A comprehensive study devoted to designing green surface-active ionic liquids (SAILs) based on the “benign-of-design” approach results in finding greener alternatives.

In this study, the impact of the length of the alkyl chain and cationic head group on the environmental biodegradability of l-phenylalanine ester derived ILs was systematically studied.

The micellar effects of 1-cetyl-2-methyl-3-(2-hydroxyiminopropyl)imidazolium and 1-cetyl-3-hydroxyiminomethylpyridinium halides in acyl transfer reactions (phosphoryl, phosphonyl, and toluenesulfonyl) were investigated. Variation of the nature of the head group does not lead to change in the reactivity of the oximate group, while the nucleophilicity follows the basicity of the functional fragment. The increase of the observed reaction rates during transfer of the disintegration of the substrates from water to the micellar pseudophase is due both to concentration of the reagents and to change in the reactivity of the oximate group. The new detergent 1-cetyl-2-methyl-3-(2-hydroxyiminopropyl)imidazolium chloride is one of the most effective functional surfactants in the decomposition of organophosphorus compounds. Key words: functional surfactants based on pyridine and imidazole, nucleophilicity, micellar effects.Functional surfactants containing an a-nucleophilic fragment in the head group are usually characterized both by high nucleophilic reactivity and by effective solubilization of electrically neutral polar substrates, including excotoxicants of organophosphorus type [1-10]. During the design of new functional detergents an important role is played by the true solubility of the surfactant in water, the basicity of the functional group, and its reactivity. However, the introduction of the functional fragment often leads to a decrease in the solubility of the surfactant in water [1,2,5,8]. Therefore, during study of the micellar effects of such detergents, as during their use in systems for the decomposition of excotoxicants, it is necessary to introduce an inert surfactant -a co-detergent, and this makes the system multicomponent and less attractive from the practical standpoint. The nucleophilicity of functional detergents can be predicted on the basis of the reactivity of analogs not forming micelles [1,2,[7][8][9][10]. This opens up the possibility of specific modification of the structure of the surfactant with the aim of producing compounds with the required level of nucleophilicity. This is the approach that we used during the creation of functional detergents based on imidazole [7][8][9]. With variation of the position of the oximate group in the series of hydroxyiminomethyl-1-cetylpyridinium halides the variation of the observed rates of decomposition of 4-nitrophenyl diethyl phosphate corresponds likewise to the variation of the basicity of the a-nucleophilic fragment in hydroxyimino-1-methylpyridinium halides [1]. It is important to note that for oximes that are not micelle-forming compounds there is a single Brönsted relationship onto which the points for oximes containing both an imidazole ring and a pyridinium ring fit [11]. In so far as analysis of the experimental results in [1] in terms of the existing models for description of micellar effects was not made 0040-5760/08/4402-0093

Functional detergents (FD) based on pyridine and containing aldoximate, ketoximate, and hydroxamate groups were synthesized. Their reactivity in FD/CTAB comicelles toward 4-nitrophenyl 4-toluenesulfonate (NPTS), diethyl phosphate (NPDEP), and diethylphosphonate (NPDEPS) in weakly alkaline media was investigated. Functional detergents based on pyridine are effective in the decomposition of ecotoxicants; the half-lives for the transformation of the substrates into the reaction products in the presence of a functional detergent containing, for example, a ketoximate group amounts to~40 s (NPTS),~120 s (NPDEP), and~5 s (NPDEPS). By analyzing the results it was possible to establish the paths to further modification of the head group of the surfactant, i.e., by varying the structure of the oximate group at various positions of the pyridinium ring aimed at the production of low-basicity functional detergents.Functional detergents containing a heterocycle (pyridinium, imidazolium, etc.) and a fragment of an a-nucleophile in the head group are effective supernucleophilic reagents in the decomposition of phosphate esters -model analogs of pesticides, toxic warfare agents, etc. [1][2][3][4][5][6][7][8][9]. Modifications of the surfactants and the creation of new compounds were directed at the production of substances that make it possible to achieve the highest observable rates of decomposition of ecotoxicants under "mild" experimental conditions and in particular in media with acidity close to neutral. It is such compounds that are of particular interest from the practical point of view -the production of antidotes and supernucleophilic reagents that form the basis of degassing systems [1][2][3]5]. By varying the structure of the a-nucleophilic fragment it is possible to synthesize detergents in which the functional group will be fully ionized at pH £ 10.0.The present work examines the reactivity, the micellar effects of functional detergents (I)-(III), and the nucleophilicity of their methyl analogs (Ia)-(IIIa) in relation to 4-nitrophenyl diethylphosphonate (NPDEPS), diethyl phosphate (NPDEP), and 4-toluenesulfonate (NPTS). The functional detergents (II) and (III) were obtained for the first time.The direction of the investigation was chosen for the following reasons: The oximate and hydroxamate anions are typical a-nucleophiles that react anomalously quickly with organophosphorus compounds (OPC) [1][2][3][4][5][6][7][8]; oximes are widely used as antidotes, and the creation and investigation of inhibited cholinesterase reactivators based on them are currently being 292 0040-5760/08/4405-0292

