Efficient and Mild Reductive Amination of Carbonyl Compounds Catalyzed by Dual-Function Palladium Nanoparticles

Abstract

Primary amines are valuable building blocks for a large number of chemicals, developing efficient synthetic routes toward primary amines and particularly those proceeding under mild conditions are highly desirable and rather challenging. Presented here is a highly efficient procedure enabling itself to proceed in H 2 O using H 2 of 1 atm (0.1 MPa) for the reductive amination of carbonyl compounds. Several palladiumbased nanoparticle (Pd-NP) catalysts were prepared, and one emerged to be the most suitable and classified as nanoparticles, due to its high catalytic activity, reactions were allowed to proceed at room temperature using NH 3 , and the corresponding primary amines can be afforded with yields of up to 99%. Some control reactions were carried out, revealing that H 2 is pivotal for activating the Pd-NPs. The fact that the Pd-NPs can catalyze both reductive amination of carbonyl compounds and hydrogenation of imines proves Pd-NPs to be a dual-function catalyst, and a plausible mechanism was proposed.

Advances in the Catalytic Reductive Amination of Furfural to Furfural Amine: The Momentous Role of Active Metal Sites

“…Although Pd-based catalysts, due to their high hydrogenation activity, lead to the formation of secondary amine from the corresponding aldehyde in the studies mentioned above, in contrast, Pd-NPs, synthesized using various aromatic amine ligands, exhibited a remarkable activity in the reductive amination of FUR to FUA (97 %) in ammonia water, a balloon filled with H 2 , pH 2, at room temperature. [68] This indicates that having a different chemical environment surrounding the Pd active species by suitable ligands rather than having conventional metal oxide supports could alter the reaction pathway towards the selective formation of primary amines. Moreover, Pd encapsulated with hydrophobic organic amine-containing ligands could provide a hydrophobic environment and repel the water molecules, thus favoring facile and preferential adsorption/desorption of organic substrates/products when performing experiments in water.…”

“…Representative illustration of the formation of Pd-NP binding with 4-methylbenzylamine. [68] Figure 6. Activity of various catalysts yielding more than 70 % FUA as a function of temperature.…”

“…Plausible mechanism for the synthesis of amine using ammonia and hydrogen with Pd-NPs. [68] ability, Ru supported catalysts are widely studied in methanol but scarcely investigated in water.…”

Co‐Catalyzed Synthesis of Primary Amines via Reductive Amination employing Hydrogen under very mild Conditions

“…[10] In 2020, Wang and co-workers reported on palladium nanoparticles for the reductive amination of 16 aromatic ketones with aqueous ammonia under milder conditions. [11] However, extremely high catalyst loadings of 37 mol% Pd were used.…”

Palladium Oxide Nanoparticles: Preparation, Characterization and Catalytic Activity Evaluation

“…Since heterogeneous catalysis is based on processes taking place at the surface, the use of finely dispersed catalysts is often adopted in order to reduce the amount of material and maximize its catalytic effect [3,4]. For this purpose, palladium nanoparticles are widely used to catalyze organic reactions [5][6][7][8][9][10][11][12][13][14]. Similar to palladium, palladium(II) oxide (PdO) has also found applications in many catalytic processes [15][16][17][18], but few studies were carried out on the production of palladium oxide nanoparticles compared to the wide range of works concerning metallic palladium particles [19][20][21][22].…”