Arrhenius parameters with amines

Saunders and co-workers (Amin et al., 1990) determined the secondary tritium KIEs for the E2 reactions of [19] with sodium ethoxide in ethanol, [20] with potassium t-butoxide in t-butyl alcohol and [21] with potassium t-butoxide in t-butyl alcohol over a temperature range of 40°C. The Arrhenius parameters were found for each isotopic reactant and the AhIAt ratios were calculated (Table 41). The AH/AT ratios for the reactions of [19] and [21] are both less than unity, confirming that, in agreement with the model calculations, tunnelling is important in these reactions. The AHIAT ratio for the reaction of... 

Howard, J.A. and E. Furimsky. 1973. Arrhenius parameters for reactions of tert-butylperoxy radicals with some hindered phenols and amines. Can.. Chem. 51 3738-3745. 

The decomposition is first order in nitrobenzene and tetrahydronaphthalene and the Arrhenius parameters obtained with various solvents for phenyl azide and some derivatives are collected in Table 16. As seen from the data, meta substitution has no efiect on the rate, and it was concluded that the rate-determining step is N2 evolution and not ring closure to form azepines (in aniline solution). In indene, Smith observed that para substituents increased the rate of Nj evolution by about eight times however, with both meta and para substituents the amine yields varied widely and in some cases the Nj yields were not quantitative with respect to the amount of azide decomposed. Benzenes and substituted benzenes have been observed in small amounts and it appears that a minor decomposition pathway would involve azide radical loss . On the other hand, Waters reports that the thermolysis of phenyl azides proceeds by different mechanisms, depending on the medium ... 

---