Kinetic Study of the Hydrolysis of BNPP by the Cerium(III) Complex

Abstract

5,5,7,12,12,14-Hexamethyl-1,4,8,11-tetraazacyclotetradecane (L) was synthesized and characterized. The kinetics of hydrolysis of bis(p-nitrophenyl)phosphate (BNPP) in the catalytic system containing macrocyclic ligand and cerium(III) was investigated. This catalytic system show high catalytic activity and better reproducibility and stability than other similar systems in the range of pH of around 5.6–7.2. The stoichiometry and spectral analysis showed that the real active species is the macrocyclic complex of cerium(III). Based on the analytical results of the specific absorption spectra, an intramolecular nucleophilic substitution mechanism for the catalytic hydrolysis of BNPP is proposed, a correlative kinetic mathematical model is established, and the corresponding thermodynamic and kinetic constants are calculated.

Keywords:

• Cerium(III)
• hydrolysis kinetics
• macrocyclic ligand
• phosphate ester

Acknowledgments

The work was supported by the Scientific and Technological Support project of Science and Technology Agency of Sichuan Province of China (No. 2010GZ0130, No. 2009JY0072), the Key Project issued by Education Department of Sichuan Province of China (No. 09ZA057), and the Specialized Research Fund for the Doctoral Program of Sichuan University of Science and Engineering (No. 2009SK4).

Notes

Conditions: pH = 6.40; [cerium(III)] = 0.5 × 10⁻² mol L⁻¹; [L] = 0.5 × 10⁻² mol L-1; [BNPP] = 5 × 10⁻⁵ mol L⁻¹.

Conditions: pH = 6.40; [Cerium(III)] = 0.5102 mol L⁻¹; [L] = 0.5 × 10⁻² mol L⁻¹; [BNPP] = 5 × 10⁻⁵ mol L⁻¹.