Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

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

ABSTRACT: An alternative to the Lindlar catalyst for the semihydrogenation reaction of alkynes to alkenes is of high interest. Here we show that palladium on carbon (Pd/C), i.e., a widely available supported Pd catalyst, is converted from an unselective to a chemoselective catalyst during the semihydrogenation reaction of alkynes, after the addition of catalytic amounts of commercially available electron-poor phosphines. The catalytic activity is ≤7 times greater, and the selectivity is comparable to that of the industrial benchmark Lindlar catalyst.

SUBMITTER: Ballesteros-Soberanas J

PROVIDER: S-EPMC9900635 | biostudies-literature | 2023 Feb

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

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

Ballesteros-Soberanas Jordi J Leyva-Pérez Antonio A

The journal of physical chemistry letters 20230123 4

An alternative to the Lindlar catalyst for the semihydrogenation reaction of alkynes to alkenes is of high interest. Here we show that palladium on carbon (Pd/C), i.e., a widely available supported Pd catalyst, is converted from an unselective to a chemoselective catalyst during the semihydrogenation reaction of alkynes, after the addition of catalytic amounts of commercially available electron-poor phosphines. The catalytic activity is ≤7 times greater, and the selectivity is comparable to that ...[more]

PMID: 36689618

Similar Datasets

Pairwise hydrogen addition in the selective semihydrogenation of alkynes on silica-supported Cu catalysts.

Project description:Mechanistic insight into the semihydrogenation of 1-butyne and 2-butyne on Cu nanoparticles supported on partially dehydroxylated silica (Cu/SiO2-700) was obtained using parahydrogen. Hydrogenation of 1-butyne over Cu/SiO2-700 yielded 1-butene with ≥97% selectivity. The surface modification of this catalyst with tricyclohexylphosphine (PCy3) increased the selectivity to 1-butene up to nearly 100%, although at the expense of reduced catalytic activity. Similar trends were observed in the hydrogenation of 2-butyne, where Cu/SiO2-700 provided a selectivity to 2-butene in the range of 72-100% depending on the reaction conditions, while the catalyst modified with PCy3 again demonstrated nearly 100% selectivity. Parahydrogen-induced polarization effects observed in hydrogenation reactions catalyzed by copper-based catalysts demonstrate the viability of pairwise hydrogen addition over these catalysts. Contribution of pairwise hydrogen addition to 1-butyne was estimated to be at least 0.2-0.6% for unmodified Cu/SiO2-700 and ≥2.7% for Cu/SiO2-700 modified with PCy3, highlighting the effect of surface modification with the tricyclohexylphosphine ligand.

| S-EPMC5369404 | biostudies-literature

Field-induced reagent concentration and sulfur adsorption enable efficient electrocatalytic semihydrogenation of alkynes.

Project description:Efficient electrocatalytic alkyne semihydrogenation with potential/time-independent selectivity and Faradaic efficiency (FE) is vital for industrial alkene productions. Here, sulfur-tuned effects and field-induced reagent concentration are proposed to promote electrocatalytic alkyne semihydrogenation. Density functional theory calculations reveal that bulk sulfur anions intrinsically weaken alkene adsorption, and surface thiolates lower the activation energy of water and the Gibbs free energy for H* formation. The finite element method shows high-curvature structured catalyst concentrates K+ by enhancing electric field at the tips, accelerating more H* formation from water electrolysis via sulfur anion-hydrated cation networks, and promoting alkyne transformations. So, self-supported Pd nanotips with sulfur modifiers are developed for electrochemical alkyne semihydrogenation with up to 97% conversion yield, 96% selectivity, 75% FE, and a reaction rate of 465.6 mmol m-2 hour-1. Wide potential window and time irrelevance for high alkene selectivity, good universality, and easy access to deuterated alkenes highlight the promising potential.

| S-EPMC8865775 | biostudies-literature

Low-Valent Molybdenum PNP Pincer Complexes as Catalysts for the Semihydrogenation of Alkynes.

