ABSTRACT
New Ways for the Full Hydrogenation of Quinoline 102
The role of the reaction parameters in mild hydrogenation of Q has been investigated previously using different noble metal-based commercial catalysts (13); Rh systems were superior, although in all cases only partial hydrogenation to py-THQ was observed. This deactivation might be due to adsorption on the active sites of reaction intermediate(s) (a, b or c) formed in the first hydrogenation step Q Æ py-THQ (Figure 1). One way to remove this deactivation was the use of highly dispersed metal catalysts, with very small crystallites that hamper the strong adsorption of reaction intermediate(s), although a higher reaction temperature (473 K) was required (14). Another way to reduce catalyst deactivation was by the addition of a Lewis base to the reaction mixture; this favored complete hydrogenation probably by competitive adsorption on the catalyst surface (13).
