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Simanenko, Yu. S.; Popov, A. F.; Karpichev, Yevgen; Prokop’eva, T. M.; Savëlova, V. A.; Bunton, Clifford A.

doi:10.1023/a:1021655813700

Cited by 28 publications

(55 citation statements)

References 18 publications

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“…Finally at pH > 10 a further increase in the rate of reaction occurs. This pH profile is similar to the reactions of hydroxylamine with 4-nitrophenyl esters of acetic acid, diethylphosphonic acid, diethylphosphoric acid, 4-toluenesulfonic acid, and N,N-dimethylcarbamic acid [3,4]. The nucleophilic reactivity of the neutral forms of N-MeHA and N,N-(Me) 2 HA (k HA w ) can be found from any point of the plateau in the range of the pH-independent transfer of the phosphonyl groups ( Fig.…”

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confidence: 67%

Reactivity of N-alkyl derivatives of hydroxylamine in decomposition of 4-nitrophenyl diethylphosphonate in water and in cetyltrimethylammonium bromide micelles

et al. 2007

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Neutral forms of hydroxylamine, N-methylhydroxylamine, and N,N-dimethylhydroxylamine are typical a-nucleophiles in water. In comparison with aryl anions of similar basicity their rate of reaction in the decomposition of 4-nitrophenyl diethylphosphonate is increased by about 10 2 times. Decomposition of the substrate is accelerated in cetyltrimethylammonium bromide micelles (about 4 to 30 fold). Hydroxylamine and its N-alkyl derivatives are the most effective low basicity nucleophiles. The sole factor responsible for the micellar effects is the concentration of the reagent in the surfactant micelles.Hydroxylamine (HA) is a unique a-nucleophile: its neutral and anionic forms are particularly effective decomposers of acyl compounds as substrates, including extremely toxic phosphate esters, over a wide range of acidic media (pH ³ 6.0) [1-4]. In particular, the anion of hydroxylamine is the "leader" among a-nucleophiles in nucleophilic substitution reactions with electron-poor centers -carbon, phosphorus, sulfur -and its reactivity is close to the limit for a-nucleophiles. N-Alkylhydroxylamines -N-methyl-and N,N-dimethylhydroxylamines (N-MeHA and N,N-(Me) 2 HA) are also typical a-nucleophiles. In fact, in reactions with an activated ester -bis(2,4-dinitrophenyl) phosphate -HA, N-MeHA, and N,N-(Me) 2 HA have anomalously high reactivity (³10 times faster than O-methylhydroxylamine) [1,2]. Nevertheless, it is not evident that the a-effect and the order of change in nucleophilicity of HA and its N-alkyl derivatives would remain the same with less reactive substrates. With the objective of constructing a system for the destruction of ecotoxicants it is necessary to take into account a whole range of factors, including solubility in water. One method for increasing the solubilization of organophosphorus compounds (OPC) is to carry out reactions in aqueous solutions of surface-active substances. The correct choice of surfactant -cationic, neutral, or anionic -for decomposition of OPC should lead to an increase in the observed rate of reaction.In the present work the reactivity of neutral forms N-methylhydroxylamine and N,N-dimethylhydroxylamine in water and hydroxylamine, N-methylhydroxylamine, and N,N-dimethylhydroxylamine in the presence of a cationic surfactant -0040-5760/07/4304-0247

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confidence: 67%

Reactivity of N-alkyl derivatives of hydroxylamine in decomposition of 4-nitrophenyl diethylphosphonate in water and in cetyltrimethylammonium bromide micelles

et al. 2007

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“…Functionalized micelles containing a bound nucleophile accelerate reactions at acyl or phosphoryl groups. [74,[86][87][88][89][90][91][92][93][94][95][96] In general, cationic micelles accelerate the reaction of neutral substrates with anionic reactants, for example, hydroxide ions, [46,[97][98][99][100][101] oximate ions, [84,86,[102][103][104] fluoride ions, [83] or thiolate ions. [105] Miller et al [100] found that the main causes for the 16.5-fold increase in the reaction rate of the basic hydrolysis of homologous nitrophenyl esters of carboxylic acids in latices functionalized with quaternary ammonium groups was a 90 000-fold increase in substrate concentration and a 10-fold increase in the hydroxide ion concentration.…”

