Solvent effect, quantification and correlation analysis of the nucleophilicities of cyclic secondary amines

• Published in: Chemical papers Vol. 77; no. 1; pp. 307 - 319
• Main Authors: Hanen, Raissi, Faouzi, Mahdhaoui, Sahbi, Ayachi, Taoufik, Boubaker
• Format: Journal Article
• Language: English
• Published: Warsaw Versita 2023; Springer Nature B.V
• Subjects: Amines; Biochemistry; Biotechnology; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Correlation analysis; Density functional theory; Free energy; Industrial Chemistry/Chemical Engineering; Materials Science; Medicinal Chemistry; Nucleophiles; Original Paper; Parameters; Rate constants; Solvent effect; Solvents; Benzofurazans; Kinetic; Theoretical nucleophilicity index (ω; ); Equation of Mayr; Secondary cyclic amines; Nucleophilicity parameter
• ISSN: 0366-6352; 1336-9075; 2585-7290
• DOI: 10.1007/s11696-022-02483-8

Kinetics of the S N Ar reactions of four 7-L-4-nitrobenzofurazans 1a-d (L = Cl, OC 6 H 5 , OCH 3 , Im + , Cl − ) with three cyclic secondary amines 2a-c in methanol as well as in dimethylsulfoxide (DMSO) at 20 °C were reported. The derived second-order rate constants ( k ) in both solvents and the previously published E parameters of electrophiles 1a-d were used to determine the nucleophile-specific parameters N and s N for these series of amines according to the linear free energy relationship log k (20 °C) =  s N ( N  +  E ). The solvent effect and the electronic nature of substituent L on the reaction rate were examined quantitatively on the basis of kinetic measurements, leading to linear correlations of log ( k Methanol ) versus log ( k DMSO ) and log ( k ) versus Hammett’s substituent constants ( σ ). In addition, theoretical nucleophilicity index (ω −1 ) for these series of amines 2a-c has been calculated using a density functional theory (DFT) method and demonstrated that these values are linearly related to the experimental nucleophilicity parameters ( N ).