Kinetics of the Reactions of 4-Nitrochlorobenzene with Substituted Phenols in the Presence of Potassium Carbonate
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The kinetics of 4-nitrochlorobenzene (4-NCB) reactions with substituted phenols in the presence of potassium carbonate in N,N-dimethylacetamide was studied. Depending substituents, the reactivity of the phenols is changed in the series 3-NO2> 4-Cl > H > 4-Br > 3-CH3> 3-NH2, which is consistent with the series of their acidity. The reaction rates satisfactorily correlate with the pKavalues of the corresponding substituted phenols. Based on kinetic data (first-order and zero-order reactions with respect to phenol and 4-NCB, respectively, and the consistency of the reactivity and acidity of substituted phenols), the deprotonation of phenols is considered as the rate-determining step of the overall reaction under the test conditions. A reaction scheme was proposed for the synthesis of diaryl ethers in the presence of potassium carbonate. It involves a heterogeneous step of phenol deprotonation, which takes place on the surface of potassium carbonate, and a homogeneous step of the interaction of potassium phenolates with 4-NCB. Under the reaction conditions, the resulting bicarbonate decomposes with the formation of potassium carbonate and with the release of carbon dioxide and water.
KeywordsEther Dioxide Phenol Carbon Dioxide Acidity
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