Elucidation of the Nucleophilic Potential of Diazocyclopentadiene

Abstract

Diazocyclopentadiene reacts with benzhydrylium ions (Ar2CH+) to give 2,5-dibenzhydryl-substituted diazocyclopentadienes. The kinetics have been determined photometrically in dichloromethane under pseudo-first-order conditions using diazocyclopentadiene in excess. Plots of the second-order rate constants (log k 2) versus the electrophilicity parameters E of the benzhydrylium ions gave the nucleo­philicity parameter N = 4.84 and susceptibility s N = 1.06 for diazo­cyclopentadiene according to the correlation log k(20 °C) = s N(E + N). Diazocyclopentadiene thus has a similar nucleophilic reactivity as pyrrole. Previously reported electrophilic substitutions of diazocyclopentadiene are rationalized by these parameters and new reaction possibilities are predicted.

Measuring Kinetics under Vibrational Strong Coupling: Testing for a Change in the Nucleophilicity of Water and Alcohols

“…10 -5 M to obtain absorbance values of around 1. [21,28,29] In contrast, we used significantly higher concentrations of E of approx. 2.4 mM.…”

“…Numerous studies of the capture of carbocations by alcohols and water report that this reaction can proceed with or without general base catalysis. [29][30][31][32] In other words, a base like lutidine may be involved in the rate-determining step. Thus, we initially studied the dependency of the reaction rate on the concentration of lutidine to investigate whether general base catalysis is relevant in our system.…”