Study of immobilized candida rugosa lipase for biodiesel fuel production from palm oil by flow microcalorimetry

Enzymatic transesterification of palm oil with methanol and ethanol was studied. Of the four lipases that were tested in the initial screening, lipase Candida Rugosa (CR) resulted in the highest yield of mono alkyl esters. Lipase CR was further investigated in immobilized form within an activated carbon as support. The activated carbon was prepared by activation physical. Using the immobilized lipase CR, the effects of water and alcohol concentration, enzyme loading and enzyme thermal stability in the transesterification reaction were investigated. The optimal conditions for processing 50 g of palm oil were: 37 °C, 1:14.5 oil/methanol molar ratio, 1.0 g water and 500 mg lipase for the reactions with methanol, 35 °C, 1:15.0 oil/ethanol molar ratio, 1.0 g water, 500 mg lipase for the reactions with ethanol, and 35 °C, 1:10.0 oil/n-butanol molar ratio, 1.0 g water, 500 mg lipase for the reactions with ethanol. Subject to the optimal conditions, methyl and ethyl esters formation of 70 and 85 mol% in 1 h of reaction were obtained for the immobilized enzyme reactions. The flow microcalorimetry is an important and novel techniques is used in evaluation of biodiesel production.     

Multiphase equilibria for binary and ternary mixtures containing propionic acid,n-butanol,butyl propionate,and water

Isothermal vapor–liquid equilibrium (VLE) data were measured for propionic acid + butyl propionate at 373.15 and 393.15 K, and isothermal vapor–liquid–liquid equilibrium (VLLE) data were also measured for n-butanol + water, butyl propionate + water, and water + n-butanol + butyl propionate at temperatures ranging from 323.15 to 393.15 K. No azeotrope was found in propionic acid + butyl propionate. The mutual solubility data of the binary aqueous systems were correlated well with the NRTL model accompanying with temperature-dependent parameters. Improvement on the calculation of saturated vapor compositions has been made by using two-term virial equation with one adjustable binary interaction parameter to represent the non-ideality of the vapor phase. The model parameters determined from the binary VLLE data of n-butanol + water and butyl propionate + water and the binary VLE data of n-butanol + butyl propionate are capable of predicting satisfactorily the VLLE properties for the ternary system of water + n-butanol + butyl propionate.     

Synthesis of enantiomerically pure glycidol via a fully enantioselective lipase-catalyzed resolution

The efficient enzymatic synthesis of enantiopure 2,3-epoxypropanol (glycidol) has been achieved. The racemic glycidyl butyrate was successfully resolved by enzymatic hydrolysis using a strategy that combines different immobilization protocols and different experimental reaction conditions. A new enzyme (25 kDa lipase)—which is a lipase-like enzyme purified from the pancreatic porcine lipase (PPL) extract—immobilized on DEAE–Sepharose was selected as the optimal biocatalyst. The optimal results were obtained at pH 7, 25 °C and 10% dioxane using this biocatalyst and a very high enantioselectivity for the enzyme was displayed, obtaining both (R)-(−)-glycidyl butyrate and (R)-(+)-glycidol with enantiomeric excesses >99% (E >100). The hydrolysis of (R)-(−)-glycidyl butyrate produced pure (S)-(−)-glycidol.     

Volumetric properties of ternary (IL + 2-propanol or 1-butanol or 2-butanol + ethyl acetate) systems and binary (IL + 2-propanol or 1-butanol or 2-butanol) and (1-butanol or 2-butanol + ethyl acetate) systems

The experimental densities for the binary or ternary systems were determined at T = (298.15, 303.15, and 313.15) K. The ionic liquid methyl trioctylammonium bis(trifluoromethylsulfonyl)imide ([MOA]⁺[Tf₂N]⁻) was used for three of the five binary systems studied. The binary systems were ([MOA]⁺[Tf₂N]⁻ + 2-propanol or 1-butanol or 2-butanol) and (1-butanol or 2-butanol + ethyl acetate). The ternary systems were {methyl trioctylammonium bis(trifluoromethylsulfonyl)imide + 2-propanol or 1-butanol or 2-butanol + ethyl acetate}. The binary and ternary excess molar volumes for the above systems were calculated from the experimental density values for each temperature. The Redlich–Kister smoothing polynomial was fitted to the binary excess molar volume data. Virial-Based Mixing Rules were used to correlate the binary excess molar volume data. The binary excess molar volume results showed both negative and positive values over the entire composition range for all the temperatures.The ternary excess molar volume data were successfully correlated with the Cibulka equation using the Redlich–Kister binary parameters.     

