Photochemistry of Stilbene-Amine. Spin-Trapping Study

Article abstract of DOI:10.1021/jo00017a009

2-Methyl-2-nitrosopropane (MNP) was used as a spin-trap reagent to study the radicals formed in the photochemical reaction of substituted trans-stilbenes (TS) with tertiary amines.Seven 1,2-(p,p'-disubstituted phenyl)ethyl radicals were trapped by MNP and isolated and identified by HPLC-EPR.The nitrogen hyperfine splitting constants (hfsc) of these radicals are linearly correlated with the Hammett substituent constants δ_p.There is also a linear correlation of the nitrogen hfsc with both the single δ_p parameter and the dual δ_R, δ₁ parameters.The inductive and resonance effects are of equal importance.The correlation between proton hfsc and a single δ_p parameter is not linear.There is fair correlation between the β-proton hfsc and the dual parameters δ_R, δ₁.The only fair correlation may be due to the large dihedral angle between the nitrogen ? orbital and the N-C-H plane.