π-Arene complexes as unexpected deactivation products in alkane activation and alkene hydrogenation reactions

1981 ◽  
pp. 1217-1218 ◽  
Author(s):  
Robert H. Crabtree ◽  
Michelle F. Mellea ◽  
Jennifer M. Quirk
Keyword(s):  
Alkane Activation ◽  
Arene Complexes ◽  
Hydrogenation Reactions ◽  
Alkene Hydrogenation

scholarly journals Transfer Hydrogenation Reactions of Photoactivatable N,N’-Chelated Ruthenium(II) Arene Complexes

2017 ◽  
Vol 57 (3) ◽  
Author(s):  
Soledad Betanzos-Lara ◽  
Abraha Habtemariam ◽  
Peter J. Sadler
Keyword(s):  
Aqueous Solution ◽  
Catalytic Activity ◽  
Sodium Formate ◽  
Transfer Hydrogenation ◽  
Arene Complexes ◽  
Chelating Ligand ◽  
Spontaneous Hydrolysis ◽  
Hydrogenation Reactions ◽  
Excess Sodium ◽  
Hydrolysis Of

We show that the reaction of Ru<sup>II</sup> arene chlorido complexes of the type [(η<sup>6</sup>-arene)Ru(N,N’)Cl]<sup>+</sup> arene = p-cymene (pcym), hexamethylbenzene (hmb), indane (ind), <em>N,N’</em> = bipyrimidine (bpm) and 1,10-phenanthroline (phen) with excess sodium formate generates a very stable formate adduct through spontaneous hydrolysis of the Ru-Cl bond at 310 K and pH* = 7.0. The formate adducts are also produced when Ru<sup>II</sup> arene pyridine complexes of the type [(η<sup>6</sup>-arene)Ru(N,N’)(Py)]<sup>2+</sup> (where Py = pyridine), are irradiated with UVA (λ<sub>irr</sub> = 300-400 nm) or visible light (λ<sub>irr</sub> = 400-660 nm) under the same conditions. The Ru<sup>II</sup> arene formato adducts do not catalyse the reduction of acetone through transfer hydrogenation. However, all the complexes (except complex <strong>2</strong> which contains phen as the chelating ligand) can catalyse the regioselective reduction of NAD<sup>+</sup> in the presence of formate (25 mol equiv) in aqueous solution to form 1,4-NADH. The catalytic activity is dependent on the nature of the chelating ligand. Most interestingly, the regioselective reduction of NAD+ to 1,4-NADH can be also specifically triggered by photoactivating a RuII arene Py complex.

scholarly journals Comparison of alkene hydrogenation in carbon nanoreactors of different diameters: probing the effects of nanoscale confinement on ruthenium nanoparticle catalysis

2017 ◽  
Vol 5 (40) ◽  
pp. 21467-21477 ◽  
Author(s):  
Mehtap Aygün ◽  
Craig T. Stoppiello ◽  
Maria A. Lebedeva ◽  
Emily F. Smith ◽  
Maria del Carmen Gimenez-Lopez ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Optimum Level ◽  
Control Chemical ◽  
Competitive Hydrogenation ◽  
Hydrogenation Reactions ◽  
Alkene Hydrogenation ◽  
Nanoparticle Catalysis ◽  
Different Diameters

Exploratory, competitive hydrogenation reactions reveal the optimum level of confinement to control chemical reactions.

Structural Evidence for Lewis Acid Triggered Nitrosyl Bending in Rhenium(-I) Chloro Catalysts for Alkene Hydrogenation Reactions

2013 ◽  
Vol 2014 (1) ◽  
pp. 140-147 ◽  
Author(s):  
Yanfeng Jiang ◽  
Wenjing Huang ◽  
Helmut W. Schmalle ◽  
Olivier Blacque ◽  
Thomas Fox ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Hydrogenation Reactions ◽  
Alkene Hydrogenation

scholarly journals Ruthenium Arene Complexes with α-Aminoacidato Ligands: New Insights into Transfer Hydrogenation Reactions and Cytotoxic Behaviour

2018 ◽  
Vol 2018 (26) ◽  
pp. 3041-3057 ◽  
Author(s):  
Lorenzo Biancalana ◽  
Issam Abdalghani ◽  
Federica Chiellini ◽  
Stefano Zacchini ◽  
Guido Pampaloni ◽  
...  
Keyword(s):  
Transfer Hydrogenation ◽  
Arene Complexes ◽  
Hydrogenation Reactions ◽  
Ruthenium Arene

scholarly journals Mechanisms of Alkene and Diene Hydrogenation Reactions in H-MFI and H-CHA Zeolite Frameworks During MTO

