cis-Diazenes. Pressure Effects on Their Thermal Deazatization and Isomerization Reactions

Article abstract of DOI:10.1021/jo00302a019

Effects of pressure on solution-phase rates of overall thermal decomposition, deazatization, and isomerization of several symmetric cis-diazenes (cis-azoalkanes) have been determined in hexane and in ethanol.Increasing pressure decreases all the rates.The large positive activation volumes for deazatization (e.g., +16 to +22 cm³/mol) have been interpreted in terms of a one-bond scission mechanism and an intermediate diazenyl radical.The smaller positive activation volumes for isomerization (e.g., +5 to +7 cm³/mol) are consistent with a nonradical inversion mechanism.Dramatic differences in rates between polar and nonpolar solvents are consistent with these mechanisms.