Binary and ternary solubilities of disperse dyes and their blend in supercritical carbon dioxide

Binary and ternary solubilities of C.I. Disperse Blue 134 (1,4-bis(isopropylamino)anthraquinone) C.I. Disperse Yellow 16 (3-methyl-1-phenyl-5-pyrazolone) and their dye mixture in supercritical carbon dioxide (SC-CO₂) were measured by a flow-type apparatus. The solubility measurements were carried out at the pressure ranges from 10.0 to 25.0 MPa for the binary systems at the temperatures from 323.15 to 383.15 K and for the ternary system at 383.15 K. An empirical equation was used to correlate the experimental binary solubilities of the dyes in terms of the density of carbon dioxide. To represent accurately the binary solubility of the dyes in terms of temperature and pressure, we used a modified Peng–Robinson–Stryjek–Vera equation of state (PRSV EOS). The ternary solubilities of the dye blend could be predicted successfully from binary parameters with the modified PRSV EOS.     

Synthesis,crystal structure,and FET characteristics of thieno[2,3-b]thiophene-based bent-thienoacenes

Two novel bent-shaped thienoacenes, naphtho[2,3-b]naphtho[2′,3′:4,5]thieno[3,2-d]thiophene (bent-DNTT) and anthra[2,3-b]anthra[2′,3′:4,5]thieno[3,2-d]thiophene (bent-DATT) were synthesized from thieno[2,3-b]thiophene and their corresponding aromatic anhydrides by three steps: Friedel–Crafts acylation, acid-promoted cyclization, and reductive aromatization. The structural curvature improved the solubility of these thienoacenes in organic solvents. The bent-DNTT based FET device was fabricated by the spin-coating method. The device exhibited p-type characteristics with a mobility of 5.1 × 10^?5 cm² V^?1 s^?1. Its thin-film structure was fully characterized as an edge-on orientation with large intermolecular orbital coupling.     

A novel HMP-2 dye of high extinction coefficient designed for enhancing the performance of ZnO platelets

Newly designed cis-[Ru(H₂dcbpy) (L) (NCS)₂ (HMP-2), where L is 4-(4-(N,N-di-(p-hexyloxyphenyl)-amino)styryl)-4′-methyl-2,2′-bipyridine, sensitizing dye of high extinction coefficient than the routinely preferred ruthenium (II) cis-di(thiocyanato)bis(2,2′-bipyridyl-4,4′-dicarboxylic acid) (N3) sensitizing dye is explored. Electrochemically synthesized ZnO (plates of 4–5 μm in height and 100–150 nm in width) electrodes are dipped intentionally in N3 and HMP-2 dyes for 20 h so as to observe large surface agglomeration effect for ZnO/N3 system. Due to the local inhomogeneity resulting from the Zn²⁺/dye complex layer formed between ZnO platelets and N3 dye, its solar-to-electrical conversion efficiency is inferior than aggregation-free ZnO/HMP-2.     

Measurement and correlation of antifungal drugs solubility in pure supercritical CO2 using semiempirical models

In the present study the solubilities of two antifungal drugs of ketoconazole and clotrimazole in supercritical carbon dioxide were measured using a simple static method. The experimental data were measured at (308 to 348) K, over the pressure range of (12.2 to 35.5) MPa. The mole fraction solubilities ranged from 0.2 · 10^?6 to 17.45 · 10^?5. In this study five density based models were used to calculate the solubility of drugs in supercritical carbon dioxide. The density based models are Chrastil, modified Chrastil, Bartle, modified Bartle and Mendez-Santiago and Teja (M–T). Interaction parameters for the studied models were obtained and the percentage of average absolute relative deviation (AARD%) in each calculation was displayed. The correlation results showed good agreement with the experimental data. A comparison among the five models revealed that the Bartle and its modified models gave much better correlations of the solubility data with an average absolute relative deviation (AARD%) ranging from 4.8% to 6.2% and from 4.5% to 6.3% for ketoconazole and clotrimazole, respectively. Using the correlation results, the heat of drug–CO₂ solvation and that of drug vaporization was separately approximated in the range of (?22.1 to ?26.4 and 88.3 to 125.9) kJ · mol^?1.     

