Solubilities of anthracene,fluoranthene and pyrene in organic solvents: Comparison of calculated values using UNIFAC and modified UNIFAC (Dortmund) models with experimental data and values using the mobile order theory

The solubility of anthracene in 43 organic solvents, fluoranthene (45 solvents) and pyrene (30 solvents) has been calculated using UNIFAC and Modified UNIFAC (Dortmund) models to estimate the activity coefficient of the solute. It was found that both UNIFAC and Modified UNIFAC described better the solubilities in polar solvents like alcohols, ketones, esters and ethers than in nonpolar solvents like alkanes and aromatic hydrocarbons. UNIFAC and the Mobile Order Theory supplement each other well in calculating the solubilities, which means that one can choose the right model depending on the solvent one is using.     

Calculation of solubilities of the pesticides diuron and monuron in organic nonelectrolyte solvents using UNIFAC and modified UNIFAC (dortmund) models

The solubility of diuron (3‐(3,4‐dichlorophenyl)‐1, 1 ‐dimethyl urea) and monuron (3‐(4‐chlorophenyl)‐1, 1 ‐dimethyl urea) in 49 and 43 different organic non‐electrolyte solvents, respectively, have been calculated. It was found that Modified UNIFAC described well the solubilities both in polar solvents like alcohols, ketones, esters and ethers and in nonpolar solvents like alkanes and aromatic hydrocarbons. UNIFAC and the mobile order theory supplement each other well in calculating the solubilities, which means that one can choose the right model depending on the solvent one is using.     

阴离子聚合体系活性种聚合活性的探讨

讨论了非极性和极性溶剂中有机锂活性种的活性，指出添加少量极性添加剂或在极性溶剂中，由于溶剂化作用，有机锂活性种的聚合活性有所降低。     

Enantioselective Esterification of Racemic Ibuprofen in Solvent Media under Reduced Pressure

The enantioselective esterification of (R,S)-ibuprofen has been performed with Novozym 435^TM in solvent media under reduced pressure. The nature of the solvent affects the activity and enantioselectivity of the lipase. High esterification rates are obtained in solvents having high hydrophobicity (log P>4). On the other hand, the best enantioselectivity is obtained with solvents having low hydrophobicity (log P<3). This particular enantioselectivity trend is observed within the individual solvent families investigated (alkanes, ethers and aromatics). © Canadian Crown Copyright 1997     

萃取剂对GC-MS法测定天麻茎秆化学组分的影响

采用常见极性溶剂和非极性溶剂作为萃取试剂,在超声波辅助下,对干燥天麻茎秆粉末进行萃取,然后分别用GC-MS法对极性溶剂和非极性溶剂的提取浓缩液进行化学成分分析,比较其中化学组分的差别。结果表明:甲醇作萃取溶剂时,38种化学组分可被鉴别确认;四氯化碳作萃取溶剂时,43种化学组分可别鉴别确认,其中有24种化合物在甲醇提取浸膏中同样被检出,且可识别的化学组分中烷烃等极性较小的化合物明显增多。此结果有助于天麻茎秆化学组分的研究,可以根据所需分析目标的不同选用合适的提取溶剂。     

Solvent polarity influences product selectivity of lipase-mediated esterification reactions in microaqueous media

Esterification reactions were evaluated by using lipases fromRhizomucor miehei (Lipozyme IM20) andPseudomonas cepacia (PS-30) with equimolar levels (1.77 mmol) of undecanoic acid and glycerol or 1,3-propanediol (1,3-PD) or 1,2-propanediol (1,2-PD) in organic solvents of log P (partition coefficient between 1-octanol/water) values of (−0.33–4.5. Reaction yields (percentage of esterified undercanoate) with glycerol ranged from 1.4 to 72%, with greatest yields observed in solvents of log P 4.0–4.5 for Lipozyme, whereas the PS-30 lipase was similarly effective (27–38% yield) over the full range of solvent polarities. For both enzymes, as solvent apolarity increased, so did the extent of acylation of glycerol in the final product mixture. Reaction yields with 1,3-PD ranged from 8.1 to 64% for Lipozyme and from 18 to 84% for PS-30 lipase, with greatest yields observed for both enzymes in solvents of log P values in the range 1.2–5.0. For both lipases, the shift to greater solvent apolarity was accompanied by an increased molar ratio of diacylated-1,3-PD/monoacylated-1,3-PD in the product mixture. Reaction yields with 1,2-PD ranged from 2.5 to 45% for Lipozyme and from 12 to 52% for PS-30 lipase, with greatest yields observed in solvents of log P values in the ranges 1.4–1.9 and 1.4–4.5, respectively. The shift to greater solvent apolarity was accompanied by an increased molar ratio of diacylated-1,2-PD: monoacylated-1,2-PD in the product mixture, except for Lipozyme in the three most apolar solvents (log P of 3.5–4.5) in which there was a general attenuation of activity. These results suggest the existence of a solvent polarity influence on reaction product selectivity in multiproduct reactions, which can be partially explained on the basis of differential solvation and extraction properties of solvents.     

