Steric and Electronic Effects of Phosphane Additives on the Catalytic Performance of Colloidal Palladium Nanoparticles in the Semi‐Hydrogenation of Alkynes

Abstract

We report on the influence of phosphanes on the catalytic activity and selectivity of colloidal, tetraoctylammonium bromide (TOAB) stabilised palladium nanoparticles (NPs) in the semi‐hydrogenation of alkynes to olefins. Full characterisation of the catalytic system (HRTEM, EDX, XPS, IR, NMR) confirmed the formation of spherical particles with a narrow size distribution (1.9±0.5 nm). The catalytic performance of the Pd NPs in the semi‐hydrogenation of 1‐octyne, 2‐octyne and phenylacetylene to the respective olefins and the influences on the selectivity was investigated. The system shows high activities and selectivities at mild conditions (0 °C and 1.0 bar H2 pressure). It was shown that generally, phosphanes lead to an increase of both the reaction rate and selectivity towards the olefin where both steric and electronic effects of the ligand play a crucial role for the catalyst performance. A moderate steric demand of the ligand with a rather weak σ‐donating ability turned out to give the highest catalytic performance.

Corrugated Cobalt Titanate/Partially Reduced Graphene Oxide Heterojunctions for a Selective Isopentanol Gas Sensor

“…Therefore, corrugated CoTiO 3 /prGO may show the strongest adsorption. Besides, it also exhibits a highly selectivity to isopentanol, which can be attributed to the combination of steric effect and electronic effect . Considering the molecular structure of the analytes, pentanol, pentanal, and glutaral are linear molecules, while isopentanol is a branched molecule.…”

“…Besides, it also exhibits a highly selectivity to isopentanol, which can be attributed to the combination of steric effect and electronic effect. 46 Considering the molecular structure of the analytes, pentanol, pentanal, and glutaral are linear molecules, while isopentanol is a branched molecule. The backbone of pentanol, pentanal, and glutaral is slightly longer than that of isopentanol.…”

Electron-Poor Phosphines Enable the Selective Semihydrogenation Reaction of Alkynes with Pd on Carbon Catalysts

“…Other poisoning agents such as sulfides have been successfully used to modify the hydrogenation selectivity, by depositing sulfur on the Pd surface, , using sulfides as a support, , or combining both the palladium sulfide surface with thiol modifiers . Nitrogen doping of the catalyst near the active Pd sites, , Au sites, , and Co sites has also been proposed, as well as a more recently reported dynamic adsorption control from alkylamino chains over the Pd NPs, which was similarly performed previously with sulfur-containing groups. , In a similar fashion, phosphorus has been identified as a beneficial additive for alkyne semihydrogenation reactions, as a support itself, , in a phosphine-functionalized polymer surrounding supported Pd NPs, in phosphines on supported Pd NPs, , or as stabilizers of colloidal Pd NPs . This latter approach has been employed on other metals such as Ru or Rh .…”

“… 20 , 21 In a similar fashion, phosphorus has been identified as a beneficial additive for alkyne semihydrogenation reactions, as a support itself, 22 , 23 in a phosphine-functionalized polymer surrounding supported Pd NPs, 24 in phosphines on supported Pd NPs, 25 , 26 or as stabilizers of colloidal Pd NPs. 27 This latter approach has been employed on other metals such as Ru 28 or Rh. 29 However, the use of commercially available Pd/C modified with simple phosphine modifiers as a catalyst for the semihydrogenation reaction of alkynes has, to the best of our knowledge, not been studied yet, despite the abundance of accessible commercial phosphines and the widespread use of these ligands for organometallic complexes.…”

A combinatorial coordination-modulated approach to all-hydrocarbon-ligated intermetallic clusters

“…[1][2][3][4][5][6] Surfactants, in particular, are used to control the formation of nanocrystals with respect to size, shape and composition. [7][8][9][10] Examples of concept transfer for bottom-up wet chemical cluster synthesis are scarce. We are working on translating the insight from intermetallic materials chemistry into a corresponding chemistry of all-hydrocarbonligated atom-precise clusters (i.e.…”