Selective catalytic oxidation of cyclohexylbenzene to cyclohexylbenzene-1-hydroperoxide: a coproduct-free route to phenol

Arends, Isabel W. C. E.; Sasidharan, Manickam; Kühnle, Adolf; Duda, Mark; Jost, Carsten; Sheldon, Roger A.

doi:10.1016/s0040-4020(02)01131-6

Cited by 77 publications

(35 citation statements)

References 7 publications

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“…The formation of these byproducts is attributed to competing transannular hydrogen abstraction by an intermediate cyclododecylperoxy radical, analogous to that observed in the autoxidation of cyclohexylbenzene. [8] Decreasing the reaction temperature either with NHS or NHPI, led, as expected, to a decrease of conversion together with an increase in selectivity toward ketone and alcohol (runs 4 ± 7). The slightly higher activity already observed with the NHS system at 100 8C, became more pronounced at 75 8C (47% and 36% conversion with NHS and NHPI respectively).…”

Section: Resultssupporting

confidence: 65%

“…[8] In previous studies it was shown that for the autoxidation of cyclohexylbenzene ± in the presence of NHPI ± a higher intrinsic selectivity towards the main product of the reaction was observed. This increase of both the rate and selectivity of product formation could be explained by the fact that NHPI increased the rate of propagation and/or decreased the rate of termination.…”

Section: Mechanistic Considerations: Nhs Vs Nhpimentioning

confidence: 99%

“…If the goal is to achieve a high yield of hydroperoxide the metal catalyst should be replaced with a radical initiator, such as a peroxide, to avoid metal-catalysed decomposition of the hydroperoxide. [8] When the desired product is the ketone the metal catalyst has a second function: to catalyse the decomposition of the alkyl hydroperoxide.…”

Section: Nhsmentioning

confidence: 99%

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Aerobic Oxidation of Cycloalkanes, Alcohols and Ethylbenzene Catalyzed by the Novel Carbon Radical Chain Promoter NHS (N‐Hydroxysaccharin)

et al. 2004

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Replacement of Ishii×s N-hydroxyphthalimide (NHPI) with the novel carbon radical chain promoter N-hydroxysaccharin (NHS) affords, in combination with metal salts, notably Co, or other additives, selective catalytic autoxidation of hydrocarbons, alcohols and alkylbenzenes under mild conditions (25 ± 100 8C, O 2 1 atm). The effects of solvent, temperature and the nature of the additives were investigated to give an optimised oxidation protocol for the various systems. The NHS/Co combination was more reactive than NHPI/Co in the autoxidation of cycloalkanes. In contrast, the opposite order of reactivity was observed in the autoxidation of ethylbenzene and alcohols. It is suggested, on the basis of bond dissociation energy (BDE) considerations, that this is a result of a change in the rate-limiting step with the more reactive ethylbenzene and alcohol substrates. In the autoxidation of the model cycloalkane, cyclododecane, the best results (90% selectivity to a 4 : 1 mixture of alcohol and ketone at 24% conversion) were obtained with NHS/Co(acac) 3 in PhCF 3 at 80 8C. Competition experiments revealed that, in contrast to what is commonly believed, formation of the dicarboxylic acid by ring opening is not a result of further oxidation of the ketone product. It is suggested that ring opened products are a result of˚-scission of the cycloalkoxy radical formed via (metal-catalysed) decomposition of the hydroperoxide. This is suppressed in the presence of NHS (or NHPI) which efficiently scavenge the alkoxy radicals.

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Section: Resultssupporting

confidence: 65%

Section: Mechanistic Considerations: Nhs Vs Nhpimentioning

confidence: 99%

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Aerobic Oxidation of Cycloalkanes, Alcohols and Ethylbenzene Catalyzed by the Novel Carbon Radical Chain Promoter NHS (N‐Hydroxysaccharin)

et al. 2004

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“…PINO formation is usually facilitated by additives such as: transition metals [7,8], azo-compounds [9][10][11], peroxides [12,13], aldehydes [14], enzymes [15,16] and others [17]. For instance, when the most popular combination, i.e.…”

mentioning

confidence: 99%

N-Hydroxyphthalimide Immobilized on Poly(HEA-co-DVB) as Catalyst for Aerobic Oxidation Processes

et al. 2016

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was tested in aerobic oxidation of p-methoxytoluene and α-methylstyrene. The studied reactions were carried out in the presence of AIBN and/or Co(II) salt without solvent or in acetic acid as solvent. It was found that the obtained polymer-supported NHPI catalyst showed the best catalytic performance, which was attributed to a high content of accessible NHPI moieties. The recovery and recycling of the obtained HEA/DVB-NHPI was only possible in reactions proceeded in solvent-free conditions. Abstract In the present study, poly(HEA-co-DVB) was synthesized (loading of OH groups: 8.07 mmol OH/g, crosslinking degree: 6 % DVB) and used for N-hydroxyphthalimide (NHPI) immobilization via ester bond (NHPI loading: 2.06 mmol NHPI/g). The obtained polymeric support and poly(HEA-co-DVB)/NHPI catalyst were characterized by FT-IR and XPS spectroscopy, elemental analysis, thermogravimetry and particle size measurement. The novel polymer-supported NHPI catalyst 1 3