Project description:Low-valent molybdenum PNP pincer complexes were studied as catalysts for the semihydrogenation of alkynes. For that purpose, tBu-substituted PNP complexes PNP tBuMo(CO)2 (6a) and PNP tBuMo(CO)3 (6c) and the NNP complex NNP iPrMo(CO)2(PPh3) ((rac)-7) were synthesized and characterized. By utilizing the cyclohexyl-substituted complex PNPCyMo(CO)2(CH3CN) (5a), several diphenylacetylene derivatives are transformed to the corresponding (Z)-alkenes with good to very good diastereoselectivities (up to 91:9). Mechanistic experiments indicate an outer-sphere mechanism including metal-ligand cooperativity.

| S-EPMC9490815 | biostudies-literature

Enhancing Electrocatalytic Semihydrogenation of Alkynes via Weakening Alkene Adsorption over Electron-Depleted Cu Nanowires.

Project description:Electrochemical semihydrogenation (ESH) of alkynes to alkenes is an appealing technique for producing pharmaceutical precursors and polymer monomers, while also preventing catalyst poisoning by alkyne impurities. Cu is recognized as a cost-effective and highly selective catalyst for ESH, whereas its activity is somewhat limited. Here, from a mechanistic standpoint, we hypothesize that electron-deficient Cu can enhance ESH activity by promoting the rate-determining step of alkene desorption. We test this hypothesis by utilizing Cu-Ag hybrids as electrocatalysts, developed through a welding process of Ag nanoparticles with Cu nanowires. Our findings reveal that these rationally engineered Cu-Ag hybrids exhibit a notable enhancement (2-4 times greater) in alkyne conversion rates compared to isolated Ag NPs or Cu NWs, while maintaining over 99% selectivity for alkene products. Through a combination of operando and computational studies, we verify that the electron-depleted Cu sites, resulting from electron transfer between Ag nanoparticles and Cu nanowires, effectively weaken the adsorption of alkenes, thereby substantially boosting ESH activity. This work not only provides mechanistic insights into ESH but also stimulates compelling strategies involving hybridizing distinct metals to optimize ESH activity.

| S-EPMC11487759 | biostudies-literature

Selective Transfer Semihydrogenation of Alkynes Catalyzed by an Iron PCP Pincer Alkyl Complex.

Project description:Two bench-stable Fe(II) alkyl complexes [Fe(κ3PCP-PCP-iPr)(CO)2(R)] (R = CH2CH2CH3, CH3) were obtained by the treatment of [Fe(κ3PCP-PCP-iPr)(CO)2(H)] with NaNH2 and subsequent addition of CH3CH2CH2Br and CH3I, respectively. The reaction proceeds via the anionic Fe(0) intermediate Na[Fe(κ3PCP-PCP-iPr)(CO)2]. The catalytic performance of both alkyl complexes was investigated for the transfer hydrogenation of terminal and internal alkynes utilizing PhSiH3 and iPrOH as a hydrogen source. Precatalyst activation is initiated by migration of the alkyl ligand to the carbonyl C atom of an adjacent CO ligand. In agreement with previous findings, the rate of alkyl migration follows the order nPr > Me. Accordingly, [Fe(κ3PCP-PCP-iPr)(CO)2(CH2CH2CH3)] is the more active catalyst. The reaction takes place at 25 °C with a catalyst loading of 0.5 mol%. There was no overhydrogenation, and in the case of internal alkynes, exclusively, Z-alkenes are formed. The implemented protocol tolerates a variety of electron-donating and electron-withdrawing functional groups including halides, nitriles, unprotected amines, and heterocycles. Mechanistic investigations including deuterium labeling studies and DFT calculations were undertaken to provide a reasonable reaction mechanism.

| S-EPMC10629171 | biostudies-literature

Tripodal Pd metallenes mediated by Nb2C MXenes for boosting alkynes semihydrogenation.

Project description:2D metallene nanomaterials have spurred considerable attention in heterogeneous catalysis by virtue of sufficient unsaturated metal atoms, high specific surface area and surface strain. Nevertheless, the strong metallic bonding in nanoparticles aggravates the difficulty in the controllable regulation of the geometry of metallenes. Here we propose an efficient galvanic replacement strategy to construct Pd metallenes loaded on Nb2C MXenes at room temperature, which is triggered by strong metal-support interaction based on MD simulations. The Pd metallenes feature a chair structure of six-membered ring with the coordination number of Pd as low as 3. Coverage-dependent kinetic analysis based on first-principles calculations reveals that the tripodal Pd metallenes promote the diffusion of alkene and inhibit its overhydrogenation. As a consequence, Pd/Nb2C delivers an outstanding turnover frequency of 10372 h-1 and a high selectivity of 96% at 25 oC in the semihydrogenation of alkynes without compromising the stability. This strategy is general and scalable considering the plentiful members of the MXene family, which can set a foundation for the design of novel supported-metallene catalysts for demanding transformations.

| S-EPMC9905561 | biostudies-literature

Bench-Stable Dinuclear Mn(I) Catalysts in E-Selective Alkyne Semihydrogenation: A Mechanistic Investigation.

