112307-46-7Relevant academic research and scientific papers
Linear Free-Energy Relationship in the Pyridinolysis of 2,4-Dinitrophenyl p-Chlorobenzoate in Ethanol Aqueous Solution
Castro, Enrique A.,Valdivia, Jose L.
, p. 1668 - 1672 (1986)
The title reactions are kinetically studied in 44 wt percent aqueous ethanol at 25 deg C, ionic strength 0.2 M (KCl).A linear Broensted-type plot (log kN against basicity of the substituted pyridine, where kN is the second-order rate constant for the reactions) is found.The reactions are nucleophilic as shown by both the inhibition of the rate constant observed in the presence of added excess of 2,4-dinitrophenoxide ion and the value of the Broensted-type slope (β 0.94).Comparison of Broensted-type obtained with those found in the pyridinolyses of 2,4-dinitrophenyl benzoate (curved, with the center of curvature at pKa 9.5) and 2,4-dinitrophenyl p-nitrobenzoate (linear) under the same experimental conditions indicates that electron withdrawal from the remaining aryl group of the tetrahedral intermediate (T +/-) formed in these reactions shifts the center of the Broensted-type curvature toward higher pKa values and hence favors amine expulsion from T +/- relative to 2,4-dinitrophenoxide ion.Activation parameters for the reactions of the title substrate with 3-methyl- and 4-(dimethylamino)pyridines are reported and their values discussed in comparison with the ones found for similar reactions.