Chemoenzymatic synthesis of piperoxan,prosympal, dibozane,and doxazosin

The synthesis of both enantiomers of 1,4-benzodioxan-2-carboxylic acid 1, a key synthetic intermediate for the therapeutic agents piperoxan, prosympal, dibozane, and doxazosin was achieved with good yields and high enantioselectivities via the Arthrobacter sp. lipase catalyzed kinetic resolution of ester (±)-17a. The influence of the co-solvents and the immobilization of the lipase upon kinetic resolution demonstrated that immobilized whole cells, in the presence of n-butanol as a co-solvent, resulted in the optimal resolution of the substrate (ee ～99%, E = 535) at 258 mmol (50 g/L) substrate concentration.     

Apparent molar volumes and compressibilities of tetrabutyl-ammonium bromide in organic solvents

The densities of tetra-n-butylammonium bromide in 1-propanol, 1-butanol, acetone at (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 323.15) K and sound velocities at 298.15 K have been measured. From these data apparent molar volumes V_Φ at (288.15, 293.15, 298.15, 303.15, 308.15, 313.15, and 323.15) K and the apparent molar isenotropic compressibility K_S,Φ, at T = 298.15 K of tetrabutylammonium bromide in nonaqueous solvents have been determined. The apparent molar volumes and the apparent molar isenotropic compressibilities were fitted to the Redlich, Rosenfeld, and Mayer equation as well as to the Pitzer equation yielding infinite dilution data, which were compared to the similar quantities for tetrabutylphosphonium bromide. Moreover, the acoustical parameters such as intermolecular free length (L_f), relative association (R_A), Rao’s molar sound function (R_m), and salvation number (S_n) were calculated using the experimental data of density and sound velocity at T = 298.15 K for ammonium and phosphonium bromides. The obtained data suggest the penetration of the acetone molecule within the intraionic free space of the tetrabutyl-ammonium and phosphonium cations.     

Excess molar volume of (linalool + an alkanol) atT = 303.15 K

In this paper, densities of (linalool  +  methanol, or ethanol, or n -propanol, or n -butanol) are determined at T =  303.15 K using a vibrating-tube densimeter. The excess molar volumes V_m^Evalues are negative in all the systems over the entire composition range and correlated by the Redlich–Kister equation. The effects of chain length of alkanols onV_m^E have been discussed.     

Chemoenzymatic approach to enantiopure piperidine-based β-amino esters in organic solvents

This research concentrates on the enantioselectivities of lipase-catalysed reactions with methyl esters of 2-piperidylacetic acid and 3-piperidinecarboxylic acid derivatives. N-Acetylated 2-piperidylacetic acid methyl ester displayed good enantioselectivity (E = 66) in a 1:1 mixture of diisopropyl ether and butyl butanoate in the presence of lipase PS-C II from Burkholderia cepacia. The reaction is known as interesterification with butyl butanoate rather than alcoholysis with the butanol, because butyl butanoate has to be first hydrolysed or go through alcoholysis with MeOH in order to release butanol. Other N-protective groups (Boc, Ns, Fmoc and Bzn) gave excellent enantioselectivity (E >200) under the same conditions, and a gram-scale resolution was performed with N-Boc-2-piperidylacetic acid methyl ester. Reaction with a 3-piperidylcarboxylic acid derivative took place with disappointingly low enantioselectivity (E = 4), with Candida antarctica lipase B being the best of the lipases screened.     

Partial molar volumes of organic solutes in water. XIII. Butanols (aq) at temperatures T = 298 K to 573 K and at pressures up to 30 MPa

Density data for dilute aqueous solutions of 1-butanol, 2-butanol, 2-methyl-1-propanol (iso-butanol), and 2-methyl-2-propanol (tert-butanol) are presented together with partial molar volumes at infinite dilution calculated from the experimental data. The measurements were performed at temperatures from T = 298.15 K up to T = 573.15 K and at pressure close to the saturated vapour pressure of water, at pressures close to p = 20 MPa and p = 30 MPa. The data were obtained using a high-temperature high-pressure flow vibrating-tube densimeter.     

