The benzaldehyde oxidation paradox explained by the interception of peroxy radical by benzyl alcohol

Sankar, Meenakshisundaram; Nowicka, Ewa; Carter, Emma; Murphy, D. M.; Knight, David W.; Bethell, Donald; Hutchings, Graham J.

doi:10.1038/ncomms4332

Cited by 201 publications

(158 citation statements)

References 46 publications

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“…As butyraldehyde oxidises readily to butyric acid under the reaction conditions used, it remains unclear why relatively high butyraldehyde selectivities were obtained at low n-butanol conversions (< 10 %). Recently Sankar et al [20] demonstrated through EPR spectroscopy spin-trapping experiments that benzyl alcohol intercepts, by hydrogen atom transfer, the benzoylperoxy radicals that are involved in benzaldehyde oxidation to benzoic acid. They observed a similar inhibition system for the octanal/1-octanol system.…”

Section: Resultsmentioning

confidence: 98%

Selective Oxidation of n‐Butanol Using Gold‐Palladium Supported Nanoparticles Under Base‐Free Conditions

et al. 2014

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The base-free selective catalytic oxidation of n-butanol by O2 in an aqueous phase has been studied using Au-Pd bimetallic nanoparticles supported on titania. Au-Pd/TiO2 catalysts were prepared by different methods: wet impregnation, physical mixing, deposition-precipitation and sol immobilisation. The sol immobilisation technique, which used polyvinyl alcohol (PVA) as the stabilizing agent, gave the catalyst with the smallest average particle size and the highest stable activity and selectivity towards butyric acid. Increasing the amount of PVA resulted in a decrease in the size of the nanoparticles. However, it also reduced activity by limiting the accessibility of reactants to the active sites. Heating the catalyst to reflux with water at 90 °C for 1 h was the best method to enhance the surface exposure of the nanoparticles without affecting their size, as determined by TEM, X-ray photoelectron spectroscopy and CO chemisorption analysis. This catalyst was not only active and selective towards butyric acid but was also stable under the operating conditions.

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Section: Resultsmentioning

confidence: 98%

Selective Oxidation of n‐Butanol Using Gold‐Palladium Supported Nanoparticles Under Base‐Free Conditions

et al. 2014

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“…The presence of the truncated residues as acids rather than aldehydes during white rot of wood (Fig. 1a) presumably reflects the instability of benzaldehydes in oxidizing environments (44), in combination with the fact that wood biodegradation experiments require much longer times than in vitro DHP depolymerizations (weeks versus hours). Our data thus provide evidence that SET oxidation of lignin aromatic rings contributes to ligninolysis by C. subvermispora as well as P. chrysosporium.…”

Section: Resultsmentioning

confidence: 99%

A Highly Diastereoselective Oxidant Contributes to Ligninolysis by the White Rot Basidiomycete Ceriporiopsis subvermispora

Yelle

Kapich

Houtman

et al. 2014

Appl Environ Microbiol

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eThe white rot basidiomycete Ceriporiopsis subvermispora delignifies wood selectively and has potential biotechnological applications. Its ability to remove lignin before the substrate porosity has increased enough to admit enzymes suggests that small diffusible oxidants contribute to delignification. A key question is whether these unidentified oxidants attack lignin via singleelectron transfer (SET), in which case they are expected to cleave its propyl side chains between C ␣ and C ␤ and to oxidize the threo-diastereomer of its predominating ␤-O-4-linked structures more extensively than the corresponding erythro-diastereomer. We used two-dimensional solution-state nuclear magnetic resonance (NMR) techniques to look for changes in partially biodegraded lignin extracted from spruce wood after white rot caused by C. subvermispora. The results showed that (i) benzoic acid residues indicative of C ␣ OC ␤ cleavage were the major identifiable truncated structures in lignin after decay and (ii) depletion of ␤-O-4-linked units was markedly diastereoselective with a threo preference. The less selective delignifier Phanerochaete chrysosporium also exhibited this diastereoselectivity on spruce, and a P. chrysosporium lignin peroxidase operating in conjunction with the P. chrysosporium metabolite veratryl alcohol did likewise when cleaving synthetic lignin in vitro. However, C. subvermispora was significantly more diastereoselective than P. chrysosporium or lignin peroxidase-veratryl alcohol. Our results show that the ligninolytic oxidants of C. subvermispora are collectively more diastereoselective than currently known fungal ligninolytic oxidants and suggest that SET oxidation is one of the chemical mechanisms involved.

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“…This is a spontaneous process that takes place at ambient temperature simply upon exposing benzaldehyde to dioxygen molecules. [3,22] Thus, freshly distilled benzaldehyde 2 a was mixed with different amounts of acetonitrile, acetic acid, or HFIP (0, 0.5, 1, and 1.5 equivalents) in a dioxygen atmosphere at room temperature. The concentration of benzoic acid was determined after 4 h; the results are plotted in Figure 2 B.…”

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confidence: 99%

Selective Aerobic Oxidation of Methylarenes to Benzaldehydes Catalyzed by N‐Hydroxyphthalimide and Cobalt(II) Acetate in Hexafluoropropan‐2‐ol

2017

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Efficient and highly selective catalytic conditions for the aerobic autoxidation of methylarenes to benzaldehydes, based on N-hydroxyphthalimide (NHPI) and cobalt(II) acetate in 1,1,1,3,3,3-hexafluoropropan-2-ol (HFIP), were developed. The sustainable conditions enable a multigram scale preparation of benzaldehyde derivatives in high efficiency and with excellent chemoselectivity (up to 99 % conversion and 98 % selectivity).

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The benzaldehyde oxidation paradox explained by the interception of peroxy radical by benzyl alcohol

Cited by 201 publications

References 46 publications

Selective Oxidation of n‐Butanol Using Gold‐Palladium Supported Nanoparticles Under Base‐Free Conditions

Selective Oxidation of n‐Butanol Using Gold‐Palladium Supported Nanoparticles Under Base‐Free Conditions

A Highly Diastereoselective Oxidant Contributes to Ligninolysis by the White Rot Basidiomycete Ceriporiopsis subvermispora

Selective Aerobic Oxidation of Methylarenes to Benzaldehydes Catalyzed by N‐Hydroxyphthalimide and Cobalt(II) Acetate in Hexafluoropropan‐2‐ol

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