IMPORTANCE OF THE ORTHO EFFECT IN HYDROGEN BONDING TO VERY WEAK BASES

Abstract

“Hydrogen bonding between hydroxyl groups and very weakly basic groups such as the halogens, electron bonds and sulfur is ordinarily not observable or else the hydroxyl frequency shifts are extremely slight. If these groups occur on an aromatic ring ortho to each other, their distances of interaction are stabilized to such an extent that hydrogen bonding is demonstrated by fairly large frequency shifts. Intramolecular hydrogen bonding of this type will be discussed for such compounds as o-allyl phenol and o-propenyl phenol. Steric effects of groups substituted meta to the hydroxyl (3-position) will be presented.”