The Mechanism of Dephosphorylation of Bis(2,4-dinitrophenyl) Phosphate in Mixed Micelles of Cationic Surfactants and Lauryl Hydroxamic Acid

Silva, Marcelo; Mello, Renata Siqueira de; Farrukh, Muhammad Akhyar; Venturini, Janio; Bunton, Clifford A.; Milagre, Humberto M. S.; Eberlin, Marcos N.; Fiedler, Haidi D.; Nome, Faruk

doi:10.1021/jo9017638

Cited by 28 publications

(28 citation statements)

References 35 publications

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“…In our results, we found that BHA was slightly more hydrophobic than AHA and SHA, bound to cationic micelles hydrophobically as well as by electrostatic attraction, and has more efficient reaction with the bound substrate BNPP. It is considered that nucleophilicity is governed not only by the basicity but also by the strength of interaction between the nucleophile and the surfactant aggregate . The marked increase in nucleophilicity in micellar media was observed in the order BDMO > SHA > BHA > AHA > α‐benzoin oxime.…”

Section: Resultssupporting

confidence: 91%

“…Micellar rate effects have been quantitatively determined on the basis of pseudophase models that high local concentrations of nucleophiles are largely responsible for the rate acceleration in the interfacial micellar region . It was observed that cationic micelles accelerate the spontaneous hydrolysis of bis( p ‐nitrophenyl) phosphate (BNPP) up to 2 × 10 5 ‐fold and accelerate the reaction of hydroxamates and phosphate triesters . We herein examined micellar effects on the reactions of the less reactive phosphodiester with simple hydroxamates (Scheme ).…”

Section: Introductionmentioning

confidence: 99%

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Comparative studies on reaction of bis(p‐nitrophenyl) phosphate and α‐nucleophiles in cationic micellar media

Kumar

Satnami

Ghosh

et al. 2012

J of Physical Organic Chem

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We studied the cleave of bis(p‐nitrophenyl) phosphate (BNPP) over a pH range of 7.0–12.0 in the presence of cationic micelles of cetyldiethylethanolammonium bromide, cetyldimethylethanolammonium bromide, cetylpyridinium bromide, cetyltrimethylammonium bromide, and cetylpyridinium chloride by using different α‐nucleophiles, viz acetohydroxamate, benzohydroxamate, salicylhydroxamate, butane‐2,3‐dione monooximate, and α‐benzoin oximate ions. With the use of α‐nucleophiles in cationic micellar media, the hydrolytic cleavage of BNPP was found to be approximately 105‐fold faster than its spontaneous hydrolysis. All reactions followed pseudo‐first‐order kinetics. The effect of various concentrations of cationic micelles for the reaction of BNPP and α‐nucleophiles has been studied. The variation of kobs values of the reactions depends on the micellar structure, that is, head groups, hydrophobic tail length, and counter ion. Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Resultssupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Comparative studies on reaction of bis(p‐nitrophenyl) phosphate and α‐nucleophiles in cationic micellar media

Kumar

Satnami

Ghosh

et al. 2012

J of Physical Organic Chem

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“…Hydroxamic acid structures in equilibrium Excellent contribution was made by Nome and co-workers [38] Hydroxamic acid structures in equilibrium Excellent contribution was made by Nome and co-workers [38] …”

Section: α-Nucleophilicty Of Hydroxamates In Watermentioning

confidence: 99%

“…Nome et al [38] through several techniques studied the products and the mechanism of the reaction between LHA and BDNPP. Nome et al [38] through several techniques studied the products and the mechanism of the reaction between LHA and BDNPP.…”

