Studies on the kinetics of imidazolium fluorochromate oxidation of some meta‐ and para‐substituted anilines in nonaqueous media

Abstract

The imidazolium fluorochromate (IFC) oxidation of meta-and para-substituted anilines, in seven organic solvents, in the presence of p-toluenesulfonic acid (TsOH) is first order in IFC and TsOH and is zero order with respect to substrate. The IFC oxidation of 15 meta-and para-substituted anilines at 299-322 K complies with the isokinetic relationship but not to any of the linear free energy relationships; the isokinetic temperature lies within the experimental range. The specific rate of oxidizing species-anilines reaction (k 2 ) correlates with substituent constants affording negative reaction constants. The rate data failed to correlate with macroscopic solvent parameters such as ε r and E N T . A correlation of rate data with Kamlet-Taft solvatochromic parameters (α, β, π * ) suggests that the specific solute-solvent interactions play a major role in governing the reactivity, and the observed solvent effects have been explained on the basis of solute-solvent complexation.

Substituent and Solvent Effects on the Electrochemical Oxidation of para- and meta-Substituted Anilines

“…The values of the reaction constant, ρ, were found to be negative, which confirms the formation of a positively charged transition state. The reaction constants obtained in the present study are comparable to those of previously reported oxidation of anilines by various oxidants (percarbonate, ρ = −2.7 [28]; perborate, ρ = −3.0 [29]; pyridinium chlorochromate, [30], and imidazolium fluorochromate, ρ = −2.22 [31]). …”

Meso-tetraphenylporphyriniron(iii) chloride catalyzed oxidation of aniline and its substituents by magnesium monoperoxyphthalate in aqueous acetic acid medium

“…This was in agreement with the literature value 19 . The melting point of the product obtained is 68 o C which is in agreement with literature value 16, 20 .…”

Preferential solvational effects on the Cr(VI) oxidation of benzylamines in benzene/2‐methylpropan‐2‐ol mixtures

“…Catalysis by p-toluenesulfonic acid suggested protonation of IFC species rather than the benzylamine molecule, which would have resulted in rate retardation. Parallel observations were made in the oxidation of substituted anilines by the same oxidant [4]. The participation of protonated chromium species in Cr(VI) oxidations is well known [15].…”

“…The negative sign of the coefficients of the α term suggests that the specific interaction between the reactants and the solvent (through the HBD property) is relatively more than that between the transition state and the solvent. Since 2-methylpropan-2-ol is a typical HBD solvent, it forms a sheath of solvent shell around the lone pair of electrons residing on N-atom (as shown below) through H-bond donation or, in other words, acts as a very mild form of a blocking reagent [4,7]. Thus restricting the approach of the oxidant molecule to form the transition state and consequently retarded the rate of the oxidation.…”