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Reactions of Aryl Benzoates with Potassium Aryloxides: Solvent Effects on Reaction Pathway and Kinetics
Author(s) -
Khalfina Irina A.
Publication year - 2015
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.20909
Subject(s) - chemistry , substituent , benzoates , hammett equation , reaction rate constant , medicinal chemistry , solvent , reactivity (psychology) , aryl , potassium , reaction mechanism , inorganic chemistry , kinetics , organic chemistry , catalysis , medicine , physics , alternative medicine , alkyl , pathology , quantum mechanics
Temperature dependences of the relative reactivity of potassium aryloxides XC 6 H 4 O − K + toward 2,4‐dinitrophenyl benzoate in 50 mol% dimethylformamide (DMF)–50 mol% H 2 O mixture have been studied using the competitive reactions technique. Correlation analyses of the relative rate constants k X / k H and differences in the activation parameters (ΔΔ Н ≠ and ΔΔ S ≠ ) of the competitive reactions have revealed the existence of two isokinetic series of the reactions of 2,4‐dinitrophenyl benzoate with potassium aryloxides with electron‐donating substituent (EDS) and electron‐withdrawing substituent (EWS), respectively. We have investigated the effect of the substituent X on the activation parameters for each isokinetic series and concluded that the mechanism of the reactions of 2,4‐dinitrophenyl benzoate with potassium aryloxides XC 6 H 4 O − K + in 50 mol% DMF–50 mol% H 2 O mixture is the same as in DMF. Analysis of the obtained data with using the method of two‐dimensional reaction coordinate diagram leads to the conclusion that the variation of the solvent from DMF to 50 mol% DMF–50 mol% H 2 O mixture affects the reaction pathway. The rate constant k X for the reaction of 3‐nitrophenyl benzoate with potassium 4‐methoxyphenoxide and the relative rate constants k X / k H for the reaction of 3‐nitrophenyl benzoate with potassium aryloxides XC 6 H 4 O − K + with EDS were measured in 50 mol% DMF–50 mol% H 2 O mixtures at 25°C, and it has been shown that the addition of water to DMF does not change the mechanism but slows down these reactions.