Solubility of amphenicol bacteriostats in CO2

The solubilities of three veterinary amphenicol bacteriostats, chloramphenicol, florfenicol and thiamphenicol, were measured in supercritical carbon dioxide (SC-CO₂) by a re-circulating method at temperatures of 313.15 and 333.15 K and pressures ranging from 11.0 to 49.0 MPa. These compounds displayed very limited solubility in SC-CO₂ (10⁻⁵ to 10⁻⁷ mole fraction) over the range of experimental conditions. Chloramphenicol had the highest observed solubility of the three amphenicols, while the solubilities of florfenicol and thiamphenicol were almost an order of magnitude lower. The experimental solubility data were correlated with seven known density-based models. The density models (ln y versus ln ρ or ln ρ_r) gave better correlation than the semi-log scale of ln y versus ρ_r. Four models for ln E versus density correlations also gave better correlation than the semi-log scale of ln y versus ρ_r by introducing the enhancement factor E. The correlation accuracy of all the seven models mainly depends on the system investigated, measured density and temperature range.     

trans-Aconitic acid-based hetero-Diels-Alder reaction in the synthesis of thiopyrano[2,3-d][1,3]thiazole derivatives

The hetero-Diels-Alder reaction of 5-arylideneisorhodanines with trans-aconitic acid proceeds as a regio- and diastereoselective process with spontaneous decarboxylation of the [4+2]-adduct to furnish thiopyrano[2,3-d][1,3]thiazole (2) and chromeno[4′,3′:4,5]thiopyrano[2,3-d]thiazole (3) derivatives analogously to the use of itaconic acid as a dienophile. Conversely, the one-pot, three-component reaction of 5-arylideneisorhodanines, trans-aconitic acid and anilines proceeded without decarboxylation, leading to novel rel-(5′R,6′R,7′R)-5′-carboxy-7′-aryl-1-aryl-3′,7′-dihydro-2H,2′H,5H-spiro[pyrrolidin-3,6′-thiopyrano[2,3-d]thiazol]-2,2′,5-triones 4. Interestingly, the use of trans-aconitic acid trimethyl ester led to the opposite regioselectivity, yielding rel-(5R,6S,7S)-5-methyloxycarbonylmethyl-2-oxo-7-aryl-3,5,6,7-tetrahydro-2H-thiopyrano[2,3-d]thiazol-5,6-dicarboxylates 5. Selected compounds were examined for trypanocide activity against the bloodstream forms of Trypanosoma brucei where compound 4e showed the highest activity (IC₅₀ = 6.74 μM).     

Study of bromide salts solubility in the (m1NaBr + m2MgBr2)(aq) system at T = 323.15 K. Thermodynamic model of solution behavior and (solid + liquid) equilibria in the (Na + K + Mg + Br + H2O) system to high concentration and temperature

The bromide minerals solubility in the mixed system (m₁NaBr + m₂MgBr₂)(aq) have been investigated at T = 323.15 K by the physico-chemical analysis method. The equilibrium crystallization of NaBr·2H₂O(cr), NaBr(cr), and MgBr₂·6H₂O(cr) has been established. The solubility-measurements results obtained have been combined with all other experimental equilibrium solubility data available in literature at T = (273.15 and 298.15) K to construct a chemical model that calculates (solid + liquid) equilibria in the mixed system (m₁NaBr + m₂MgBr₂)(aq). The solubility modeling approach based on fundamental Pitzer specific interaction equations is employed. The model gives a very good agreement with bromide salts equilibrium solubility data. Temperature extrapolation of the mixed system model provides reasonable mineral solubility at high temperature (up to 100 °C). This model expands the previously published temperature variable sodium–potassium–bromide and potassium–magnesium–bromide models by evaluating sodium–magnesium mixing parameters. The resulting model for quaternary system (Na + K + Mg + Br + H₂O) is validated by comparing solubility predictions with those given in literature, and not used in the parameterization process. Limitations of the mixed solution models due to data insufficiencies at high temperature are discussed.     

