Advantageous of Ni complexes with organic ligands as catalysts for Michael addition reactions comapred to other metals?
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Ni complexes with organic ligands offer several advantages as catalysts for Michael addition reactions compared to other metals. These complexes exhibit high efficiency and enantioselectivity, making them valuable in asymmetric catalysis. The chiral Ni complexes have been shown to facilitate facial selectivity switching in Michael reactions, providing control over stereochemistry. Additionally, modifications of chiral diamine ligands in Ni complexes have led to the development of robust and recyclable catalysts with excellent enantioselectivities. Furthermore, nickel-based chiral bifunctional catalysts have been successfully designed for asymmetric Michael additions under base-free conditions, showcasing high yields and enantiomeric excess values. Overall, the unique properties of Ni complexes with organic ligands make them versatile and efficient catalysts for Michael addition reactions.
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71 Citations | Ni complexes with organic ligands offer advantages in Michael addition due to their efficiency in constructing quaternary stereogenic centers, crucial in natural product synthesis, as highlighted in the paper. |
| Nickel-based Ni complexes with organic ligands offer improved chiral induction and high yields in Michael addition reactions due to their bifunctional catalytic nature and unique chiral ancillaries. | |
18 Citations | Nickel complexes with chiral organic ligands offer robustness, recyclability, high yields, good enantioselectivities, air and moisture stability, and low catalyst loading in Michael addition reactions, surpassing other metals. |
| Ni complexes with organic ligands excel in Michael reactions due to facial selectivity switching, enabling precise control over stereochemistry. Their open-shell property and coordination isomerism enhance stereoselectivity. | |
| Nickel complexes with organic ligands offer improved activity and enantioselectivity in Michael addition reactions when activated with fluoride, simplifying catalyst design and enhancing performance compared to other metals. |
Related Questions
What is the role of metal complexes with organic ligands as catalysts for Michael addition reactions?5 answersMetal complexes with organic ligands play a crucial role as catalysts for Michael addition reactions, enabling efficient and selective transformations. These catalysts offer advantages such as high yields, reusability, and mild reaction conditions. For instance, a zinc complex with dipyridylpyrrole N-oxide ligands demonstrated high efficiency in thiol-Michael additions. Additionally, a mesoporous metal-organic framework-based Cu(II) nanocatalyst facilitated the synthesis of dihydropyrano[2,3-c]chromenes and 1H-pyrazolo[1,2-b]phthalazine-5,10-diones through Knoevenagel condensation-Michael addition-cyclization sequences. Furthermore, a β-diketiminate-supported aluminum bistriflate complex showed superior catalytic performance in Michael additions compared to existing methods. These findings highlight the significance of metal complexes with organic ligands in promoting efficient and sustainable Michael addition reactions.
What temperature does H2 react with nickel?5 answersH2 reacts with nickel at various temperatures depending on the specific reaction conditions. The dissociation and recombination rates of physisorbed H2 on a Ni(100) surface are significantly influenced by temperature, with quantum motions enhancing these rates at low temperatures. Additionally, a study on the reactivity of Ni2+/+ species with water radiolysis products showed that the reaction rates increased with temperature up to 300 °C, indicating a temperature-dependent reaction with nickel ions. Furthermore, in the context of steam reforming of ethanol for hydrogen production, a catalyst involving nickel nanoparticles on ZIF-8 support exhibited enhanced activity at moderate temperatures of 400-450 °C. Overall, the interactions between H2 and nickel occur over a range of temperatures, with varying effects on reaction rates and efficiencies.
What are basic applications of phopha michael addition?10 answersPhospha-Michael addition (PMA) is a versatile and powerful tool in organic synthesis, offering a pathway to a wide array of complex molecules and functional materials. The applications of PMA span from the synthesis of complex molecules with potential pharmaceutical relevance to the creation of materials for advanced technological applications. For instance, the pioneering work on α-fluorinated acrylates as Michael acceptors has opened new avenues for synthesizing molecules with contiguous C-P and C-CFY2 bonds, showcasing the utility of PMA in accessing fluorinated compounds with potential biological activity. Additionally, the development of bis(acyl)phosphines through PMA, followed by their oxidation to bis(acyl)phosphane oxides, highlights the method's significance in producing potent photoinitiators for radical polymerizations, which are crucial in material science and engineering.
