Infrared spectroscopy and the characterization of terfenadine crystallized from solvents

Abstract

Abstract In this paper the structural characterization of terfenadine crystallized from ethanol-water, ethanol and methanol is performed by infrared spectroscopy. The OH stretching vibration, composed of three markedly overlapped bands, is analyzed by peak fitting. The assignment of the hydrogen bonds was conducted making use of band parameters, spectroscopic data for CCl4 solutions, and molecular dynamics calculations from dimeric systems. Terfenadine just precipitated from solvents is never in the highest crystalline state. This state is reached when the samples are heated at a temperature above 100C. Some amorphous solid is coprecipitated with the crystalline phase, particularly in methanol.