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We have studied the extraction of four HA acids (HNO(3), HReO(4), HClO(4), HCl) to a hydrophobic ionic liquid (IL) 1-butyl-3-methylimidazolium-bis(trifluoromethanesulfonyl)amide (BMI(+) Tf(2)N(-)) at room temperature, in a wide range of acidic concentrations in water. The effect of tributylphosphate (TBP) as co-solvent is investigated. According to experimental observations, water dragging to the IL phase increases with added TBP and/or acids. Acid extraction is found to be weak, however, for the four acids except for concentrated HNO(3) (>3 M). Molecular dynamics simulations on model biphasic systems show that TBP is not surface active, but well dissolved in the IL. They also reveal the importance of HA acid model (either totally or half dissociated) and of the TBP content on acid extraction to the IL. Furthermore, they show that "the proton" can be extracted by TBP (H(3)O(+)(TBP)(3)"complex") without its A(-) conjugated base, via a cation transfer mechanism (BMI(+) transfer to water). Experiments and simulations show that TBP plays an important role in the mutual solubility between water and ionic liquid, by different amounts, depending on the HA acid. On the other hand, both approaches indicate that a HTf(2)N containing aqueous solution completely mixes with the [BMI][Tf(2)N] IL that contains the same Tf(2)N(-) anion.

A novel class of hydrophobic ionic liquids based on quaternary ammonium cation and bearing phosphoryl groups was synthesized. The preliminary results of U(VI) extraction from aqueous solution into the ionic liquid are presented.Room-temperature ionic liquids (RTILs) are promising alternative solvents for organic synthesis, catalysis, electrochemistry and extraction. 1 Among industrial processes, extraction and separation of actinides and lanthanides from nuclear waste is one of the most challenging fields. 2,3 Ionic-liquid phases are suitable reception media for metallic radioactive species in liquid-liquid extraction processes as they show high stability under a and c irradiations 4-6 and enhanced safety towards criticality. 7 However, the partitioning of charged metallic species is limited by the fact that RTILs are usually not effective complexing agents, so the highly hydrated metal ions remain in the aqueous phase. 8 Improvements in the extraction efficiencies have been achieved by adding organic coordinating compounds which significantly increase the distribution ratios of metal ions between the ionic liquid and aqueous phases. 9 For example, Cocalia et al. 10 studied the extraction of U(VI) by dialkylphosphoric or dialkylphosphinic acids from aqueous solutions to the ionic liquid 1-decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C 10 mim][Tf 2 N] and compared it to extraction into dodecane; partitioning measurements showed comparable patterns of distribution ratios for both the ionic liquid/ aqueous and dodecane/aqueous systems.In the industrial nuclear plutonium uranium extraction process 2 (PUREX) used worldwide, tri-n-butyl phosphate (TBP) is the uranyl extracting agent and is incorporated at 30% in dodecane. Giridhar et al. 11 reported on the extraction of U(VI) by TBP dissolved in RTIL [C 4 mim][PF 6 ] and compared its extraction ability when dissolved either in RTIL or in dodecane. The U(VI) distribution ratios are similar in the range of nitric acid concentration from 0.01 M to 4 M showing the interest of using such solvent. RTILs can be considered as alternative solvents, in replacement of the highly toxic and flammable kerosene mixtures that are used nowadays.Another very promising approach for metal extraction (and many other applications) lies in the concept of task-specific ionic liquids (TSILs). 12,13 These compounds, consisting of extracting entities grafted onto the cation of the ionic liquid, combine the properties of ionic liquids (e.g., non-volatility, non-flammability) with those of conventional extracting compounds. Upon grafting complexing substructures onto the organic cation of RTILs, the resulting TSILs behave both as the organic phase and the extracting agent, suppressing the problems encountered through extractant/solvent miscibility and facilitating species extraction and solvent recovery. Compared to the number of studies on the application of ILs in separations, TSILs have been the focus of relatively few studies. However, it has already been shown that TSILs bea...

We report a new method to assess protective groups (PGs) reactivity as a function of reaction conditions (catalyst, solvent) using raw reaction data. It is based on an intuitive similarity principle for chemical reactions: similar reactions proceed under similar conditions. Technically, reaction similarity can be assessed using the Condensed Graph of Reaction (CGR) approach representing an ensemble of reactants and products as a single molecular graph, i.e., as a pseudomolecule for which molecular descriptors or fingerprints can be calculated. CGR-based in-house tools were used to process data for 142,111 catalytic hydrogenation reactions extracted from the Reaxys database. Our results reveal some contradictions with famous Greene's Reactivity Charts based on manual expert analysis. Models developed in this study show high accuracy (ca. 90%) for predicting optimal experimental conditions of protective group deprotection.

Here, we report the data visualization, analysis and modeling for a large set of 4830 S N 2 reactions the rate constant of which (logk) was measured at different experimental conditions (solvent, temperature). The reactions were encoded by one single molecular graph -Condensed Graph of Reactions, which allowed us to use conventional chemoinformatics techniques developed for individual molecules. Thus, Matched Reaction Pairs approach was suggested and used for the analyses of substituents effects on the substrates and nucleophiles reactivity. The data were visualized with the help of the Generative Topographic Mapping approach. Consensus Support Vector Regression (SVR) model for the rate constant was prepared. Unbiased estimation of the model's performance was made in cross-validation on reactions measured on unique structural transformations. The model's performance in cross-validation (RMSE = 0.61 logk units) and on the external test set (RMSE = 0.80) is close to the noise in data. Performances of the local models obtained for selected subsets of reactions proceeding in particular solvents or with particular type of nucleophiles were similar to that of the model built on the entire set. Finally, four different definitions of model's applicability domains for reactions were examined.

The “creativity” of Artificial Intelligence (AI) in terms of generating de novo molecular structures opened a novel paradigm in compound design, weaknesses (stability & feasibility issues of such structures) notwithstanding. Here we show that “creative” AI may be as successfully taught to enumerate novel chemical reactions that are stoichiometrically coherent. Furthermore, when coupled to reaction space cartography, de novo reaction design may be focused on the desired reaction class. A sequence-to-sequence autoencoder with bidirectional Long Short-Term Memory layers was trained on on-purpose developed “SMILES/CGR” strings, encoding reactions of the USPTO database. The autoencoder latent space was visualized on a generative topographic map. Novel latent space points were sampled around a map area populated by Suzuki reactions and decoded to corresponding reactions. These can be critically analyzed by the expert, cleaned of irrelevant functional groups and eventually experimentally attempted, herewith enlarging the synthetic purpose of popular synthetic pathways.

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Chemoinformatics / In silico design / Complexation / ExtractionSummary. Chemoinformatics approaches open new opportunities for computer-aided design of new efficient metal binders. Here, we demonstrate performances of ISIDA and COMET software tools to predict stability constants (log K ) of the metal ion/organic ligand complexes in solution and to design in silico new molecules possessing desirable properties. The predictive models for log K of lanthanides complexation in water have been developed. Some new uranyl binders based on monoamides and on phosphoryl-containing podands were suggested theoretically, then synthesized and tested experimentally. Reasonable agreement between experimental uranyl distribution coefficients and theoretically predicted values has been observed.