Thermal ion-molecule reactions in oxygen-containing molecules. Condensation-elimination reactions in n-propyl acetate

Abstract

Thermal ion-molecule reactions in n-propyl acetate have been studied using a time-of-flight mass spectrometer. The appearance potentials and ionization efficiency curves of the fragment and product ions were measured by an RPD technique and the fine structures in the curves were clarified. The protonated molecular ion resulted from the proton transfer reactions of CH 3COOH 2 + and CH 3CO + with n-propyl acetate, and the protonated dimer ion from the condensation reaction of the protonated molecular ion with an n-propyl acetate molecule. In the proton transfer reaction by CH 3COOH 2 +, the transfer of the carboxyl group proton predominates as compared with that of the acetyl group proton. The acetylated ions were formed by the condensation and condensation-elimination reactions, and the condensation-elimination reaction involving CH 3COOH 2 + is via a cross-elimination mechanism which eliminates a water molecule.