Measurements and predictions of density and carbon dioxide solubility in binary mixtures of ethanol and n-decane

The solubility of carbon dioxide (CO₂) in binary mixtures of ethanol and n-decane has been measured using an in-house developed pressure-volume-temperature (PVT) apparatus at pressures up to 6 MPa and two different temperatures (303.2 and 323.2 K). Three different binary mixtures of ethanol and n-decane were prepared, and the densities of the prepared mixtures were measured over the studied pressure and temperature ranges. The experimental data of CO₂ solubility in the prepared mixtures and their saturated liquid densities were then reported at each temperature and pressure. The solubility data indicated that the gas solubility reduced as the ethanol mole fraction in the liquid mixture increased. The dissolution of CO₂ in the liquid mixtures resulted in the increase in the saturated liquid densities. The impact of gas dissolution on the saturated liquid densities was more pronounced at the lower temperature and lower ethanol compositions. The experimental solubility and density data were compared with the results of two cubic equations of state (EOSs), Soave–Redlich–Kwong (SRK) and Peng–Robinson (PR). The modeling results demonstrated that both EOSs could predict the solubility data well, while the saturated liquid densities calculated with the PR EOS were much better than those predicted with the SRK EOS.     

Phase diagrams of binary systems containing n-alkanes,or cyclohexane,or 1-alkanols and 2,3-pentanedione at atmospheric and high pressure

Phase equilibria, for the binary systems {n-alkanes (tridecane, octadecane, or eicosane), or cyclohexane, or 1-alkanol (1-hexadecanol, or 1-octadecanol, or 1-eicosanol) + 2,3-pentanedione} have been determined using a cryometric dynamic method at atmospheric pressure. The influence of pressure on liquidus curve up to 800 MPa was determined for (tridecane, or cyclohexane + 2,3-pentanedione) systems. A thermostated apparatus for the measurements of transition pressures from the liquid to the solid state in two component isothermal solutions (pressometry) was used. The freezing and melting temperatures at a constant composition increase monotonously with pressure. The high-pressure experimental results obtained at isothermal conditions (p–x) were interpolated to well known T–x diagrams.Immiscibility in the liquid phase was observed only for the n-alkanes mixtures. The solubility decreases with an increase of the number of carbon atoms in the n-alkane, or 1-alkanol chain. The higher intermolecular solute–solvent interaction was observed for the 1-alkanols.Experimental solubility results are compared with values calculated by means of the NRTL equation (n-alkanes) and the NRTL and UNIQUAC ASM equations utilizing parameters derived from SLE and LLE results. The existence of a solid–solid first-order phase transition in tridecane, eicosane and 1-alkanols has been taken into consideration in the calculations. The correlation of the solubility data has been obtained with the average root-mean-square deviation of temperature σ < 1.0 K with both equations. The pressure–temperature–composition relation of the high-pressure (solid + liquid) phase equilibria, was satisfactorily presented by the polynomial.     

(Liquid + liquid) equilibrium data for the separation of 2,3-butanediol from aqueous streams using tetraoctyl ammonium 2-methyl-1-naphthoate

Microbiological production of 2,3-butanediol (2,3-BD) through fermentation using renewable feedstock is a promising option for the production of bio based chemicals. Liquid–liquid extraction could be a more efficient process, if a proper solvent is used. Tetraoctyl ammonium 2-methyl-1-naphthoate [TOA MNaph] is a tailor made hydrophobic ionic liquid that may be applied for the recovery of 2,3-BD from aqueous streams. In this work, the (liquid + liquid) equilibrium data for {2,3-BD + water + [TOA MNaph]} at (313.2, 333.2, and 353.2) K have been obtained and correlated to the NRTL and UNIQUAC activity coefficient models. Root square mean deviations (RMSD) values of 1.54% (NRTL) and 1.88% (UNIQUAC) were obtained, showing that both models can properly describe the experimental data. Compared to conventional solvents [TOA MNaph] presents a good balance between distribution coefficient (D_2,3BD = 1.08) and selectivity (S = 11.47).     

