Dibutyl Ether Research Articles

Enantioselective whole-cell biotransformation of acetophenone to S-phenylethanol by Rhodotorula glutinis. Part II. Aqueous–organic systems: Emulsion and membrane bioreactors

This paper reports the development and performance of a membrane bioreactor for biotransformations (MBB) using organic solvent nanofiltration membranes for the bioreduction of acetophenone to S-phenylethanol by whole cells of Rhodotorula glutinis. It follows a previous paper dealing with the kinetics of this reaction in aqueous media [R. Valadez-Blanco, A.G. Livingston, Enantioselective whole-cell biotransformation of acetophenone to S-phenylethanol by Rhodotorula glutinis. Part I. Product formation kinetics and feeding strategies in aqueous media, Biochem. Eng. J. 46 (2009) 44–53]. A number of organic solvents were tested, with dibutyl ether found to be the best solvent in terms of toxicity and organic/aqueous partition coefficients. Despite the fact that most of the MBBs were mass-transfer limited, their reaction rates were comparable to those of the aqueous systems, with prolonged biocatalytic activity due to in situ product extraction. The use of direct injection of substrate and glucose to the aqueous phase, together with high biomass concentrations, resulted in the highest overall product formation and acceptable reaction rates. This strategy also avoided the need for additional cumbersome downstream processing to recover the product from the aqueous phase. In contrast, direct-contact biphasic reactors proved to be unsuitable for this biotransformation due to poor product partition or high volatility of the solvents.

Production of no-carrier-added 117mSn from proton irradiated antimony

A method for production of no-carrier-added 117mSn (NCA 117mSn) has been developed. It includes proton irradiation of thick antimony targets and chemical recovery of 117mSn by extraction of Sb with dibutyl ether and chromatographic purification on silica gel column. The method provides production of curie amounts of 117mSn with specific activity about 1000 Ci/g and high radionuclidic purity.

Excess Enthalpies of Binary and Ternary Mixtures Containing Dibutyl Ether, Cyclohexane, and 1-Butanol at 298.15 K

Experimental excess enthalpies of the ternary system dibutyl ether (DBE) + cyclohexane + 1-butanol and the corresponding binary systems at 298.15 K are reported. A quasi-isothermal flow calorimeter has been built and tested to make the measurements. All the binary and the ternary systems show endothermic character. The experimental data have been fitted using a polynomial equation for the binary and ternary systems. The values of the standard deviation indicate good agreement between the experimental results and those calculated from the equation.

Excess molar volume and derived thermodynamic properties of binary mixtures of 2-methyl-1-butanol and 2-ethyl-1-butanol + different ethers at the temperature range of 293.15 to 313.15 K

Densities of the binary liquid mixtures of 2-ethyl-1-butanol + dibutyl ether (DBE) or ethylene glycol mono butyl ether (EGMBE), 2-methyl-1-butanol + DBE, have been measured as a function of the composition at temperature range of 293.15 to 313.15 K and atmospheric pressure. The measurements have been carried out using an Anton Paar model DMA 4500 oscillating u-tube densitometer. The excess molar volume, V m E, the excess thermal coefficient, α E, and the isothermal expansion coefficient of excess molar enthalpy, (∂ H m E/∂ P) T,x , were calculated from the experimental densities. It is indicated that the excess molar volume is negative for 2-methyl-1-butanol + DBE over the entire mole fraction range, and decreases with increasing temperature. The V m E value is positive for the binary mixture of EGMBE + 2-ethyl-1-butanol over the entire mole fraction range, and decreases with increasing temperature. This quantity is negative for the binary mixture of 2-ethyl-1-butanol + DBE over the entire mole fraction range, and decreases with increasing temperature in the limit of pure ether and increases with increasing temperature in the limit of pure alcohol. The excess molar volumes were correlated with Redlich–Kister equation.

