Heterogeneously Catalyzed Selective Acceptorless Dehydrogenative Aromatization to Primary Anilines from Ammonia via Concerted Catalysis and Adsorption Control.

Abstract

Although catalytic dehydrogenative aromatization from cyclohexanones and NH3 is an attractive synthetic method for primary anilines, using a hydrogen acceptor was indispensable to achieve satisfactory levels of selectivity in liquid-phase organic synthetic systems without photoirradiation. In this study, we developed a highly selective synthesis of primary anilines from cyclohexanones and NH3 via efficient acceptorless dehydrogenative aromatization heterogeneously catalyzed by an Mg(OH)2-supported Pd nanoparticle catalyst in which Mg(OH)2 species are also deposited on the Pd surface. The basic sites of the Mg(OH)2 support effectively accelerate the acceptorless dehydrogenative aromatization via concerted catalysis, suppressing the formation of secondary amine byproducts. In addition, the deposition of Mg(OH)2 species inhibits the adsorption of cyclohexanones on the Pd nanoparticles to suppress phenol formation, achieving the desired primary anilines with high selectivity.