Section: Lossen Rearrangement In Micellesmentioning

confidence: 99%

From α-nucleophiles to functionalized aggregates: exploring the reactivity of hydroxamate ion towards esterolytic reactions in micelles

et al. 2015

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Owing to the rising threats of neurotoxic organophosphosphorus compounds, facile and efficient decontamination systems are required. Since the last few decades, the search for promising α-nucleophiles for straightforward and eco-friendly decontamination reactions using α-nucleophiles has been considerably boosted up. Among these, hydroxamic acids have been widely studied due to their potential α-nucleophilicity towards carbon and phosphorus based esters. This account summarizes our research on α-nucleophilicity of hydroxamate ions in water and micelles towards esterolytic reactions. Efforts of our group in the last few years have been collectively judged and compared with the crucial findings of researchers in the relevant field. The present article sheds light on the rich chemistry of the hydroxamate ion as a perfect candidate to degrade organophosphorus esters (i.e. nerve agents, pesticides and their simulants) in water, in micelles of conventional surfactants, and in functionalized micelles. The current report also provides an insight into the possible nature and mechanisms of these reactions. A brief account of the biological activities of hydroxamic acids that have recently spurred research in medicine against some fatal diseases has been included.

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“…The kinetic results reveal that hydroxamate attacks nucleophilically to the P=O center (Scheme ). Nome et al reported a detailed mechanism of a reaction of benzohydroxamate and laurylhydroxamate ion with bis(2,4‐dinitrophenyl) phosphate. NMR spectroscopy and ES‐MS study allow monitoring of the most important species with time for the reaction of BDNPP.…”

Section: Resultsmentioning

confidence: 99%

O‐Nucleophilicity of Hydroxamate Ions for Cleavage of Carboxylate and Phosphate Esters in Cationic Micelles

Satnami

Karbhal

Dewangan

2014

Int J of Chemical Kinetics

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The nucleophilic reactivities of hydroxamate (HA−) ions of the structure RCONHO− [R = CH3 (acetohydroxamate, AHA−), C6H5 (benzohydroxamate, BHA−), 2‐OHC6H4 (salicylhydroxamate, SHA−), and 4‐CH3OC6H4 (4‐methoxbenzohydroxamate, MBHA−)] for the hydrolysis of p‐nitrophenyl benzoate (PNPB), tris(3‐nitrophenyl) phosphate (TRIS), and bis(2,4‐dinitrophenyl) phosphate (BDNPP) have been examined kinetically. Over the pH range of 6.7–11.4, the α‐nucleophile (HA−) accelerates deacylation of PNPB and dephosphorylation of TRIS (in cetyltrimethylammonium bromide (CTAB) micelle, 2.0 × 10−3 M). The salicylhydroxamate ion encountered effective catalysis than AHA−, BHA−, and MBHA− ions. The monoanionic SHA− and dianionic SA2− forms of salicylhydroxamic acid are the reactive species. The hydroxamic acid concentration–dependent critical micelle concentration (cmc) and fractional ionization constant (α) and of CTAB provide qualitative information for the micellar incorporation of the hydroxamate ion. The ab initio calculations performed on the hydroxamate ions at restricted Hartree–Fock using the 6‐311G (d,p) basis set revealed the O‐nucleophilicity of hydroxamate ions toward C=O and P=O centers. On the basis of ab initio calculation, it has been concluded that hydroxamic acids can exist into E‐amide and Z‐amide forms. The large stable amide or imide anions of hydroxamate are strong nucleophilic for the esterolytic cleavage of carboxylate and phosphate esters.

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The Mechanism of Dephosphorylation of Bis(2,4-dinitrophenyl) Phosphate in Mixed Micelles of Cationic Surfactants and Lauryl Hydroxamic Acid

Cited by 28 publications

References 35 publications

Comparative studies on reaction of bis(p‐nitrophenyl) phosphate and α‐nucleophiles in cationic micellar media

Comparative studies on reaction of bis(p‐nitrophenyl) phosphate and α‐nucleophiles in cationic micellar media

From α-nucleophiles to functionalized aggregates: exploring the reactivity of hydroxamate ion towards esterolytic reactions in micelles

O‐Nucleophilicity of Hydroxamate Ions for Cleavage of Carboxylate and Phosphate Esters in Cationic Micelles

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