Ion—molecule reactions of CH 3+ and CD 3+ with acetic acid, methyl acetate, dimethyl ether and ethylene oxide

Abstract

A tandem Dempster-ion cyclotron resonance mass spectrometer was used to study the reactions of CH 3 + and CD 3 + ions with acetic acid, methyl acetate, dimethyl ether, and ethylene oxide at near thermal translational energies (∼0.1 eV). The only product observed for CH 3 + and CD 3 + reactions with acetic acid or methyl acetate was CH 3CO +. Reaction of CH 3 + with ethylene oxide yields C 2H 3O + (45%), C 2H 4O + (3%), C 2H 5O + (6%), C 2H 3 + (7%), CHO + (28%), C 2H 5 + (5%), and CH 3O + (6%). Reaction of CD 3 + with ethylene oxide results in considerable isotopic scrambling in the ionic products. The reaction of CH 3 + with dimethyl ether yields only two ionic products, C 2H 5O + (95%) and C 2H 6O + (5%). However, CD 3 + reactions with dimethyl ether show that reaction occurs primarily via a trimethyloxonium ion intermediate (∼60%), which dissociates to yield CD 3OCH 2 +, CH 3OCH 2 +, and CH 3OCD 2 + products. The remainder of the reaction products may be attributed to hydride abstraction (35%) and charge transfer (∼5%).