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Here, we propose an optimised protocol for controlling the initial water activity (aw) in organic reaction mixtures with soluble lipase to ensure reproducible and consistent enzyme activity measurements. Pre‐equilibration above saturated salt solutions was used to set aw of the reaction media, where aw was tracked with a hygrometer. Consistent stirring of the suspension and volume correction to compensate for solvent evaporation were found to be critical. The protocol was tested on Candida antarctica lipase B (CALB) in soluble and immobilised forms in three organic solvents (acetonitrile, methyl tert‐butyl ether, and hexane) at four different water activities ranging from 0.12 to 0.97. Soluble and immobilised CALB had similar aw‐profiles and showed the highest enzyme activity in hexane. The optimised protocol expands the possibility to study enzyme kinetics from immobilised enzymes to soluble enzymes. [ABSTRACT FROM AUTHOR]

Chitin is an abundant natural nitrogen-containing biopolymer with great application potential in materials, environment, energy, and health. However, the structure characteristics and processing technologies have required intense research in related applications. In particular, there have been great efforts to developing solvents for chitin, and the results so far are quite encouraging. This review summarizes the main solvent systems used for chitin, namely the aqueous solvent systems (mineral acids, inorganic salt aqueous solutions, alkali aqueous solutions) and non-aqueous ones (LiCl-dimethylacetamide solvents, CaCl2·2H2O saturated methanol, ionic liquids, deep eutectic solvents, and protic organic solvents). The solvent properties, dissolution methods, and solution properties are discussed in detail. Special attention is paid to the dissolution mechanism in each system. This review can provide a reference for understanding the dissolution behavior of chitin and finding suitable solvents for it. [ABSTRACT FROM AUTHOR]

The solubility behavior and solution chemistry of CL-20/MTNP (2,4,6,8,10,12-hexanitro-hexaaza-isowurtzitane/1-methyl-3,4,5-trinitropyrazole) energetic cocrystals in organic solvents were first investigated to offer some important information on thermodynamics. The phase solubility diagram (PSD) and eutectic point (Keu1) of three solvents were also determined. Moreover, the solubility behavior of CL-20/MTNP energetic cocrystals was explained using the solubility product and solution complexation theories. The solution complexation results indicated that the CL-20/MTNP cocrystal has the strongest complexation effect in ethanol. The Keu1 values were all below 1 in three studied solvents, suggesting that the CL-20/MTNP cocrystal was less soluble than the other two pure components. Furthermore, studying the solubility behavior and solution chemistry of the CL-20/MTNP cocrystals has provided further insights into the screening, preparation and scaling-up of energetic cocrystals. [ABSTRACT FROM AUTHOR]

The present study elucidates the extended nature of the weak interaction between methanol and chloroform in its mixture using steady-state, ultrafast and single molecule spectroscopic methods. UV-vis absorption spectroscopy using a solvatochromic dye indicates a synergistic solvation in the methanol-chloroform binary solvent mixture, which causes the solvatochromic dye to sense increased polarity compared to the bulk counterparts. Such synergism was not observed in the emission study and is explained by the weak nature of the interaction between methanol and chloroform. Fluorescence anisotropy and single molecule fluorescence spectroscopy are employed to understand the nature of such weak interaction on femtosecond to microsecond time scale. Retardation of both the rotational and translational diffusion of the reporter molecule indicates that the observed weak interaction is extended over large dimension in the condensed phase. [ABSTRACT FROM AUTHOR]

In the present study results related to the in vivo administration of Natural Deep Eutectic Solvents (NADES)-solubilized berberine are reported for the first time. NADES are mixtures of small natural compounds having a melting point significantly lower than that of any individual component. Such solvents have gained much attention of the scientific community in the green chemistry area, being considered useful alternatives to common organic solvents. NADES can be used also as administration vehicles, and this can be attractive for nutraceutical products when eutectics are formed with food grade ingredients. In this work, different NADES were prepared using mainly food grade constituents and were tested as solvents for the alkaloid berberine. Three selected NADES/berberine solutions and an aqueous suspension were orally administered to mice with in dose of 50 mg/Kg. Blood levels of berberine were measured by a LC-MS/MS method. The pharmacokinetic analysis revealed a 2-20 fold increase in blood concentration of NADES/berberine with significant changes in pharmacokinetic profile. Natural Deep Eutectic Solvents may thus be considered attractive solubilizing agents and may also play a role in the increase of absorption of poorly bioavailable natural products such as berberine. [ABSTRACT FROM AUTHOR]

