Aerobic Oxidation of Alkylaromatics using a Lipophilic <i>N</i>‐Hydroxyphthalimide: Overcoming the Industrial Limit of Catalyst Solubility

Petroselli, Manuel; Franchi, Paola; Lucarini, Marco; Punta, Carlo; Melone, Lucio

doi:10.1002/cssc.201402132

Cited by 41 publications

(37 citation statements)

References 44 publications

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“…10,11 The stable nitroxyl radical TEMPO acts as a mediator in the presence of sodium bromide and sodium hypochlorite, to selectively oxidize the primary hydroxyl groups in cellulose. 19,20 The NHPI/NaBr/NaClO system oxidize also the primary hydroxyl groups in cellulose, see Fig. phthalimide-N-oxyl (PINO) which is generated in situ from its parent hydroxyl amine, N-hydroxyphthalimide (NHPI) and an adequate cocatalyst.…”

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confidence: 99%

One-shot carboxylation of microcrystalline cellulose in the presence of nitroxyl radicals and sodium periodate

et al. 2015

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Water soluble cellulose derivatives are highly required products for many practical purposes, expanding the limited applications of pure cellulose, caused by highly ordered hydrogen bond network and high crystallinity. In this connection, this paper, presents a new approach to obtain water soluble carboxyl-functionalized cellulosic materials, combining two of the most common selective oxidation protocols for cellulose, i.e. the nitroxyl mediated and periodate, in one-shot reaction. It was found that, under specific reaction conditions, fully oxidized, 2,3,6-tricarboxy cellulose can be obtained in high amounts. The other valuable oxidized fractions were found to possess large amounts of carboxylic groups, as determined by potentiometric titration. 13 C-NMR evidenced the presence of three distinctive carboxylic groups in the fully oxidized product, whereas for the partially oxidized samples, 13 C CP-MAS solid-state NMR did not detect any carbonyl signals. The oxidized products were characterized by means of FTIR and X-ray 2 photoelectron spectroscopy (XPS). Moreover, the changes on the degree of polymerization occurred after oxidative treatments were viscometrically determined.

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One-shot carboxylation of microcrystalline cellulose in the presence of nitroxyl radicals and sodium periodate

et al. 2015

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“…Ishii initiated this approach by suggesting the introduction of lipophilic chains onto the aromatic ring of the N ‐hydroxy derivative . Nevertheless, we recently demonstrated that Ishii's proposed catalyst 1 (Scheme ), when used in processes that require a high control of selectivity in hydroperoxide, is far from ideal . Indeed, not only is its solubility still low under mild conditions, in spite of its higher lipophilic character, but the carboxylic group, by which the alkyl tail is linked to the NHPI moiety, also affects the NO‐H BDE due to its electron‐withdrawing character, leading to an increase of 0.7 kcal mol −1 .…”

Section: Introductionmentioning

confidence: 99%

Lipophilic N‐Hydroxyphthalimide Catalysts for the Aerobic Oxidation of Cumene: Towards Solvent‐Free Conditions and Back

Petroselli

Melone

Cametti

et al. 2017

Chemistry A European J

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A new class of lipophilic N-hydroxyphthalimide (NHPI) catalysts designed for the aerobic oxidation of cumene in solvent-free conditions was synthesized and tested. The specific strategy proposed for the introduction of lipophilic tails on the NHPI moiety leads to lipophilic catalysts that-while completely preserving the activity of the precursor-allow the catalytic oxidation to be conducted in neat cumene, for the first time. The corresponding cumyl hydroperoxide is obtained in good yields (28-52 %) and with high selectivity (95-97 %), under mild conditions. Importantly, the presence of a polar solvent is no longer required to guarantee complete solubilization of the catalyst. On the other hand, the oxidation conducted in neat cumene reveals the unexpected necessity of using small amounts of acetonitrile to fully promote the hydrogen atom transfer process and prevent the catalyst from detrimental hydrogen-bond (HB) driven aggregation.

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“…Oxidation reactions carried out in the presence of NHPI often require polar solvent due to low solubility of NHPI in hydrocarbons. As solvent elimination is an important factor in green chemistry, to overcome this problem, some lipophilic derivatives of NHPI has been synthesized and applied in solvent-free oxidations of alkylaromatics [13][14][15]. In this paper, in contrast to previous studies, the catalytic aerobic cleavage of alkenes in solvent-free conditions has been performed.…”

Section: Introductionmentioning

confidence: 99%

Solvent-free aerobic oxidative cleavage of alkenes catalyzed by N-hydroxyphthalimide

Pyszny

Orlińska

2017

Reac Kinet Mech Cat

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The aerobic oxidative cleavage of a-methylstyrene and other benzylic olefins catalyzed by N-hydroxyphthalimide (NHPI) under solvent-free conditions is described. The reaction was remarkably accelerated by the addition of azo-initiator (2,2 0 -azobis(2-methylpropionitryl)) or transition metal salts (Mn, Cu, Co) in combination with NHPI. Alkylammonium salts and acetophenone were successfully applied to increase the solubility of the polar NHPI catalyst in non-polar substrates. The effects of the catalyst and reaction parameters on the conversion of the substrate and the selectivity for ketones were investigated. New insights into the oxidation mechanism and NHPI-ammonium salt interaction are presented.

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Aerobic Oxidation of Alkylaromatics using a Lipophilic N‐Hydroxyphthalimide: Overcoming the Industrial Limit of Catalyst Solubility

Cited by 41 publications

References 44 publications

One-shot carboxylation of microcrystalline cellulose in the presence of nitroxyl radicals and sodium periodate

One-shot carboxylation of microcrystalline cellulose in the presence of nitroxyl radicals and sodium periodate

Lipophilic N‐Hydroxyphthalimide Catalysts for the Aerobic Oxidation of Cumene: Towards Solvent‐Free Conditions and Back

Solvent-free aerobic oxidative cleavage of alkenes catalyzed by N-hydroxyphthalimide

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