scholarly journals Secondary Phosphine Oxide-Activated Nickel Catalysts for Site-Selective Alkene Isomerization and Remote Hydrophosphination

2021 ◽  
Author(s):  
Lin Huang ◽  
En Qi Lim ◽  
Ming Joo Koh
Keyword(s):  
Phosphine Oxide ◽  
Nickel Catalysts ◽  
Spectroscopic Studies ◽  
Secondary Phosphine ◽  
Carbonyl Groups ◽  
Catalytic Systems ◽  
Nickel Hydride ◽  
Catalytically Active ◽  
Site Selective

Catalytic systems that are readily modifiable to achieve olefin migration or remote functionalization are highly sought-after in chemical synthesis. Here, we show that the combination of a commercially available nickel(II) pre-catalyst and a secondary phosphine oxide ligand enables site- and stereoselective alkene transposition for up to nine double-bond migrations within terminal and internal olefins under mild reductive conditions. Substrates bearing diverse functionalities including Brønsted acidic and reducible carbonyl groups are tolerated. Mechanistic and spectroscopic studies revealed the in situ generation of a catalytically active nickel-hydride species triggered by oxidative addition of the phosphine oxide. The reaction is amenable to regioconvergent isomerization as well as β-selective remote hydrophosphination when stoichiometric secondary phosphine oxide/base were employed.

Hydrogen peroxide decomposition on a two-component CuO-Cr2O3 catalyst

1988 ◽  
Vol 53 (8) ◽  
pp. 1636-1646 ◽  
Author(s):  
Viliam Múčka ◽  
Kamil Lang
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Extreme Values ◽  
Catalytic Properties ◽  
Active Components ◽  
Catalytic Systems ◽  
Heterogeneous Catalytic ◽  
Peroxide Decomposition ◽  
Two Component ◽  
Catalytically Active

Some physical and catalytic properties of the two-component copper(II)oxide-chromium(III)oxide catalyst with different content of both components were studied using the decomposition of the aqueous solution of hydrogen peroxide as a testing reaction. It has been found that along to both basic components, the system under study contains also the spinel structure CuCr2O4, chromate washable by water and hexavalent ions of chromium unwashable by water. The soluble chromate is catalytically active. During the first period of the reaction the equilibrium is being established in both homogeneous and heterogeneous catalytic systems. The catalytic activity as well as the specific surface area of the washed solid is a non-monotonous function of its composition. It seems highly probable that the extreme values of both these quantities are not connected with the detected admixtures in the catalytic system. The system under study is very insensitive with regard to the applied doses of gamma radiation. Its catalytic properties are changed rather significantly after the thermal treatment and particularly after the partial reduction to low degree by hydrogen. The observed changes of the catalytic activity of the system under study are very probably in connection with the changes of the valence state of the catalytically active components of the catalyst.

scholarly journals Experimental and Theoretical Studies of Sonically Prepared Cu–Y, Cu–USY and Cu–ZSM-5 Catalysts for SCR deNOx

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 824
Author(s):  
Przemysław J. Jodłowski ◽  
Izabela Czekaj ◽  
Patrycja Stachurska ◽  
Łukasz Kuterasiński ◽  
Lucjan Chmielarz ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Ultrasonic Irradiation ◽  
Active Phase ◽  
Spectroscopic Studies ◽  
In Situ Drifts ◽  
Ft Ir ◽  
Diffuse Reflectance Infrared ◽  
Experimental And Theoretical Studies

The objective of our study was to prepare Y-, USY- and ZSM-5-based catalysts by hydrothermal synthesis, followed by copper active-phase deposition by either conventional ion-exchange or ultrasonic irradiation. The resulting materials were characterized by XRD, BET, SEM, TEM, Raman, UV-Vis, monitoring ammonia and nitrogen oxide sorption by FT-IR and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). XRD data confirmed the purity and structure of the Y/USY or ZSM-5 zeolites. The nitrogen and ammonia sorption results indicated that the materials were highly porous and acidic. The metallic active phase was found in the form of cations in ion-exchanged zeolites and in the form of nanoparticle metal oxides in sonochemically prepared catalysts. The latter showed full activity and high stability in the SCR deNOx reaction. The faujasite-based catalysts were fully active at 200–400 °C, whereas the ZSM-5-based catalysts reached 100% activity at 400–500 °C. Our in situ DRIFTS experiments revealed that Cu–O(NO) and Cu–NH3 were intermediates, also indicating the role of Brønsted sites in the formation of NH4NO3. Furthermore, the results from our experimental in situ spectroscopic studies were compared with DFT models. Overall, our findings suggest two possible mechanisms for the deNOx reaction, depending on the method of catalyst preparation (i.e., conventional ion-exchange vs. ultrasonic irradiation).

