132332-04-8Relevant articles and documents
Tobacco Smoke Chemistry. 4. A Mass Spectral Study of Alkyl 3-Hydroxy-4-pyrones
Arnarp, Jan,Bielawski, Jacek,Dahlin, Britt-Marie,Dahlman, Olof,Enzell, Curt R.,Pettersson, Tore
, p. 916 - 926 (2007/10/02)
3-Hydroxy-4-pyrone and a series of C-alkylated 3-hydroxy-4-pyrones have been synthesized and their behaviour under electron impact investigated.The fragmentation pathways were elucidated with the aid of accurate mass measurements, metastable ion analysis and deuterium labelling.All compounds examined gave a detectable molecular ion which undergoes a retro Diels-Alder type process accompanied by hydrogen transfer to give characteristic ions, which in many cases allow differentiation of positional isomers.Loss of carbon monoxide is encountered from several ions, but to any substantial extent from the molecular ions only in the cases of 3-hydroxy-4-pyrone and 5-hydroxy-2-methyl-4-pyrone.Instead, the more general fragmentation routes involve extrusion of a hydrogen or an alkyl radical from the molecular ion prior to the elimination of carbon monoxide.When the alkyl substituent in 2-alkyl-3-hydroxy- or 2-alkyl-5-hydroxy-4-pyrone has three or more consecutive carbons the molecular ion loses an alkene fragment by a McLafferty type of reaction.The even mass ions formed by this process constitute the base peak in most spectra of this type.Another rearrangement reaction giving even mass ions after loss of an alkene fragment, occurs when the alkyl substituent in the 2-alkyl-3-hydroxy-4-pyrones is branched at the α-carbon.Moreover, γ-bond cleavage of the alkyl side chain vicinal to the hydroxy group becomes important due to anchimeric assistance by the hydroxy group.
