Polymorphism and solvates. Application to pharmaceutical compounds

Abstract
This article is the text of the lecture presented for the XXVII JEEP in Montpellier. Polymorphism is well known in inorganic chemistry, it is relative to the variation of temperature and pressure. In organic chemistry the subject is more delicate because it does not depend only on these two functions, but also the way of preparation of the substance, the nature of the solvent of crystallisation, its rate of evaporation, and for melted compounds, the rate of cooling is also an important factor. In these conditions the study of polymorphism cannot be dissociated of the study of solvates. General knowledge will be presented in this paper, but also some particular cases in which equilibrium is difficult to reach.