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A mass spectral study of stable neutral enols
Author(s) -
Peake D. A.,
Stanley J.,
Kingsbury C. A.,
Gross M. L.
Publication year - 1986
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.1210210907
Subject(s) - tautomer , chemistry , enol , isomerization , mass spectrum , ion , hydrogen atom , photochemistry , ring (chemistry) , keto–enol tautomerism , cyclohexanone , radical ion , stereochemistry , medicinal chemistry , organic chemistry , catalysis , alkyl
The high‐resolution mass spectra of two stable enol tautomers, 4,6‐diethanoyl‐1‐methyl‐5‐phenyl‐3‐cyclohex‐ene‐1,3‐diol (2) and 4‐ethanoyl‐5‐hydroxy‐2‐(1‐hydroxyethylidene)‐5‐methyl‐3‐phenylcyclohexanone (3), and the corresponding diketone tautomer, 2,4‐diethanoyl‐5‐hydroxy‐5‐methyl‐3‐phenylcyclohexanone (1), are reported. Collisional activation of the molecular ions and major ionic fragments is used to assign decomposition pathways and to compare ion structures. Ionized 1 and 2 do not interconvert by a keto‐enol tautomerism, but isomerize to a common intermediate. This isomerization probably involves opening of the cyclohexanone ring and transfer of the enolizable hydrogen, and is followed by elimination of water. The radical cation of 3 does not interconvert with [1] + ˙ and [2] + ˙ Instead, [3] + ˙ dissociates by loss of an acetyl radical and eliminates water via a higher‐energy pathway. As a result, the mass spectra of 1 and 2 are similar, whereas the mass spectrum of 3 is unique.