High-Energy X-ray Diffraction Study on the Intramolecular Structure of 2-Aminoethanol in the Liquid State

High-energy X-ray diffraction measurements were carried out for liquid 2-aminoethanol (NH2CH2CH2OH, MEA) in order to obtain direct information on the conformation of MEA in the liquid state, in which competition between intra- and intermolecular hydrogen bonds might occur. Least-squares fitting analysis was applied to the high-Q region of the observed total interference term with excellent statistical accuracies. Independent parameters, the C-C, C-O, and C-N interatomic distances, bond angles, angle OCC and angle CCN, and a dihedral angle angle(NCC)-(CCO), were successfully obtained. It has been concluded that the MEA molecule takes the gauche conformation with the dihedral angle angle(NCC)-(CCO) = 53(3)degrees, suggesting the formation of the intramolecular hydrogen bond is dominant in the liquid state.