全氟壬烯氟两相体系及其在酯化反应中的应用

Some apolar organic solvents is miscible with perfluorous nonene to form fluorous biphase systems.Perfluorous nonene could be used as a green solvent in equimolar esterification of carboxylic acids with alcohols without removal of water or ester formed. Perfluorous nonene made the esterification equilibrium to move right and the yields of esterification to enhance in different degrees as compared with that in the absence of perfluorous nonene. After esterification perfluorous nonene is easy to be recovered and recycled.     

Solvent Effects on the Selectivity of Palladium-Catalyzed Suzuki-Miyaura Couplings

The use of polar solvents MeCN or dimethylformamide (DMF) was previously shown to induce a selectivity switch in the Pd/P^tBu₃-catalyzed Suzuki-Miyaura coupling of chloroaryl triflates. This phenomenon was attributed to the ability of polar solvents to stabilize anionic transition states for oxidative addition. However, we demonstrate that selectivity in this reaction does not trend with solvent dielectic constant. Unlike MeCN and DMF, water, alcohols, and several polar aprotic solvents such as MeNO₂, acetone, and propylene carbonate provide the same selectivity as nonpolar solvents. These results indicate that the role of solvent on the selectivity of Suzuki-Miyaura couplings may be more complex than previously envisioned. Furthermore, this observation has the potential for synthetic value as it greatly broadens the scope of solvents that can be used for chloride-selective cross coupling of chloroaryl triflates.     

The influence of organic solvents on transphosphatidylation by phospholipase D from peanut in anhydrous organic solvents

Phospholipase D (PLD) is widely used for the transphosphatidylation of phospholipids, which is conventionally performed in biphasic systems. The influence of organic solvents on transphosphatidylation by peanut PLD in anhydrous organic solvents was studied and, for the first time, compared to that of a biphasic system in this paper. The results demonstrated that PLD activity from peanut was influenced by solvents of different polarity in anhydrous organic solvents, and the influence tendency of organic solvents (diethyl ether, chloroform, methylenechloride) on transphosphatidylation by peanut PLD in anhydrous organic solvents was the same as that in a biphasic system consisting of water and a hydrophobic organic solvent.     

反相气相色谱法研究聚合物的热力学行为(Ⅱ)聚乙二醇-溶剂热力学参数的测定

采用反相气相色谱法 (IGC)测定了聚乙二醇 (PEG)的溶解度参数以及溶剂与 PEG相互作用的溶解焓、混合焓和蒸发焓。结果表明 :烷烃类溶剂溶解 PEG为吸热反应 ,是 PEG的非溶剂 ;甲苯、乙酸乙酯溶解 PEG为放热反应 ,是 PEG的良溶剂。所得结果与前文结论相一致     

