Akademik Veri Yönetim Sistemi
5th National Catalysis Conference, Adana, Türkiye, 23 - 26 Nisan 2014
Transition metal nanoparticles (NPs) have been used as active heterogeneous catalysts in various catalytic reactions owing to their high surface to volume ratio. The nanoparticles of all catalytically active transition metals have been prepared by using different methods and tested in various catalytic reactions[1]. Besides the monometallic nanoparticles, the interest in use of two metal-comprising (bimetallic) nanoparticles as heterogeneous catalysts has been increased in recent years[2]. The alloy or core-shell structured bimetallic NPs might be more active, selective and stable catalyst than their monometallic counterparts in a certain reaction due to the synergistic effects between the two metals[3]. Recently, we reported that AuPd and AgPd alloy NPs are highly active catalysts in the formic acid dehydrogenation while Au, Ag or Pd NPs showed no or very limited activity[4]. Additionally, we showed that chemically derived graphene (CDG) is a unique support material for the NPs catalysis in organic reactions owing to its graphitic plane near each NP that helps to absorb aromatic component in the reactants, pulling them in close range contact with the catalyst[5]. On the other hand, aromatic primary amines (R-NH2) are important class of compounds used as intermediates in the synthesis of numerous pharmaceuticals, dyes, polymers and natural products[6]. The selective reduction of aromatic nitro/nitrile is the best method for the synthesis of industriallyimportant aromatic amine derivatives.
In this study, a facile synthesis of R-NH2 from the aromatic nitro/nitrile compounds via AuPd NPs catalyzed tandem hydrolysis of ammonia borane (AB) and hydrogenation reaction is presented. The AuPd NPs were prepared by co-reduction of hydrogen tetrachloroaurate(III) hydrate (HAuCl4·xH2O) and palladium(II) acetylacetonate (Pd(acac)2) by borane-morpholine complex (BM) in oleylamine (OAm)[4a]. To study NP catalysis, the as-prepared AuPd NPs were first assembled on CDG (AuPd-CDG) via sonication in the hexane dispersion for 1h. The AuPd-CDG is a highly active catalyst for the tandem hydrolysis and hydrogenation of R-NO2 and/or R-CN compounds in aqueous solution at room temperature. A variety of R-NO2 and/or R-CN compounds were tested and the respective R-NH2 obtained by synthetic yield reaching up to 100% in 5-30 minutes.