The rearrangement of N-triarylmethyl anilines to their p-triarylmethyl derivatives
(EN)
Siskos, M. G.
(EN)
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
(EL)
Siskos, M. G.
(EN)
The N-triarylmethyl anilines Ph(3)C-NHAr (Ar=Ph, o-Me-C6H4, m-Me-C6H4, p-Me-C6H4, p-O2N-C6H4, p-Ph(3)C-C6H4) and Ar'C-3-NHPh [Ar'C-3=Ph(2)(2-Py)C, Ph(2)(3-Py)C, Ph(2)(4-Py)C, (p-(t)Bu-C6H4)(3)C] prepared by the reaction of Ph(3)C-Cl with anilines ArNH2 and of the corresponding chlorides Ar'C-3-Cl with aniline (at 50-100 degrees C), undergo a Hofmann-Martius rearrangement to p-triarylmethyl derivatives (i.e., p-Ar'C-3-C6H4-NH2 far Ar=Ph) when they are heated (similar to 185 degrees C) with equimolar amounts of PhN(+)H(3)Cl(-). The latter catalyses the rearrangement probably through the formation of the instable anilinium salt Ar'C-3-N+H2ArCl- that serves as a Ar'C-3(+) ion source. Ar'C-3(+) in a second step (electrophilic aromatic substitution) leads with excess of ArNH2 to p-substituted derivatives (e.g. p-Ar'C-3-C6H4-NH2), A free radical mechanism, resonable in view of the high temperatures used (similar to 185 degrees C), could be excluded; Ar'C-3-NHAr undergoes homolysis of the C-N bond to Ar'C-3(.) radicals at temperatures higher than 200 degrees C, a fact which was established using ESR spectroscopy and product analysis.
(EN)
