Pyrolysis of hydrazines and their derivatives often results in homolytic cleavage of the N N bonds, but
molecular rearrangements and eliminations are also observed in many cases. Thermal reactions in solution,
in the solid state, and in the gas phase under static, flow, and flash vacuum pyrolysis conditions
are considered in this review. Arrhenius or Eyring activation parameters are reported whenever available,
but the original literature should always be consulted, as these parameters are often derived under
widely different experimental conditions. The compound classes investigated include open-chain and
cyclic hydrazine derivatives and their relationship with azomethine imines, N-amino-heterocycles, Nisocyanoamines
and N-isocyanatoamines, N-aminocarbodiimides, azines, hydrazones, semicarbazides
and semicarbazones, hydrazides, aminimides, amidrazones, azimines, triazenes, tetrazadienes, pentazadienes
and hexazatrienes, and triazines. Understanding of reaction mechanisms is emphasized whenever
possible. Reactive intermediates involved in these pyrolysis reactions include ketenes, ketenimines and
other cumulenes, free radicals and diradicals, zwitterions, carbenes, nitrenes, nitrile ylides, nitrile imines,
arynes and azetes.