Infrared identification of barbiturates with particular reference to the occurrence of polymorphism

Abstract

Abstract Infrared spectra of twelve substituted barbituric acids, in a total of 34 polymorphic forms, have been compared. Comparison of a sample spectrum with that of an authentic specimen provides a reliable means of identification, provided that both are in the same crystalline form. To ensure consistent production of a single form a specific treatment is recommended for each substance exhibiting polymorphism.