The cobalt carbonate hydroxide one-dimensional (1D) needle-like nanostructure is grown on the non-woven fabric via hydrothermal method. The 1D interlaced needle-like structure not only reduces the pore size of the non-woven fabric but also provides rough micro-nano structure of the superhydrophilic cobalt carbonate hydroxide/non-woven fabric, which is endowed with superhydrophobicity by coating with polydimethylsiloxane (PDMS). The resulting superwetting non-woven fabrics exhibit high separation efficiency for a series of surfactant-stabilized organic solvent/water emulsions (more than 99.3% for both W/O and O/W emulsions) and preferable recyclability (more than 10 cycles). The fluxes for all W/O and O/W emulsions are above 300 L m−2 h−1. Meanwhile the superhydrophobic fabric exhibits outstanding chemical stability in acid, alkaline and salt solution, and good mechanical durability after abrasion test with sandpaper. The comprehensive performances of the superwetting fabrics based on 1D nanostructure make them possible to be promising material for the separation of organic solvent/water mixtures in polluted water in harsh environments. [Display omitted] • The superwetting non-woven fabrics are fabricated by grafting one-dimensional (1D) needle-like nanostructure. • The 1D structure reduces the pore size of the non-woven fabric and provides rough micro-nano structure. • The resulting fabrics exhibit high separation efficiency and favorable reusability for surfactant-stabilized emulsions. • The superhydrophobic fabric possesses outstanding chemical stability and good mechanical durability. [ABSTRACT FROM AUTHOR]

Several errors and shortcomings in the paper by Liu et al. (J. Solution Chem. 45:932-946, 2016) concerning the calculation of Abraham model solution descriptors of telmisartan are discussed. The authors' calculated solute descriptors give an unreasonable value for the water to 1-octanol partition coefficient of telmisartan, which is eight orders of magnitude smaller than values predicted by other methods. The correct computation methodology for determining solute descriptors from experimental solubility data is presented. [ABSTRACT FROM AUTHOR]

This work presents a straightforward methodology to achieve small linear trinuclear molecules based on the CoII-carboranylcarboxylate system obtained by carving a 1D polynuclear analogous system with the use of diethylether. The reaction of the carboranylcarboxylic ligand, 1-CH3-2-CO2H-1,2-closo-C2B10H10 (LH) with different cobalt salts leads to the polynuclear compound [Co2(μ-H2O)(1-CH3-2-CO2-1,2-closo-C2B10H10)4(THF)4], 1 and the polymeric [Co(μ-H2O)(1-CH3-2-CO2-1,2-closo-C2B10H10)2]n(H2O)n2. This latter 1D chain has been obtained by an unprecedented synthetic strategy for the isolation of cobalt(ii) compounds. [Co3(μ-H2O)2(1-CH3-2-CO2-1,2-closo-C2B10H10)6(H2O)2(C4H10O)2], 3 is formed by the dissociation of the polymeric structure that forms 2 when a mild coordinating solvent such as diethylether is added. These compounds have been characterized by analytical and spectroscopic techniques. X-ray analysis of 1 and 3 revealed that 1 presents a dinuclear structure whereas 3 is trinuclear; in both cases a six-coordinated CoII compound with water molecules bridging each of the two CoII centres has been observed. The magnetic properties of 1 and 3 show a weak antiferromagnetic behaviour, respectively, between the CoII centres mediated by two carboxylate ligands and a molecule of water. [ABSTRACT FROM AUTHOR]

Many solution processing methods of exfoliation of layered materials have been studied during the last few years; most of them are based on organic solvents or rely on surfactants and other funtionalization agents. Pure water should be an ideal solvent, however, it is generally believed, based on solubility theories that stable dispersions of water could not be achieved and systematic studies are lacking. Here we describe the use of water as a solvent and the stabilization process involved therein. We introduce an exfoliation method of molybdenum disulfide (MoS2) in pure water at high concentration (i.e., 0.14 ± 0.01 g L−1). This was achieved by thinning the bulk MoS2 by mechanical exfoliation between sand papers and dispersing it by liquid exfoliation through probe sonication in water. We observed thin MoS2 nanosheets in water characterized by TEM, AFM and SEM images. The dimensions of the nanosheets were around 200 nm, the same range obtained in organic solvents. Electrophoretic mobility measurements indicated that electrical charges may be responsible for the stabilization of the dispersions. A probability decay equation was proposed to compare the stability of these dispersions with the ones reported in the literature. Water can be used as a solvent to disperse nanosheets and although the stability of the dispersions may not be as high as in organic solvents, the present method could be employed for a number of applications where the dispersions can be produced on site and organic solvents are not desirable. [ABSTRACT FROM AUTHOR]

Abstract: The electric conductance of solutions of sulfuric, oxalic, benzoic, and salicylic acid (up to 0.02M) in dioxane–water mixed solvents (90% and 93% dioxane by mass) has been studied in the presence and absence of TiO2 and Al2O3 (0.5–5% by mass). TiO2 and Al2O3 enhanced the conductance of solutions of organic acids in aqueous dioxane. The conductance is interpreted in terms of adsorption of acid in molecular form, dissolution of ceramic oxides in form of anionic complexes, and leaching of acidic impurities from ceramic oxides. [Copyright &y& Elsevier]

