Thermal Behaviour of Some Organic Compounds with Ionic Character

Abstract

The thermal decomposition of Li, Na, K, Rb, Cs salts of formic, acetic, propionic and n-butyric acids have been investigated in air and inert gas atmosphere. The differences between the processes are described as a function of the nature of the atmosphere. It has been established that quantiative chemical analysis can be more accurately performed in oxygen atmosphere while the decomposition processes may be more precisely obtained by applying an inert gas environment. According to our experiments, the characteristic temperatures of lithium salts and formates show remarkable change with composition, while with other carboxylic acid alkali salts the peak temperature does not change significantly. In interpreting the changes in the thermal decomposition caused by substitution of the hydrogen atoms of the methyl group by alkyl and phenyl groups in the case of acetates, the mechanism described in the literature was also taken into consideration.

Nine members of the aliphatic dicarboxylic acid homologous series have been compared to show how characteristic temperatures change with the increase of the molecular weight in the case of mono sodium and disodium salts also. Study of the thermal behaviour of alkali phenolates revealed that these compounds are highly sensitive to any change of the experimental conditions. It is also characteristic that the decomposition of phenolates with and without crystal water content is markedly different even in temperature ranges above crystal water release. Their great thermal stability is also remarkable.