The transition metal-free synthesis of β-hydrazonophosphine oxides via PMA further demonstrates the method's applicability in generating precursors for phosphorylated N-heterocycles, α-aminophosphonates, and vinylphosphonates, which are valuable in medicinal chemistry and agriculture. The broad scope of PMA is also evident in its role in the efficient formation of C-C and C-X bonds, contributing to the synthesis of natural products and drugs through tandem sequences like the Robinson annulation.
Moreover, the asymmetric organocatalyzed PMA to iminochromenes, yielding chiral chromene derivatives with high enantioselectivity, underscores the technique's potential in asymmetric synthesis, a critical aspect of pharmaceutical manufacturing. The unusual regioselectivity achieved in the phosphine-catalyzed Michael addition of arylcyanoacetates to allenoates opens new possibilities for accessing molecular structures with quaternary centers, further expanding the synthetic utility of PMA.
Functionalized phosphonates, accessible via phosphite addition, demonstrate the method's relevance in producing compounds with applications in various fields, including materials science and drug development. The use of ultrasound activation in PMA, as shown in the condensation of imidazole with ethyl acrylate, illustrates the method's adaptability to innovative activation techniques, potentially enhancing reaction efficiencies and selectivities. The generation of nitrosoalkenes from phosphine oxides and phosphonates for subsequent Michael additions further exemplifies the method's versatility in constructing α-amino phosphine oxides and phosphonates, compounds of interest in synthetic and medicinal chemistry. Lastly, the application of PMA in curable compositions for substrate coating, utilizing a tertiary phosphine catalyst, highlights the method's industrial relevance, particularly in the development of quick-curing materials for various applications.
In summary, the basic applications of phospha-Michael addition are multifaceted, ranging from the synthesis of biologically active molecules and materials for technological applications to the development of asymmetric synthesis methods and innovative industrial processes.
Chemical precipitation of Nickel from surface water?5 answersChemical precipitation of nickel from surface water can be achieved by controlling the physicochemical conditions of the liquid media. Nickel hydroxide (Ni(OH)2) is the main precipitate formed in the process. The precipitation of nickel hydroxide can be optimized using supersaturation controlled precipitation. The pH of the solution plays a crucial role in the precipitation process, with pH 3 being the starting point for nickel precipitation and complete precipitation occurring at pH 11. Additionally, the precipitation of nickel can also occur in the presence of other metals such as aluminum, cobalt, iron, zinc, and copper. The precipitation efficiency of these metals varies with pH, with pH 3 being effective for iron precipitation and pH 5.5 being effective for ferrous ions. Therefore, by controlling the pH of the solution, it is possible to achieve the chemical precipitation of nickel and other metals from surface water.
What are the effects of nickel addition on the microstructure of medium Mn steel?5 answersThe addition of nickel to medium-Mn steel has various effects on the microstructure. The presence of nickel, along with manganese, leads to the formation of retained austenite (RA), fine-grained ferrite, and martensite. Nickel also affects the stability of the austenite phase, with higher nickel content providing higher stability. Additionally, nickel-enriched austenite contributes to the excellent mechanical properties of the steel, including high yield strength, tensile strength, total elongation, and impact energy. On the other hand, the addition of nickel can also affect the precipitation behavior of other phases. For example, in Fe-Mn-Al-Ni shape memory alloys, the addition of nickel inhibits the precipitation process of non-transforming γ-phase. Overall, the addition of nickel to medium-Mn steel has a significant impact on the microstructure and mechanical properties of the steel.
Why Nickel-Based Catalyst Methane?5 answersNickel-based catalysts are commonly used for methane conversion due to their low cost and high efficiency. These catalysts can promote the directional regulation of reaction products, leading to faster reactions, energy savings, and reduced consumption. However, challenges such as Ni agglomeration and carbon deposition during high-temperature reactions need to be addressed. Extensive research has been conducted to design and synthesize more active nickel-based catalysts for high CO2 conversion and CH4 selectivity. The introduction of a catalyst in the CO2-CH4 reforming reaction can overcome issues such as low conversion rates, long reaction times, and high energy consumption. Nickel-based catalysts have been shown to exhibit high catalytic performance in methane combustion. Additionally, the use of nickel clusters supported by titanium carbide has been found to be effective in the nonoxidative conversion of methane to C2 products. Overall, nickel-based catalysts offer a promising solution for methane conversion, with ongoing research focused on improving their performance and stability.