Micellar and Solvent Effects on the Rate of Reaction Between L-Tyrosine and Ninhydrin

Abstract

Kinetics of the reaction of L-tyrosine and ninhydrin has been studied spectrophotometrically at pH = 5.0 and temperature 80°C in aqueous, aqueous-organic and aqueous cationic micelles of cetyltrimethylammonium bromide (CTAB). The product formed in all the media remains the same. Also, the reaction is catalyzed in both organic solvent and CTAB micellar media. The results obtained in micellar media are treated quantitatively in terms of pseudo-phase model. The rate constants and binding constants with the micelles have been evaluated.

Keywords:

• Kinetics
• L-tyrosine
• micellar catalysis
• ninhydrin
• nonaqueous solvents

Notes

[Ninhydrin] = 5.0 × 10⁻³ mol dm⁻³, [Tyrosine] = 1.0 × 10⁻⁴ mol dm⁻³.

^a [CTAB] = 2.0 × 10⁻² mol dm⁻³, Temperature = 80°C.

^a [CTAB] = 2.0 × 10⁻² mol dm⁻³.

^b Calculated from Eyring Equation. [Ninhydrin] = 5.0 × 10⁻³ mol dm⁻³, [Tyrosine] = 1.0 × 10⁻⁴ mol dm⁻³, pH = 5.0.

^a Calculated from Equation (2). [Ninhydrin] = 5.0 × 10⁻³ mol dm⁻³, [Tyrosine] = 1.0 × 10⁻⁴ mol dm⁻³, pH = 5.0, Temperature = 80°C.

^a [CTAB] = 2.0 × 10⁻² mol dm⁻³. [Ninhydrin] = 5.0 × 10⁻³ mol dm⁻³, [Tyrosine] = 1.0 × 10⁻⁴ mol dm⁻³, pH = 5.0, Temperature = 80°C.

^a [CTAB] = 2.0 × 10⁻² mol dm⁻³. [Tyrosine] = 1.0 × 10⁻⁴ mol dm⁻³, [Ninhydrin] = 5.0 × 10⁻³ mol dm⁻³, pH = 5.0, Temperature = 80°C.