Catalytic destruction of malathion by metallomicelle layers

Abstract

Two micellized Cu(II) and Fe(III) ion complexes were synthesized and found to possess good catalytic activity in the cleavage of the malathion/cupric (ferric) complex thionate ester. The complexes form metallomicelles, which bind the substrate by coordinating with the thionate sulfur in the malathion (which is chemically similar to the nerve agent sarin). Possible reasons for the rate acceleration include enhanced electrophilicity of the micellized metals, enhanced surface activity, and the recognized ability of cationic micelles to accelerate the cleavage of the thionate ester. The results of kinetic data (half-life times) for malathion degradation were 13.7 and 8.3 min in the presence of Cu(II) and Fe(III) metallomicelle layers, respectively.The destruction of organophosphorus (OP) toxic chemical agents as well as pesticides is generally affected by the use of sodium hydroxide and hypochlorite (1,2). However, the latter are known to have certain undesirable properties, including corrosiveness and toxicity.Studies with the pesticide malathion have shown that cationic micelles speed the degradation rate (3). Micelles of functionalized surfactant (a cationic surfactant that is widely used in the destruction of organophosphorus toxic agents) have been extensively investigated as esterolytic reagents (4).Previous research demonstrated that metal ions catalyze the hydrolysis of phosphothionate esters (5). Also, transition metal ion-based catalysts greatly accelerate phosphate triesters cleavage(6). We have recently studied the efficiency of cationic surfactants containing copper in potentiating their destruction of OP agents (7). Here we investigate catalytic hydrolysis of malathion (as a simulant of the chemical warfare agent sarin, which, like malathion, has an easily hydrolyzed P-O bond) (8) by new metallomicelle layers. The objective of our study was to examine the effect of copper(II) or iron(III) micellar layers on the phosphorodithionate ester hydrolysis; both metal ions showed firstorder constants. EXPERIMENTAL PROCEDURESGeneral. Kinetic traces were recorded by using a HewlettPackard Model, MS 5988 gas chromatograph/mass spectrometer equipped with a DB-5 capillary column (0.25 µm film, 0.25 mm × 30 m). Carrier gas was helium. GC conditions (9,10) were as follows: injection at 270°C for a 1 µL in ether. The oven temperature was programmed from 60 to 270°C for 34 min.Surface tension measurements (11) were determined with a Du Nouy ring tensiometer (type 8451; Krüss, Hamburg, Germany).UV spectra were recorded with a PerkinElmer 552 Spectrophotometer.Microelemental analyses were performed with a Vario EL Elementar (National Research Center, Cairo, Egypt).Chemicals. Malathion [O,O-dimethyl-S-1,2-bis (ethoxycarbonyl) ethyl phosphorodithionate, 88% actual purity] was obtained from Sumitomo Co. (Cairo, Egypt). Dodecyl pyridinium chloride monohydrate, cupric chloride dihydrate, and anhydrous ferric chloride were from Aldrich Chemical Co. Ltd. (Cairo, Egypt).General procedure for the synthesis of complexes. Stoichiomet...

Crystal structure of benzyl triphenyl phosphonium chlorometallate: Some surface and biological properties of their metallosurfactant derivatives

“…A saturated solution of equimolar proportions of benzyl triphenyl phosphonium chloride (BTPPC) and anhydrous CuCl 2 or FeCl 3 in absolute ethanol was refluxed for 2 h with continuous stirring [4][5]. After 3 days, red-brown or yellow plate like crystals for complexes 1 or 2, respectively, was separated, filtered and recrystallized from hot absolute ethanol and dried in a vacuum desicator.…”

“…Numerical details are presented in Table 1 Complex 1 or 2 (0.1 mmol) was dissolved in ethanol (20 ml) and an ethanolic solution of dodecylamine (a) or hexadecyl pyridinium chloride (b) was added. The reaction mixture was refluxed with stirring for 3 h [4][5]. The raw product was separated after 3 days, recrystallization and Table 2.…”

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“…In designing a metal containing surfactant systems, one model has a metal bound to head group [3,[6][7][8], and the other one has the metal cation bound to the counter ion of the cationic surfactant [4,5]. Studies on chloro and bromo complexes of copper(II) have been reported [9,10], in a special case, where the ratio [Cu 2+ ]:[X] = 1:3 (X = Cl, Br) has a monomeric three coordinate complex [9].…”

Ferrocene‐Based Cationic Surfactants: Surface and Antimicrobial Properties

“…In designing a metal-containing surfactant system, the metal may be directly bound to the head group [1][2][3] or to the counterion of the cationic surfactant [4][5][6].…”