Reactivity Consequences of Conformational Isomerism in 1-Propanol

We present an electronic-structure study of the O(P-3) 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 alpha, beta, and gamma sites (C alpha < C beta < C gamma) does not apply to the gauche-gauche' conformer, for which abstraction at one of the C gamma sites exhibits a lower barrier than at the two C beta 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.