Thermal stability and decomposition of sulphur and selenium compounds

Thermal analysis of fusion and decomposition processes was carried out on organosulphur and organoselenium compounds in order to establish thermal stability criteria. Degradation and fusion temperatures of 20 biological active compounds, synthesized by our research group were determined using thermogravimetry (TG) and differential scanning calorimetry (DSC). Analysis of the thermal data indicated that: (a) in general, sulphur compounds are more stable than selenium compounds; (b) the pyridine ring diminished stability of sulphur and selenium compounds much more than the carbocyclic aromatic rings did (6a > 9a; 2b > 3b); (c) selenomethyl derivatives are more stable than selenoethyl and selenoisopropyl compounds; (d) a chlorine atom on selenocompounds has surprising effects.