Analytical pyrolysis of alkylammonium tetraphenylborates

Various alkylammonium, dialkylammonium, trialkylammonium and tetraalkylammonium tetraphenylborates were prepared. The thermal decomposition curves of RNH₃BPh₄, R₂NH₂BPh₄, R₃NHBPh₄ and R₄NBPh₄ (where R=Me, Et, n-Bu) in nitrogen atmosphere indicate that the elimination of volatile matter leads to the formation of both 1:1 complex of trialkylamino triphenylborane and dialkylamino diphenylborene. Further elimination of volatile matter leads to the formation of borazine at 600-680°C. When borazine is further heated at 980-1090°C an exothermic change indicates the polycyclic condensation of the borazine leading to the formation of boron nitride. The volatile matter evolved in these reactions was measured quantitatively and reaction mechanisms were suggested.