Antisolvent crystallization was performed to precipitate roxithromycin particles from organic solutions. Roxithromycin was dissolved in acetone at different concentrations and each solution was injected into an aqueous antisolvent leading to prompt particle formation. The effects of various experimental variables (solution injection rate, solution concentration, and temperature) on the particle size of roxithromycin were investigated. In addition to these variables, the effect of ultrasound on the resulting particle size was investigated by changing process parameters such as wave intensity (power output), sonication time, and the moment of ultrasonic application. When the drug solution was rapidly injected into the antisolvent, smaller crystals were obtained. Smaller crystals were obtained when solutions with high drug concentrations were used and also when the crystallization took place at lower temperatures. The particle size decreased with the increasing power output of ultrasound and with the increasing sonication time. It was also found that the ultrasonic wave induced the reduction of the particle size only when the ultrasound was applied to the solution at the initial stage of crystallization. [ABSTRACT FROM AUTHOR]

We have set out a procedure for the prediction of solubilities of drugs and other compounds in a wide range of solvents, based on the Abraham solvation equations. The method requires a knowledge of solubilities of a given compound in a few solvents, as shown by our own experimental data on apocynin, diapocynin, dehydrodivanillin, and dehydrodi(methyl vanillate). The procedure is especially useful for very hydrophobic compounds such as cholesteryl acetate and cholesterol that we give as examples. Other examples include vanillin and 3,4-dichlorobenzoic acid. If the solubility in water is available, then this alone is sufficient to predict solubilities in organic solvents, provided that the Abraham descriptors are available for the compound. Predictions can be made for solubilities in some 85 solvents. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 1500–1515, 2010 [ABSTRACT FROM AUTHOR]

The purpose of this work was to explore the kinetics of naphthalene adsorption on an activated carbon from aqueous and organic solutions. Kinetic curves were fitted to different theoretical models, and the results have been discussed in terms of the nature and properties of the solvents, the affinity of naphthalene to the solutions, and the accessibility to the porosity of the activated carbon. Data was fitted to the pseudo-second order kinetic model with good correlation coefficients for all the solution media. The faster adsorption rate was obtained for the most hydrophobic solvent (heptane). The overall adsorption rate of naphthalene seems to be controlled simultaneously by external (boundary layer) followed by intraparticle diffusion in the porosity of the activated carbon when water, ethanol and cyclohexane are used as solvents. In the case of heptane, only two stages were observed (pore diffusion and equilibrium) suggesting that the limiting stage is the intraparticle diffusion. The low value of the boundary thickness supports this observation. [Copyright &y& Elsevier]

The article presents the four organic laboratory experiments which explore the advantages of alternative reaction media. These experiments introduce green chemistry into educational settings easily and reap multiple benefits. These illustrate that the alternative solvents or reaction media reduce the use of hazardous or volatile organic solvents and enhance transformations by increasing the rate of reaction. It also found that product recovery is simplified and concomitantly minimizes the quantity of waste generated from product isolation.

Micellization of several surfactants in water−organic solvent mixtures has been investigated. Only solvents localized mainly in the bulk phase of the micellar solutions (they do not incorporate into the micelles) were studied, with either higher or lower permittivity than that of pure water. Results show that the influence of organic solvent addition on the aggregation process can be approximately accounted for by considering the changes in the bulk phase cohesive energy density, described by the Gordon parameter, G. To our knowledge, this is the first time that, for a given surfactant, the Gibbs energies of micellization, Δ GM°, obtained in several water−organic solvent mixtures have been fitted together. It is worth noting that data from different research groups have been considered. The Δ GM° versus Gcorrelation will permit the estimation of the variations in the Gibbs energy of micellization upon addition of known quantities of a given polar organic solvent. Speaking in a general way, organic solvent addition results in the bulk phase becoming a better solvent for the surfactant molecules. This would make the hydrophobic tail transfer from the bulk phase into the micelles less favorable and, as a consequence, Δ GM° increases (becomes less negative), making the aggregation process less spontaneous. [ABSTRACT FROM AUTHOR]

Cross-linked protein-coated microcrystals (CLPCMCs) of subtilisin Carlsberg (SC), and lipases from Candida rugosa (CRL) and Burkholderia cepacia (BCL) were prepared by cross-linking protein-coated microcrystals (PCMCs). These showed enhanced reaction rates for transesterification in organic solvents of different polarity compared with PCMCs. CLPCMCs of SC were catalytically active up to 80°C in octane and gave 98% conversion in 6 h, while PCMCs gave only 58% conversion in 8 h and conversions did not further increase with time. The Fourier transform infrared spectra showed that the alpha-helical content of CLPCMCs (unlike that of PCMCs) of SC were similar to what is reported for free SC in water. [ABSTRACT FROM AUTHOR]