The synthesis of N-derivatives of 3-aminoperylene and their absorption and fluorescence properties

N-Acetyl and N-triazinyl 3-aminoperylenes were prepared. N-(4,6-Dichloro-1,3,5-triazin-2-yl)-3-aminoperylene was synthesized by the condensation of 3-aminoperylene with cyanuric chloride; other N-triazinyl derivatives were prepared by the successive substitution of chlorine atoms with methoxy or aniline groups. The structure and purity of the compounds were confirmed by elemental analysis, NMR spectroscopy and mass spectrometry. The UV/vis absorption, fluorescence and excitation spectra as well as the fluorescence quantum yields for the compounds were measured in dibutyl ether, 1,4-dioxane, ethyl acetate and acetonitrile; fluorescence lifetimes were measured in ethyl acetate and dimethyl sulfoxide. The influences of both the character of the N-substituent and the solvent polarity upon the spectra and quantum yields are discussed.

Drastic solid-state fluorescence enhancement behaviour of imidazo[4,5- a]naphthalene-type fluorescent hosts upon inclusion of polyethers and tert-butyl alcohol

As one of the most promising materials for the construction of desirable solid-state fluorescent system, new solid-state fluorescent host–guest system, which consists of the imidazo[4,5- a]naphthalene-type fluorescent hosts 2 and sterically hindered guest molecules were designed and prepared. The crystals of 2 exhibit sensitive colour change and drastic fluorescence enhancement behaviour upon polyethers (diethylene glycol dimethyl ether (DGDM), diethylene glycol diethyl ether (DGDE) and diethylene glycol dibutyl ether (DGDB)) or tert-butyl alcohol. A comparison of the X-ray crystal structures of the guest-free and polyether- and tert-butyl alcohol-inclusion compounds indicates that the enclathrated polyether or tert-butyl alcohol molecule decrease the π-stacking between hosts and enlarge the distance between the host–host aromatic planes. On the bases of the spectral data and the crystal structures, the effects of the enclathrated sterically hindered guest on the drastic solid-state fluorescence enhancement behaviour of the host–guest crystals are discussed.

Viscosity and Density Measurements of Diisopropyl Ether and Dibutyl Ether at Different Temperatures and Pressures

Experimental results of viscosity and density of diisopropyl ether and dibutyl ether are reported over the temperature range from (243.15 to 373.15) K. The measurements were performed at pressures from atmospheric pressure or above saturation up to the maximum pressure, which were approximately 21.7 MPa for diisopropyl ether and 21.1 MPa for dibutyl ether. The measurements were performed simultaneously using a vibrating-wire instrument operated in the forced mode of oscillation. The present results for both properties are compared with values from the literature when possible. The overall uncertainties of these results are ± 2.0 % in viscosity and ± 0.2 % in density. The measurements were correlated with the Tait-type equation for density and hard-sphere scheme for viscosity. For diisopropyl ether, the average absolute deviations of measurements from the correlations of viscosity and density are 0.39 % and 0.008 %, respectively. With regard to dibutyl ether, the average absolute deviations of the present results from the correlations are 0.21 % for viscosity and 0.009 % for density.

Excess molar enthalpies for the binary and ternary mixtures of ether compounds (di-isopropyl ether, di-butyl ether, propyl vinyl ether) with ethanol and isooctane at 298.15 K

Excess molar enthalpy (HE) data at 298.15 K are reported for the binary systems di-isopropyl ether (1)+ethanol (2), di-isopropyl ether (1)+isooctane (2), ethanol (1)+isooctane (2), di-butyl ether (1)+ethanol (2), di-butyl ether (1)+isooctane (2), propyl vinyl ether (1)+ethanol (2) and propyl vinyl ether (1)+isooctane (2). These data were obtained by using an isothermal flow calorimeter. The experimental binary HE data were well correlated with the Redlich-Kister model, and infinitely dilute partial excess molar enthalpies for each binary were calculated with the fitted Redlich-Kister parameters. Additionally, the isoclines of HE for ternary systems di-isopropyl ether (1)+ethanol (2)+isooctane (3), di-butyl ether (1)+ethanol (2)+isooctane (3) and propyl vinyl ether (1)+ethanol (2)+isooctane (3) at 298.15 K were calculated by using the Radojkovic equation. HE for all the measured systems in this work shows that mixing is endothermic.

