Cu(II) mediated oxidation of L-phenylalanine with chromic acid in micellar medium: A kinetic and mechanistic approach

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.