The distribution of microamounts of La, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y nitrates between aqueous HNO3 solutions and solutions of tetraphenylmethylenediphosphine dioxide, diphenyl(diethylcarbamoylmethyl)phosphine oxide, and dibutyl(diethylcarbamoylmethyl)phosphine oxide in organic solvents in the presence of l-butyl-3-methylimidazolium hexafluorophosphate (BMImPF6) was studied. The stoichiometry of the extractable complexes was determined. The influence of the HNO3 concentration and the nature of the extractant and organic solvent on the synergistic effect observed in the REE extraction in the presence of BMImPF6 in the organic phase was analyzed. The possibility of using a macroporous polymeric sorbent impregnated with a mixture of tetraphenylmethylenediphosphine dioxide and BMImPF6 for the recovery of REE(III), U(VI), and Th(IV) from HNO3 solution was demonstrated. [ABSTRACT FROM AUTHOR]

The aim of this study was to characterize the quantitative analyzed EEG (electroencephalogram) findings (qEEG) in chronic solvent encephalopathy (CSE) patients and study whether the qEEG findings associate with the duration and intensity of the solvent exposure. Also, the diagnostic value of qEEG in CSE is discussed. The EEG of 47 male CSE patients was analyzed. The laboratory's own reference EEG values of 24 healthy male subjects formed the laboratory control group. We also used an agematched control group of 100 male blue-collar workers without occupational solvent exposure. The main finding of our study was that the power of the frontal theta band is increased in the CSE patient group compared with the laboratory control group. This suggests that the frontal cortex may be susceptible to the noxious effects of solvents. However, this difference was not seen in comparison with the matched control group, and thus, the connection with solvent effects remains uncertain. The variables indicating the level of solvent exposure did not associate with the power of the theta activity in the frontal area. Because of the small amount and unspecificity of the observed abnormalities, qEEG cannot be recommended to be used in the clinical diagnostics of solvent encephalopathy. [ABSTRACT FROM AUTHOR]

Abstract: The inverse Kirkwood–Buff integral (IKBI) approach is applied to the preferential solvation of F−, Cl−, Br−, I−, and in aqueous mixtures of the co-solvents (S) methanol (MeOH), ethanol (EtOH), t-butanol (t-BuOH), 1,2-ethanediol (EG), glycerol (Gly), acetone (Me2CO), acetonitrile (MeCN), formamide (FA), N,N-dimethylformamide (DMF), N,N,N′,N′,N″,N″-hexamethyl phosphoric triamide (HMPT), and dimethylsulfoxide (DMSO), as far as the relevant data exist in the literature. Fluoride anions are selectively solvated by the water up to large mole fractions (x S ⩾0.4) of S=EtOH, t-BuOH, Me2CO, MeCN, and DMF, and up to lower contents (x S ∼0.1) of MeOH, EG, FA, and DMSO. The other anions are preferentially solvated by water to diminishing extent as their sizes become larger, and the largest ones show some preference for S in water-rich mixtures of MeOH and FA, whereas in aqueous Gly even chloride is preferentially solvated by the Gly. The competition between the co-solvent and the anion for the hydrogen bonds that water molecules donate is the main cause for the observed preferential solvation behaviour. [Copyright &y& Elsevier]

To develop a simple, low-molecule, and cost-effective organocatalyst for the coupling of epoxides with CO2, we have screened this coupling reaction in different organic solvents and found that DMF is an efficient organic catalyst for the coupling of epoxides with CO2 to give cyclic carbonates in high yield. In some cases, the catalytic activity of DMF can be significantly increased by the addition of catalytic amount of H2O. [ABSTRACT FROM AUTHOR]

Biphasic systems can overcome the problem of low productivity in conventional media and have been exploited for biocatalysis. Solvent-tolerant microorganisms are useful in biotransformation with whole cells in biphasic reactions. A solvent-tolerant desulfurizing bacterium, Pseudomonas putida A4, was constructed by introducing the biodesulfurizing gene cluster dszABCD, which was from Rhodococcus erythropolis XP, into the solvent-tolerant strain P. putida Idaho. Biphasic reactions were performed to investigate the desulfurization of various sulfur-containing heterocyclic compounds in the presence of various organic solvents. P. putida A4 had the same substrate range as R. erythropolis XP and could degrade dibenzothiophene at a specific rate of 1.29 mM g (dry weight) of cells-1 h-1 for the first 2 h in the presence of 10% (vol/vol) p-xylene. P. putida A4 was also able to degrade dibenzothiophene in the presence of many other organic solvents at a concentration of 10% (vol/vol). This study is a significant step in the exploration of the biotechnological potential of novel biocatalysts for developing an efficient biodesulfurization process in biphasic reaction mixtures containing toxic organic solvents. [ABSTRACT FROM AUTHOR]

