Unimolecular and Bimolecular Reactions of the β-Distonic Ion CH3CH2OH+CH2CH2. : An Experimental and Theoretical Study

Article abstract of DOI:10.1021/j100027a026

In the gas phase, the unimolecular reaction of the metastable β-distonic ion 1, CH3CH2OH⁺CH2CH2^., yields a CH3CHOH⁺ fragment ion.Experiments using isotopomers of 1 and ab initio calculations show that two pathways lead to its dissociation: (i) a 1,4-H migration leading to the α-distonic ion 2, CH3CH^.OH⁺CH2-CH3 with subsequent elimination of C2H5^.; (ii) a H transfer within a ^.+ intermediate complex 3 followed by loss of C2H5^..Two isomerization processes can occur prior to dissociation: a rapid permutation of the CH2 groups in the radical chain and a reversible 1,5-H migration.The calculated transition state for 1,5-H migration and those arising on the fragmentation pathways are close in energy and correspond to relatively reactions of 1 with several neutral molecules are shown to be accompanied by the same 1,4- and 1,5-H migrations.The structures of the different isomeric ions thus formed were characterized by their specific ion-molecule reactions.The energy required for the various processes observed arises from the stabilization in the initial encounter complexes between 1 and each neutral molecule.