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“…[7] ly, Sheldon et al have reported phenol synthesis by means of the NHPI-catalyzed aerobic oxidation of cyclohexylbenzene. [8] We now report an efficient synthesis of naphthalenediols via aerobic oxidation of diisopropylnaphthalenes catalyzed by NHPI and AIBN.The aerobic oxidation of 1 was chosen as a model reaction and was carried out in the presence of catalytic amounts of AIBN and NHPI under various conditions (Table 1). …”

mentioning

confidence: 99%

Synthesis of Naphthalenediols by Aerobic Oxidation of Diisopropylnaphthalenes Catalyzed by N‐Hydroxyphthalimide (NHPI)/α,α′‐Azobisisobutyronitrile (AIBN)

2004

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Naphthalenediols were successfully synthesized in a one-pot reaction through the oxidation of diisopropylnaphthalenes with air catalyzed by Nhydroxyphthalimide (NHPI) combined with a,a'-azobisisobutyronitrile (AIBN) followed by decomposition with sulfuric acid. Thus, the oxidation of 2,6-diisopropylnaphthalene with air (20 atm) in the presence of AIBN (3 mol %) and NHPI (10 mol %) in CH 3 CN at 75 8C for 21 h followed by treatment with 0.3 M H 2 SO 4 gave 2,6-naphthalenediol in 92% yield.Keywords: homogeneous catalysis; hydroperoxides, N-hydroxyphthalimide; oxidation; radicals Phenols and naphthols are an important class of compounds needed for the syntheses of dyes, pharmaceuticals and polymers. In particular, naphthalenediols are essential components of intelligent polymers such as engineering plastics and liquid crystalline polymers. 2,6-Naphthalenediol (2) has attracted much attention for its chemical and physical properties as a liquid crystalline monomer material. A classical process for the production of 2 is based on the sulfonation of naphthalene followed by alkali fusion of the resulting sulfonates.[1]However, 2 is difficult to synthesize in high yield by this method, which results in a complex mixture of several sulfonated products. It has been reported that the reaction of b-naphthol with hydrogen peroxide in the presence of a Lewis acid like SbF 5 produces 2, but this method also brings about a mixture of several regioisomeric naphthalenediols.[2] There have been several patents on the synthesis of 2 by the oxidation of 2,6-diisopropylnaphthalene (1) followed by treatment of the resulting 2,6-bis(2-hydroxy-2-propyl)naphthalene with H 2 O 2 and H 2 SO 4 .[3]The phenol synthesis through cumene hydroperoxide obtained by the aerobic oxidation of isopropylbenzene is well known as the Hock process. Recently, this methodology was applied to the synthesis of 2,6-bis(1-hydroperoxy-1-methylethyl)naphthalene (4) and 2-isopropyl-6-(1-hydroperoxy-1-methylethyl)naphthalene (5).[4] In a previous paper, we have reported the aerobic oxidation of methylbenzenes like toluene and xylene to the corresponding carboxylic acids using N-hydroxyphthalimide (NHPI) as a key catalyst.[5] In addition, we reported the epoxidation of olefins with ethylbenzene hydroperoxide, generated in situ from the aerobic oxidation of ethylbenzene by NHPI, in the presence of Mo(CO) 6.[6] This fact shows that the NHPI-catalyzed oxidation of alkylbenzenes can be applied to the synthesis of alkyl hydroperoxides from alkylbenzenes. [7] ly, Sheldon et al. have reported phenol synthesis by means of the NHPI-catalyzed aerobic oxidation of cyclohexylbenzene. [8] We now report an efficient synthesis of naphthalenediols via aerobic oxidation of diisopropylnaphthalenes catalyzed by NHPI and AIBN.The aerobic oxidation of 1 was chosen as a model reaction and was carried out in the presence of catalytic amounts of AIBN and NHPI under various conditions (Table 1). 1Compound 1 was allowed to react under O 2 (1 atm) in the presence of AIBN (3 mol %) an...

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Selective catalytic oxidation of cyclohexylbenzene to cyclohexylbenzene-1-hydroperoxide: a coproduct-free route to phenol

Cited by 77 publications

References 7 publications

Aerobic Oxidation of Cycloalkanes, Alcohols and Ethylbenzene Catalyzed by the Novel Carbon Radical Chain Promoter NHS (N‐Hydroxysaccharin)

Aerobic Oxidation of Cycloalkanes, Alcohols and Ethylbenzene Catalyzed by the Novel Carbon Radical Chain Promoter NHS (N‐Hydroxysaccharin)

N-Hydroxyphthalimide Immobilized on Poly(HEA-co-DVB) as Catalyst for Aerobic Oxidation Processes

Synthesis of Naphthalenediols by Aerobic Oxidation of Diisopropylnaphthalenes Catalyzed by N‐Hydroxyphthalimide (NHPI)/α,α′‐Azobisisobutyronitrile (AIBN)

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