Efficient oxidation of p-xylene to terephthalic acid by using N,N-dihydroxypyromellitimide in conjunction with Co-benzenetricarboxylate

Xu, Luo; Chen, Fan; Jiang, Haoran; Xia, Yuan

doi:10.1016/j.apcata.2020.117569

Cited by 16 publications

(6 citation statements)

References 43 publications

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“…PINO-catalyzed oxidation of primary benzylic C–H bonds has also been addressed. As for secondary benzylic sites, a hydroperoxide is formed as an intermediate, which further reacts with transition metals (cobalt/copper) through the corresponding aldehyde to a carboxylic acid (Scheme , left). − Interestingly, under similar conditions, upon running the reaction in hexafluoroisopropanol (HFIP) in place of acetic acid as solvent (Scheme , right), aldehydes were obtained as products . The hydrogen bonding from the fluorinated solvent results in poorer stabilization of the acyl radical to prevent further oxidation to carboxylic acids.…”

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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“…Xu et al [ 53 ] tested the efficacy of the MOF cobalt–benzenetricarboxylate (BTC) when in conjunction with NHPI, since this compound is a very effective catalyst for oxidation under mild conditions and as an initiator. Both catalysts alone could not perform the oxidation of p- xylene at 100 °C, and after 12 h, no product was detected (using acetonitrile as the solvent and 3 MPa of O 2 ); however, when used in combination, the conversion of p- xylene reached 57%, with the main product being p- toluic acid.…”

Section: Catalytic Advancesmentioning

confidence: 99%

“… The mechanism proposed for the oxidation of p- xylene, which is catalyzed by Co-BTC/NDHPI X = CH 3 , COOH. Adapted from [ 53 ]. …”

Section: Figures Schemes and Tablesmentioning

confidence: 99%

p-Xylene Oxidation to Terephthalic Acid: New Trends

Lapa

Martins

2023

Molecules

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Large-scale terephthalic acid production from the oxidation of p-xylene is an especially important process in the polyester industry, as it is mainly used in polyethylene terephthalate (PET) manufacturing, a polymer that is widely used in fibers, films, and plastic products. This review presents and discusses catalytic advances and new trends in terephthalic acid production (since 2014), innovations in terephthalic acid purification processes, and simulations of reactors and reaction mechanisms.

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“…Over the years, attempts have been made to develop a safer and greener synthesis route for TPA, including the elimination of purification steps via a new spray concept (Li et al, 2013), development and use of new types of homogeneous catalysts involving bromide salts of manganese, cobalt and copper (Holiday et al, 1998;Pérez et al, 2011), N-hydroxyimide (Falcon et al, 2010), heterogeneous cobalt-based catalysts (Xu et al, 2020;Vakros, 2021) and application of high-temperature liquid water to replace AcOH solvent (Dunn & Savage, 2002;Fraga-Dubreuil & Poliakoff, 2006).…”

Section: Introductionmentioning

confidence: 99%

Effect of Process Conditions on Catalytic Hydrothermal Oxidation of p-Xylene to Terephthalic Acid

Yeop¹,

Ismail²,

Daud³

2022

JST

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This study investigates the influence of hydrothermal process conditions on the yield of terephthalic acid (TPA). Deionised water was employed as a green reaction medium substitute for acetic acid solvent widely used in the Amoco oxidation process for TPA production. Utilising the unique properties of water at elevated temperature and pressure, TPA was synthesised from p-xylene under subcritical (250 °C, 300 °C and 350 °C) and supercritical (400 °C) water conditions in a 10 mL micro-bomb batch reactor. Process conditions, including hydrogen peroxide (H2O2) oxidant concentrations, manganese bromide (MnBr2) catalyst and water loadings, were varied at a fixed reaction time of 60 minutes. The p-xylene conversion and TPA yield were determined using high-performance liquid chromatography (HPLC). In addition, the presence of chemical functional groups and chemical compositions of the reaction products were examined using Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometer (GC-MS), respectively. It was found that an optimum TPA yield of 94.56% was observed at 350°C with hydrogen peroxide, deionised water and manganese bromide catalyst set at 1.5 mL, 2.5 mL, and 2 mL, respectively. Other major reaction products identified were p-tolualdehyde and 1,4-hydroxymethyl benzaldehyde.

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Efficient oxidation of p-xylene to terephthalic acid by using N,N-dihydroxypyromellitimide in conjunction with Co-benzenetricarboxylate

Cited by 16 publications

References 43 publications

Organic Synthesis Using Nitroxides

Organic Synthesis Using Nitroxides

p-Xylene Oxidation to Terephthalic Acid: New Trends

Effect of Process Conditions on Catalytic Hydrothermal Oxidation of p-Xylene to Terephthalic Acid

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