N-Hydroxyphthalimide on a Polystyrene Support Coated with Co(II)-Containing Ionic Liquid as a New Catalytic System for Solvent-Free Ethylbenzene Oxidation

Talik, Gabriela; Osial, Anna; Grymel, Mirosława; Orlińska, Beata

doi:10.3390/catal10121367

Cited by 8 publications

(7 citation statements)

References 44 publications

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“…To develop a more easily recyclable nitroxide catalyst, NHPI derivatives were immobilized on polystyrene , or on silica, and also, readily separable imidazolium-based NHPI derivatives were developed . Enantioselective radical C–H activation was investigated using chiral imidoxyl radicals.…”

Section: Oxidation Reactionsmentioning

confidence: 99%

Organic Synthesis Using Nitroxides

Leifert

Studer

2023

Chem. Rev.

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Nitroxides, also known as nitroxyl radicals, are long-lived or stable radicals with the general structure R 1 R 2 N−O • . The spin distribution over the nitroxide N and O atoms contributes to the thermodynamic stability of these radicals. The presence of bulky N-substituents R 1 and R 2 prevents nitroxide radical dimerization, ensuring their kinetic stability. Despite their reactivity toward various transient C radicals, some nitroxides can be easily stored under air at room temperature. Furthermore, nitroxides can be oxidized to oxoammonium salts (R 1 R 2 N�O + ) or reduced to anions (R 1 R 2 N−O − ), enabling them to act as valuable oxidants or reductants depending on their oxidation state. Therefore, they exhibit interesting reactivity across all three oxidation states. Due to these fascinating properties, nitroxides find extensive applications in diverse fields such as biochemistry, medicinal chemistry, materials science, and organic synthesis. This review focuses on the versatile applications of nitroxides in organic synthesis. For their use in other important fields, we will refer to several review articles. The introductory part provides a brief overview of the history of nitroxide chemistry. Subsequently, the key methods for preparing nitroxides are discussed, followed by an examination of their structural diversity and physical properties. The main portion of this review is dedicated to oxidation reactions, wherein parent nitroxides or their corresponding oxoammonium salts serve as active species. It will be demonstrated that various functional groups (such as alcohols, amines, enolates, and alkanes among others) can be efficiently oxidized. These oxidations can be carried out using nitroxides as catalysts in combination with various stoichiometric terminal oxidants. By reducing nitroxides to their corresponding anions, they become effective reducing reagents with intriguing applications in organic synthesis. Nitroxides possess the ability to selectively react with transient radicals, making them useful for terminating radical cascade reactions by forming alkoxyamines. Depending on their structure, alkoxyamines exhibit weak C−O bonds, allowing for the thermal generation of C radicals through reversible C−O bond cleavage. Such thermally generated C radicals can participate in various radical transformations, as discussed toward the end of this review. Furthermore, the application of this strategy in natural product synthesis will be presented.

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Section: Oxidation Reactionsmentioning

confidence: 99%

Organic Synthesis Using Nitroxides

Leifert

Studer

2023

Chem. Rev.

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“…PS‐NHPI was formed by immobilizing NHPI on chloromethyl polystyrene resins by ester bonds (Scheme 56). Oxidation reaction proceeded via formation of PINO radical [98] . NHPI in PS, PVC and PC polymer matrices was used for developing carbon dots (C–Dots) that were further used for preparing highly luminescent composites possessing excellent photo luminescent properties.…”

Section: Nhpi Catalyzed Reactionsmentioning

confidence: 99%

Recent Advances in N‐Hyrdoxypthalimide: As a Free Radical Initiator and its Applications

Bhardwaj

Grover²,

Rasool

et al. 2022

Asian J Org Chem

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N‐Hydroxypthalimide (NHPI) has become a powerful and versatile organocatalyst, it has been known to catalyze various free‐radical processes leading to the wide range of organic transformations. Primarily, phthalimido‐N‐oxyl (PINO) radical formed from NHPI is highly efficient abstraction species for carrying out radical chain reactions. In this review, we have discussed about the most important and successful reactions from last six years, with their plausible reaction mechanisms. This review broadly covers the type of bond formation such as carbon‐carbon, carbon‐oxygen and carbon‐nitrogen bond formations. We have also highlighted various types of reaction strategies where in combination with divergent reagent systems it helps to construct different types of molecules which further find applications in the synthesis of complex set of biologically active molecule. NHPI catalyzed oxidation reactions of different class of organic compounds are also reviewed.

