28053-14-7Relevant academic research and scientific papers
Synthesis, thermochemistry, and reactions of vicinal bis(azoalkanes). The chemistry of α- and β-azo radicals
Engel, Paul S.,Wang, Chengrong,Chen, Yanqin,Rüchardt, Christoph,Beckhans, Hans-Dieter
, p. 65 - 74 (2007/10/02)
Two vicinal bis(azo)alkanes, 8P and 8B, were prepared from acetone phenylhydrazone (APH) and acetone tert-butylhydrazone (ATBH), respectively. Thermolysis of 8P above 130°C in the presence of thiophenol affords APH in quantitative yield, showing that the central C-C bond of 8P cleaves in preference to the usual C-N homolysis of azoalkanes. The resulting radicals 9P recombine to the C-N dimer 16P about 40 times faster than to the more stable C-C dimer 8P. From the combustion heat of 8P, we deduce that its strain enthalpy Hs is 5.5 kcal/mol, while the resonance stabilization energy (RSE) of 9P is 15.3 kcal/mol. The tert-butyl analog 8B loses 2 mol of N2, showing that C-N homolysis greatly dominates over C-C homolysis. Nevertheless, we estimate that the latter process would occur with ΔG* (150°C) > 40.3 kcal/mol, which implies that the RSE of aliphatic hydrazonyl radical 9B is at least 6 kcal/mol below that of 9P and is little or no more than the RSE of the 1,1-dimethylallyl radical.
ALKALINE ISOMERIZATION OF PHENYLHYDRAZONES TO ALKYLPHENYLDIIMIDES
Kuznetsov, M.A.,Suvorov, A.A.
, p. 1684 - 1691 (2007/10/02)
When solutions pf phenylhydrazones in tri- or tetraethylene glycol are heated in the presence of the corresponding sodium glycolate, they undergo isomerization to alkylphenyldiimidates.There is a marked decrease in the isomerization rate in the transition from the hydrazones of aldehydes to the hydrazones of ketones.With the phenylhydrazones of ketones the reaction takes place almost unambiguously, but in the case of hydrazones of aldehydes it is complicated to an appreciable extent by side processes such as indolization and aminonitrile cleavage.
