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Updated: Jul 10, 2026

Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
Gas chromatography-mass spectrometry analysis of regioisomeric ring substituted methoxy methyl phenylacetones
Tamer Awad1, Jack DeRuiter, C Randall Clark
1Department of Pharmacal Sciences, School of Pharmacy, Auburn University, Auburn, AL 36849, USA.
Abstract:
The methoxy methyl phenylacetones share an isobaric relationship (equivalent mass but different elemental composition) to the controlled precursor substance 3,4-methylenedioxyphenylacetone. The 10 methoxy methyl phenylacetones as well as the methylenedioxyphenylacetones show essentially equivalent mass spectra with major fragment ions at m/z 135 and 43. Those methoxy methyl phenylacetones with the methoxy group substituted ortho to the benzylic cation in the m/z 135 ion show a further fragmentation to lose formaldehyde (CH2O) and yield a significant ion at m/z 105. The loss of formaldehyde from the ortho methoxy benzyl cation was confirmed using commercially available regioisomeric 2-, 3-, and 4-methoxyphenylacetones. The 10 regioisomeric methoxy methyl phenylacetones were prepared from the appropriately substituted benzaldehydes. Complete gas chromatographic resolution of all ten regioisomeric ketones was obtained on a stationary phase containing modified beta-cyclodextrin. Using the cyclodextrin containing phase, the ortho methoxy-substituted ketones (K1-K4) eluted before the meta-methoxy-substituted ketones (K5-K8) and the para-methoxy-substituted ketones (K9-K10) showed the greatest affinity for the stationary liquid phase and eluted last. Complete separation of the 10 ketones was not obtained on Rtx-1 and Rtx-200 columns.
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