The polymorphism of phenobarbitone

Abstract

Abstract The polymorphism of phenobarbitone has been investigated using infrared spectroscopy, X-ray diffraction and differential scanning calorimetry. Eight crystalline modifications have been isolated and shown to have distinguishable infrared absorption spectra and X-ray powder diffraction patterns. Other forms were found to be present in mixed crystals and molecular compounds obtained from mixtures of phenobarbitone with other barbiturates. Differential thermograms of three forms of thialbarbitone are also given.