Comparison of two MCM-41 grafted TEMPO catalysts in selective alcohol oxidation

Brunel, Daniel; Fajula, François; Nagy, J.B.; Deroide, B.; Verhoef, Michel J.; Veum, Lars; Peters, Joop A.; Bekkum, H. van

doi:10.1016/s0926-860x(00)00886-3

Cited by 132 publications

(80 citation statements)

References 40 publications

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“…It is available (as Si-TEMPO, 71) from Aldrich and other suppliers. 156 Other silica-bound materials are ester-linked 72, 273 aminelinked 73 (to MCM-41 or SBA-15, mesoporous silicas) 309,310 , and ester-linked…”

Section: Ionic Liquidmentioning

confidence: 99%

Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

2009

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The discovery in 1959 of stable nitroxide‐based free radicals such as the prototypical 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) led to their use as electron spin resonance (ESR) spin labels in chemistry, biomedicine, and materials science. These nitroxides are prepared by the oxidation of secondary amines that contain no hydrogen atoms on the alpha‐carbons. The unique redox properties of nitroxides enable their use as oxidants in organic synthesis. The varied preparation and uses of oxoammonium salts as stoichiometric oxidants for alcohols are one subject of this review. Oxoammonium ions as oxidants for alcohols have a number of advantages, for example, the method is heavy‐metal free and some of the reactions can be performed in water or aqueous mixtures. A few side reactions are associated with these oxidations. The most serious is the fast reaction of the oxoammonium ion with free amines The several ways these oxidation reactions can be carried out are discussed in detail. They are: Oxidations using stoichimetric quantities of preformed oxoammonium salts carried out in either acidic, neutral, or basic conditions; reactions in which stoichiometric quantities of oxoammonium salts are generated in situ by disproportionation of a nitroxide in the presence of a strong acid; nitroxide‐catalyzed oxidations using a secondary oxidant; efficient nitroxide‐catalyzed oxidations of primary alcohols to carboxylic acids; and oxidations of primary alcohols or hemiacetals that can lead to lactones.

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Section: Ionic Liquidmentioning

confidence: 99%

Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

2009

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“…The reaction with benzyl alcohol was also carried out with 0.1 mol % and 0.05 mol % of catalyst, obtaining a conversion of 99% after 10 and 20 h respectively. Furthermore, catalyst 47 was more active than TEMPO immobilized on MCM-41 [37]. The same conversions were achieved using polymers with superior surface area, obtained by copolymerization of monomer 46 and divinylbenzene.…”

Section: Miscellaneous Examplesmentioning

confidence: 59%

Advances in Organic and Organic-Inorganic Hybrid Polymeric Supports for Catalytic Applications

2016

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Abstract:In this review, the most recent advances (2014)(2015)(2016) on the synthesis of new polymer-supported catalysts are reported, focusing the attention on the synthetic strategies developed for their preparation. The polymer-supported catalysts examined will be organic-based polymers and organic-inorganic hybrids and will include, among others, polystyrenes, poly-ionic liquids, chiral ionic polymers, dendrimers, carbon nanotubes, as well as silica and halloysite-based catalysts. Selected examples will show the synthesis and application in the field of organocatalysis and metal-based catalysis both for non-asymmetric and asymmetric transformations.

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“…Accordingly, no degradation of the ormosil structure in the buffered alkaline reaction environment (pH 9.1) was observed by EPR and FTIR analysis of the catalyst prior to and after 7 reaction runs (which may be compared to the chemical behavior of materials like hydrophilic MCM-41-grafted TEMPO which is unusable [8] above pH 8 due to dissolution of the crystalline silica).…”

Section: Resultsmentioning

confidence: 99%

Oxidation of Amino Diols Mediated by Homogeneous and Heterogeneous TEMPO

et al. 2004

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The conversion of amino diols to aminohydroxy acids by oxidation of the primary hydroxy group mediated by homogeneous and heterogeneous TEMPO (2,2,6,6-tetramethylpiperidine 1-oxyl radical) is reported. The synthesis uses NaOCl as primary oxidant and TEMPO, either dissolved in the homogeneous phase or entrapped in a sol-gel matrix, as catalytic mediator. Homogeneous TEMPO is suitable for the oxidation of aliphatic methylamino diols, while the hybrid organic-inorganic silica sol-gel catalysts are more selective mediators for the oxidation of benzylic amino diols like the potent antibiotic chloramphenicol which, under homogeneous conditions, are unselectively oxidized to benzoic acids.

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Comparison of two MCM-41 grafted TEMPO catalysts in selective alcohol oxidation

Cited by 132 publications

References 40 publications

Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

Oxoammonium‐ and Nitroxide‐Catalyzed Oxidations of Alcohols

Advances in Organic and Organic-Inorganic Hybrid Polymeric Supports for Catalytic Applications

Oxidation of Amino Diols Mediated by Homogeneous and Heterogeneous TEMPO

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