Premium
A possible ethanol‐catalyzed rearrangement of vitamin K 1 detected by gas chromatography/mass spectrometry
Author(s) -
Osman Abdimajid,
Hannestad Ulf
Publication year - 2008
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.3807
Subject(s) - chemistry , epoxide , mass spectrometry , double bond , mass spectrum , intramolecular force , hexane , gas chromatography , chromatography , ring (chemistry) , ion , ethanol , vitamin , analytical chemistry (journal) , catalysis , stereochemistry , organic chemistry , biochemistry
We studied vitamin K 1 (20), vitamin K 1 (25), and vitamin K 1 epoxide in n ‐hexane and ethanol solutions by gas chromatography/mass spectrometry (GC/MS) utilizing a DB‐5 MS fused‐silica capillary column. In ethanol solutions of K 1 , we observed an extra peak eluting from the GC column with somewhat longer retention time than K 1 (20). A similar peak following K 1 (25) was also found. These peaks were not found in n ‐hexane solutions of K 1 . A close examination of the mass spectra of these peaks indicated that they were vitamin K 1 variants containing a base peak at m/z 225 characteristic of the methylnaphthoquinone ring with a four‐carbon side chain. In addition, they contained the molecular ions of K 1 (20) and K 1 (25), respectively. We conclude that K 1 (20) and K 1 (25), but not K 1 epoxide, might undergo rearrangements in ethanol involving an intramolecular proton transfer and a shift of the β , γ ‐double bond on the phytyl side chain toward the ring. The conjugation of the phytyl double bond with the quinone ring is probably the driving force of the rearrangement. We emphasize, however, that our conclusion is based only on mass spectral analysis and would require further investigation by other spectroscopic methods. Copyright © 2008 John Wiley & Sons, Ltd.