No abstract

We consider the factors responsible for the nucleophilicity and micellar effects of surfactants based on imidazole and pyridine, functionalized by an oximate group. The reactivity of the functional detergents, as for oximes not forming micelles, is described by a nonlinear Brönsted plot with an inflection point at the pK a of the oximate group,~8.5-9.0. The major contribution to the increase in the degradation rate of ecotoxins by supernucleophilic systems based on functional surfactants (by a factor of 10 2 to 10 3 compared with the methyl analogs) comes from the effect of concentration of the substrate. The established characteristics make possible targeted modification of the surfactant structure and obtaining detergents with a specified reactivity level.Design of reagents for fast and irreversible degradation of ecotoxins, including organophosphorus compounds (OPCs), requires designing systems having both high nucleophilicity and high solubilizing ability relative to hydrophobic substrates. Using a-nucleophiles as the basis for such systems makes it possible to provide anomalously high rates of nucleophilic cleavage of organophosphorus compounds [1][2][3]. The special interest in study of the reactivity of typical representatives of this class of reagents, oximate ions (Ox -), is first of all due to the fact that effective antidotes are found among them: re-activators of the acetylcholinesterase inhibited by organophosphorus compounds, the search for which is being vigorously pursued at the moment [4]. There is no doubt that the level of biological activity of the antidotes is directly connected with the high reactivity of Ox -ions [4][5][6][7]. Detailed kinetic analysis of their behavior suggests that the nucleophilicity of Ox -ions cannot be described in terms of a single Brönsted equation [4][5][6][7]. Curvature of the Brönsted plots for reactions of Ox -ions with substrates containing electron-deficient centers and the "leveling off" of the reactivity at p a Ox K -> 8.5-9.0 may be connected with both energetically unfavorable solvation effects of the solvent, the contribution of which becomes more and more significant as the basicity of the nucleophile increases, and also with a change in the structure of the transition state [4][5][6][7]. Nevertheless, for the studied reaction series, it is unlikely that such a considerable change in the structure of the transition state would occur as the basicity of the Oxions increases [7].The similar character of the Brönsted plots for interaction of Ox -ions with different acyl-containing substrates clearly shows that it is hardly possible to modify the structure and synthesize an oxime whose nucleophilicity in aqueous solution 94 0040-5760/10/4602-0094

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The reactivity of a-nucleophilic groups in functional detergents is comparable with those for analogous compounds which do not form micelles. Methods are proposed for the modification of surface active compounds to produce supernucleophilic systems for the decomposition of organophosphorus compounds. A new functional detergent -1-cetyl-3-(2-hydroxyiminoethyl)imidazolium chloride -is the most powerful of the investigated surface active reagents capable of achieving half lives for the decomposition of 4-nitrophenyl diethyl phosphonate and 4-nitrophenyl diethyl phosphate of £2 and 14 s respectively.Attempts to construct reagents for the effective decomposition of organophosphorus compounds, particularly exotoxicants (pesticides, war gases, etc.), is without doubt a current problem [1]. The high observed rate of reaction is important but so also is the solubilization of organophosphorus compounds which are difficult to dissolve in water. It is frequently these factors which determine attempts to modify the structures of the reagents [2, 3]. Previously we showed [3-6] that a promising direction for the solution of this problem is the creation of microheterogeneous systems based on a new class of functional surface active substances (SAS) in the composition of which imidazole ring and specific a-nucleophilic units (I-III, R = C 16 H 33 ) were included, which decomposed organophosphorus compounds -4-nitrophenyl esters of diethylphosphoric acid (NPDEP) and diethylphosphonic acid (NPDEPS) -anomalously rapidly.The micellar effects of the functional SAS result from the concentration of the substrate (S) in the micellar pseudophase and the change in the ionization rates of the a-nucleophilic unit and its reactivity on transferring the reaction from water (aq) to the 0040-5760/06/4205-0295