DETERMINATION OF DOUBLE-BOND POSITIONS IN TRIUNSATURATED COMPOUNDS BYMEANS OF GAS-CHROMATOGRAPHY MASS-SPECTROMETRY OF DIMETHYL DISULFIDE DERIVATIVES

The determination of the positions of double bonds after dimethyl disu lfide (DMDS)) addition is described for triunsaturated compounds (alka trienes and an ester). Different DMDS derivatives were studied accordi ng to the numbers, n(1) and n(2), of methylene groups separating the d ouble bonds. When n(1) and n(2) are smaller than four, a bicyclic thio ether is formed and a predictable fragmentation pathway is observed in each case after electron ionization, allowing the determination of th e positions of the three double bonds and the molecular structure of t he compounds. (C) 1997 by John Wiley & Sons, Ltd.