Cu(II) mediated oxidation of L-phenylalanine with chromic acid in micellar medium: A kinetic and mechanistic approach
Abhishek Srivastava, Rajeev Kumar Dohare, Nitin Srivastava, Ruchi Singh
Abstract
The objective of the proposed investigation is to examine the influence of cationic, anionic, and neutral surfactants on the Cu(II) facilitated L-Phenylalanine (Pheala) oxidation using chromic acid. The oxidation rate is ascertained by measuring the decrease in absorbance at a wavelength of 350 nm, which is an indicator of the Cr(VI) concentration. The reaction's advancement is assessed employing the pseudo-first-order condition as a gauge for [H + ], [Cr(VI)], ionic strength, [Pheala], [Cu(II)], [Surfactant], and temperature. Pheala and Cr(VI) interact stoichiometrically in a ratio of 3:2. Across the spectrum of concentrations examined, the studied reaction reflects fractional-first-order kinematics in relation to both [Pheala], and Cu(II), first-order reliance on the [Cr(VI)], and fractional-second-order for [H + ]. A zero salt effect is suggested by the observed constancy in oxidation rate with the inclusion of electrolyte. The oxidation rate is 3.5 times enhanced by Cu(II) solution (as a catalyst) at ppm concentration. SLS micellar media enables a further twofold increase in the rate of Pleala oxidation. TX-100 also promotes Pheala oxidation, however, CTAB, a cationic surfactant, inhibits it. As a catalyst, SLS exhibits the best compatibility with Cu(II) metal salt.