Thermal stability of primary and secondary phosphine oxides formed as a reaction of phosphine oxide with ketones

2016 ◽  
Vol 191 (11-12) ◽  
pp. 1480-1481 ◽  
Author(s):  
E. V. Gorbachuk ◽  
E. K. Badeeva ◽  
S. A. Katsyuba ◽  
P. O. Pavlov ◽  
Kh. R. Khayarov ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Phosphine Oxide ◽  
Secondary Phosphine ◽  
Phosphine Oxides ◽  
Thermal Stability Of

Enantio-Differentiating Hydrogenation of 2-Octanone over Modified Nickel Catalysts Prepared by an In Situ Modification

2002 ◽  
Vol 75 (12) ◽  
pp. 2695-2696 ◽  
Author(s):  
Tsutomu Osawa ◽  
Nobuyo Ozaki ◽  
Tadao Harada ◽  
Osamu Takayasu
Keyword(s):  
Nickel Catalysts ◽  
In Situ Modification

In-situ infrared spectroscopic studies of hydroxyl in amphiboles at high pressure

2016 ◽  
Vol 101 (3) ◽  
pp. 706-712 ◽  
Author(s):  
Elizabeth C. Thompson ◽  
Andrew J. Campbell ◽  
Zhenxian Liu
Keyword(s):  
High Pressure ◽  
Spectroscopic Studies ◽  
Infrared Spectroscopic

scholarly journals Insertion of Phosphenium Ions into a Bicyclo[1.1.0]Tetraphosphabutane Iron Complex

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3920
Author(s):  
Martin Weber ◽  
Gábor Balázs ◽  
Alexander V. Virovets ◽  
Eugenia Peresypkina ◽  
Manfred Scheer
Keyword(s):  
Diffraction Analysis ◽  
Room Temperature ◽  
31P Nmr ◽  
Spectroscopic Studies ◽  
Iron Complex ◽  
The Novel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phosphenium Ions

By reacting [{Cp‴Fe(CO)2}2(µ,η1:1-P4)] (1) with in situ generated phosphenium ions [Ph2P][A] ([A]− = [OTf]− = [O3SCF3]−, [PF6]−), a mixture of two main products of the composition [{Cp‴Fe(CO)2}2(µ,η1:1-P5(C6H5)2)][PF6] (2a and 3a) could be identified by extensive 31P NMR spectroscopic studies at 193 K. Compound 3a was also characterized by X-ray diffraction analysis, showing the rarely observed bicyclo[2.1.0]pentaphosphapentane unit. At room temperature, the novel compound [{Cp‴Fe}(µ,η4:1-P5Ph2){Cp‴(CO)2Fe}][PF6] (4) is formed by decarbonylation. Reacting 1 with in situ generated diphenyl arsenium ions gives short-lived intermediates at 193 K which disproportionate at room temperature into tetraphenyldiarsine and [{Cp‴Fe(CO)2}4(µ4,η1:1:1:1-P8)][OTf]2 (5) containing a tetracyclo[3.3.0.02,7.03,6]octaphosphaoctane ligand.

scholarly journals Toward a mechanistic understanding of electrocatalytic nanocarbon

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Erik J. Askins ◽  
Marija R. Zoric ◽  
Matthew Li ◽  
Zhengtang Luo ◽  
Khalil Amine ◽  
...  
Keyword(s):  
Spectroscopic Studies ◽  
Synthetic Methods ◽  
Computational Studies ◽  
Molecular Models ◽  
Chemical Production ◽  
True Nature ◽  
Catalytic Mechanisms ◽  
Mechanistic Understanding ◽  
Further Development

AbstractElectrocatalytic nanocarbon (EN) is a class of material receiving intense interest as a potential replacement for expensive, metal-based electrocatalysts for energy conversion and chemical production applications. The further development of EN will require an intricate knowledge of its catalytic behaviors, however, the true nature of their electrocatalytic activity remains elusive. This review highlights work that contributed valuable knowledge in the elucidation of EN catalytic mechanisms. Experimental evidence from spectroscopic studies and well-defined molecular models, along with the survey of computational studies, is summarized to document our current mechanistic understanding of EN-catalyzed oxygen, carbon dioxide and nitrogen electrochemistry. We hope this review will inspire future development of synthetic methods and in situ spectroscopic tools to make and study well-defined EN structures.

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