Hydroalkylation of Aniline with Pd-Al2O3 and NaCl-AlCl3

The hydroalkylation of aniline in a palladium-fused salt system was examined under hydrogen pressure. By using 0.5% Pd-Al2O3 and fused salt (NaCl-AlCl3), N-cyclohexylaniline (4) was formed as the main product at temperatures below 300°C ; at higher temperatures, the cyclohexyl group rearranged to form nuclear alkylated products, o-and p-cyclohexylaniline, (5) and (6). The yield of 4 was 27.7% at 280°C ; those of 5 and 6 were 5.4 and 7.3%, respectively, at 400°C. The reaction mechanism for the hydroalkylation of aniline with this catalytic system is discussed.