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RESEARCH PRODUCT
ChemInform Abstract: Modified Photobehavior of Carboxylic Acid Derivatives Induced by Protonation.
Maria J. CastelloGregorio AsensioAntonia Simon-fuentesMiguel A. MirandaAna M. Amatsubject
chemistry.chemical_classificationchemistry.chemical_compoundchemistryPhotoisomerizationCarboxylic acidIonic bondingMaleic anhydrideSulfuric acidProtonationGeneral MedicineMedicinal chemistryOleumIondescription
Abstract A series of carboxylic acid derivatives 1–6 containing a second interacting function have been converted into the corresponding O -protonated species or acylium ions upon treatment with 96% sulfuric acid or oleum, respectively, at room temperature. The resulting stable cations have been spectroscopically characterized and submitted to irradiation. Cis-trans photoisomerization was observed in the ionic speciesderived from trans -crotonic, fumaric and maleic acids, and maleic anhydride. By contrast protonated crotonolactone 5a+ was found to be photostable. Finally, protonated α-bromobutyrolactone 6a+ was clean and efficiently dehydrohalogenated to 5a+ upon irradiation. Since the normal n → π* photoreactions of the uncharged carboxylic acid and their derivatives are inhibited under these conditions, protonation can be envisaged as a chemical selective method for photoprotection of the carboxy group.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 1987-08-18 | ChemInform |