Investigation of phase equilibria of levulinic acid distribution between aqueous phase to organic phase by Aliquat 336 in different modifiers

The extraction of levulinic acid by tricaprylmethylammonium chloride (Aliquat 336) dissolved in five alcohols solvents (isoamyl alcohol, hexan-1-ol, octan-1-ol, nonan-1-ol, decan-1-ol) and five esters solvents (dimethyl phthalate, dimethyl adipate, dimethyl succinate, dimethyl glutarate, diethyl carbonate), two ketones (diisobutyl ketone (DIBK), methyl isobutyl ketone (MIBK)) were investigated to understand effect of modifier on levulinic acid extraction. In addition to these Aliquat 336 + modifier system, the experiments were done also with single solvents. All measurements were carried out T = 298.15 K. Organic solutions of Aliquat 336 are being used increasingly to separate organic acids from aqueous mixture solutions by reactive extraction. The extent to which the organic phase may be loaded with levulinic acid is explained as a loading ratio, Z_Z, extraction efficiency E and, distribution coefficients K_D were calculated. The maximum extraction efficiency was obtained value of 72.1 for isoamyl alcohol. The extraction equilibrium constant, K_E, has been calculated for each modifier. Furthermore, Freundlich, Langmuir, and LSER model equations have been obtained for experimental data of alcohols.     

Determination of the absolute configuration of the male aggregation pheromone, 2-methyl-6-(4′-methylenebicyclo[3.1.0]hexyl)hept-2-en-1-ol, of the stink bug Erysarcoris lewisi (Distant) as 2Z,6R,1′S,5′S by its synthesis

Lipase-catalyzed asymmetric acetylation of a mixture of (6R,1′S,4′S,5′R)- and (6R,1′R,4′R,5′S)-7′-norsesquisabinen-4′-ol (3) afforded a separable mixture of the recovered former and the acetate of the latter. The recovered alcohol was oxidized to (6R,1′S,5′R)-sesquisabina ketone (2), whose absolute configuration could be assigned by its CD comparison with (1R,5S)-sabina ketone (4). Conversion of (6R,1′S,5′R)-sesquisabina ketone (2) to the bioactive pheromone revealed the stereostructure of the male aggregation pheromone of the stink bug Erysarcoris lewisi (Distant) to be (2Z,6R,1′S,5′S)-2-methyl-6-(4′-methylenebicyclo[3.1.0]hexyl)hept-2-en-1-ol (sesquisabinen-1-ol, 1).     

Phase behaviour of 1-hexyloxymethyl-3-methyl-imidazolium and 1,3-dihexyloxymethyl-imidazolium based ionic liquids with alcohols,water, ketones and hydrocarbons: The effect of cation and anion on solubility

The liquid–liquid equilibrium (LLE), or solid–liquid equilibrium (SLE) of more than 20 binary systems containing 1-hexyloxymethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)-imide [C₆H₁₃OCH₂MIM][Tf₂N] with alcohol (butan-1-ol, or hexan-1-ol, or octan-1-ol), water and ketone (3-pentanone, or cyclopentanone) and of 1-hexyloxymethyl-3-methyl-imidazolium tetrafluoroborate [C₆H₁₃OCH₂MIM][BF₄] with alcohol (methanol, or ethanol, or butan-1-ol, or hexan-1-ol, or octan-1-ol), water and ketone (3-pentanone, or cyclopentanone) have been measured. The solubility of dialkoxy-imidazolium salts: (1) 1,3-dihexyloxymethyl-imidazolium bis(trifluoromethylsulfonyl)-imide [(C₆H₁₃OCH₂)₂IM][Tf₂N] in alcohol (butan-1-ol, or hexan-1-ol, or octan-1-ol, or decan-1-ol), in water and hydrocarbon (benzene, hexane and cyclohexane); (2) 1,3-dihexyloxymethyl-imidazolium tetrafluoroborate [(C₆H₁₃OCH₂)₂IM][BF₄] in alcohol (hexan-1-ol, or octan-1-ol, or decan-1-ol) and water have been measured. Measurements were carried out by using a dynamic method from T = 275 K to the boiling point of the solvent. In this work a systematic study of the impact of different factors on the phase behaviour of hexyloxy-imidazolium-based ionic liquids with polar and nonpolar solvents has been presented. Most of the examined systems showed immiscibility in the liquid phase with an upper critical solution temperature (UCST), or complete solubility of the ionic liquid at room temperature in many solvents. An increase in the alkyl chain length of alcohol resulted in an increase in the UCST. The choice of anion was shown to have large impact on the solubility: by changing the anion [Tf₂N]⁻ to [BF₄]⁻, the solubility dramatically decreased and the UCST increased. By contrast, increasing hydrogen bonding opportunities with the solvent by replacing a methyl group with the second alkoxy-group on the imidazolium ring results in an increase of the solubility.     

