ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

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

Raissi Hanen, Mahdhaoui Faouzi, Ayachi Sahbi, and Boubaker Taoufik

Laboratoire de Chimie Hétérocyclique, Produits Naturels et Réactivité (LR11ES39), Faculté des Sciences, Université de Monastir, Monastir, Tunisia

E-mail: boubaker_taoufik@yahoo.fr

Received: 4 May 2022  Accepted: 9 September 2022

Abstract:

Kinetics of the S_NAr reactions of four 7-L-4-nitrobenzofurazans 1a-d (L = Cl, OC₆H₅, OCH₃, 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).

Keywords: Kinetic; Equation of Mayr; Nucleophilicity parameter (N); Theoretical nucleophilicity index (ω−1); Benzofurazans; Secondary cyclic amines

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-022-02483-8

Chemical Papers 77 (1) 307–319 (2023)