Binary Liquid−Liquid Equilibrium (LLE) for Dibutyl Ether (DBE) + Water from (288.15 to 318.15) K and Ternary LLE for Systems of DBE + C1 ∼ C4 Alcohols + Water at 298.15 K

The binary liquid−liquid equilibrium (LLE) data for the system dibutyl ether (DBE) + water from (288.15 to 318.15) K and the ternary LLE data for systems of DBE + C1 ∼ C4 alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 2-butanol) + water at 298.15 K were analytically determined at atmospheric pressure using stirred and thermoregulated cells. The experimental binary and ternary LLE data were correlated with the NRTL and UNIQUAC activity coefficient models. In addition, the distribution and selectivity of C1 ∼ C4 alcohols as solvents were analyzed.

Phase Equilibrium Properties of Binary and Ternary Mixtures Containing Dibutyl Ether, Cyclohexane, and Heptane or 1-Hexene at T = 313.15 K

New experimental isothermal P, x, y data for the ternary systems dibutyl ether + cyclohexane + heptane and dibutyl ether + cyclohexane + 1-hexene and for the binary systems dibutyl ether + 1-hexene and dibutyl ether + heptane at 313.15 K are reported. Data reduction by Barker’s method provides correlations for GE, using the Margules equation for the binary systems and the Wohl expansion for the ternary systems. Wilson, NRTL, and UNIQUAC models have been applied successfully to both of the binary and ternary mixtures presented here.

Thermodynamics of Mixtures Containing Alkoxyethanols. Part XXVI. Densities, Excess Molar Volumes, Speeds of Sound at (293.15, 298.15, and 303.15) K, and Isentropic or Isothermal Compressibilities at 298.15 K for 2-Methoxyethanol + Alkoxyethanol or 2-Propoxyethanol + Dibutylether Systems

Densities, ρ, and speeds of sound, u, for the systems 2-methoxyethanol (2ME) + 2-ethoxyethanol (2EE), or + 2-butoxyethanol (2BE), or + 2-(2-methoxyethoxy)ethanol (22MEE) and for the 2-propoxyethanol (2PE) + dibutylether (DBE) mixture have been measured at (293.15, 298.15, and 303.15) K and atmospheric pressure using a vibrating-tube densimeter and sound analyzer (Anton Paar model DSA-5000). The ρ and u values were used to calculate excess molar volumes, VE, at the mentioned temperatures, molar excess heat capacities at constant volume, CVE, at 298.15 K, and deviations from the ideal behavior at 298.15 K of the thermal expansion coefficient, ΔαP, and of the isentropic and isothermal compressibilities, ΔκS and ΔκT, respectively. In DBE systems, HE(molar excess enthalpy) and VE decrease with the size of the 2-alkoxyethanol. In 2ME + alkoxyethanol mixtures, these magnitudes increase with the size of the second compound, although their values depend on the number of etheric atoms of this component.

Parameters influencing asymmetric synthesis of (R)-mandelonitrile by a novel (R)-hydroxynitrile lyase from Eriobotrya japonica

(R)-Mandelonitrile was successfully synthesized by an enzymatic transcyanation reaction of benzaldehyde and acetone cyanohydrin catalyzed by a hydroxynitrile lyase from Eriobotrya japonica (EjHNL) in an aqueous-organic biphasic system. The effects of pH, temperature, organic solvent, substrate concentration and enzyme concentration on the initial activity and enantioselectivity of the enzyme were studied. Both pH and temperature had a large effect on the initial velocity and enantiomeric excess (e.e.) of the product, (R)-mandelonitrile. High enantiomeric purity of the product was observed at low pH and temperature because the non-enzymatic reaction producing racemates of mandelonitrile was almost suppressed. The optimum pH and temperature to obtain high e.e. were pH 4.0 and 10°C, respectively. Surprisingly, the organic solvents had a significant influence on the initial velocity of the reaction but less influence on the enantiomeric purity of product. The EjHNL was very stable in ethyl acetate, diethyl ether, methyl-t-butyl ether, diisopropyl ether, dibutyl ether and hexane for 12h. The best solvent for the highest initial velocity and e.e. was diethyl ether with an optimum aqueous phase content of 50% (v/v). The initial reaction rate increase as the aqueous phase content rose, but when the content was more than 50%, a reduction of e.e. was observed. Increasing the concentration of the substrates accelerated the initial velocity, but caused a slight decrease in the e.e. of the product. Under the optimized conditions, the conversion and e.e. of (R)-mandelonitrile for 3h were 40 and 99%, respectively. The aqueous phase containing the enzyme also showed considerably efficient reusability for 4 batch reactions.

