Phase Transfer Catalysis: Oxidation of 2-Methyl-1-butanol

In liquid–liquid systems, the substrates in the liquids are inaccessible to each other for the reaction. By adding a small quantity of phase transfer catalyst, the reaction can be made accessible and accelerated. The present study involves the phase transfer catalyzed oxidation of 2-methyl-1-butanol by quaternary ammonium permanganate (tricaprylyl methyl ammonium permanganate). The attempt was to compare the kinetics under homogeneous and heterogeneous conditions. Experiments were conducted in a batch reactor to determine the kinetics under homogeneous conditions. A baffled borosilicate agitated reactor was used to find the enhancement factor and the kinetics under heterogeneous conditions. The rate constants determined under both homogeneous and heterogeneous conditions agreed very well. The oxidation was found to be first order with respect to each of the reactants, quaternary ammonium permanganate and the alcohol, resulting in an overall second order rate expression. Aliquat336 (tricaprylylmethylammonium chloride) was found to be the best compared with the other catalysts tested (triethylbenzylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide and tetrabutylammonium hydrogen sulfate) and it gave an enhancement factor of 9.8.

Graphical abstractThe oxidation of 2-methyl-1-butanol by potassium permanganate was carried out by using tricaprylylmethyl ammonium chloride as the phase transfer catalyst (PTC), under both homogeneous and heterogeneous conditions. The kinetics obtained was compared.A baffled borosilicate agitated reactor was employed to find the enhancement factor and the kinetics under heterogeneous conditions. 2-methyl-1-butanol and PTC in benzene was contacted with aqueous potassium permanganate for the oxidation.The oxidation was found to be first order with respect to each of the reactants, quaternary ammonium permanganate and the alcohol. Aliquat336, giving an enhancement factor of 9.8, was found to be a better PTC than other catalysts tested.Figure optionsDownload full-size imageDownload as PowerPoint slide