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“…The loading of NHPI was estimated to be 6.09 mmol/g NPCSs through nitrogen conservation, which surpassed the NHPI loading in other reported heterogeneous catalysts to the best of our knowledge. [31][32][33]35,48 The TGA curves showed only 7.1% weight loss for raw PNCSs during a temperature increase from 100 to 600 °C, mainly attributed to the removal of oxygen-containing groups (Figure 3h). Comparatively, QPD-NPCSs and NHPI-NPCSs started to decompose at 212 °C and significantly lost 64.1 and 75.9% of their weight, thus demonstrating a similar NHPI loading of 6.11 mmol/g.…”

Section: Characterizations Of Npcss and Nhpi-npcssmentioning

confidence: 99%

“…The development of powerful heterogeneous NHPI catalysts covalently supported on shaped substrates was a desirable approach for industrial use . In comparison with common spherical immobilized materials including silica and polymeric spheres, , biomass-derived NPCSs could be a promising selection for heterogeneous catalysts by virtue of their sustainability, low cost, high chemical resistance, good mechanical strength, and adsorption performance . Previous NHPI-anchored catalysts usually involved environment-unfriendly metallic chemicals, and developing efficient heterogeneous catalytic systems under nonmetallic conditions was highly alluring from the perspective of green catalysis.…”

Section: Introductionmentioning

confidence: 99%

Universal Mass Production of Biomass-Derived Nanosized Porous Carbon Spheres as a Superior Nonmetal Catalyst for Aerobic Oxidation of Hydrocarbons

Shao

et al. 2022

ACS Sustainable Chem. Eng.

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The microscopic quantum effect, spherical morphology, and fast mass transfer properties render nanosized porous carbon spheres (NPCSs, <100 nm) of great utilitarian value in numerous applications, including catalysis. However, the preparation of monodisperse NPCSs was typically low output and high cost due to their large surface energy along with nanosized particles. In this study, we designed a high-yield hydrothermal carbonization process of soluble starch with the aid of poly-(diallyldimethylammonium chloride) to fabricate monodisperse carbonaceous spheres with a tunable nanosize of 43−97 nm. This synthesis still functioned well at starch concentrations as high as 520 g/L and in a 10-fold extended experiment with a yield of 49.1 g. The proposed methodology showed good versatility among various biomass-based carbon sources, including glucose, maltose, glucan, potato starch, barley starch, and corn starch. The subsequent static-air calcinations could facilely introduce rich mesoporosity onto nanosized carbonaceous spheres. N-Hydroxyphthalimide (NHPI) covalently anchored on NPCSs were first prepared as heterogeneous catalysts by polyamidamine dendrimer-based quaternization and amidate modification with 4-carboxyl-NHPI. These dendrimeric NPCSs contributed to the high NHPI loading (6.09 mmol/g). The synergistic effects between the loaded NHPI and the quaternized dendrimer afforded 45% conversion and 72% selectivity in the catalytic oxidation of ethylbenzene into acetophenone at 95 °C under 1 atm O 2 for 16 h, which was superior to the performance of unsupported NHPI. This anchored NHPI demonstrated good catalytic oxidation performance for various hydrocarbons and favorable reusability in a nine-run test. Their positively charged surface could prevent nanocatalyst agglomeration during the catalytic process. The nonmetal system, sustainable high-yield nanocarrier material, and high-loading active catalyst with good reusability are the advantages of the designed catalysis.

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N-Hydroxyphthalimide on a Polystyrene Support Coated with Co(II)-Containing Ionic Liquid as a New Catalytic System for Solvent-Free Ethylbenzene Oxidation

Cited by 8 publications

References 44 publications

Organic Synthesis Using Nitroxides

Organic Synthesis Using Nitroxides

Recent Advances in N‐Hyrdoxypthalimide: As a Free Radical Initiator and its Applications

Universal Mass Production of Biomass-Derived Nanosized Porous Carbon Spheres as a Superior Nonmetal Catalyst for Aerobic Oxidation of Hydrocarbons

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