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

Abstract

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.

Oxime functionality in surfactant self-assembly: An overview on combating toxicity of organophosphates

“…LG R 2 X = O or S LG = leaving group R 1 and R 2 = alkyl, alkoxy, alkylthio or amino groups Oximes reduce the effects of such hazardous compounds and have attracted attention of scientists worldwide [36][37]. Of these, pyridinium aldoximes have emerged to be effective antidotes against OP-pesticides and nerve agent intoxications.…”

Catalytic hydrolysis of phosphodiesters by nucleophilic ions in gemini micellar media

“…The catalytic activity of relevant nucleophiles is determined on the basis of basicity and strength of nucleophiles. The dissociation constant of various α‐nucleophiles such as hydrogen peroxide (H 2 O 2 ), acetohydroxamic acid (AHA), benzohydroxamic acid (BHA), salicylhydroxamic acid (SHA), and BDMO has been reported . Kinetic experiments were carried out to assess the ability of gemini surfactants with nucleophile system to hydrolyze the BNPP.…”

“…As the surfactant concentration is increased, so is the concentration of counter (Br − ) ions added to the medium. Bromide ions (unreactive) compete with reactive ions in the Stern layer and inhibit the reaction . The rate data show that the variation of rate constants below the CMC is difficult to quantify due to reactant‐induced micellization and interaction with non‐micellized surfactants.…”

“…In this study, we observed that BDMO shows higher catalytic activity compared with other nucleophiles for the cleavage of BDNPP in gemini micellar media. Gemini micellar media accelerate 10 2 ‐fold the micellar catalysis than cetylpyridinium chloride (CPC), cetyldiethylethanolammonium bromide, cetyldimethyethanolammonium bromide, cetylpyridinium bromide, and CTAB …”

“…In our previous paper, we studied the cleavage of BNPP with different α‐nucleophiles in cationic micellar media. It was observed that BDMO − showed significant enhanced catalytic efficiency compared with AHA, BHA and SHA in cationic micellar media under the reaction conditions: temp.…”