The influence of hydrophobic amines on hydrolysis of bis(p-nitrophenyl) methylphosphonate in micellar solutions of cetylpyridinium bromide

Abstract

The kinetics of hydrolysis of bis (p-nitrophenyl] methylphosphonate in the presence of prima/3' aliphatic amines in aqueous micellar solutions of cetylpyridinium bromide was studied. Tile reaction proceeds via tv, o routes, alkaline hydrolysis and amine-catalyzed hydrolysis according to the general basic catalysis mechanism. The contributions of these routes and the catalytic effect of mieelles depend on the hydrophobicity of the amines. The formation of different types of miceltes was found, and their characteristic parameters were determined by tensiometr7 and high-resolution t H N M R spectroscopy with a magnetic field pulse gradient.Key words: kinetics, hydrolysis, bistp-nitrophenyl) methylphosphonate, amines, micetles. cetytpyridinium bromide. ~|t NMR spectroscopy, diffusion.Micellar catalysis is a nontraditional method of affecting the reactivity of org~mic compounds.l'2 Elucidation of the factors that determine the efficiency of micellar catalysis is a topical task. The line of investigation of micelle formation and micellar catalysis is tightly connected with the problems of enzymology, because most processes involving enzymes cxzcur in highly organized systems, namely, cell membranes and subceflular species. Micellar solutions can ser~'e as convenient models for the investigation of it/ vitro processes occurring in a living cell) Functionalization of micelles of cationic suffactants by incorporation of long-chain amines (i.e., the /brmation of mixed aggregates bearing a fixed active site responding to the variation of the medium pH and the component ratio) can result in the design of biomimetic systems. These systems exhibit catalytic activity in nucleophilic cleavage processes, in particular, in the transfer of acyl and phospho~t groups.This work is a continuation of our study dealing with the catalytic properties of micellar systems consisting of a surfactant and a primary' aliphatic amine. 4,5 It is aimed at elucidating the relationship between the structures of microaggregates and their influence on the rate and mechanism of cleavage of ester bonds. For this purpose. using bis(ao-nitrophenyt) methylphosphonate (1) as the sttbstrate, we studied the kinetics of hydrolysis of esters of tetracoordinated phosphorus in the presence of primar7 amines with nonbranched chains in aqueous micellar solutions of cetylpyridinium bromide (CPB). A number of characteristic parameters of the system confirming the fomaation of micellar aggregates of various types were determined by independent physical methods (tensiometry" and high-resolution ~H NMR spectroscopy with a magnetic field pulse gradient). ExperimentalThe solvents and amines were purified by standard procedures. CPB samples were twice reprecipitated with ether from ethanol. Phosphonatc 1 was synthesized and purified by a procedure reported previously. 6The formation of tile O-(p-nitrophenyl) methylphosphonic acid monoanion upon hydrolysis of compound 1 in solutions of CPB in the presence of decylamine is proved by the fact that its chemical shift in the 3t...

Effects of solubilized dodecylamine on the microstructure of cetylpyridinium bromide-n-butanol-hexane-water system studied by pulsed-gradient spin echo NMR and ESR spin label methods

“…The distribution of water in the system is important for different hydrolytic reactions. For example, earlier we found that the water content in the microemulsion interface influences the rate of ester hydrolytic destruction [11].…”

“…Earlier we have studied the kinetic properties of primary aliphatic amines in various self-organized solutions and have discussed the peculiarities of microemulsion influence on the rate and mechanism of nucleophilic substitution processes [10,11]. However, the presence of reactants in the system can produce structural changes in the microemulsion medium and the aim of this study is to reveal the influence of primary long-chain amines on the structural properties of microemulsion.…”

Elucidating the Effect of Aliphatic Molecular Plugs on Ion-Rejecting Properties of Polyamide Membranes

“…Nevertheless, the critical micelle concentration (CMC) of decylamine was reported to be 9.5 × 10 −4 M for nonprotonated from 2.7 × 10 −3 M for 75% protonation, while fully protonated form apparently does not form micelles. 61 There is no experimental data on the effect of salt on the CMC of decylamine, but the CMC of a slightly longer surfactant dodecyldimethylammonium chloride was found to be 16.2 times lower in 1 M NaCl solution than in neat water. 62 Still, it seems reasonable to assume that decylamine does not form micelles at pH 3.7 and 9.3 and may behave similarly to DTAB, with regard to surface adsorption on polyamide.…”

Applications of primary alkylamines in nanoparticles formation and stabilization

“…As emphasized by Mirgorodskaya and his colleagues in their work they showed that Critical Micellar Concentration (CMC) of chloride primary alkyl amines (chloride salt of Decyl and Octyl amine) depend on protonation degree of head group. They conclude that as the percentage of protonation increase, the concentration needs to form micelles also increase (Mirgorodskaya et al, 2000). Table summarized CMC values for chloride salt of Decylamine and Octadecylamine depending on protonation degree of amine head (Table 1).…”