Accurate determination of the double bond positions in unsaturated long chain compounds remains a challenging task, even in this advanced spectroscopic era. The most current analytical approaches to this problem rely on the use of mass spectrometry. Conventional MS is inherently unreliable, mainly because of the rapid isomerization of the molecular ions. One solution to this problem is the prior chemical derivatization of the analyte. This method has been commonly used by laboratories that do not specialize in MS, but it suffers from several drawbacks, including the need for a second derivatization step and the possibility of interference from other functional groups on the analyte during the derivatizations.In this regard, we developed a new chemical derivatization method for the determination of double bond positions in unsaturated long chains. Our method is based on the cross metathesis reaction between a target compound and a simple olefin. Depending on the cross metathesis partner used, the fragments produced have distinct physicochemical properties that are suitable for LC/MS and GC/MS analysis. The position of the double bond can easily be deduced by comparing the molecular mass changes. Both of the presented approaches are equally reliable, and applicable at a sub-miligram scale.

Facile method for determining the double bond positions with cross-metathesis

244th National Meeting (2012)

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