The removal of pharmaceuticals (diclofenac and clofibric acid) from aqueous solution by using single and two-phase ozonation system was investigated. The second phase consisted of a reusable, fluorinated hydrocarbon (FC 40). with an ozone solubility of 10–12 times that of water. The research was carried out in a continuous and semi-continuous system. The influence of pharmaceuticals concentration, ozone dosage and contact time between FC 40 phase and aqueous solution were measured. Low extraction coefficients of pharmaceuticals suggest the aqueous phase as a reaction medium, while ozonation in the presence of tertbutanol indicates a radical mechanism of the destruction reactions. The results show that the removal efficiency of pharmaceuticals by fluorinated solvent/ozone combined system is higher when compared with aqueous phase ozonation. [ABSTRACT FROM AUTHOR]

The article discusses various aspects of fluorous chemistry. Fluorous chemistry involves the study of the structure, composition, properties, and reactions of highly fluorinated molecules, molecular fragments, and materials. Fluorous chemistry concentrates on resource- and time-consuming separation, in order to improve the material economy, and thus bears the hallmark of a potentially environmentally friendly technology. Highly fluorinated alkanes and ethers are usually colorless liquids of high density, inert, nontoxic, nonpolar, and, due to their very weak intermolecular forces, hydrophobic and lipophobic. Organic compounds generally exhibit low affinities for fluorous solvents relative to organic solvents. Fluorous chemistry possesses the advantage of easy separation based on different affinities of organic and fluorous molecules. In the separation by liquid-liquid extraction, a catalytic or stoichiometric reaction can be carried out in the fluorous biphase system. With a temperature increase, the organic and fluorous solvents become miscible, and the reaction is carried out under homogeneous conditions in the higher temperature monophasic limit.

The results of a quantitative structure−property relationship (QSPR) analysis of 127 different solvent scales and 774 solvents using the CODESSA PRO program are presented. QSPR models for each scale were constructed using only theoretical descriptors. The high quality of the models is reflected by the squared multiple correlation coefficients that range from 0.726 to 0.999; only 18 models have R2 < 0.800. This enables direct theoretical calculation of predicted values for any scale and/or for any organic solvent, including those previously unmeasured. The molecular descriptors involved in the models are classified and discussed according to (i) the origin of their calculation (i.e., constitutional, geometric, charge-related, etc.) and (ii) the commonly accepted classification of physical interactions between the solute and solvent molecules in liquid (condensed) media. A reduced matrix 774 (solvents) × 100 (solvent scales) was selected for the principal component analysis (PCA) by taking into account only the solvent scales with more than 20 experimental data points. The first 5 principal components account for 75% of the total variance. The robustness of the PCA model obtained was validated by the comparison models development for restricted submatrices of data and with the results obtained for the full data set. The total variance accounted for by the first three PCs, for the submatrices with the same number of solvent scales but different numbers of solvents, varies from 68.2% to 59.0%. This demonstrates that the total variance described by the first 3 components is essentially stable as the number of solvents involved varies from 100 to 774. Subsequently, a matrix with 703 diverse solvents and 100 solvent scales was selected for the general classification of the solvents and scales according to the scores and loadings obtained from the PCA treatment. Classification of the theoretical molecular descriptors, derived from the chemical structure alone, according to their relevance to specific types of intermolecular interaction (cavity formation, electrostatic polarization, dispersion, and hydrogen bonding) in liquid media enables a more easily comprehensible physical interpretation of the QSPR of molecular properties in liquids and solutions. The reported QSPR models for solvent scales with theoretical molecular descriptors and the results of the PCA analysis are potentially of great practical importance, as they extend the applicability of correlations with empirical solvent scales to many previously unmeasured systems. [ABSTRACT FROM AUTHOR]

Solute solvent interactions on the keto-enol tautomerism of 2-nitrocyclohexanone in several organic solvents and room-temperature ionic liquids (RTILs) have been analyzed in terms of multiparameter equations. Permittivity and cohesive pressure values of the RTILs, unavailable by direct measurements, have been derived. [ABSTRACT FROM AUTHOR]

Abstract: Prediction of the optimal extraction solvent based on the solubility parameter to extract the typical organochlorine pesticides from Jiangxi red soil was reported in this paper. Hildebrand solubility parameters, including dispersion coefficient (δ d), polarity (δ p) and hydrogen bonding (δ h), of extraction solvents (including hexane, dichloromethane, hexane/methanol (4:1, v/v), hexane/acetone (1:1, v/v), hexane/dichloromethane (1:1, v/v) and organochlorine pesticides were calculated using group contribution method. The solvents, such as hexane/methanol (4:1, v/v) and hexane/acetone (1:1, v/v) were selected as ideal extraction solvents to extract o,p′-DDT o,p′-DDE and o,p′-DDD with high recoveries (>82%), furthermore, these solvents can be used to extract α-endosulfan, Endrin and HCB with the reliable recoveries (>75%). The estimated finding by solubility parameters was supported by the results of soxhlet extraction. [Copyright &y& Elsevier]

