Kinetics of the alkaline hydrolysis of fenuron in aqueous and micellar media

Abstract

The kinetics of the hydrolysis of fenuron in sodium hydroxide has been investigated spectrometrically in an aqueous medium and in cationic micelles of cetyltrimethylammonium bromide (CTAB) medium. The reaction follows first-order kinetics with respect to [fenuron] in both the aqueous and micellar media. The rate of hydrolysis increases with the increase in [NaOH] in the lower concentration range but shows a leveling behavior at higher concentrations. The reaction followed the rate equation, 1/k obs = 1/k, where k obs is the observed rate constant, k is rate constant in aqueous medium, and K is the equilibrium constant for the formation of hydroxide addition product. The cationic CTAB micelles enhanced the rate of hydrolytic reaction. In both aqueous and micellar pseudophases, the hydrolysis of fenuron presumably occurs via an addition-elimination mechanism in which an intermediate hydroxide addition complex is formed. The added salts decrease the rate of reaction. C 2007

Alkaline Hydrolysis of Methyl Decanoate in Surfactant-Based Systems

“…In addition to the nonionic surfactants, alkyltrimethylammonium bromides with an alkyl chain length from 10 to 16 have been investigated as cationic surfactants to evaluate the impact of the hydrophobicity of the surfactant on the reaction performance. The cationic surfactants have been applied as they frequently show the potential to increase the reaction rate of hydrolysis reactions. − …”

Effects of Surfactants on the Rate of Chemical Reactions

“…The emulsifier surfactant, DSB, at a level greater than its CMC generated particle nuclei by micelle nucleation and controlled the particle size, particle size distribution, and the rate of polymerization. surfactants first increase and then decrease with increase in surfactant concentration [61][62][63][64][65][66][67][68] and the catalytic effect of cationic surfactants increases with the increase of their chain length [61,66,68]. Also, the reaction rate decreases in the presence of anionic surfactants [63,65,67,69] and decreases with increase in the surfactant chain length [70].…”

Reactivity in organised assemblies

“…Similarly, base-catalysed hydrolysis of fenuron, another urea derivative, was explored by the same authors in cationic micelles. 55 The rate acceleration of the hydrolysis can be explained by the stabilisation of the negatively charged intermediates by the surfactant molecules.…”