Conformational analysis and intramolecular interactions in 2-haloethanols and their methyl ethers

The conformational isomerism of 2-haloethanols and their methyl ethers has been theoretically investigated in the isolated state and rationalized on the basis of intramolecular interactions. One of the gauche conformers of 2-haloethanols is significantly more stable than the remaining forms, particularly due to intramolecular hydrogen bonding OH⋯X. Natural bond orbital analysis and comparison with the corresponding methyl ethers, which do not experience intramolecular hydrogen bonding, reinforce this finding. The electrostatic nature of the hydrogen bonding was found to be preponderant, while the hyperconjugative contribution for this interaction increases on going from F to I.