafter, whilst carrying out a steam distillation, the cold solution of the diazonium salt is introduced dropwise into a mixture of 56g of copper sulphate, 21 g of urea, 70 ml of water and 2 ml of concentrated sulphuric acid. The speed of addition is regulated so that the phenol formed is immediately carried away. The distillate is cooled and is extracted repeatedly with ether. The ether solutions are combined and dried, the solvent is driven off and the residue is rectified. 37 g (yield: 52%) of 4-fluoro-3-trifluoromethyl-phenol, distilling at 84° C under 15 mm, are obtained.

Provenance & Evidence