Effect of Ionic Micelle on the Oxidation of Diethylene Glycol by N-Bromophthalimide

Abstract

The kinetics of oxidation of diethylene glycol (DEG) by N-bromophthalimide (NBP) in the acidic medium in the presence of cetyltrimethylammonium bromide (CTAB), that is, cationic surfactant has been studied. In addition to kinetic experiments, conductivity measurements have also been done to obtain critical micelle concentration and other thermodynamic properties. The kinetic observations indicate fractional order dependence with respect to Substrate and inverse fractional order with respect to perchloric acid (HClO₄). The reaction has a first order dependence on NBP. Reaction is strongly catalyzed by CTAB, mercuric acetate (CH₃COO)₂Hg and phthalimide (NHP) found to inhibit the rate of reaction. The applicability of kinetic model, Berezin's model, has been tested to explain the observed micellar effect. On the basis of experimental findings, a pertinent mechanism is proposed.

Keywords:

• Cetyltrimethylammonium bromide
• diethylene glycol
• kinetics
• micellar catalysis
• N-bromophthalimide
• oxidation

Y. R. K. thanks the University Grants Commission, New Delhi, for the Research Project grant.

Notes

Reaction condition: [CTAB] 1 × 10⁻³ mol dm⁻³, [Hg (OAc)₂] = 5 × 10⁻⁴ mol dm⁻³, temp = 40°C.

Reaction conditions: [NBP] = 2 × 10⁻⁴ mol dm⁻³; [DEG] = 4 × 10⁻² mol dm⁻³; [Hg(OAc)₂] = 5 × 10⁻⁴ mol dm⁻³, [CTAB] = 1.0 × 10⁻³, Acetic acid (20%)(v/v), temp = 313 K.

Reaction condition: [DEG] = 4 × 10⁻² mol dm⁻³, [NBP] = 2 × 10⁻⁴ mol dm⁻³, [CTAB] 1 × 10⁻³mol dm⁻³, [Hg (OAc)₂] = 5 × 10⁻⁴ mol dm⁻³, [HClO₄] = 10 × 10⁻⁵ mol dm⁻³, Acetic acid (20%)(v/v), temp = 40°C.