The Preparation of Quinolines by a Modified Skraup Reaction

It has been found that a modification in the method of bringing together the reactants of Skraup's procedure for synthesizing quinolines results in a marked reduction of the violence of the original reaction and in a substantial increase in yield of quinoline or substituted quinoline. The ease of carrying out the reaction is such that it can be utilized safely and economically on a commercial scale. Examples of the modified method are given for quinoline, 8-hydroxyquinoline, and 5-chloro-8-hydroxyquinohne. The method was applied to the Doebner–von Miller reaction for the synthesis of 8-hydroxyquinaldine and 5-chloro-8-hydroxyquinaldine with somewhat less improvement than in its application to the Skraup reaction.