Heterolytic breakdown

Szabo et al. [64] used NH4HSO4 as a solvent to enable reproducible kinetic data to be obtained for NH4NO3 decomposition. The first step is identified as thermal dissociation followed by heterolytic breakdown of the nitric acid formed ... 

The combination of neutral non-aromatic and zwitterionic aromatic contributing valence bond structures confers a distinctive chemical reactivity to quinone methides, which has attracted the interest of a tremendous number of chemist and biochemists. This chapter reviews reactions that generate quinone methides, and the results of mechanistic studies of the breakdown of quinone methides in nucleophilic substitution reactions. The following pathways for the formation of quinone methides are discussed (a) photochemical reactions (b) thermal heterolytic bond... 

Free radicals are produced when chemical bonds are broken by what is termed a homolytic process (13.144), as distinct from a heterolytic process in which ions are obtained (13.145). The former may be effected by thermal or photochemical means (thermolysis or photolysis), by excitation in flames, by electrolysis, by electron impact in mass spectrometers, or during radiochemical breakdown processes. 

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