New In Situ Catalysts Based on Nitro Functional Pyrazole Derivatives and Copper (II) Salts for Promoting Oxidation of Catechol to o-Quinone

Herein, new substituted ligands based on pyrazole (L-1-L-4) were synthesized via a one-step by condensing (1H-pyrazole-1-yl) methanol with different primary amine compounds. The present work utilized the catalytic properties of the in situ complexes formed by these ligands with various copper (II) salts viz. Cu(CH3COO)(2), CuSO4, CuCl2, and Cu(NO3)(2) for the oxidation of catechol to o-quinone. The studies showed that the catalytic activities depend on the nature and concentration of the ligand, the nature of the counterion, and the solvent. It was observed that the complex formed by L-2 and Cu(CH3COO)(2) exhibited good catalytic activity in methanol with V-max of 41.67 mu mol L-1 min(-1) and K-m of 0.02 mol L-1.

Automated summary

In this study, new substituted ligands based on pyrazole (L-1-L-4) were synthesized via a one-step condensation reaction. These ligands formed in situ complexes with various copper (II) salts, and catalyzed the oxidation of catechol to o-quinone. The catalytic activity depended on the ligand, counterion, and solvent. The complex formed by L-2 and Cu(CH3COO)(2) exhibited the highest catalytic activity in methanol.