In-situ changes of thermo-mechanical properties of poly(lactic acid) film immersed in alcohol solutions

Poly (lactic acid) (PLA) has properties suitable for many applications. However, PLA's properties are affected by environmental conditions. In this study, the glass-rubber transition temperatures (T_g) of PLA films were measured during immersion (i.e., in-situ) in pure alcohols and alcohol aqueous solutions using a dynamic mechanical analysis technique. The T_g of PLA decreased when immersed in alcohols. For pure aliphatic alcohols, the T_g reduction became smaller as the number of carbons (C1–C10) in the alcohol main chains increased. The Fox equation and the Hansen solubility parameters (HSP)/Flory-Huggins (FH) model were used to explain the T_g reduction. The relationships explained the interactions between PLA and pure alcohols with small molecules (C1–C8), but bigger pure alcohols (C9–C10) did not fit the prediction. The chemical isomerism in pure propanol (i.e., propan-1-ol and propan-2-ol) did not affect the T_g reduction. The T_g reduction in propan-2-ol aqueous solutions was concentration dependent although the partition coefficients based on the HSP and the FH parameters did not fit this relationship. The in-situ immersion of PLA in alcohol solutions could be used to evaluate the change in T_g from the T_g of dry PLA.     

Coupling reactions of aryl bromides with 1-alkynols catalysed by a tetraphosphine/palladium catalyst

cis,cis,cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane/[PdCl(C₃H₅)]₂ system catalyses efficiently the coupling reactions of aryl halides with a variety of alkynols such as propargyl alcohol, but-1-yn-4-ol, pent-1-yn-5-ol or hex-1-yn-6-ol. The catalyst can be used at low loading. Higher reaction rates were observed in the presence of but-1-yn-4-ol, pent-1-yn-5-ol or hex-1-yn-6-ol than with propargyl alcohol. The protection of the alcohol functions as an ether or a silyloxy group led generally to similar or better results than the reactions performed with the unprotected alcohols.     

Sn ← S1 and Tn ← T1 absorption spectra of highly purified chrysene in solution

Time-resolved S_n ← S₁ and T_n ← T₁ absorption spectra were observed for highly purified chrysene in THF solution. Formerly assigned to the S₄ ← S₁ band located in the 17200–17600 cm⁻¹ (581-568 nm) region. S_n ← S₁ was reassigned to S₆ ← S₁. The S₄ ← S¹, S₅ ← S₁, S₇ ← S¹ and S₈ ← S₁ bands were also observed at 13500 cm⁻¹ (740 nm). 15700 cm⁻¹ (635 nm). 19000 cm⁻¹ (525 nm), and 20400 cm⁻¹ (490 nm), respectively. The relevant molar extinction coefficients were 7100 (S₄ ← S₁), 15000 (S₅ ← S¹), 14000 (S₆ ← S₁), 19000 (S₇ ← S₁), and 14000 M⁻¹ cm⁻¹ (S₈← S₁).     

Laser flash photolysis study of triplets of cyclobutanethiones

Five cyclobutanethiones with different chromophores at the 3-position were examined for triplet state behaviour in benzene using laser excitation into their low lying nπ^*1 band systems. A weak transient absorption attributable to the triplet state is observed in all these cases. Results concerning triplet lifetimes, intersystem crossing yields (S₁ → T₁), self-quenching kinetics and kinetics of energy transfer to all-trans-1,6-diphenyl-1,3,5-hexatriene and oxygen and quenching by di-t-butyl nitroxide (DTBN) are presented. Intersystem crossing yields estimated with reference to p,p′-dimethoxythiobenzophenone are roughly unity in all five cases. Self-quenching rates are found to be less than diffusion limited and this is attributed to steric crowding at the α positions (dimethyl group). The rates of oxygen and DTBN quenching compare well with those reported for several other thiones in the literature. No transients other than the triplet were detected in the above cyclobutane-thiones.     

