Personal Blog. Facebook is showing information to help you better understand the purpose of a Page.
Second‐order rate constants for the reactions of 2‐aryl‐4,6‐dinitrobenzotriazole 1‐oxides 1a‐d with some 4‐X‐substituted phenoxide ions 2a‐d (X = OCH 3, H, Cl, and CN) have been measured in aqueous solution at 20°C. The p K a values for the σ‐complexation processes of a series of benzotriazole 1a‐d measured in water have been used to determine their electrophilicity parameters E according to the correlation E = –3.20 – 0.662 p K a (F. Boubaker, and R. Goumont, J Org Chem, 2005, 70, 6242–6253). For these reactions, plots of log k versus the electrophilicity parameters E of the benzotriazoles 1a‐d were linear, allowing to derive the nucleophilicity parameters N and s for phenoxide ions as defined by the Mayr equation log k 1 (20°C) = s ( E + N) (H.
![Taoufik Taoufik](/uploads/1/2/5/5/125508301/121683488.png)
Angew Chem, Int Ed Engl 1994, 33, 938–957). The N values are found to cover a range of nucleophilicity from 6.85 to 10.22, going from 4‐cyanophenoxide 2d for the least reactive ion to 4‐methoxyphenoxide 2a for the most reactive nucleophile.
Good linear correlations were found between the nucleophilicity parameters N of phenoxide ions 2a‐d and the p K a values of their conjugate acids ( N = –3.05 + 1.25 p K a) and the constants of the substituents X ( N = 9.21 – 2.51).