The use of ion‐molecule reactions in the mass spectrometric location of double bonds

Abstract

Abstract A method for the location of the positions of carbon‐carbon double bonds using high pressure mass spectrometry is proposed. A known olefinic molecular ion reacts with a second, unknown olefin to form a four‐centre complex, which fragments with retention of the structural identity of methylene and substituted methylene groups to eliminate a new olefin molecule and to form an unsaturated ion from which the position of the double bond in the unknown olefin can be inferred. Vinyl methyl ether proved to be a convenient reagent gas and its molecular ion undergoes the required reaction with several classes of olefinic compound. Conjugated dienes and unsaturated compounds containing electronegative groups do not undergo this reaction.