Spectroscopic studies on a set of ionic liquids were performed using different solvatochromic probe molecules. Different probes were found to characterize ionic liquids as solvents differently. Mixtures of ionic liquids with organic solvents exhibit nonlinear behaviour of polarity with composition as measured by Reichardt's dyes. [ABSTRACT FROM AUTHOR]

Proton nuclear magnetic resonance (NMR) spin-spin relaxation and imaging have been applied to investigate white Portland cement pastes during hydration in the absence and in the presence of organic solvents. The main organic solvent investigated was methanol, alone or together with the organic waste 2-chloroaniline (2-CA), an aromatic amine representative of an important class of highly toxic compounds. For all the analysed samples, prepared with a solvent-to-cement ratio of 0.4, the decay of the echo magnetization has been fitted by adopting a model that combines an exponential component with a gaussian one. The calculated independent relaxation parameters have been discussed in terms of morphological and dynamical changes that occur during the cement hardening process and pore formation. Three kinds of water molecules: “solid-like” (chemically and physically bound), “liquid-like” (porous trapped) and “free” water, endowed with anisotropic, near isotropic and isotropic motion, respectively, were identified. Spin-echo images collected on the same samples during the hydration kinetics, allowed the changes of water and solvents spatial distribution in the porous network to be monitored, showing percolation phenomena and confirming the multimodal open channels structure of the hardened cement system. Both T2 relaxation and imaging data indicated that a pronounced delay occurs in the cement hardening when organics are present. © 2004 Elsevier Inc. All rights reserved. [Copyright &y& Elsevier]

A comparative study is made of the solvent effect on the kinetics of arylsulfonation of benzhydrazide with 3-nitrobenzenesulfonyl chloride in aqueous-organic solutions (water-2-propanol, water-dioxane, water-tetrahydrofuran, and water-acetonitrile) at 298 K. The arylsulfonation product can be obtained in nearly theoretical yield at the initial reactant concentrations of 0.1 M in the water-dioxane, water-MeCN, and water-THF mixtures containing above 30 wt % water. [ABSTRACT FROM AUTHOR]

Describes the transcriptional analysis of the ostA/imp gene involved in organic solvent sensitivity in Escherichia coli. No-heat inducible expression of ostA observed by Northern blotting analysis, indicating that the contribution was very small; Deletion analysis of fusions demonstrating that the two promoters contributed almost equally to the constitutive expression of the ostA gene.

Objectives. A case–control study was conducted in Verona, Italy, to assess the relationship between occupation, occupational exposures and systemic sclerosis (SSc). Methods. Fifty-five cases (46 female and nine male) and 171 controls were recruited. Interviews provided work histories, including job titles, industry and likelihood of occupational exposure to silica, hand–arm vibration, organic solvents, and other chemicals. Odds ratios (ORs) and 95% confidence intervals (95% CI) were estimated. Results. Female teachers (OR 3.4, 95% CI 1.2–10.1) and textile workers (OR 2.1, 95% CI 1.0–4.6) were at an increased risk of SSc. Compared with those never exposed, age-adjusted and gender-adjusted ORs were 2.3 (95% CI 1.0–5.4) among subjects exposed to organic solvents, 2.5 (95% CI 0.8–8.0) for exposure to selected chemicals, 1.7 (95% CI 0.4–7.6) for exposure to silica, and 1.5 (95% CI 0.5–4.8) for usage of vibrating tools. When data analysis was stratified according to gender, only men showed a significant increase in risk for exposure to solvents and selected chemicals. Conclusions. The findings of this study tend to support the role of organic solvents and certain chemicals in SSc causation. The association with teaching and working in the textile industry suggests that other exposures are involved in the aetiology of SSc among women. However, because of the small number of subjects, particularly in stratified analyses, chance cannot be ruled out as an explanation of some findings of this study. [ABSTRACT FROM AUTHOR]

