Mass Spectra of Trimethylsilyl Derivatives of Long Chain Alcoho ls and Cyclic Alcohols

Abstract

Mass spectra of the trimethylsilyl(TMS)derivatives of straight chain secondary alcohols having carbon numbers 9 and 12 respectively and of steric isomers of methylcyclohexanol and cyclohexanediol have been measured. A specific fragmentation of the TMS derivatives of secondary alcohols is considered to be a-cleavage to TMS ether linkage, and the relationship between two fragment peaks induced from this cleavage and the orientation of functional groups have been discussed. The TMS derivatives of methylcyclohexanol have no evident difference in mass spectra between and trans isomers, but cis and trans-4-methyl isomers give a strong peak intensity at M/e 129 and a very weak one at M/e 143. On the other hand, cis-and trans-isomers of the TMS derivatives cyclohexane-1, 2-diol give quite similar mass spectra, but the mass spectra of those of 1, 3- and 1, 4-diols have some differences in the peak intensities at M/e 81, 147 and 170. The relationship between mass spectra and stereochemical structures has also been discussed.