(Liquid + liquid) phase equilibria of 1-alkyl-3-methylimidazolium methylsulfate with alcohols,or ethers,or ketones

Solubilities of binary mixtures that contain a room-temperature ionic liquid and an organic solvent – namely, 1,3-dimethylimidazolium methylsulfate, [mmim][CH₃SO₄], or 1-butyl-3-methylimidazolium methylsulfate, [bmim][CH₃SO₄] with an alcohol (hexan-1-ol, or octan-1-ol, or nonan-1-ol, or decan-1-ol), or an ether (dipropyl ether, or dibutyl ether, or methyl-1,1-dimethylethyl ether, or methyl-1,1-dimethylpropyl ether), or a ketone (pentan-2-one, or pentan-3-one, or hexan-2-one, or heptan-4-one, or cyclopentanone) – have been measured by a visual method from T = 270 K to the boiling temperature of the solvent. The (liquid + liquid) equilibria curves were predicted by the COSMO-RS method. For [bmim][CH₃SO₄], the COSMO-RS predictions correspond better with experimental results than do the predictions for [mmim][CH₃SO₄].Complete miscibility has been observed in the systems of [mmim][CH₃SO₄] with water and with alcohols ranging from methanol to octan-1-ol and that of [bmim][CH₃SO₄] with water and with alcohols ranging from methanol to decan-1-ol at the temperature T = 310 K.     

Ultrasonic Studies in Binary Mixtures of 1-2-Dibromoethane with Alcohols at 303.15 K

Abstract

Isentropic compressibility data, K_S of 1,2-Dibromoethane + Propan-1-ol, + butan-1-ol, + pentan-1-ol, hexan-1-ol, heptan-1-ol and octan-1-ol at 303.15 K are reported. Deviations in isentropic compressibility, K_S values are found to be negative for mixtures of 1,2-dibromoethane with propan-1-ol over the entire range of composition and while in butan-1-ol the δK_S values are negative at lower molefractions and positive at higher molefractions. Therefore as the chain length increases it is showing the positive deviations. The data are interpreted in terms of specific interactions between the components.     

Study of Densities, Viscosities and Ultrasonic Speeds of Binary Mixtures Containing 1,2-Dimethoxyethane and an Alkan-l-ol at 298.15 K

The viscosity deviation (Δη), the excess molar volume (V ^E) and the ultrasonic speed (u) have been investigated from viscosity (η) and density (ρ ) measurements of binary liquid mixtures of 1,2-dimethyoxyethane with methanol, ethanol, propan-1-ol, butan-1-ol, pentan-1-ol, hexan-1-ol or octan-1-ol over the entire range of composition at 298.15 K. The excess volumes are negative over the entire range of composition for all of the mixtures with the exception of hexan-1-ol and octan-1-ol. The excess isentropic compressibilities (K _S ^E) and viscosity deviations are negative for all of the mixtures. The magnitudes of the negative values of V ^E decrease with the number of carbon atoms of the alkan-1-ol. The trend of increasing K _S ^E values with the chain length of the alkanol is similar to that observed in the case of V ^E. Graphs of V ^E, Δ η, K _S ^E, Δ u, L _f ^E and Z ^E against composition are presented as a basis for a qualitative discussion of the results.     

Ruthenium-catalyzed reduction of racemic tricarbonyl(η-aryl ketone)chromium complexes using transfer hydrogenation: A simple alternative to the resolution of planar chiral organometallics

Racemic planar chiral (η⁶-aryl ketone)Cr(CO)₃ complexes (aryl ketone = 1-indanone, 1-tetralone, 4-chromanone and thiochroman-4-one) were prepared by refluxing the aryl ketone with Cr(CO)₆ in a 10:1 mixture of dibutyl ether and THF. The reductions of the organometallic ketones by transfer hydrogenation in 2-propanol containing KOH and the catalyst precursor, generated from [RuCl₂(η⁶-benzene)]₂ and (−)-ephedrine, resulted in optically active syn-(R,S)-(η⁶-aryl alcohol)Cr(CO)₃ and (R)-(η⁶-aryl ketone)Cr(CO)₃ compounds in 31-97% ee. Reduction of racemic (η⁶-thiochroman-4-one)Cr(CO)₃ with the catalyst precursor generated from (+)-norephedrine, instead of (−)-ephedrine, inverted the configuration of the products obtained. Syn-(S,R)-(η⁶-thiochroman-4-ol)Cr(CO)₃ and (S)-(η⁶-thiochroman-4-one)-Cr(CO)₃ were isolated in 49% and >95% ee, respectively. The free aryl ketones were reduced using the same conditions as their respective chromium complexes, giving aryl alcohols in high ee (>95%). Reactions of non-rigid acetophenone, propriophenone and their tricarbonylchromium complexes resulted in moderate to low ee.     

