Abstract
The catalytic hydrogenation of e-caprolactem to hexamethylenimine was carried out in a heterogeneous liquid phase reaction. Among the hydrogenation catalysts, Raney-Co showed an excellent activity and selectivity. The maximum yield of 88% was obtained with this catalyst at 190°C for 10 hrs in the medium of isoropylalcohol. At a higher temperature both the yield and the selectivity were decreased. In these cases, N-isopropyl hexamethylenimine and cyclohexanone were obtained as the by-products. The activity of Raney-Co was compared with those of Raney-Ni, Cu and Fe. With the Ni catalyst, the produced imine decomposed to yield piperidine and other undesirable by-products, while the Cu and Fe catalysts were almost inactive to the hydrogenation.
Also, δ-valerolactam and γ-butyrolactam were hydrogenated with Raney-Co catalyst in good yield.