Project description:Dinuclear manganese hydride complexes of the form [Mn2 (CO)8 (μ-H)(μ-PR2 )] (R=Ph, 1; R=iPr, 2) were used in E-selective alkyne semi-hydrogenation (E-SASH) catalysis. Catalyst speciation studies revealed rich coordination chemistry and the complexes thus formed were isolated and in turn tested as catalysts; the results underscore the importance of dinuclearity in engendering the observed E-selectivity and provide insights into the nature of the active catalyst. The insertion product obtained from treating 2 with (cyclopropylethynyl)benzene contains a cis-alkenyl bridging ligand with the cyclopropyl ring being intact. Treatment of this complex with H2 affords exclusively trans-(2-cyclopropylvinyl)benzene. These results, in addition to other control experiments, indicate a non-radical mechanism for E-SASH, which is highly unusual for Mn-H catalysts. The catalytically active species are virtually inactive towards cis to trans alkene isomerization indicating that the E-selective process is intrinsic and dinuclear complexes play a critical role. A reaction mechanism is proposed accounting for the observed reactivity which is fully consistent with a kinetic analysis of the rate limiting step and is further supported by DFT computations.

| S-EPMC9509449 | biostudies-literature

Highly Active and Stable Pt-Pd Alloy Catalysts Synthesized by Room-Temperature Electron Reduction for Oxygen Reduction Reaction.

Project description:Carbon-supported platinum (Pt) and palladium (Pd) alloy catalyst has become a promising alternative electrocatalyst for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. In this work, the synthesis of highly active and stable carbon-supported Pt-Pd alloy catalysts is reported with a room-temperature electron reduction method. The alloy nanoparticles thus prepared show a particle size around 2.6 nm and a core-shell structure with Pt as the shell. With this structure, the breaking of O-O bands and desorption of OH are both promoted in electrocatalysis of ORR. In comparison with the commercial Pt/C catalyst prepared by conventional method, the mass activity of the Pt-Pd/C catalyst for ORR is shown to increase by a factor of ≈4. After 10 000-cycle durability test, the Pt-Pd/C catalyst is shown to retain 96.5% of the mass activity, which is much more stable than that of the commercial Pt/C catalyst.

| S-EPMC5396164 | biostudies-literature

H2O as the Hydrogen Donor: Stereo-Selective Synthesis of E- and Z-Alkenes by Palladium-Catalyzed Semihydrogenation of Alkynes

Project description:It is very desirable

| S-EPMC10061537 | biostudies-literature

E-Selective Manganese-Catalyzed Semihydrogenation of Alkynes with H2 Directly Employed or In Situ-Generated.

Project description:Selective semihydrogenation of alkynes with the Mn(I) alkyl catalyst fac-[Mn(dippe)(CO)3(CH2CH2CH3)] (dippe = 1,2-bis(di-iso-propylphosphino)ethane) as a precatalyst is described. The required hydrogen gas is either directly employed or in situ-generated upon alcoholysis of KBH4 with methanol. A series of aryl-aryl, aryl-alkyl, alkyl-alkyl, and terminal alkynes was readily hydrogenated to yield E-alkenes in good to excellent isolated yields. The reaction proceeds at 60 °C for directly employed hydrogen or at 60-90 °C with in situ-generated hydrogen and catalyst loadings of 0.5-2 mol %. The implemented protocol tolerates a variety of electron-donating and electron-withdrawing functional groups, including halides, phenols, nitriles, unprotected amines, and heterocycles. The reaction can be upscaled to the gram scale. Mechanistic investigations, including deuterium-labeling studies and density functional theory (DFT) calculations, were undertaken to provide a reasonable reaction mechanism, showing that initially formed Z-isomer undergoes fast isomerization to afford the thermodynamically more stable E-isomer.

| S-EPMC8859827 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data