Article: Water- and acid-mediated excited-state intramolecular proton transfer and decarboxylation reactions of ketoprofen in water-rich and acidic aqueous solutions

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TitleWater- and acid-mediated excited-state intramolecular proton transfer and decarboxylation reactions of ketoprofen in water-rich and acidic aqueous solutions
AuthorsLi, MD1
Yeung, CS1
Guan, X1
Ma, J1
Li, W1
Ma, C1
Phillips, DL1
Issue Date2011
PublisherWiley - V C H Verlag GmbH & Co KGaA. The Journal's web site is located at http://www.wiley-vch.de/home/chemistry
CitationChemistry - A European Journal, 2011, v. 17 n. 39, p. 10935-10950 [How to Cite?]
DOI: http://dx.doi.org/10.1002/chem.201003297
AbstractWe present an investigation of the decarboxylation reaction of ketoprofen (KP) induced by triplet excited-state intramolecular proton transfer in water-rich and acidic solutions. Nanosecond time-resolved resonance Raman spectroscopy results show that the decarboxylation reaction is facile in aqueous solutions with high water ratios (water/acetonitrile≥50 %) or acidic solutions with moderate and strong acid concentration. These experimental results are consistent with results from density functional theory calculations in which 1) the activation energy barriers for the triplet-state intramolecular proton transfer and associated decarboxylation process become lower when more water molecules (from one up to four molecules) are involved in the reaction system and 2) perchloric acid, sulfuric acid, and hydrochloric acid can shuttle a proton from the carboxyl to carbonyl group through an initial intramolecular proton transfer of the triplet excited state, which facilitates the cleavage of the C-C bond, thus leading to the decarboxylation reaction of triplet state KP. During the decarboxylation process, the water molecules and acid molecules may act as bridges to mediate intramolecular proton transfer for the triplet state KP when KP is irradiated by ultraviolet light in water-rich or acidic aqueous solutions and subsequently it generates a triplet-protonated carbanion biradical species. The faster generation of triplet-protonated carbanion biradical in acidic solutions than in water-rich solutions with a high water ratio is also supported by the lower activation energy barrier calculated for the acid-mediated reactions versus those of water-molecule-assisted reactions. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
ISSN0947-6539
2011 Impact Factor: 5.925
2011 SCImago Journal Rankings: 0.455
DOIhttp://dx.doi.org/10.1002/chem.201003297
ReferencesReferences in Scopus
DC Field
Value
dc.contributor.authorLi, MD
dc.contributor.authorYeung, CS
dc.contributor.authorGuan, X
dc.contributor.authorMa, J
dc.contributor.authorLi, W
dc.contributor.authorMa, C
dc.contributor.authorPhillips, DL
dc.date.accessioned2012-08-16T05:48:28Z
dc.date.available2012-08-16T05:48:28Z
dc.date.issued2011
dc.description.abstractWe present an investigation of the decarboxylation reaction of ketoprofen (KP) induced by triplet excited-state intramolecular proton transfer in water-rich and acidic solutions. Nanosecond time-resolved resonance Raman spectroscopy results show that the decarboxylation reaction is facile in aqueous solutions with high water ratios (water/acetonitrile≥50 %) or acidic solutions with moderate and strong acid concentration. These experimental results are consistent with results from density functional theory calculations in which 1) the activation energy barriers for the triplet-state intramolecular proton transfer and associated decarboxylation process become lower when more water molecules (from one up to four molecules) are involved in the reaction system and 2) perchloric acid, sulfuric acid, and hydrochloric acid can shuttle a proton from the carboxyl to carbonyl group through an initial intramolecular proton transfer of the triplet excited state, which facilitates the cleavage of the C-C bond, thus leading to the decarboxylation reaction of triplet state KP. During the decarboxylation process, the water molecules and acid molecules may act as bridges to mediate intramolecular proton transfer for the triplet state KP when KP is irradiated by ultraviolet light in water-rich or acidic aqueous solutions and subsequently it generates a triplet-protonated carbanion biradical species. The faster generation of triplet-protonated carbanion biradical in acidic solutions than in water-rich solutions with a high water ratio is also supported by the lower activation energy barrier calculated for the acid-mediated reactions versus those of water-molecule-assisted reactions. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
dc.description.natureLink_to_subscribed_fulltext
dc.identifier.citationChemistry - A European Journal, 2011, v. 17 n. 39, p. 10935-10950 [How to Cite?]
DOI: http://dx.doi.org/10.1002/chem.201003297
dc.identifier.doihttp://dx.doi.org/10.1002/chem.201003297
dc.identifier.epage10950
dc.identifier.hkuros203396
dc.identifier.isiWOS:000296262400020
dc.identifier.issn0947-6539
2011 Impact Factor: 5.925
2011 SCImago Journal Rankings: 0.455
dc.identifier.issue39
dc.identifier.pmid21850720
dc.identifier.scopuseid_2-s2.0-80052849918
dc.identifier.spage10935
dc.identifier.urihttp://hdl.handle.net/10722/159295
dc.identifier.volume17
dc.languageeng
dc.publisherWiley - V C H Verlag GmbH & Co KGaA. The Journal's web site is located at http://www.wiley-vch.de/home/chemistry
dc.publisher.placeGermany
dc.relation.ispartofChemistry - A European Journal
dc.relation.referencesReferences in Scopus
dc.subject.meshAcids - chemistry
dc.subject.meshAnti-Inflammatory Agents, Non-Steroidal - chemistry
dc.subject.meshDecarboxylation
dc.subject.meshKetoprofen - chemistry
dc.subject.meshProtons
dc.subject.meshSpectrum Analysis, Raman
dc.subject.meshWater - chemistry
dc.titleWater- and acid-mediated excited-state intramolecular proton transfer and decarboxylation reactions of ketoprofen in water-rich and acidic aqueous solutions
dc.typeArticle
Author Affiliations
  1. The University of Hong Kong