Elucidation of fragmentation pathway of long chain base by molecular orbital calculation

Hideki KISHINE and Akira HAYASHI

(Received : November 13, 1996 ; Accepted for publication : December 18, 1996)

The fragmentation pathway of the ions, [M-15(CH₃)]⁺ and [M-15-90(TMSOH)]⁺, of O-trimethylsilyl(TMS) derivatives of long chain base detected by gas chromatography combined with electron-impact mass spectrometry were studied by molecular orbital calculation(AM1).
The calculation results showed that the [M-15]⁺ cyclic ion was produced by the loss of one methyl radical from the TMS group of C-1 and then the [M-15-90]⁺ ion was produced by the loss of the TMSOH from the [M-15]⁺ ion.
Elucidation of the structure of the m/z 132 ion ([H₂NCHCH₂OTMS]⁺) was also carried out using molecular orbital calculation(AM1).

Keywords: Long-chain base, Trimethylsilyl(TMS) derivatives, GC/MS, Fragmentation, Molecular orbital calculation

Text in Japanese