Thermal elimination of hydrogen chloride from adducts of aromatic amines with boron trichloride with reference to borazole formation

The adducts of 2,3,5,6-tetrachloroaniline, 2,4,6-tribromoaniline, pentafluoroaniline, 2-bromoaniline, and N-methylaniline with boron trichloride have been prepared and the elmination of hydrogen chloride from them in boiling benzene and in more basic solvents has been examined. Some kinetic measurements have been made. The first product of reaction in benzene, which is anilinodichloroborane for each amine except pentafluoroaniline, has been isolated and characterised. In no case was borazole isolated from reaction in boiling benzene. The compound 2-nitro-4-trifluoromethylanilinodichloroborane has also been characterised. The reaction of aromatic amines with BCl₃ in general, and the possible mechanisms of formation of borazoles by elimination of hydrogen chloride from them are discussed.