Conformational Analysis of CmH2m+1OCH2CH2OH (m = 1-4): The Role of CH.cntdot..cntdot..cntdot.O Intramolecular Interactions

Abstract

Structures and energies of the more stable conformations of C ~ H ~ ~ + I O C H ~ C(HCm~EOl, Hm = 1-4) have been determined by gradient geometry refinement at ab initio level. For m = 3 (C~EIa)n d m = 4 (C~EI )t,h e results show that attractive CH-O intramolecular interactions associated with the formation of five-membered rings in the alkylic fragments of these molecules lead to the stabilization of gauche arrangements in the CC-CO axes. Since these CH-O interactions compete, in energy terms, with conformational effects, they are found to have important structural consequences. In addition, the formation of five-membered rings closed by CH-O and OH-O contacts gives rise to vibrational couplings in the C(H2)tO!C(H2) moieties and to conformationally sensitive vibrations.