Micelle Effects of Functionalized Surfactants, 1-Cetyl-3-(2-hydroxyiminopropyl)imidazolium Halides,in Reactions with p-Nitrophenyl p-Toluenesulfonate,Diethyl p-Nitrophenyl Phosphate,and Ethyl p-Nitrophenyl Ethylphosphonate

1-Cetyl-3-(2-hydroxyiminopropyl)imidazolium chloride and bromide were synthesized for the first time. These compounds are functionalized zwitterionic surfactants which give rise to micelle formation in aqueous solution. Kinetic and thermodynamic analysis of nucleophilic cleavage of p-nitrophenyl p-toluenesulfonate, diethyl p-nitrophenyl phosphate, and ethyl p-nitrophenyl ethylphosphonate in the presence of 1-cetyl-3-(2-hydroxyiminopropyl)imidazolium halide micelles showed that the latter are powerful nucleophilic reagents whose kinetic behavior can be described in terms of a simple pseudophase distribution model. The efficiency of substrate solubilization with zwitterionic surfactant micelles and the reactivity of the oximate fragment in the micelle phase were estimated on a quantitative level. The observed acceleration of S_N2 reactions with the examined p-nitrophenyl esters relative to analogous reactions of zwitterionic 1-methyl-3-(2-hydroxyiminopropyl)imidazolium halides is, respectively, 12800, 550, and 900 times; it is explained mainly by increased concentration of the reactants in micelles.     

Intramolecular Catalysis in Reactions of Hydroxamic Acids

Among hydroxamate ions (typical nucleophiles), anomalously high nucleophilicity relative to 4-nitrophenyl diethyl phosphonate is seen in anions which have general basic catalytic sites that provide anchimeric assistance for proton transfer in the transition state.     

Micellar Effects of Functional Detergents – 1-Cetyl-3-(2-hydroxyiminopropyl)imidazolium Halides – in Reactions with 4-Nitrophenyl Toluenesulfonate and 4-Nitrophenyl Diethyl Phosphate

An anomalously large increase was found in the rate of cleavage of 4-nitrophenyl 4-toluenesulfonate (13000 times) and diethylphosphate (550 times) by the zwitterionic micelles of 1-cetyl-3-(2-hydroxyiminopropyl)imidazolium chloride and bromide. Detailed kinetic and thermodynamic analysis of these processes made it possible to establish that the main factor responsible for the high rates of reaction in the micellar phase is the concentration of the reagents.     

Nucleophilic Reactivity of Hydroxide and Hydroperoxide Ions in Aqueous-Alcoholic Media and of HCO<Stack><Subscript>4</Subscript><Superscript>−</Superscript></Stack> Ion in Water

Nucleophilic reactivity of hydroxide and hydroperoxide ions toward ethyl 4-nitrophenyl ethylphosphonate, diethyl 4-nitrophenyl phosphate, 4-nitrophenyl 4-toluenesulfonate, and 4-nitrophenyl dimethylcarbamate in the system H₂O₂-KOH was studied in aqueous-alcoholic solutions at 25°C. The rate of reactions of both anions with ethyl 4-nitrophenyl ethylphosphonate, diethyl 4-nitrophenyl phosphate, and 4-nitrophenyl dimethylcarbamate and of hydroxide ion with 4-nitrophenyl 4-toluenesulfonate increases with rise in the fraction of the alcohol in mixtures of water with isopropyl and tert-butyl alcohols, while the reaction rate of hydroperoxide ion with 4-nitrophenyl 4-toluenesulfonate decreases. The rate of reactions of both anions with all the above substrates in mixtures of water with ethylene glycol decreases as the fraction of the latter rises. The apparent rate of the reaction of ethyl 4-nitrophenyl ethylphosphonate with anionic nucleophiles in the system H₂O₂-HO^?-HCO ₃ ^? in water at pH 8.5 almost does not depend on the concentration of ammonium hydrogen carbonate up to a value of 1 M, and it increases when the NH₄HCO₃ concentration exceeds 1 M. Mixtures of water with the lower monohydric alcohols were recommended for use as components of H₂O₂-HO^?-HCO ₃ ^? systems for oxidative decomposition of ecotoxicants.     

The α-effect of oximate ions and solvent effect in the transfer of the toluenesulfonyl group in aqueous dimethylsulfoxide

The kinetic behaviour of oximate ions was studied in the transfer of the toluenesulfonyl group in aqueous dimethylsulfoxide (0–95 vol.% DMSO). The solvation effects of the solvent are a factor controlling the nucleophilicity and magnitude of the α-effect of the oximate ions. L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R. Lyuksemburg ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 36, No. 1, pp. 30–35, January–February, 2000.     

Organotrihalide Complexes: α-Nucleophiles and Effective Oxidizing Agents in Decomposition Reactions of Organophosphorus Compounds in Water and Surfactant Micelles

We have studied the nucleophilic and oxidative reactivity of the system HOBr/BrO^–, in water and in the presence of different types of surfactants, relative to 4-nitrophenyldiethylphosphate, 4-nitrophenyl- 4´-toluenesulfonate (nucleophilic substitution), and 4-nitrophenol (oxidation). As the source of "active" bromine, we used organotrihalide complexes. The micellar effects of the surfactants in nucleophilic substitution reactions are adequately described within both a pseudophase distribution model and an ion-exchange model. Just transferring the reaction from water to micelles of a cationic surfactant leads to an increase in the observed rates of reaction of the BrO^– ion with esters by up to a factor of 20-30 and an increase in the rate for reaction of HOBr with nitrophenol by up to a factor of 5, while the HOBr/BrO^– system is one of the most effective systems in decomposition of organophosphorus compounds.     

Hydroxylamine anion — an effective α-nucleophile in acyl transfer reactions

A kinetic-thermodynamic analysis of the behavior of hydroxylamine in reactions with acetic, toluenesulfonic, diethylphosphoric, and diethylphosphonic acid 4-nitrophenyl esters was conducted. Using the Brönsted approach, it was shown that hydroxylamine is a unique -nucleophile, and its neutral and anionic forms are powerful acyl acceptors.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 30, No. 2, pp. 75–79, March–April, 1994.     

Permanent transfer of the acyl group of aryltoluenesulfonates to arylate ions in aqueous demethylsulfoxides

The permanent equilibrium transfer of the toluene-sulfonate group to arylate ions in 80 vol. % aqueous DMSO ( = 0.1 KCl) at 25°C has been studied. The full kinetic and thermodynamic analysis has shown that the reaction is based on a matched symmetrical mechanism. The factors responsible for an increase in the reactivity of the arylate onions, when the reaction is carried out in 80% aqueous DMSO instead of in water, is discussed.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 30, No. 6, pp. 319–322, November–December, 1994.