Syntheses and properties of H-1,2,3-triazoles

About twenty new H-1,2,3-triazoles (T) were readily synthesized by nucleophilic attack of sodium azide on activated acetylenes in dimethylformamide. Typical activating groups were COR, COOR, O₂NC₆H₄ PO(OC₂H₅, COT, and (C₆H₅)₃P⁺. Propynyl 4-triazolyl ketone or phenylethynyl 4-triazolyl ketone may be converted to acylic adducts (triazolylketoenamines), biheteroaromatic systems (isoxazolytriazoles, pyrazolytriazoles), as well as to ditriazolyl ketones. Certain T properties were examined in detail. The apparent pK′s for our group of ca 30 triazoles were in the range 4·95?9·45 in ethanol-water (v/v 1/1) at 25°. The Hammett correlation for five 4-aryl-T was log K_a = 0·89σ^? ?9·21 and for seven 4-aryl-5-carbethoxy-T was log K_a = 1·45σ?6·95. The UV spectra of T are similar to those of other heteroaromatic and phenyl compounds: interesting analogies between triazolyl and phenyl, e.g., ”ortho“ crowding effects, appear to be indicated in the spectra of compounds related to biphenyl, stilhene and benzophenone. With regard to structure assignment on the basis of spectra, characteristic features of UV and IR spectra of the H-1,2,3-triazoles are discussed.     

Thermodynamic Properties of Binary Liquid Mixtures of n-Dodecane with an Alkan-1-ol or an Alkan-2-ol at 298.15 K: A Comparative Study

Experimental densities (ρ), viscosities (η), and speeds of sound (u) of the binary mixtures of n-dodecane with an alkan-1-ol (hexan-1-ol, heptan-1-ol, octan-1-ol) or an alkan-2-ol (hexan-2-ol, heptan-2-ol and octan-2-ol) were measured over the whole mixture composition range at T = 298.15 K. From these data, the excess molar volume ( $ V_{\text{m}}^{\text{E}} $ V m E ), deviations in viscosity (Δη), and excess isentropic compressibility ( $ \kappa_{S}^{\text{E}} $ κ S E ) have been calculated. The results were fitted by means of the Redlich–Kister equation, in order to estimate the binary coefficients and standard errors. Differences among these binary systems are ascribed to the different association abilities of the alkan-1-ols and alkan-2-ols. Experimental data on the constituted binaries were analyzed using McAllister’s multi-body interaction model, the Jouyban–Acree model, the Prigogine–Flory–Patterson theory, and the Bloomfield and Dewan model. The experimental and calculated quantities are used to study the nature of mixing behavior among the mixtures.     

Crystal structures,luminescence, and thermal properties of lanthanide complexes with 2,3,4-trimethoxybenzoic acid and 1,10-phenanthroline

The complexes of [Ln(2,3,4-tmoba)₃phen]₂ (Ln = Dy (1), Eu (2), Tb (3); 2,3,4-tmoba = 2,3,4-trimethoxybenzoate; phen = 1,10-phenanthroline) were synthesized and characterized by a series of techniques including the elemental analysis, IR and fluorescent spectra and TG/DSC-FTIR technology. The crystal structures were determined by X-ray crystallography. Each complex include two Ln³⁺ ions, six 2,3,4-tmoBA and two phen molecules forming a binuclear structure, giving the coordination number of nine. The three-dimensional IR accumulation spectra of gaseous products for the complexes 1 to 3 are analyzed and the thermal decomposition processes are further authenticated. Through means of differential scanning calorimeter (DSC), two solid-solid phase transition endothermic peaks were found in the complex 2, which was different from the complexes 1 and 3. The heat capacities of these complexes were measured and fitted to a polynomial equation with the least squares method for each complex on the basis of the reduce temperature x (x = [T − (T_max + T_min)/2]/[(T_max − T_min)/2]) over the range from (256.15 to 476.15) K. Subsequently, the smoothed molar heat capacities and thermodynamic functions (H_T−H_298.15 K), (S_T−S_298.15 K), and (G_T−G_298.15 K) of the complexes 1 to 3 were calculated based on the fitted polynomial of the heat capacities. The fluorescent intensity of the complexes 2 and 3 are markedly improved as well.     

