THE THERMAL INVESTIGATION OF SOME NORMAL PROPYLAMMONIUM SALTS IN THE SOLID-STATE

Normal propylammonium salts of general formula (C3H7)nNH4-nX, where X is Cl, Br or HSO4 and n is 1-3, have been synthesised. The purity of the salts was checked by elemental analyses and none of the salts was found to contain free acid or base. Some of the salts are very hygroscopic; they undergo dehydration before decomposition, showing identical endothermic DTA peak(s). The anhydrous salts undergo thermal decomposition leading to total volatilisation. Some of the salts also show phase transition. In some cases, DTA phase transition peaks escape detection because they overlap with DTA dehydration peaks. The activation energy E(a)star, enthalpy change DELTAH and entropy change DELTAS were evaluated for the dehydration and decomposition reactions of the salts, using some standard methods. A linear correlation between the values of E(a)star and DELTAS for the decomposition reaction of the salts was observed. The order of stability of the salts with respect to E(a)star and the number of propyl groups is also given.