The most important manufacturing processes for aniline and other bulk arylamines are based on the continuous catalytic hydrogenation of nitro compounds, employing heterogeneous copper, nickel or platinum-group metals. For more complex amines produced on a smaller scale, homogeneous catalysis with its greater possibilities for chemo-and regioselective hydrogenation is increasingly the method of choice. A newer alternative process of increasing importance for aniline and phenylenediamines is the nucleophilic amination of phenols. The catalytic amination of haloarenes has also been employed commercially. Amination processes also find application in the production of pyridines and pyrroles.