Thermochemistry and unimolecular reactivity of protonated α,ω-aminoalcohols in the gas phase

Competitive deamination and dehydration of protonated alpha,omega-antmoalcohols (1,2-aminoethanol (1), 1,3-aminopropanol (2), 1,4-aminobutanol (3) and 1,5-aminopentanol (4)) in the gas-phase has been examined by both tandem mass spectrometry experiments including metastable ions decompositions and collisional activation (CA) techniques and molecular orbital calculations. For all the precursor molecules 1-4, CA experiments demonstrate that the low energy product ions are either a protonated cyclic amine or a protonated cyclic ether. The mechanisms of the internal nucleophilic substitution reactions leading to these products have been detailed at the MP2/6-31G* level of theory. The thermochemistry associated with the initial protonation process of 1-4 has been examined up to the G2(MP2,SVP) level. (Int J Mass Spectrom 217 (2002) 195-230) (C) 2002 Elsevier Science B.V All rights reserved.