Catalysis of Aryl Ester Hydrolysis in the Presence of Metallomicelles Containing a Copper(II) Diethylenetriamine Derivative

Abstract

The novel metallosurfactant Cu(II)-1-tetradecyldiethylenetriamine (Cu(II)TDET) was prepared, and the hydrolyses of 2-acetoxy-5-nitrobenzoic acid (1), 4-acetoxy-3-nitrobenzoic acid (2), 4-nitrophenyl acetate (3), and 2-nitrophenyl acetate (4) in the presence of micellar Cu(II)TDET were examined. The rate of ester hydrolysis for the series followed the order 1 approximately 2>3>4. The larger observed rate (kpsi) for 1 and 2 was attributed to (i) electrostatic interaction between the carboxylate anion and the cationic metallomicelle surface and (ii) the formation of a ternary complex metal:surfactant ligand:substrate (MLnS). The position of the carboxylate anion in the substrate did not significantly affect catalysis. Similar rates were observed when the carboxylate anion was ortho to the acyl ester 1 or para to the reaction center 2. The absence of a significant difference may be associated with the ternary complex coordination geometry, which unfavorably aligned the ligated substrate and the metal-bound hydroxyl. Mixed micellar solutions containing Cu(II)TDET and MTAB or Triton X-100 were examined. Added cosurfactants have a pronounced effect on the catalytic activity of Cu(II)TDET. At a low concentration of Cu(II)TDET the addition of MTAB or Triton X-100 increased the pseudo-first-order rate constant (kpsi) for the hydrolysis of 1 and 3 relative to the rate in pure Cu(II)TDET. The addition of a cosurfactant increased the total micellar volume (VM), promoting substrate incorporation within the pseudophase. At higher metallosurfactant concentration, the rate enhancement was smaller due to the dilution of the substrate within the co-micellar pseudophase.

XAS Study of a Metal-Induced Phase Transition by a Microbial Surfactant

“…1,2 Assemblies of metal-chelating surfactants have been utilized in a variety of fields such as catalysis, 3,4 environmental remediation of toxic metals, 5,6 and magnetic resonance imaging contrast agents. 7 Some metal chelating surfactants undergo a change in aggregate morphology upon metal coordination.…”

Metallomicelles as potent catalysts for the ester hydrolysis reactions in water

“…Investigations were also carried out with the metallomicelle mediated esterolysis of different substituents on the substrate [49]. rate of hydrolysis over the neutral one.…”

Complexation of 1-Alkyl-4-Aza-1-Azoniabicyclo[2.2.2]Octane Bromides with Transition Metal Cations in Acetone

“…[1], при цинковании, меднении и других процессах гальванотехники [2], в магнитно-резонансной томографии [3,4], в качестве антимикробных и антигрибковых агентов [5], катализаторов реакции Сузуки -Мияура [6], Дильса -Альдера [7], гидрогенизации [8], окисления [9], гидролиза эфиров фосфорных и карбоновых кислот [10,11] и других химических процессов. Все более широкое применение комплексов ПАВ с металлами и потребность в усилении их функциональной активности приводят к необходимости получения новых представителей этого типа соединений и установления зависимости их свойств от природы ПАВ (лиганда) и металла.…”