LOW MOLAR-MASS AND OLIGOMERIC HEXAZADIENES - SYNTHESIS, THERMOLYSIS AND PHOTOLYSIS

Several new low molar mass 1,6-diarylhexazadiene model compounds and a oligomeric structure, containing hexazadiene units in the main chain, were prepared by N-N-coupling of aromatic diazonium salts with hydraz ine derivatives. Thermolytic and photolytic decomposition of these lab ile compounds have been studied in detail. A strong dependence of the decomposition rate on the substitution pattern was observed. Electron donating aromatic substituents as well as methyl groups at N-3 and N-4 position decrease stability in photolysis and thermolysis. On the oth er hand electron withdrawing aromatic substituents and acetyl groups a t N-3 and N-4 stabilize the hexazadiene unit. Kinetics analysis showed that in some cases the decomposition reaction may be described by uni molecular one step pathway. Activation energies and rate constants hav e been evaluated. The oligomeric hexazadiene exhibits a somewhat highe r stability towards heat and light compared to the low molar mass mode l compounds.