Objectives. The screening and identification of occupational liver or other organ-system injury related to long-term, low-level solvent exposure are difficult in clinical practice. We studied the feasibility of the use of common laboratory tests combined with a detailed exposure history. Methods. The relationships between laboratory tests and exposure to organic solvents were studied in regression modelling adjusted to age, alcohol consumption, gender and body mass index (BMI). The subjects were 29 solvent-exposed workers and 19 referents. Laboratory tests included serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), carbohydrate-deficient transferrin (CDT), alkaline phosphatase (ALP), creatinine, cholesterol, HDL-cholesterol, triglycerides, blood glucose and total and conjugated bilirubin. Positive hepatitis serology, systemic diseases or medications with known hepatic effects and current pregnancy were exclusion criteria. The main exposures of each subject were identified. Current solvent exposure status, exposure during the past 3 months, exposure during the past 5 and 10 years, and total life-time exposure were recorded. Results. AST (P=0.0031), ALT (P=0.0015) and cholesterol (P=0.0110) correlated positively with cumulative solvent exposure in the past 5 years, total bilirubin with current exposure (P=0.0380), and glucose with exposure in the past 5 (P<0.0001) and 10 (P=0.0003) years. Triglycerides correlated positively with exposure in the past 5 (P=0.0025) and 10 (P=0.0059) years and with life-time exposure (P=0.0005). Creatinine correlated negatively with exposure in the past 10 years (P=0.0300) and life-time exposure (P=0.0005). Most laboratory values were within the normal range. Conclusions. These results suggest a multi-system health effect of solvents. The laboratory data had some similarities with those in the metabolic syndrome. The screening and diagnostics of solvent-related conditions should be based on a thorough work history and a set of carefully selected laboratory tests. No single test seems sufficient for this purpose. [ABSTRACT FROM AUTHOR]

Objective. The objective of this study was to determine to what extent the substitution of solvent-based paint by water-based paint has reduced potential exposure to organic solvents for spray painters in car repair shops. Methods. Full-shift personal air sampling (n=79) was carried out over 3 consecutive days in eight car repair shops. Blood samples on the Monday morning (n=26) and at the end of the shift on the Wednesday (n=26), were analysed for organic solvents by headspace techniques. Results. Toluene was the organic solvent detected at the highest geometric mean concentration in air samples when solvent-based paint systems were used (0.8 ppm), whereas xylene was found at the highest level when water-based systems were used (0.25 ppm). Toluene, isopropanol, acetone and butyl acetate were detected at higher concentrations when solvent-based paint was used than when water-based paint was employed. The additive factor, based on Norwegian limit values, was three-times higher for the painters using solvent-based paint (0.15) than for those using water-based paint (0.05). On Wednesday after shift the geometric mean of toluene in blood was significantly higher for the painters using solvent-based paint (0.044 μg/ml) than for the painters using water-based paint (0.007 μg/ml). There was a significant correlation between toluene in personal air samples and toluene in blood samples taken at the end of the shift on the same day. Conclusions. When solvent-based paint systems were used the additive factor for organic solvent exposure was three-times higher than when water-based systems were employed. The exposure levels of the organic solvents were well below the Norwegian limit values. The significant correlation between the toluene concentration in air and blood samples indicated that the uptake of organic solvents was correspondingly reduced. At the levels of organic solvents presently described the risk of acute and chronic health effects caused by organic solvents is low. [ABSTRACT FROM AUTHOR]

Objective. To examine if xylenes and xylene isomers in end-of-shift urine are good biological indicators of low-level exposure to each solvent, similarly to toluene in urine. Methods. The study was conducted in the latter half of a working week. Furniture makers, 86 subjects in total (76 men and ten women), participated in the study in combination with 11 non-exposed subjects. Time-weighted average (8-h TWA) exposures to mixtures of toluene (TOL-A), xylenes (XYLs-A), ethylbenzene (EB-A), acetone (ACE-A) etc. were monitored with diffusive samplers for lipophilic and hydrophilic solvents, respectively. Urine samples (i.e., TOL-U, XYLs-U, EB-U, ACE-U, etc.) were collected at the end of the shift and subjected to head-space gas chromatography analysis for each solvent. The exposure–excretion relationship was examined by simple as well as multiple regression analysis. Results. The exposures to TOL and XYLs were around or below current occupational exposure limit levels. The exposures to other solvents [i.e., ACE, EB, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), etc.] were at substantially lower levels. The correlation of the TWA solvent exposure concentration with the concentration of the corresponding solvent in the end-of-shift urine sample was close for TOL, and also almost equally close in the case of XYLs and each of the three XYL isomers. Whereas the slope of the regression line for XYLs was significantly less steep than that for TOL when compared on an equi-molar basis, there was no difference among the three XYL isomers. No confounding effects of age, sex and co-exposure to other solvents were detected. The observation confirms previous reports that TOL-U is a good marker of TOL vapor exposure, indicates that XYL-U is also a reliable marker of exposure to vapors of XYLs or any of the three XYL isomers, and suggests that estimation of exposure to vapors of XYLs (i.e., three isomers in combination) is possible by the determination of one of the XYL isomers in urine, once the proportion of the isomers in air is known. Possible association of water solubility with solvent levels in urine is discussed. Conclusions Biological monitoring of exposure by means of analysis of end-of-shift urine for mother solvent is possible, not only in the case of TOL as previously reported, but also in cases of XYLs, either for three isomers in combination or separately. [ABSTRACT FROM AUTHOR]

