Authors:G. P. Bettinetti, C. Caramella, F. Giordano, A. La Manna, C. Margheritis, and C. Sinistri
Thermal analysis of the binary system benzoic acid (BA) and trimethoprim (TMP) provided evidence of the formation of two molecular compounds. BA-TMP and two crystalline forms of (BA)2-TMP were characterized on the basis of their thermodynamic parameters as well as of crystallographic and spectroscopic properties. The availability of these compounds (by recrystallization) allowed interpretation of thermal effects in the DSC curves of the mixtures and the theoretical phase diagrams could be drawn. The results are consistent with the model of a very slight dissociation of the molecular compounds in the melt.