2019 ◽  
Author(s):  
Mykela DeLuca ◽  
Christina Janes ◽  
David Hibbitts
Keyword(s):  
Selective Hydrogenation ◽  
Density Functional ◽  
High Pressures ◽  
Catalyst Deactivation ◽  
Zeolite Catalysts ◽  
As Species ◽  
Methanol To Olefin ◽  
Hydrogenation Reactions ◽  
Alkene Hydrogenation ◽  
Thermodynamic Instability

<p>Co-feeding H<sub>2</sub> at high pressures increases zeolite catalyst lifetimes during methanol-to-olefin (MTO) reactions while maintaining high alkene-to-alkane ratios; however, the mechanisms and species hydrogenated by H<sub>2</sub> co-feeds to prevent catalyst deactivation remain unknown. This study uses periodic density functional theory (DFT) to examine hydrogenation mechanisms of MTO product C<sub>2</sub>–C<sub>4</sub> alkenes, as well as species related to the deactivation of MTO catalysts such as C<sub>4</sub> and C<sub>6</sub> dienes, benzene, and formaldehyde in H-MFI and H-CHA zeolite catalysts. Results show that dienes and formaldehyde are selectively hydrogenated in both frameworks at MTO conditions because their hydrogenation transition states proceed via allylic and oxocarbenium cations which are more stable than alkylcarbenium ions which mediate alkene hydrogenation. Diene hydrogenation is further stabilized by protonation and hydridation at α,δ positioned C-atoms to form 2-butene from butadiene and 3-hexene from hexadiene as primary hydrogenation products. This α,δ-hydrogenation directly leads to selective hydrogenation of dienes; pathways which hydrogenate dienes at the α,β-position (e.g., forming 1-butene from butadiene) proceed with barriers 20 kJ mol<sup>-1</sup> higher than α,δ-hydrogenation and with barriers nearly equivalent to butene hydrogenation, despite α,β-hydrogenation of butadiene also occurring through allylic carbocations. Hydrogenation of formaldehyde, a diene precursor, occurs with barriers that are within 15 kJ mol<sup>-1</sup> of diene hydrogenation barriers, indicating that it may also contribute to increasing catalyst lifetimes by preventing diene formation. Benzene, in contrast to dienes and formaldehyde, is hydrogenated with higher barriers than C<sub>2</sub>–C<sub>4</sub> alkenes despite proceeding via stable benzenium cations because of the thermodynamic instability of the product which has lost aromaticity. Carbocation stabilities predict the relative rates of alkene hydrogenation and in some cases shed insights into the hydrogenation of benzene, dienes, and formaldehyde, but cation stabilities alone cannot account for the poor hydrogenation of benzene or the facile hydrogenation of dienes, boosted by stabilization conferred by a,δ-hydrogenation. This work suggests that the main mechanisms of catalyst lifetime improvement with high H<sub>2</sub> co-feeds is reduction of diene concentrations through both their selective hydrogenation and hydrogenation of their precursors to prevent formation of deactivating polyaromatic species.</p>

Cobalt-catalyzed alkene hydrogenation by reductive turnover

2021 ◽  
pp. 153047
Author(s):  
Vincent van der Puyl ◽  
Ruairi O. McCourt ◽  
Ryan A. Shenvi
Keyword(s):  
Alkene Hydrogenation

Catalytic asymmetric hydrogenation reaction by in situ formed ultra-fine metal nanoparticles in live thermophilic hydrogen-producing bacteria

Nanoscale ◽  
2021 ◽  
Author(s):  
Wei Bing ◽  
Faming Wang ◽  
Yuhuan Sun ◽  
Jinsong Ren ◽  
Xiaogang Qu
Keyword(s):  
Metal Nanoparticles ◽  
Catalytic Hydrogenation ◽  
Asymmetric Hydrogenation ◽  
Environmentally Friendly ◽  
Hydrogenation Reaction ◽  
Highly Efficient ◽  
Hydrogenation Reactions ◽  
Live Bacteria ◽  
Catalytic Asymmetric Hydrogenation

An environmentally friendly biomimetic strategy has been presented and validated for the catalytic hydrogenation reaction in live bacteria. In situ formed ultra-fine metal nanoparticles can realize highly efficient asymmetric hydrogenation reactions.

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