Thermodynamic properties of CO2 absorption in hydroxyl ammonium ionic liquids at pressures of (100–1600) kPa

Solubility of CO₂ in six hydroxyl ammonium ionic liquids 2-hydroxyethanaminium acetate [hea], bis(2-hydroxyethyl)ammonium acetate [bheaa], 2-hydroxy-N-(2-hydroxyethyl)-N-methylethanaminium acetate [hhemea], 2-hydroxyethanaminium lactate [hel], bis(2-hydroxyethyl)ammonium lactate [bheal], 2-hydroxy-N-(2-hydroxyethyl)-N-methylethanaminium lactate [hhemel] at temperatures (298.15, 313.15, and 328.16) K and pressures ranging from (100 to 1600) kPa was determined. From the experimental solubility data, the Henry’s constant of CO₂ for each hydroxyl ammonium ionic liquids was estimated and reported as a function of temperature. Furthermore, enthalpy and entropy of absorption were obtained from estimated Henry’s constant. The results showed that the solubility increase with increasing pressure and decrease with increasing temperature and the solubility of CO₂ in these six hydroxyl ammonium ionic liquids was in sequence: [hea] > [bheaa] > [hel] > [bheal] > [hhemel] > [hhemea].     

Study of the solubility of CO2, H2S and their mixture in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate: Experimental and modelling

New experimental results are presented for the solubility of carbon dioxide, hydrogen sulfide in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate ([C₈mim][PF₆]) at temperatures range from (303.15 to 353.15) K and pressures up to about 2 MPa. The solubility of the mixture of CO₂/H₂S in [C₈mim][PF₆] under various feed compositions were also measured at temperatures of (303.15, 323.15 and 343.15) K and the pressure up to 1 MPa. The solubility of carbon dioxide and hydrogen sulfide increased with increasing pressure and decreased with increasing temperature and the solubility of H₂S is about three times that of CO₂ in the particular ionic liquid studied. The measured data were correlated using extended Henry’s law included Pitzer’s virial expansion for the excess Gibbs energy, and the generic Redlich–Kwong cubic equation of state proposed for gas/ionic liquid systems. The correlations from the two models show quite good consistency with the experimental data for CO₂/IL and H₂S/IL binary mixtures within experimental uncertainties. For CO₂/H₂S/IL ternary mixtures, the RK model shows better correlation with the experimental values. We also studied the effect of cation alkyl chain length on the CO₂ and H₂S solubility by comparison of the experimental data of this study with those of previous reports. As the cation alkyl chain length became longer, the solubility of CO₂ and H₂S increased in the ionic liquid. Additionally, the influence of the anion on the solubility is studied by comparing the solubility of CO₂ and H₂S in [C₈mim][PF₆] with those in [C₈mim][Tf₂N]. As a result, CO₂ and H₂S have higher solubility in the IL with [Tf₂N]⁻ as the anion.     

Heterometallic 3d–4f coordination polymers: Synthesis,characterization and magnetic properties of 1D zigzag chains containing samarium and terbium

Reaction of the copper precursor [Cu(MeOsaltn)(H₂O)] (H₂MeOsaltn = N,N′-bis(3-methoxysalicylidene)-1,3-diaminopropane) with Ln(NO₃)₃·6H₂O (Ln = Sm and Tb) and pyrazine-2,3-dicarboxylic acid (H₂pyrdic) results in the formation of 1D zigzag chains with the general formula of [Cu(MeOsaltn)Ln(NO₃)(pyrdic)]_n·nDMF. X-ray crystal structures reveal that the samarium and terbium compounds are isostructural and crystalize in the orthorhombic space group Pbcn. The chains are composed of heterodinuclear copper–lanthanide building blocks which are linked by the pyrazine-2,3-dicarboxylate bridging units. Temperature-dependent susceptibility measurements indicate antiferromagnetic exchange interactions for the samarium–copper chain whereas for the terbium–copper compound ferromagnetic interactions are observed.     

Synthesis and characterization of three Cu(II), Zn(II), Cd(II) supramolecular complexes bridged by biphenyl 2,2′-dicarboxylate

Three complexes, M₂(bpy)₂(bpdc)₂·xH₂O [M = Cu, x = 0; M = Zn or Cd, x = 2], have been hydrothermally synthesized by 1,1′-biphenyl-2,2′-dicarboxylic acid (H₂bpdc) with 2,2′-bipyridine (bpy) to form binuclear molecules. In each, the two bpdc groups align the two opposing planar [M(bpy)]²⁺ cations. The molecules are connected by C–H⋯O hydrogen bonds, π–π stacking, and C–H⋯π interactions to form three dimensional supramolecular networks. Furthermore, at room temperature, complex 3 exhibits strong photoluminescence.     

