Low molar mass and oligomeric hexazadienes. Synthesis, thermolysis and photolysis

Abstract

AbstractSeveral 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 hydrazine derivatives. Thermolytic and photolytic decomposition of these labile 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 N3 and N4 position decrease stability in photolysis and thermolysis. On the other hand electron withdrawing aromatic substituents and acetyl groups at N3 and N4 stabilize the hexazadiene unit. Kinetics analysis showed that in some cases the decomposition reaction may be described by unimolecular one step pathway. Activation energies and rate constants have been evaluated. The oligomeric hexazadiene exhibits a somewhat higher stability towards heat and light compared to the low molar mass model compounds.