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Isobutane chemical ionization mass spectra of unsaturated alcohols
Author(s) -
Munson Burnaby,
Feng TaMin,
Ward Harry D.,
Murray Roger K.
Publication year - 1987
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210220906
Subject(s) - chemistry , protonation , intramolecular force , double bond , isobutane , mass spectrum , photochemistry , chemical ionization , solvation , carbon fibers , ether , carbocation , ion , medicinal chemistry , ionization , organic chemistry , catalysis , materials science , composite number , composite material
Analysis of the isobutane chemical ionization mass spectra of hexenols, cyclohexenols and various syn/anti pairs of bicyclic and tricyclic homoallylic alcohols shows that: (i) the spectra of the allylic alcohols are dominated by [M + H – H 2 O] + and [M + C 4 H 9 –H 2 O] + ions and contain traces of [M + H] + ions; (ii) [M + H] + ions are prominent in the spectra of acyclic and certain cyclic homoallylic alcohols; and (iii) [M + H] + ions dominate the spectra of other acyclic unsaturated alcohols. The [M + H] + ions may result from either: (a) protonation of the hydroxyl group, followed by a very rapid intramolecular proton transfer from the protonated hydroxyl group to the carbon–carbon double bond or internal solvation of the protonated hydroxyl group by the carbon–carbon double bond; and/or (b) direct protonation of the carbon–carbon double bond with significant internal solvation of the resulting carbocation by the hydroxyl group, which may lead to carbon–oxygen bond formation to give a protonated cyclic ether. The consequences of placing various geometric constraints on the possible intramolecular interactions between the hydroxyl group and the carbon–carbon double bond in unsaturated alcohols are explored.