Solubility of novel open-chain crown ether bridged diphosphates in supercritical carbon dioxide

The solubility of newly synthesized chelating agents, i.e., tetraethylene glycol bis (2-ethylhexyl) dimethyl diphosphate (EG4EH), tetraethylene glycol bis (n-octyl) dimethyl diphosphate (EG4Oct), and tetraethylene glycol bis (2-butoxyethyl) dimethyl diphosphate (EG4BOE) in supercritical carbon dioxide (scCO₂) were determined at temperatures ranging from (318.15 to 333.15) K and pressures ranging from (12 to 21) MPa. Solubility increases in the order of EG4Oct (MW = 606.33) < EG4BOE (MW = 582.26) < EG4EH (MW = 606.33), indicating that branched side chains of the ligands play an important part in increasing solubility in scCO₂. Semi empirical density-based models proposed by Bartle and Chrastil were used to correlate the experimental data, and AARD values were calculated to be (1.2 to 2.9)% and (0.40 to 0.93)% for Bartle and Chrastil model, respectively. Additionally, the partial molar volumes of those compounds were estimated following the theory developed by Kumar and Johnston.     

Thermodynamic aspects of solubility,solvation and partitioning processes of some sulfonamides

The thermodynamic aspects of sublimation processes of three sulfonamides with the general structures C₆H₅–SO₂NH–C₆H₄–R (R = 4-NO₂) and 4-NH₂–C₆H₄–SO₂NH–C₆H₄–R (R = 4-NO₂; 4-CN) were studied by investigating the temperature dependence of vapor pressure using the transpiration method. These data together with those obtained earlier for C₆H₅–SO₂NH–C₆H₄–R (R = 4-Cl) and 4-NH₂–C₆H₄–SO₂NH–C₆H₄–R (R = 4-Cl; 4-OMe; 4-C₂H₅) were analyzed and compared. A correlation was derived between sublimation Gibbs free energies and the sum of H-bond acceptor factors of the molecules. Solubility processes of the compounds in water, phosphate buffer with pH 7.4 and n-octanol (as phases modeling various drug delivery pathways) were investigated and corresponding thermodynamic functions were calculated as well. Thermodynamic characteristics of the sulfonamides solvation were evaluated. Also in this case a correlation between solubility/solvation Gibbs free energy values and the sum of H-bond acceptor factors was observed. For the sulfonamides with various substituents at para-position the processes of transfer from one solvent (water or buffer) to n-octanol were studied by a diagram method combined with analysis of enthalpic and entropic terms. Distinguishing between enthalpy and entropy, as is possible through the present approach, leads to the insight that the contribution of these terms is different for different molecules (entropy- or enthalpy-determined). Thus, in contrast to the interpretation of only the Gibbs free energy of transfer (extensively used for pharmaceuticals in the form of the partition coefficient, log P), the analysis of thermodynamic functions of the transfer process provides additional mechanistic information. This may be important for further evaluation of the physiological distribution of drug molecules and may provide a better understanding of biopharmaceutical properties of drugs.     

Solubilities of benzoin,propyl 4-hydroxybenzoate and mandelic acid in supercritical carbon dioxide

A semi-flow type apparatus was used to measure the equilibrium solubilities of benzoin , propyl 4-hydroxybenzoate, and mandelic acid in supercritical carbon dioxide at 308.15, 318.15, and 328.15 K over the pressure range from 9 to 24 MPa. New equilibrium data of solid solubility in supercritical carbon dioxide are presented. The approach to solid–fluid phase equilibrium is examined based on a plug flow fluid–solid mass transfer model. The Soave–Redlich–Kwong and the Peng–Robinson equations of state (EOS), with the van der Waals and the Huron–Vidal type mixing rules were used to correlate the experimental data. The solid solubility data were also correlated with density based semi-empirical equations of Chrastil, and Santiago–Teja. It is shown that these solid solubility data are correlated with reasonably good accuracy using optimally fitted parameters.     