The Abraham general solvation model is used to predict the saturation solubility of crystalline nonelectrolyte solutes in organic solvents. The derived equations take the form of log (C[sub S] /C[sub W] ) = c + rR[sub 2] + sπ[sub 2] [sup H] + aΣα[sub 2] [sup H] + bΣβ[sub 2] [sup H] + vV[sub x] and log (C[sub S] /C[sub G] ) = c + rR[sub 2] + sπ[sub 2] [sup H] + aΣα[sub 2] [sup H] + bΣβ[sub 2] [sup H] + l log L[sup (16)] where C[sub S] and C[sub W] refer to the solute solubility in the organic solvent and water, respectively, C[sub G] is a gas-phase concentration, R[sub 2] is the solute's excess molar refraction, V[sub x] is McGowan volume of the solute, Σα[sub 2] [sup H] and Σβ[sub 2] [sup H] are measures of the solute's hydrogen-bond acidity and hydrogen-bond basicity, π[sub 2] [sup H] denotes the solute's dipolarity and (or) polarizability descriptor, and log L[sup (16)] is the solute's gas-phase dimensionless Ostwald partition coefficient into hexadecane at 298 K. The remaining symbols in the above expressions are known equation coefficients, which have been determined previously for a large number of gas–solvent and water–solvent systems. Computations show that the Abraham general solvation model predicts the observed solubility behavior of anthracene, phenanthrene, and hexachlorobenzene to within an average absolute deviation of about ±35%.Key words: solubility predictions, organic solvents, nonelectrolyte solutes, partition coefficients.On a utilisé le modèle général de solvatation d'Abraham pour faire des prédictions relatives à la solubilité de saturation de solutés cristallins non-électrolytes, dans des solvants organiques. Les équations dérivées sont de la forme log (C[sub S] /C[sub W] ) = c + rR[sub 2] + sπ[sub 2] [sup H] + aΣα[sub 2] [sup H] + bΣβ[sub 2] [sup H] + vV[sub X] et log (C[sub S] /C[sub G] ) = c + rR[sub 2] + sπ[sub 2] [sup H] + aΣα[sub 2] [sup H] + bΣβ[sub 2] [sup H] + l log L[sup (16)] dans lesquelles C[sub S] et C[sub W] se réfèrent respectivement à la solubilité du soluté dans le solvant organique et dans l'eau, C[sub G] est une concentration en phase gazeuse, R[sub 2] est la réfraction molaire en excès du soluté, V[sub X] est le volume de McGowan du soluté, Σα[sub 2] [sup H] et Σβ[sub 2] [sup H] sont respectivement des mesures de l'acidité et de la basicité de la liaison hydrogène du soluté, π[sub 2] [sup H] correspond à un descripteur du caractère dipolaire et de la polarisabilité du soluté et log L[sup (16)] est le coefficient de partition d'Oswald, sans dimension, du soluté en phase gazeuse, dans l'hexadécane, à 298 K. Les autres symboles de ces expressions sont des coefficients d'équation connus qui ont été déterminés antérieurement pour un grand nombre de systèmes gaz–solvant et eau–solvant. Les calculs montrent que le modèle général de solvatation d'Abraham permet de prédire le comportement de solubilité observé pour l'anthracène, le phénanthrène e l'hexachlorobenzène dans les limites d'une déviation moyenne absolue d'environ ±35%. Mots clés : prédictions de solubilité, solvants organiques, solutés non-électrolytes, coefficients de partition. [Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

There is no dramatic evidence as yet that the use of solvents is increasing at a rate sufficient to justify the prominence they have been assigned. With this thought in mind, the author highlights the broad benefits, drawbacks and limitations of using nonaqueous solvents in processing, and assesses the specific functions they [night realistically be expected to play m light of other major changes which are occurring in the industry. [ABSTRACT FROM AUTHOR]

This article focuses on the active catalyst in proline-mediated reactions. The α-amination and the α-aminoxylation of aldehydes are two recent additions to the rapidly expanding list of proline-based reactions introduced with the discovery of the Hajos-Parrish-Eder-Wiechert-Sauer reaction and elegantly revived by List, with the intermolecular aldol reaction. A key question is whether the low solubility of proline in organic solvents complicates kinetic analyses by including a solid-liquid transport step in the overall observed rate process.

Review: 183 refs. [ABSTRACT FROM AUTHOR]

Review: 87 refs. [ABSTRACT FROM AUTHOR]

Review: 72 refs. [ABSTRACT FROM AUTHOR]

Molecular packing structure in pentacene films prepared from the Afzali's precursor soluble in general organic solvents was characterized by in-plane grazing-incidence X-ray diffraction (GIXD) measurements. The crystallographic ab plane of pentacene was parallel to the surface of a Si substrate. Crystal structure of pentacene near the substrate was identified as the thin-film phase. [ABSTRACT FROM AUTHOR]