Gold‐Palladium‐Alloy‐Catalyst Loaded UiO‐66‐NH₂ for Reductive Amination with Nitroarenes Exhibiting High Selectivity

Abstract

AuÀPd alloy catalysts were successfully loaded into aminefunctionalized metal-organic framework (MOF, UiO-66-NH 2 ) via direct absorption/reduction method. The existence of Pd in the alloy was revealed by using in situ fourier transform infrared spectroscopy (FTIR) with CO as probe molecules. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) results demonstrated the AuÀPd alloys were well dispersed within the robust UiO-66-NH 2 . AuÀPd alloy nanoparticles with low Pd content were well dispersed within UiO-66-NH 2 and exhibited high stability and selectivity for N-benzylaniline (98%) in the direct reductive amination with benzaldehyde and nitrobenzene.

Encapsulation of Metal Nanoparticles within Metal–Organic Frameworks for the Reduction of Nitro Compounds

“…Alloying two or more different transition metals allows the catalytic activity of the MNPs to be tuned. In one of the examples, alloyed Au–Pd NPs were loaded into UiO-66-NH 2 MOF catalyst via adsorption/reduction method to obtain AuPd@UiO-66(Zr)-NH 2 and their activity was examined in the reductive amination with nitroarenes [60]. Powder XRD indicated no changes in the crystallinity of UiO-66(Zr)-NH 2 during the loading of these NPs.…”

“…TEM images and corresponding histograms of particle size distribution for as-synthesized Au-Pd 0.03 @UiO-66-NH 2 ( a , b ) and the sample after reaction ( c , d ). Reproduced with permission from [60]. …”

Metal-based Heterogeneous Catalysts for One-Pot Synthesis of Secondary Anilines from Nitroarenes and Aldehydes

“…Liang and co-workers reported a series of catalysts for DRA, based on Au–Pd alloys well dispersed within amine functionalized metal-organic framework (MOF, UiO-66-NH 2 ) [ 115 ]. However, only Au–Pd alloy nanoparticles with low Pd content (Au-Pd 0.03 @UiO-66-NH 2 ) exhibited high selectivity for DRA with benzaldehyde and nitrobenzene, and thus the sole synthesis of N -benzylaniline in 93% yield was obtained in cyclohexane as solvent at 50 °C under 1.0 MPa of H 2 .…”

Catalytic Reductive Amination of Aldehydes and Ketones With Nitro Compounds: New Light on an Old Reaction

“…In the last decade, numerous other catalytic systems were developed based on supported palladium (Sydnes et al, 2008;Sreedhar et al, 2009;Dell'anna et al, 2011;Wei et al, 2013;Zhou et al, 2015;Sharma et al, 2017), platinum (Hu et al, 2011;Cirujano et al, 2013), rhodium (Huang et al, 2015), iridium Pintado-Sierra et al, 2013;Sui et al, 2017), ruthenium (Del Pozo et al, 2012), silver (Artiukha et al, 2017), and gold (Yamane et al, 2009;Artiukha et al, 2015) nanoparticles. Heterobimetallic systems such as Pd-Ag (Li et al, 2013;Chen et al, 2015), Pd-Au (Cho et al, 2018;Yin et al, 2018), Ni-Pd (Nişanci et al, 2015), and Rh-Co (Park and Chung, 2015) were also shown to be efficient catalysts for the reductive alkylation of nitro compounds. With noble metal catalysts, reductive alkylation of nitro compounds is performed under mild conditions (r.t. to 100 • C) and low hydrogen pressure (typically, 1-25 bar).…”