Versatile Ru-based metathesis catalysts designed for both homogeneous and heterogeneous processes

The synthesis of new ruthenium-based catalysts applicable for both homogeneous and heterogeneous metathesis is described. Starting from the Hoveyda-Grubbs first generation (1) and the Hoveyda-Grubbs second generation (2) catalysts the homogeneous catalysts [RuCl((RO)₃Si–C₃H₆–N(R′)–CO–C₃F₆–COO)(CH–o-O–iPr–C₆H₄)(SIMes)] (4: R = Et, R′ = H; 5: R = R′ = Me) (SIMes = 1,3-bis(2,4,6-trimethylphenyl)-4,5-dihydroimidazol-2-ylidene) were prepared by substitution of one chloride ligand with trialkoxysilyl functionalized silver carboxylates (RO)₃Si–C₃H₆–N(R′)–CO–C₃F₆–COOAg (3a: R = Et, R′ = H; 3b: R = R′ = Me). These homogeneous ruthenium-species are among a few known examples with mixed anionic ligands. Exchange of both chloride ligands afforded the catalysts [Ru((RO)₃Si–C₃H₆–N(R′)–CO–C₃F₆–COO)(CH–o-O–iPr–C₆H₄)(SIMes)] (9: R = Et, R′ = H; 11: R = R′ = Me) and [Ru((RO)₃Si–C₃H₆–N(R′)–CO–C₃F₆–COO)(CH–o-O–iPr–C₆H₄)(PCy₃)] (8: R = Et, R′ = H; 10: R = R′ = Me). The reactivity of the new complexes was tested in homogeneous ring-closing metathesis (RCM) of N,N-diallyl-p-toluenesulfonamide and TONs of up to 5000 were achieved. Heterogeneous catalysts were obtained by reaction of 4, 5 and 8–11 with silica gel (SG-60). The resultant supported catalysts 4a, 5a, 8a–11a showed reduced activity compared to their homogenous analogues, but rival the activity of similar heterogeneous systems.     

Measurement and correlation of solubility of anthraquinone dyestuffs in supercritical carbon dioxide

Solubility data of 1,4-diaminoanthraquinone (C.I. Disperse Violet 1) and 1,4-bis(ethylamino)anthraquinone (C.I. Solvent Blue 59) in supercritical carbon dioxide (sc-CO₂) have been measured at the temperatures of (323.15, 353.15, and 383.15) K and over the pressure range from (12.5 to 25.0) MPa by a flow-type apparatus. The solubility of two anthraquinone dyestuffs was obtained over the mole fraction ranges of (1.3 to 26.1) · 10⁻⁷ for 1,4-diaminoanthraquinone (C.I. Disperse Violet 1) and (1.1 to 148.5) · 10⁻⁷ for 1,4-bis(ethylamino)anthraquinone (C.I. Solvent Blue 59). The experimental results have been correlated with the empirical equations of Mendez-Santiago–Teja and Kumar–Johnston expressed in terms of the density of sc-CO₂, and also analyzed thermodynamically by the regular solution model with the Flory–Huggins theory and the Peng–Robinson equation of state modified by Stryjek and Vera (PRSV-EOS) with the conventional mixing rules. Good agreement between the experimental and calculated solubilities of the dyestuffs was obtained.     

Interaction parameters and (solid + liquid) equilibria calculation for KCl–H2O–HCl–C2H5OH,K2SO4–H2O–H2SO4 and K2SO4–H2O–C2H5OH mixed solvent-electrolyte systems

This work deals with the prediction and experimental measurements of the (solid + liquid) equilibrium (SLE) in acid medium for industrial purposes. Specific systems including KCl–ethanol–water–HCl and K₂SO₄–water–H₂SO₄ were analyzed. At first, a critical discussion of SLE calculations was given, based on the well-known UNIQUAC extended and LIQUAC models. Two new proposals were derived, considering the explicit necessity of a new reference state for SLE calculations for the studied (solvents + acid) mixtures. The solubility of KCl in water–ethanol–HCl mixed solvents was measured in the temperature range of 300.15 to 315.15 K using an analytical gravimetric method. These results combined with some other experimental data reported in the open literature let us to propose a set of parameters for the new models. They included the interaction parameters between ethanol and the H⁺ ion. The prediction capability of the new models, for calculations in acid medium, was illustrated. Experimentally, it was observed that the (K₂SO₄ + water + H₂SO₄) system presented the unusual behavior of increasing K₂SO₄ solubility with an increase in the sulfuric acid concentration. This was accurately predicted by the newly proposed models.