Analysis of norpropoxyphene Cyclization in Methanol by LCMS

An Investigation of Norpropoxyphene Cyclization in Methanol

Authors: Huahua Jian PhD, Sandra Ybarra, Derrell Johnson MS, Isil Dilek PhD and Uma Sreenivasan PhD
Presented at SOFT, October 2009

Abstract
Dextropropoxyphene, a synthetic opioid analgesic, is widely prescribed for the relief of mild to moderate pain. It is primarily metabolized to norpropoxyphene in humans through N-demethylation. In most methods, analysis of norpropoxyphene involves a strong base-catalyzed conversion to norpropoxyphene amide to help improve the chromatography.

The solution behavior of norpropoxyphene in the prescence and absence of base was examined by HPLC, LC/MS, and 1H NMR. The results support the formation of a cyclic intermediate in solution. Literature precedence exists for the involvement of a cyclic intermediate in the base-catalyzed conversion of norpropoxyphene to norpropoxyphene amide as well as in the formation of cyclic dinorpropoxyphene.

We propose a mechanism for the formation of this cyclic intermediate and its impact in the analysis of norpropoxyphene by LC/MS. We offer HPLC and ¹H NMR evidence which corroborate the formation and time of the formation of this cyclic intermediate in solution will also be discussed.

view poster

return to papers and poster presentations