PO A 7 THERMAL CHARACTERISATION OF SOME NEW BIS-XANTHINE DERIVATIVES

In our previous papers [1,2] thermal and pharmaceutical characterisation of some new xanthine derivatives has been presented. In order to enhance and multiply the pharmacological properties of theophylline, the bis-xanthine derivatives, with various substituents in the 8-position have been synthesised. Their chemical structures have been assessed by infrared (IR) and 1H-NMR spectroscopy and elementary analysis, being: This paper deals with thermal behaviour of seven bis-xanthine derivatives followed by thermogravimetry (TG) and differential scanning calorimetry (DSC) and their pharmacological activity. It has been established that the substituent significantly influences the thermal behaviour of the compounds. Some bis-xanthine derivatives (XXIX, XXXII), XXXIII) melt without decomposition as relatively low temperatures and decompose in two steps, while the others ones melt with decomposition and their thermo-oxidative decomposition takes place in a single step, This step is characterised by an intermediary onset temperature placed between those of theophylline and bis-xanthine but the temperature correspondin