CORRELATION ANALYSIS OF STRUCTURE & REACTIVITY IN THE OXIDATION OF AROMATIC ALDEHYDES BY 2-PICOLINIUM CHLOROCHROMATE

The reaction of 2-picolinium chlorochromate (PICC) with thirty-six monosubstituted benzaldehydes in dimethylsulphoxide (DMSO) results in the production of the corresponding benzoic acids by oxidation. An enzymatic reaction exhibiting Michaelis-Menten kinetics was observed in relation to the reactants. The process is facilitated by hydrogen ions; the hydrogen ion dependency is expressed as kobs= a + b [H+]. The oxidation of deuterated benzaldehyde (PhCDO) showed a significant main kinetic isotope impact. The reaction was examined in nineteen distinct organic solvents, and the influence of the solvent was analyzed using Taft's and Swain's multi-parametric equations. The oxidation rates of benzaldehydes with para and meta substitutions exhibited a strong association using Charton's tri-parametric LDR equation. On the other hand, the oxidation of benzaldehydes with ortho substitutions showed a good correlation using the tetra-parametric LDRS equation. The oxidation of benzaldehydes with para-substituents is more influenced by the delocalized effect compared to the oxidation of compounds with ortho- and meta-substituents, which show a stronger reliance on the field effect. The occurrence of a positive value of  indicates the existence of an electron-deficient reaction center in the rate-determining step (r.d.s.). The reaction experiences steric acceleration due to the ortho-substituents. An appropriate mechanism has been suggested.