Synthesis of picolines and other aza-aromatics from arylamines by isomerization-rearrangement and from dinitriles by hydrogenation-cyclization reactions

摘要

New routes for the syntheses of α- and β-picoline and other valuable aza-aromatics with applications in the pharmaceutical and agricultural industry are described. Aniline and other arylamines, like toluidines, naphthylamines and m- phenylenediamine, all react to the corresponding o-methylsubstituted aza-aromatics when exposed to high NH_3 pressure and elevated temperature in the presence of acid catalysts. Zeolites show the best performance around 10 Mpa and 600 K. The results can be explained if it is assumed that the reaction starts with addition of NH_3 to the arylamine, followed by ring opening to an enamino-imine intermediate through a reverse also reaction, ring closure and NH_3 elimination.