Process for preparing substituted and unsubstituted arylalkylamines

Abstract

An arylisonitrosoalkanone is hydrogenated in the presence of a noble metal catalyst and a weak carboxylic acid to form an arylalkanolamine which is then hydrogenated in the presence of a strong mineral acid and the transition metal catalyst to form an arylalkylamine. When the arylisonitrosoalkanone is an isonitrosoacetophenone, the isonitrosoacetophenone is prepared by one of two methods. In the first method, a substituted or an unsubstituted isonitrosoacetophenone is prepared from a corresponding substituted or unsubstituted acetophenone by oxidizing the acetophenone to form a substituted or an unsubstituted phenylglyoxalacetal in a reactor, hydrolyzing the phenylglyoxal acetal in the same reactor to form a corresponding substituted or unsubstituted phenylglyoxal, and condensing the phenylglyoxal with hydroxylamine or a salt thereof in the same reactor to form the substituted or unsubstituted isonitrosoacetophenone. Alternatively, the substituted or unsubstituted isonitrosoacetophenone is prepared from the corresponding substituted or unsubstituted acetophenone by reacting the substituted or unsubstituted acetophenone in water with a source of a nitrosonium ion in the presence of a strong acid to form a corresponding substituted or unsubstituted phenylglyoxal, and condensing the phenylglyoxal with hydroxylamine or a salt thereof to form the substituted or unsubstituted isonitrosoacetophenone. In either method, any strong acid that might be present in the reaction mass following the condensation to the isonitrosoacetophenone shall be removed therefrom prior to initiating the hydrogenation of the isonitrosoacetophenone to the arylalkanolamine.