Thermodynamic study of perfluorohexane + ether mixtures : VLE, LLE, and HE

Vapour–liquid equilibria (VLE), liquid–liquid equilibria (LLE), and excess enthalpies ( H E) of binary mixtures of perfluoro- n-hexane plus an ether (diethyl, dipropyl, dibutyl, butyl methyl, and butyl ethyl ether), have been determined using a head-space gas-chromatographic technique, a turbidimetric apparatus, and a heat-flow calorimeter, respectively. A recently designed titration technique and calculation procedure have been used to obtain H E from heats of solution. The observed liquid–liquid coexistence curves have been compared with those predicted by the activity coefficients γ i and their temperature dependence. All mixtures are strongly endothermic ( H E > 0) and show large positive deviations from ideality ( G E > 0), which increase with the size of the ether. Molecular interactions have been examined by calculating and discussing solvation functions and Kirkwood–Buff (KB) integrals. Perfluorohexane proved to be an inert molecule that interacts with ethers more weakly than hexane.

Rate and equilibrium constants for Grignard reaction with alkoxysilanes and ketones

Kinetics of tetraethoxysilane reaction with n-butylmagnesium chloride, specifically solvated with dibutyl ether, diethyl ether, THF, and triethylamine, was studied in toluene. Also isopropylmagnesium chloride, isopropyltriethoxysilane, and diisopropylketone were involved in a similar investigation. The pseudo-first-order rate constants determined at a great excess of these organomagnesium compounds were used for separation of the appropriate equilibrium and rate constants. An advantage of the method consists in preclusion of non-specific solvation effects when effects of donor solvents are considered. In separate experiments, thermodynamic parameters were determined for rate and equilibrium constants, measured for the reaction of tetraethoxysilane with n-butylmagnesium chloride solvated with dibutyl ether in toluene, and also in bulk dibutyl ether. The implication of steric and solvation effects on this reaction is discussed.

N–H...O hydrogen bonding. FT-IR, NIR and 1H NMR study of N-methylpropionamide – Dialkyl ether systems

The paper reports the results of FT-IR, NIR and 1H NMR study of N-methylpropionamide in carbontetrachloride solution and in presence of ethers as the O-electron donors: Diehylether (DEE), Diisopropylether (DiPE), Methyl- t-Buthylether (MtBE), Dibutylether (DBE) and Dipenthylether (DPE). The spectroscopic characteristics for N–H...O hydrogen bonded complexes are given. Also, the equilibrium constants for 1:1 complex formation, at 25 °C were determined using IR, NIR and 1H NMR measurements.

Enthalpy of solvation correlations for gaseous solutes dissolved in dibutyl ether and ethyl acetate

Data have been assembled from the published literature on the enthalpies of solvation for 68 compounds dissolved in dibutyl ether and for 79 compounds dissolved in ethyl acetate. It is shown that an Abraham solvation equation with five descriptors can be used to correlate the experimental enthalpies of solvation in dibutyl ether and ethyl acetate to within standard deviations of 1.88 and 2.16 kJ/mol, respectively. The derived correlations provide very accurate mathematical descriptions of the measured enthalpy of solvation data at 298 K, which in the case of ethyl acetate span a range of about 71 kJ/mol. Mathematical correlations have also been derived for predicting the enthalpies of solvation in dibutyl ether, ethyl acetate, water and 15 additional organic solvents based on the Goss modified version of the Abraham model. Expressions based on this latter model were found to correlate the experimental enthalpies of solvation to within an overall average standard deviation of 2.29 kJ/mol for the 18 solvents studied.

