Oleylamine‐Stabilized Copper(0) Nanoparticles: An Efficient and Low‐Cost Catalyst for the Dehydrogenation of Dimethylamine Borane

Abstract

Copper(0) nanoparticles, in situ generated from the reduction of copper(II) 2‐ethylhexanoate during the dehydrogenation of dimethylamine borane (DMAB) at 50.0±0.1 °C in toluene solution, are active catalysts in hydrogen generation from DMAB, but not very stable against agglomeration. Addition of 5.0 equivalents of oleylamine (OAm) was found to stabilize copper(0) nanoparticles noticeably, while maintaining high catalytic activity. Oleylamine‐stabilized copper(0) nanoparticles could be isolated from the solution and characterized by XRD, TEM, UV/Vis, attenuated total reflectance (ATR)‐FTIR, and 11B NMR spectroscopies. Our report also includes (i) comparative catalytic activities of copper(0) nanoparticles in the absence and presence of OAm depending on the initial [OAm]/[Cu] ratio, catalyst concentration, substrate concentration, and temperature, (ii) the catalytic lifetime of copper(0) nanoparticles in the absence and presence of OAm in the dehydrogenation of DMAB at 50.0±0.1 °C, (iii) testing the ease of isolation and reusability of copper(0) nanoparticles in the absence and presence of OAm in the dehydrogenation of DMAB, (iv) the results of quantitative kinetic poisoning experiments by using 1,10‐phenanthroline, showing that copper(0) nanoparticles are kinetically competent catalysts in the dehydrogenation of DMAB.

Green dehydrogenation of dimethylamine borane catalyzed by cheaply copper(0) nanocatalysts without any stabilizer at nearly room temperature

“…This assumption was confirmed by our recent work, in which oleylamine was used as a stabilizer and highly active copper(0) nanoparticles were synthesized throughout the dehydrogenation of DMAB in toluene solution at a relatively higher reaction temperature (50.0 ± 0.1°C) [25]. Moreover, this study, like our previous studies [26,27], supports that the best results for the synthesis of active and stable Cu(0) NCats are obtained from the dehydrogenation of DMAB under solvent-free (green) environmental conditions.…”

Surprisingly high sensitivity of copper nanoparticles toward coordinating ligands: consequences for the hydride reduction of benzaldehyde

“…of P(n-Bu) 3 , only nanoscaled species smaller than 5 nm were found on the TEM grid. Noticeably, the same effect occurred by replacing the phosphine by a typical ligand for copper complexes, DBU (1,8-diazabicyclo[5.4.0]undec-7ene), [51][52][53] or even by oleylamine 13 (Scheme 3B). However, neither of these suspensions of leached copper nanoparticles showed catalytic property for the reduction of benzaldehyde with phenylsilane.…”

“…In order to obtain pure Cu(0) nanoparticles, colloidal syntheses are of interest as they allow working in an organic solvent with a large variety of ligands, enabling the tuning of the capping species at the surface of the nanoparticles. [12][13][14][15][16][17] The reactivity of the nanoparticles can be controlled by the interaction between the ligand and the metallic center. [18][19][20][21][22] In some cases, ligands can be detrimental to the integrity of the NPs due to the leaching of metal-ligand complexes into the medium, as it has been thoroughly studied for Pd-based catalytic systems.…”

In-situ Prepared Tungsten(VI) Oxide Supported Pd0 NPs; Remarkable Activity and Reusability in H2 Releasing from Dimethylamine Borane

“…The rate of hydrogen evolution depends on metal catalyst using in dehydrogenation reactions [10,11]. Among transition metal nanoparticles, especially ruthenium has been used as a catalyst in dehydrogenation reactions [10,12,13,14,15] . However, there are few reports on the usage of palladium based on heterogeneous catalyst in H 2 evolution from DMAB: three of them are mono metallic [16,17,18] and five of them are bimetallic [19,20,21,22] or trimetallic [23] that act as heterogeneous catalysts.…”