Use of microwave irradiation for rapid synthesis of perfluorooctanoyl derivatives of fatty alcohols, a new derivative for gas chromatography-mass spectrometric and fast atom bombardment mass spectrometric study

Abstract

Structural analyses of fatty alcohols as acetate, trifluoroacetate and trimethylsilyl derivatives are frequently used in lipid biochemistry. Those derivatives produce molecular ions ( m z ) < 400. Perfluorooctanoyl derivatives of fatty alcohols which can produce ions in the range of 600–700 ( m z ) have never been studied before. We prepared perfluorooctanoyl derivatives of fatty alcohols by heating them with perfluorooctanoyl chloride for 15 min at 60°C. Using low-power microwave irradiation (240 W), we can reduce the reaction time to only 2 min. The yields of the derivatives were quantitative by both microwave technique and conventional heating as evidenced by absence of starting material (fatty alcohols) in the HPTLC analysis. The mass spectral fragmentation patterns of the derivatives obtained by microwave irradiation are identical to the derivatives prepared by conventional heating. We also prepared trimethylsilyl derivatives of fatty alcohols, a widely used derivative, in 1.5 min using microwave irradiation (power 3, 240 W) where the conventional technique requires 20 min. We conclude that microwave irradiation can be employed for rapid preparation of perfluorooctanoyl and trimethylsilyl derivatives of fatty alcohols for gas chromatography-mass spectrometric analysis.