Riehm quinoline synthesis

What is Riehm quinoline synthesis?

The synthesis of 2,4-dimethylquinoline, also known as the Riehm quinoline synthesis, involves the thermal condensation (through prolonged heating) of aniline hydrochloride (arylamine hydrochloride) and acetone or mesityl oxide. This reaction was first reported by Engler and Riehm in 1885.

Riehm quinoline synthesis - general reaction scheme
Riehm quinoline synthesis

Additionally, the reaction results in the evolution of water and methane, and may produce other hydrocarbons. The Riehm quinoline synthesis can be performed with or without the use of condensation reagents (aluminium chloride, AlCl3, or phosphorus pentachloride, PCl5).