Gutmann's Donor Numbers Correctly Assess the Effect of the Solvent on the Kinetics of SNAr Reactions in Ionic Liquids |
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| Authors: | Jazmín Alarcón‐Espósito Prof. Dr. Renato Contreras Prof. Dr. Ricardo A. Tapia Dr. Paola R. Campodónico |
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| Affiliation: | 1. Departamento de Química, Facultad de Ciencias, Universidad de Chile, Casilla, Santiago, Chile;2. Facultad de Química, Pontificia Universidad Católica de Chile, Código Postal, Santiago, Chile;3. Centro de Química Médica, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Código Postal, Santiago, Chile |
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| Abstract: | We report an experimental study on the effect of solvents on the model SNAr reaction between 1‐chloro‐2,4‐dinitrobenzene and morpholine in a series of pure ionic liquids (IL). A significant catalytic effect is observed with reference to the same reaction run in water, acetonitrile, and other conventional solvents. The series of IL considered include the anions, NTf2?, DCN?, SCN?, CF3SO3?, PF6?, and FAP? with the series of cations 1‐butyl‐3‐methyl‐imidazolium ([BMIM]+), 1‐ethyl‐3‐methyl‐imidazolium ([EMIM]+), 1‐butyl‐2,3‐dimethyl‐imidazolium ([BM2IM]+), and 1‐butyl‐1‐methyl‐pyrrolidinium ([BMPyr]+). The observed solvent effects can be attributed to an “anion effect”. The anion effect appears related to the anion size (polarizability) and their hydrogen‐bonding (HB) abilities to the substrate. These results have been confirmed by performing a comparison of the rate constants with Gutmann's donicity numbers (DNs). The good correlation between rate constants and DN emphasizes the major role of charge transfer from the anion to the substrate. |
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| Keywords: | anion (solvent) effects Gutmann's donicity numbers ionic liquids Lewis acidity/basicity |
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