Structure-reactivity correlation in the pyridinolysis of substituted phenyl acetates |
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| Institution: | 1. Department of Pharmacy, Indira Gandhi National Tribal University, Amarkantak 484887, India;2. Department of Pharmacology and Experimental Therapeutics, College of Pharmacy & Pharmaceutical Sciences, University of Toledo, OH, USA;3. Department of Biomedical Sciences, Tuskegee University, Tuskegee, AL, USA;4. College of Pharmacy and Pharmaceutical Sciences, St. John’s University, NY, USA;5. School of Pharmaceutical Sciences, Rajiv Gandhi Proudyogiki Vishwavidyalaya, Bhopal 462036, India;1. Department of Neurosurgery, The National Hospital for Neurology and Neurosurgery, Queen Square, London, UK;2. Department of Neuropathology, The National Hospital for Neurology and Neurosurgery, Queen Square, London, UK;1. Dental Biomaterials Department, Faculty of Oral and Dental Medicine, Delta University for Science and Technology, Gamasa, Egypt;2. Chemistry Department, Faculty of Science, Mansoura University, Mansoura, Egypt;1. School of Pharmacy, Jiangsu University, Zhenjiang 212013, PR China;2. College of Chemistry and Chemical Engineering, Chongqing University of Technology, Chongqing 400054, PR China |
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| Abstract: | The pyridinolysis of substituted phenyl acetates in acetonitrile was investigated with an electric conductivity method. The rates of these reactions were increased with electron-donating group in pyridine and electron-withdrawing group in phenyl acetate, ?x (X;substituents in phenyl ring) values increase gradually according to the electron-donating ability in pyridine substituents, but the |?y|(Y;substituents in pyridine ring) values decrease with that of substituents. The β values increase with increasing electron-withdrawing ability of the substituents in the phenyl ring, it can be inferred that N---C bond formation increases progressively p-methyl to p-nitrophenyl acetates. This is in agreement with prediction of substituent effects for a simple SN2 displacement reaction. The sensitivity parameters, β and ?, are inter-related and are themselves sensitive to the reactivity of the system. All above results are interpreted in terms of a dissociative SN2 mechanism involving a metastable tetrahedral intermediate. |
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