Section: Solvolyses and Metalloenzyme Modelsmentioning

confidence: 99%

Reactions in Micellar Systems

2005

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The notion of "green chemistry" has encouraged even synthetic organic chemists to include water as a solvent. Incredible selectivities and activities can be achieved through the addition of amphiphiles with a defined structure. The morphology of supramolecular assemblies or associates formed by surfactants vary according to the temperature and concentration. As a rule, reactions are typically conducted using simple spherical aggregates, that is, micelles in the nanometer range. The strong polarity gradient present between the hydrophilic surface and the hydrophobic core of the micelle means that both nonpolar and polar reagents can be solubilized. This solubilization results in reactants becoming more concentrated within the micelle than in the surrounding water phase and leads to an acceleration of the reaction and causes selective effects. The kinetic treatment of reactions in micellar systems can be accomplished by considering them as microheterogeneous two-phase systems.

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“…The method for determining the pseudo-first order rate constant has been described elsewhere in detail [6]. All solutions for kinetic measurements were prepared with twice distilled water.…”

Section: Methodsmentioning

confidence: 99%

“…We have previously [4,5] demonstrated that surfactants containing specific fragments of organic a-nucleophiles (oximates, amidoximates, hydroximates) which cause anomalously high rates of decomposition ecotoxicant substrates are most effective nucleophilic systems described in the literature. At the same time, detailed extrathermodynamic analysis of the kinetic behavior of the whole class of a-nucleophiles in water indicated that anionic inorganic a-nucleophiles are the most effective for decomposition of organophosphorus compounds, and their reactivity can be described by a single Brönsted relation [6]. Hypohalite anions in water react with electrophilic substrates at rates limiting for typical organic a-nucleophiles.…”

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Micellar effects of cetyltrimethylammonium dibromobromate in phosphoryl group transfer reactions

et al. 2007

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The nucleophilic reactivity of cetyltrimethylammonium dibromobromate (CTABr 3 ) with respect to organophosphorus compounds -4-nitrophenyl esters of diethylphosphoric (NPDEP) and diethylphosphonic acids (NPDEPN) -has been studied. Solution of CTABr 3 in aqueous alkali solutions generated the hypobromite anion, which permitted the formation of a micellar system with reactive a-nucleophilic counterion. The kinetics of this system was described in terms of a simple pseudo-phase model, the half-life for the conversion of the organophosphorus substrates into reaction products was 95 s (NPDEP) and 12 s (NPDEPN).The influence of micelles and other microheterogeneous aggregates on the rate of chemical reactions has been intensively studied in the last decade which has provided a basis for the development of quantitative descriptions of the observed effects and proposals for methods for the practical use of micellar systems [1,2]. Micellar effects of surfactants in the reactions of anionic nucleophiles may be used to create systems capable of rapid and irreversible decomposition of toxic organophosphorus compounds -esters and haloid anhydrides of phosphorus acids. The use of toxic pesticides, a number of which include esters of dialkylphosphoric acid (paraoxon), dialkylthiophosphoric acid (metaphos, parathion, phenitrothion) and dialkyldithiophosphoric acid (timet), accompanied by contaminated soil and ground water, while enormous stores of these substances require treatment for ecologically well-based recovery [3].0040-5760/07/4304-0241

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Cited by 28 publications

References 18 publications

Reactivity of N-alkyl derivatives of hydroxylamine in decomposition of 4-nitrophenyl diethylphosphonate in water and in cetyltrimethylammonium bromide micelles

Reactivity of N-alkyl derivatives of hydroxylamine in decomposition of 4-nitrophenyl diethylphosphonate in water and in cetyltrimethylammonium bromide micelles

Reactions in Micellar Systems

Micellar effects of cetyltrimethylammonium dibromobromate in phosphoryl group transfer reactions

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