Densities, Excess Molar Volumes, Speeds of Sound at (293.15, 298.15, and 303.15) K and Isentropic Compressibilities at 298.15 K for 1-Butanol, 1-Pentanol, or 1-Hexanol + Dibutylether Systems

Densities, p, and speeds of sound, u, of systems formed by 1-butanol (1-BuOH), 1-pentanol (1-PeOH), or 1-HxOH (1-hexanol) and dibutylether (DBE) have been measured at (293.15, 298.15, and 303.15) K and atmospheric pressure using a vibrating-tube densimeter and sound analyzer Anton Paar model DSA-5000. The p and u values were used to calculate excess molar volumes, V E , and deviations from the ideal behavior of the thermal expansion coefficient, α P , and of the isentropic compressibilities, κ T . The V E variation with the chain length of the 1-alkanol shows the existence of structural effects for systems including longer 1-alkanols.

Phase Equilibria of (1-Ethyl-3-methylimidazolium Ethylsulfate + Hydrocarbon, + Ketone, and + Ether) Binary Systems

The mutual solubilities of [EMIM][EtSO4], namely, 1-ethyl-3-methylimidazolium ethylsulfate, with n-alkanes (hexane or octane), aromatic hydrocarbons (benzene, toluene, or ethylbenzene), ketones (pentan-2-one, pentan-3-one, hexan-2-one, or heptan-4-one), ethers (dibutyl ether, tert-butyl-methyl ether, tert-butyl-ethyl ether, or tetrahydrofuran), and with dimethylsulfoxide, DMSO, have been measured at ambient pressure by a dynamic method from (250 to 420) K. The upper critical solution temperatures (UCSTs) were not observed for these systems, because they were at a temperature >420 K. The solubilities of [EMIM][EtSO4] in n-alkanes and aromatic hydrocarbons decrease with an increase of the molecular weight of the solvent. The experimental results have been correlated using the NRTL equation. The average root-mean square deviation of the equilibrium mole fraction for all the liquid−liquid equilibrium (LLE) data was 0.0033.

Cleavage of the ether bond by electron impact: differences between linear ethers and tetrahydrofuran

Dissociative electron attachment (DEA) to diethyl ether yielded primarily the C(2)H(5)O(-) ion, with a strong Feshbach resonance band at 9.1 eV and a weaker shape resonance band at 3.89 eV. Very similar spectra were obtained for dibutyl ether, with C(4)H(9)O(-) bands at 8.0 and 3.6 eV. Some of these primary ions subsequently lost H(2) and yielded weaker signals of the C(2)H(3)O(-) and C(4)H(7)O(-) ions. In contrast, DEA to the cyclic ether tetrahydrofuran (THF) yielded mainly a fragment of mass 41, presumably deprotonated ketene, at 7.65 eV. The low-energy band was missing in THF. H(-) with two bands at 6.88 and 8.61 eV, and an ion of mass 43 (presumably deprotonated acetaldehyde) with two bands at 6.7 and 8.50 eV were also observed. We propose that in the primary DEA step the C-O bond is cleaved in both the open-chain and the cyclic ethers. In the open-chain ethers the excess energy is partitioned between the (internal and kinetic) energies of two fragments, resulting in an RO(-) ion cool enough to be observed. The CH(2)(CH(2))(3)O(-) ion resulting from cleavage of the C-O bond in THF contains the entire excess energy (more than 6 eV at an electron energy of 7.65 eV) and is too short-lived with respect to further dissociation and thermal autodetachment to be detected in a mass spectrometer. These findings imply that there could be a substantial difference between the fragmentation in the gas phase described here and fragmentation in the condensed phase where the initially formed fragments can be rapidly cooled by the environment.

Femtosecond dynamics of electron transfer in a neutral organic mixed-valence compound

In this article we report a femtosecond time-resolved transient absorption study of a neutral organic mixed-valence (MV) compound with the aim to gain insight into its charge-transfer dynamics upon optical excitation. The back-electron transfer was investigated in five different solvents, toluene, dibutyl ether, methyl- tert-butyl ether (MTBE), benzonitrile and n-hexane. In the pump step, the molecule was excited at 760 nm and 850 nm into the intervalence charge-transfer band. The resulting transients can be described by two time constant. We assign one time constant to the rearrangement of solvent molecules in the charge-transfer state and the second time constant to back-electron transfer to the electronic ground state. Back-electron transfer rates range from 1.5 × 10 12 s −1 in benzonitrile through 8.3 × 10 11 s −1 in MTBE, around 1.6 × 10 11 s −1 in dibutylether and toluene and to 3.8 × 10 9 s −1 in n-hexane.