Phase behavior of laundry surfactants in polar solvents

Laundry surfactants are usually mixtures of ionic and nonionic detergents that exhibit a complex phase behavior. Here the ternary phase behavior of an isotropic and a liquid crystalline (LC) surfactant mixture has been examined in water/solvent systems. The size of the LC area in the ternary phase diagram was correlated to solvent parameters including the dielectric constant and the Gordon cohesiveness parameter. The Gordon parameter was found to have a linear relationship with the amount of solvent needed to go from an LC to an isotropic state over a wide range of solvents from polar to apolar. For solvents in which no surfactant aggregation (micellar or inverted micellar) is expected, the size of the LC area is linear with the reciprocal of the dielectric constant of the solvent. On diluting practical detergent liquids with water, a large LC area can be avoided by using solvents with a relatively low dielectric constant and with a relatively low molecular weight. The aggregated state of the surfactant mixtures in the isotropic regions of the phase diagram was studied using the solvatochromic fluorescent probe Nile Red. In the water corner of the phase diagram, the surfactants are aggregated into micelles. In strongly polar solvents, such as glycerol, ethylene glycol, formamide, and ethanolamine, the surfactants are also aggregated into micelles. In somewhat less polar solvents, such as methanol, ethanol, and t-butanol, the surfactant molecules are randomly distributed. In the surfactant-rich corner of the phase diagram of the isotropic mixture, the surfactant forms inverted micelles. An inverted micelle-to-micelle transition could be observed on dilution in ethylene glycol as a discontinuity in the trend of the Nile Red fluorescence maxima.     

Tandem Epoxidation‐Alcoholysis or Epoxidation‐Hydrolysis of Glycals Catalyzed by Titanium(IV) Isopropoxide or Venturello’s Phosphotungstate Complex

Venturello’s phosphotungstate complex and titanium(IV) isopropoxide [Ti(O‐i‐Pr)₄] were successfully used as catalysts for the epoxidation‐alcoholysis of glycals using hydrogen peroxide [H₂O₂]. Reaction substrates included a range of variously protected glycals and different alcohols were used as solvents. Ti(O‐i‐Pr)₄ was only effective in methanol as solvent, but gave methyl glycosides in high yields and high selectivities. The Venturello complex proved to be a very versatile and efficient catalyst. Apart from epoxidation‐alcoholysis in alcoholic solvents it also showed activity in biphasic conditions to allow for glycosylation of long‐chain alcohols and was very effective in the stereoselective dihydroxylation of benzylated glucal.     

Epoxidation of cyclohexene over basic mixed oxides derived from hydrotalcite materials: Activating agent, solvent and catalyst reutilization

Synthesis and characterization of basic hydrotalcite-like derived catalysts were carried out and the resulting materials were tested in cyclohexene epoxidation. The reaction being dependent on the activating agent and the solvent of the reaction. Several nitriles and amides were used as activating agents and various compounds of different nature (protic and aprotic, polar and apolar) were analyzed as epoxidation solvents. The highest epoxide yield and cyclohexene conversion were achieved by using benzonitrile and methanol as activating agent and solvent, respectively. In the present work the reutilization of these solids in cyclohexene epoxidation has been tested by regeneration. The catalyst washed with the solvent after one reaction did not enhance the catalytic properties of the fresh solid. Nevertheless the activation of the solid up 600 °C provided a good activity after four runs.     

Effect of Reaction Medium on the Yield and Composition of the Products of the Liquid-Phase Ozonization of Brown Coal

The effect of solvent polarity on the yield and composition of the ozonization products of brown coal from the Balakhtinskoe deposit was studied. The greatest yield of soluble oxygen-containing products was obtained upon ozonization in polar solvents—glacial acetic acid and acetone. The application of chlorinated solvents and lower alcohols, including their aqueous solutions, was less effective.     

Influence of solvent composition and degree of reaction on the formation of surface microtopography in a thermoset siloxane-urethane system

The effects of solvent composition and degree of reaction prior to film formation leading to the formation of a biphasic microtopographical surface in a crosslinked siloxane-urethane coating system were explored. For the solvent composition study, a D-optimal mixture design study was carried out using methyl n-amyl ketone (MAK), toluene, ethyl 3-ethoxypropionate (EEP), butyl acetate (BA) and isopropyl alcohol (IPA) as solvents. The study revealed that the presence of slow evaporating solvents MAK, EEP and the absence of fast evaporating solvent IPA in the solvent composition with a minimal amount of BA favored formation of a structured surface. Control over the domain size could be obtained by varying the MAK:EEP ratio in solvent compositions having a fixed amount of BA. The effect of mixing time on the formation of surface domains was studied. At short mixing times (<2 h) and long mixing times (>7 h), no surface phase separation is observed, while at intermediate times a ‘window’ was found where surface microdomains of similar size are generated. Doubling the level of catalyst halves the mixing time required to generate surfaces with microdomains. Scanning electron microscopy (SEM) studies with energy dispersive X-ray mapping and dynamic mechanical analysis (DMA) were done in order to understand the development of the phases in the PDMS-polyurethane system.     

