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Surface Oxidation of Phenolic Aldehydes: Fragmentation, Functionalization, and Coupling Reactions

[Image: see text] Substantial amounts of phenolic aldehydes, represented by the structures of syringaldehyde, vanillin, and 4-hydroxybenzaldehyde, are emitted to the atmosphere during biomass burning. The oxidative transformation of phenolic aldehydes during atmospheric transport has the potential t...

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Autores principales: Rana, Md. Sohel, Guzman, Marcelo I.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2022
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9512012/
https://www.ncbi.nlm.nih.gov/pubmed/36070234
http://dx.doi.org/10.1021/acs.jpca.2c04963
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author Rana, Md. Sohel
Guzman, Marcelo I.
author_facet Rana, Md. Sohel
Guzman, Marcelo I.
author_sort Rana, Md. Sohel
collection PubMed
description [Image: see text] Substantial amounts of phenolic aldehydes, represented by the structures of syringaldehyde, vanillin, and 4-hydroxybenzaldehyde, are emitted to the atmosphere during biomass burning. The oxidative transformation of phenolic aldehydes during atmospheric transport has the potential to modify the physicochemical properties of particulates, which play a vital role in Earth’s climate and human health. Herein, thin solid films made of syringaldehyde, vanillin, and 4-hydroxybenzaldehyde are oxidized in contact with O(3)(g) under a relative humidity of 74% representative of average global conditions. New physical insights into the surface reactions are achieved by analyzing isopropanol-extracted films before and during oxidation by multiple techniques. Changes in electronic transitions at 220, 310, and 350–400 nm registered by UV–vis spectroscopy show that the oxidized films have enhanced mass absorption coefficients at λ > 300 nm. Electrospray ionization (ESI) mass spectrometry (MS) and ion chromatography with conductivity and MS detection of extracted oxidized films confirm aromatic ring cleavage of syringaldehyde and vanillin by O(3)(g) with the production of carboxylic acids. Carboxylic acids were observed as anions ([M – H](−)) at m/z 45 (formic acid), 73 (glyoxylic acid), 75 (glycolic acid), 89 (oxalic acid), 115 (maleic acid), 117 (mesoxalic acid), 119 (tartronic acid), and 129 (maleic acid monomethyl ester), while other polyfunctional products were registered by ultrahigh-pressure liquid chromatography with UV–vis and MS detection. In situ production of hydroxyl radicals is confirmed by demethoxylation products and ipso attack at the C(1) ring position holding the −C(H)=O group. The order of reactivity increased with the number of methoxy substituents that donate electron density to the aromatic ring. Combined oxidation mechanisms for the three compounds are proposed based on all of the experimental observations and explain the contribution of aged biomass burning material to secondary organic aerosol formation.
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spelling pubmed-95120122023-09-07 Surface Oxidation of Phenolic Aldehydes: Fragmentation, Functionalization, and Coupling Reactions Rana, Md. Sohel Guzman, Marcelo I. J Phys Chem A [Image: see text] Substantial amounts of phenolic aldehydes, represented by the structures of syringaldehyde, vanillin, and 4-hydroxybenzaldehyde, are emitted to the atmosphere during biomass burning. The oxidative transformation of phenolic aldehydes during atmospheric transport has the potential to modify the physicochemical properties of particulates, which play a vital role in Earth’s climate and human health. Herein, thin solid films made of syringaldehyde, vanillin, and 4-hydroxybenzaldehyde are oxidized in contact with O(3)(g) under a relative humidity of 74% representative of average global conditions. New physical insights into the surface reactions are achieved by analyzing isopropanol-extracted films before and during oxidation by multiple techniques. Changes in electronic transitions at 220, 310, and 350–400 nm registered by UV–vis spectroscopy show that the oxidized films have enhanced mass absorption coefficients at λ > 300 nm. Electrospray ionization (ESI) mass spectrometry (MS) and ion chromatography with conductivity and MS detection of extracted oxidized films confirm aromatic ring cleavage of syringaldehyde and vanillin by O(3)(g) with the production of carboxylic acids. Carboxylic acids were observed as anions ([M – H](−)) at m/z 45 (formic acid), 73 (glyoxylic acid), 75 (glycolic acid), 89 (oxalic acid), 115 (maleic acid), 117 (mesoxalic acid), 119 (tartronic acid), and 129 (maleic acid monomethyl ester), while other polyfunctional products were registered by ultrahigh-pressure liquid chromatography with UV–vis and MS detection. In situ production of hydroxyl radicals is confirmed by demethoxylation products and ipso attack at the C(1) ring position holding the −C(H)=O group. The order of reactivity increased with the number of methoxy substituents that donate electron density to the aromatic ring. Combined oxidation mechanisms for the three compounds are proposed based on all of the experimental observations and explain the contribution of aged biomass burning material to secondary organic aerosol formation. American Chemical Society 2022-09-07 2022-09-22 /pmc/articles/PMC9512012/ /pubmed/36070234 http://dx.doi.org/10.1021/acs.jpca.2c04963 Text en © 2022 The Authors. Published by American Chemical Society https://creativecommons.org/licenses/by-nc-nd/4.0/Permits non-commercial access and re-use, provided that author attribution and integrity are maintained; but does not permit creation of adaptations or other derivative works (https://creativecommons.org/licenses/by-nc-nd/4.0/).
spellingShingle Rana, Md. Sohel
Guzman, Marcelo I.
Surface Oxidation of Phenolic Aldehydes: Fragmentation, Functionalization, and Coupling Reactions
title Surface Oxidation of Phenolic Aldehydes: Fragmentation, Functionalization, and Coupling Reactions
title_full Surface Oxidation of Phenolic Aldehydes: Fragmentation, Functionalization, and Coupling Reactions
title_fullStr Surface Oxidation of Phenolic Aldehydes: Fragmentation, Functionalization, and Coupling Reactions
title_full_unstemmed Surface Oxidation of Phenolic Aldehydes: Fragmentation, Functionalization, and Coupling Reactions
title_short Surface Oxidation of Phenolic Aldehydes: Fragmentation, Functionalization, and Coupling Reactions
title_sort surface oxidation of phenolic aldehydes: fragmentation, functionalization, and coupling reactions
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9512012/
https://www.ncbi.nlm.nih.gov/pubmed/36070234
http://dx.doi.org/10.1021/acs.jpca.2c04963
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