Nucleophilic substitution reaction of carboxylate and phosphate esters with hydroxamate ions in microemulsions

Reactivity studies of carbon, phosphorus and sulfur‐based acyl sites with tertiary oximes in gemini surfactants

“…The order of reactivity for all the substrates can be depicted as PNPA > PNPB > PNPDPP > BDNPP > PNPTS. The nucleophilic efficacy of both the nucleophiles is quite less towards the suphonyl ester when compared to phosphonyl and carboxyl esters . This difference may be due to least electrophilicity of S = O center, than P = O and C = O centers.…”

“…The value of the surface pressure at the CMC (π CMC ) was obtained from Eqn , where γ o indicates the surface tension of pure solvent, and γ CMC is the surface tension at the CMC. This parameter shows that the maximum reduction of surface tension is due to the adsorption of surfactant molecules and observed when surfactant begins to micellize and not adsorb anymore at the surfaces . Therefore, it demonstrates the effectiveness of the surface tension reduction.…”

“…The rate maxima are independent of the type of surfactants, but the magnitude of rate constant depends on type of surfactants. The observed rate maxima are due to the dilution effect of enhanced concentration of gemini surfactant . Gemini surfactants, linked by different spacer groups, offer di‐cationic head group that is significantly higher in electrostatic interactions.…”

Effects of Micelles and Vesicles on the Oximolysis of p‐Nitrophenyl Diphenyl Phosphate: A Model System for Surfactant‐Based Skin‐Defensive Formulations against Organophosphates

“…Such formulations could, in principle and at the same time, increase oxime reactivity, solubilize the (water‐insoluble) phosphate pesticide (or insecticide) and catalyze the decomposition of the agent. In this context it is important to note that surfactants aggregates, often employed in the formulation of pharmaceutical products, incorporate oximes and modify oximolysis rates 9–17. In particular, micelles of positively charged single‐chain surfactants increase the rate of oximolysis of organophosphorus model compounds.…”

“…In particular, micelles of positively charged single‐chain surfactants increase the rate of oximolysis of organophosphorus model compounds. 10–17 Single‐chain positively charged surfactants, however, can not be formulated as lotions because of their toxicity 18–20. Positively charged double chain surfactants, however, exhibit much lower levels of toxicity and are routinely used in the cosmetic industry in the formulation of hair softeners 21–26.…”