On the formation of protonated acetic acid from ionized n‐alkanoic acids in the gas phase

Abstract By means of collisional activation mass spectrometry and semi‐empirical molecular orbital calculations (MNDO) it is shown that the [C 2 H 5 O 2 ] + ions from metastable molecular ions of n ‐pentanoic and hexanoic acid have the structure of carbonyl protonated acetic acid [CH 3 C(OH) 2 ] + . The MNDO calculated geometries of this ion and some other isomeric forms are given together with the Δ H f 0 values.