Computational Analysis of the Solid-State and Solvation Properties of Carbamazepine in Relation to its Polymorphism

The solvent-dependent polymorphism of the active pharmaceutical ingredient (API) carbamazepine is interpreted from calculations of the solid-state and API-solvent intermolecular interactions. These simulations suggested that apolar solute-solute interactions could be disrupted by apolar solvents. In contrast, the polar solute-solute interactions were found to be easily disrupted by polar and protic solvents. This is consistent with experimental observations that the crystallization of the metastable form II is more dominant in apolar solvents. The Mercury program remains the gold standard in terms of usability; however, further expansion into more complex simulation techniques could make this package of even greater use in pharmaceutical manufacturing workflows.     

Underexposed polar residues and protein stabilization

Increasing protein stability is interesting for practical reasons and because it tests our understanding of protein energetics. We explore here the feasibility of stabilizing proteins by replacing underexposed polar residues by apolar ones of similar size and shape. We have compared the stability of wild-type apoflavodoxin with that of a few carefully selected mutants carrying Y → F, Q → L, T → V or K → M replacements. Although a clear inverse correlation between native solvent exposures of replaced polar residues and stability of mutants is observed, most mutations fail to stabilize the protein. The promising exceptions are the two Q → L mutations tested, which characteristically combine the greatest reduction in polar burial with the greatest increase in apolar burial relative to wild type. Analysis of published stability data corresponding to a variety of mutant proteins confirms that, unlike Y → F or T → V replacements, Q → L mutations tend to be stabilizing, and it suggests that N → L mutations might be stabilizing as well. On the other hand, we show that the stability changes associated to the apoflavodoxin mutations can be rationalized in terms of differential polar and apolar burials upon folding plus a generic destabilizing penalty term. Simple equations combining these contributions predict stability changes in a large data set of 113 mutants (Y → F, Q → L or T → V) similarly well as more complex algorithms available on the Internet.     

Accelerated weathering and chemical resistance of polyurethane powder coatings

A study of the weathering mechanism of innovative polyurethane powder coatings has been performed. UV-B irradiation and condensation cycle accelerated tests were carried out on two different polyurethane powder coating formulations for outdoor applications. Using Fourier transform infrared spectroscopy and microscope observation, it was possible to analyze the photochemical and morphological modifications. In addition, the color and gloss changes were measured. Organic coatings are often in contact with solvents in particular during cleaning actions. The chemical resistance was then studied considering the evolution of the corrosion barrier property of the coating as a function of the solvent contact time. Electrochemical impedance spectroscopy measurements were carried out. Methylethylketone (polar) and xylene (apolar) were considered as representative solvents. Due to the strong polarity, the first solvent showed a strong interaction with the hydrogen bonds between the polyurethane chains causing the solvent uptake. The amount of solvent uptake depends on the coating chains rigidity caused by the different polyester resin monomers. The apolar xylene presented no significant interaction with the coatings.     

气体溶解度的分子热力学(Ⅱ)——气体在极性溶剂中的Henry常数

本文将胡英、徐英年、Prausnitz建立的气体在非极性溶剂中溶解度的分子热力学模型推广到极性溶剂系统,并用它计算了气体在水、醇、酮、卤代苯及萘的取代物中的Henry常数.在193.15—573.15K的广阔温度范围内,对于分子偶极矩最大为2.83德拜(Debye)的13种溶剂、共81个系统,一般只用一个可调参数,本模型均得到较好的计算结果.     

The solubility of poly(vinylidene chloride) in solvent mixtures

Effective solvents for poly(vinylidene chloride) (PVDC) were obtained by mixing a polar aprotic solvent with a less polar solvent of cyclic structure. The polar components included sulfoxides, N,N-dialkylamides, and N-alkyl lactams. The cyclic cosolvents included aliphatic and aromatic hydrocarbons, ketones, ethers, and thioethers. The problem of solubility of a crystalline polymer in a mixed solvent was analyzed by extending the Flory theory of melting point depression to three component mixtures. The results predict that favorable mixtures arise when at least one of the components interacts strongly with the polymer but is nearly incompatible with the cosolvent. This is in qualitative agreement with the observed behavior of PVDC.