Reactivity Consequences of Conformational Isomerism in 1-Propanol.

We present an electronic-structure study of the O(3P) reaction with all 5 conformers of 1-propanol. Calculation of the potential energy profile along 37 hydrogen-abstraction reaction pathways reveals that exclusive consideration of the popular all- anti conformer fails to capture essential details of 1-propanol's reactivity. For instance, the expected trend in barrier heights for abstraction at carbon α, β, and γ sites (Cα < Cβ < Cγ) does not apply to the gauche- gauche' conformer, for which abstraction at one of the Cγ sites exhibits a lower barrier than at the two Cβ sites. This and other anomalies are traced to the ability of 1-propanol's O-H moiety to establish intramolecular hydrogen bonds in gauche C-C-O-H conformations. This study highlights the importance conformational sampling for linear alcohols in studies ranging from gas-phase reaction dynamics to adsorption on solid surfaces.