Hydrochloric Acid → 4-(5-Trifluoromethylpyrid-2-yloxy)phenylisocyanate

Participants

Reaction Conditions

Reaction Steps

20.3 g (0.08 mol) of 4-(5-trifluoromethylpyrid-2-yloxy)aniline are dissolved in 200 ml of dry chlorobenzene. This solution is cooled to -20° C. and rapidly added a solution of 3.7 g of gaseous HCl in 80 ml of dry chlorobenzene. The resultant crystalline slurry is cooled to -30° C. and a strong flow of about 40 g of phosgene is introduced over 1 hour. The addition of phosgene is then discontinued and the reaction mixture is stirred for 1 hour at 20° C. and subsequently for 1 hour in an oil bath at 110° C. A clear solution forms which is then cooled in a stream of nitrogen and, with stirring, excess phosgene is expelled with nitrogen. First the chlorobenzene is distilled off under normal pressure and then the isocyanate is distilled off under a high vaccum. Boiling point 105°-107° C./0.03 mbar; yield>90%.

Provenance & Evidence