Thermoanalytical investigations on heterocyclic organic compounds. Part I. Thermal decomposition of pyrazolinoimides

Pyrazolinoimides undergo denitrogenation reaction upon heating to form the cyclopropane derivatives and the corresponding olefins. They are studied by dynamic TG, DTG, DTA and DSC techniques. The enthalpies and kinetic parameters are evaluated. Further decomposition of the compounds led to carbon, and in some cases, polymeric products are suspected to be formed. The fluorene derivatives behave differently and undergo irreversible isomerization in the melt prior to decomposition. Practical mechanistic steps are postulated in order to explain the formation of the decomposition, rearrangement and isomerization products during thermal treatment.