Solubility and Solution Thermodynamic Properties of 4-(4-Hydroxyphenyl)-2-butanone (Raspberry Ketone) in Different Pure Solvents

The solubility of 4-(4-hydroxyphenyl)-2-butanone (raspberry ketone) in six pure solvents was experimentally determined at temperatures ranging from 283.15 to 313.15 K under the pressure 0.10 MPa by employing a gravimetrical method. The experimental results indicate that the solubility of raspberry ketone in all studied solvents is temperature dependent, a rise in temperature brings about an increase in solubility. The experimental solubility data of raspberry ketone in six pure solvents (acetone, ethanol, ethyl acetate, n-propyl alcohol, n-butyl alcohol, and distilled water) was correlated by using several commonly used thermodynamic models, including the Apelblat, van’t Hoff and λh equations. The results of the error analysis indicate that the van’t Hoff equation was able to give more accurate and reliable predictions of solubility with root-mean-square deviation less than 0.56%. Furthermore, the changes of dissolution enthalpies (Δ_diss H°), dissolution entropies (Δ_diss S°) and dissolution Gibbs energies (Δ_diss G°) of raspberry ketone in the solvents studied were estimated by the van’t Hoff equation. The positive value of Δ_diss H°, Δ_diss S°, and Δ_diss G° indicated that these dissolution processes of raspberry ketone in the solvents studied were all endothermic and enthalpy-driven.     

Studies on the diastereoselective allylation of aldehydes with enantiopure 2-sulfinylallyl building blocks

A comparative study on the allylation of aldehydes with enantiopure (S_S)-2-(p-tolylsulfonyl)-prop-2-en-1-ol (S_S)-1a and the corresponding chloride (S_S)-1b under two different reaction systems is reported. In general, better yields were obtained from chloride (S_S)-1b, whereas higher diastereoinduction was observed from alcohol (S_S)-1a. The sense of diastereoinduction is the same in both systems and the stereochemistry of the major diastereomer has been determined. Moreover, the configurational stability of the sulfoxide group on the resulting sulfinyl homoallylic alcohols 3 has been proven in each reaction system, which demonstrates the efficiency of the sulfoxide group as chiral auxiliary in these allylation processes. Finally, as an example of the synthetic potential of the resulting adducts, a total synthesis of natural enantioenriched (S)-nicotine from sulfinylalcohol 3h is reported.     

MeV Si ions bombardments effects on thermoelectric properties of SiO2/SiO2+Ge nanolayers

The performance of the thermoelectric materials and devices is shown by a dimensionless figure of merit, ZT=S²σT/K, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature and K is the thermal conductivity. ZT can be increased by increasing S, increasing σ, or decreasing K. We have prepared the thermoelectric generator device of SiO₂/SiO₂+Ge multilayer superlattice films using the ion beam assisted deposition (IBAD). The 5 MeV Si ion bombardments have been performed using the AAMU Pelletron ion beam accelerator at five different fluences to make quantum structures (nanodots and/or nanoclusters) in the multilayer superlattice thin films to decrease the cross plane thermal conductivity, increase the cross plane Seebeck coefficient and cross plane electrical conductivity. To characterize the thermoelectric generator devices before and after MeV Si ions bombardments at the different fluences we have measured the cross-plane Seebeck coefficient, the cross-plane electrical conductivity, and the cross-plane thermal conductivity, Raman spectra to get some information about the sample structure and bond structures among the used elements in the superlattice thin film systems.     

Autoxidation of isotachysterol

Isotachysterol, the acid-catalyzed isomerization product of vitamin D₃, produces seven previously unknown oxygenation products in a self-initiated autoxidation reaction under atmospheric oxygen in the dark at ambient temperature. They are (5R)-5,10-epoxy-9,10-secocholesta-6,8(14)-dien-3β-ol (6a), (5S)-5,10-epoxy-9,10-secocholesta-6,8(14)-dien-3β-ol (6b), (10R)-9,10-secocholesta-5,7,14-trien-3β,10-diol (7a), (10S)-9,10-secocholesta-5,7,14-trien-3β,10-diol (7b), (7R,10R)-7,10-epoxy-9,10-secocholesta-5,8(14)-dien-3β-ol (8), 5,10-epidioxyisotachysterol (9) and 3,10-epoxy-5-oxo-5,10-seco-9,10-secocholesta-6,8(14)-dien-10-ol (10). The formation of these products is explained in terms of free radical peroxidation chemistry.     

First total synthesis of modiolide A, based on the whole-cell yeast-catalyzed asymmetric reduction of a propargyl ketone

While the first total synthesis of modiolide A (1a), a 10-membered ring lactone with a marine-origin was achieved, an important chiral building block for constructing the chirality at C-4 in 1a, (S)-6-[(4-methoxybenzyl)oxy]-1-trimethylsilyl-1-hexyn-3-ol (3a) was obtained in as high as 96.1% ee. Asymmetric reduction of a silylated propargyl ketone (5) mediated by whole-cell of Pichia minuta IAM 12215 was established. This yeast-mediated reduction was also applicable to provide stereochemically pure (3S,5R)-5-[(4-methoxybenzyl)oxy]-1-trimethylsilyl-1-hexyn-3-ol (15), a synthetic intermediate for the related 10-membered lactone, tuckolide (16).