A green route to enantioenriched (S)-arylalkyl carbinols by deracemization via combined lipase alkaline-hydrolysis/Mitsunobu esterification

Herein we report results of the chemoenzymatic deracemization of a range of secondary benzylic acetates 1a–9a via a sequence of hydrolysis with CAL-B lipase in non-conventional media, combined with esterification of the recovered alcohol according to the Mitsunobu protocol following an enzymatic kinetic resolution (KR). The KR of racemic acetates 1a–9a via an enzymatic hydrolysis, with CAL-B lipase and Na₂CO₃, in non-aqueous media was optimized and gave high selectivities (E ? 200) at good conversions (C >49%) for all of the substrates studied. This method competes well with the traditional one performed in a phosphate buffer solution. The deracemization using Mitsunobu inversion gave the (S)-acetates in moderate to excellent enantiomeric excess 75% < ee < 99%, in acceptable isolated yields 70% < yield < 89%, and with some variations according to the acetate structure.     

Lipase-immobilized biocatalytic membranes for enzymatic esterification: Comparison of various approaches to membrane preparation

In this paper, lipase-immobilized membranes were prepared by both non-covalent and covalent immobilization methods using (i) lipase adsorption on membranes, (ii) inclusion of enzyme in membrane structure by filtration and (iii) covalent attachment of lipase to membrane. The catalytic properties of these membranes have been studied in reaction of butyloleate synthesis through esterification of oleic acid with n-butanol in isooctane. Ultrafiltration membranes made of regenerated cellulose (C030F) and polyethersulphone (PM30) were used for lipase immobilization. It was found that the lipase inclusion in the wide porous supporting layer of membrane was the most efficient method in preparing highly effective biocatalytic membranes. The degree of oleic acid conversion using these membranes was about 70–72% with a reaction time of 8 h. It was shown that the distribution profile of the lipase in the membrane was important for the effective enzyme utilization.The profile imaging atomic force microscopy (AFM) technique was used to visualize surfaces of lipase-immobilized biocatalytic membranes. AFM has also been used to directly quantify interactions between lipase-coated tip and membrane surfaces. It was concluded that the direct measurements of the interaction force between the enzyme-coated tip and the membrane surface would be a useful and practical approach for the choice of membranes as porous polymeric support for lipase immobilization through adsorption.     

Osmotic and apparent molar properties of binary mixtures alcohol + 1-butyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid

In this work, physical properties (densities and speeds of sound) for the binary systems {1-propanol, or 2-propanol, or 1-butanol, or 2-butanol, or 1-pentanol + 1-butyl-3-methylimidazolium trifluoromethanesulfonate} were experimentally measured from T = (293.15 to 323.15) K and at atmospheric pressure. These data were used to calculate the apparent molar volume and apparent molar isentropic compression which were fitted to a Redlich–Meyer type equation. This fit was used to obtain the corresponding apparent molar properties at infinite dilution. On the other hand, the osmotic and activity coefficients and vapor pressures of these binary mixtures were also determined at T = 323.15 K using the vapor pressure osmometry technique. The Extended Pitzer model of Archer was employed to correlate the experimental osmotic coefficients. From the parameters obtained in the correlation, the mean molal activity coefficients and the excess Gibbs free energy for the studied mixtures were calculated.     

Excess molar enthalpies of the binary systems: (Dibutyl ether + isomers of pentanol) at T = (298.15 and 308.15) K

In this work, we present the experimental measurements of excess molar enthalpies for the binary systems of dibutyl ether with different isomers of pentanol: 1-pentanol, 2-pentanol, 3-pentanol, 3-methyl-2-butanol, 2-methyl-1-butanol, 3-methyl-1-butanol and 2-methyl-2-butanol; all of them at T = (298.15 and 308.15) K and atmospheric pressure. Our goal was to determine the influence of the OH-group position on the different isomers of pentanol in the excess molar enthalpies of the binary systems studied. For this purpose we have analysed their experimental effective-reduced dipole moments. All values of excess molar enthalpies for the mixtures studied are positive whereas the results obtained for the effective-reduced dipole moments of the isomers of pentanol are similar.     

Compressed liquid densities of 1-butanol and 2-butanol at temperatures from 313 K to 363 K and pressures up to 25 MPa

(p, ρ, T) properties were determined in liquid phase for 1-butanol and 2-butanol at temperatures from 313 K to 363 K and pressures up to 25 MPa using a vibrating tube densimeter. The uncertainty is estimated to be lower than ±0.2 kg · m⁻³ for the experimental densities. Nitrogen and water were used as reference fluids for the calibration of the vibrating tube densimeter. Experimental densities of 1-butanol and 2-butanol were correlated with a short empirical equation and the 11-parameter Benedict–Webb–Rubin–Starling equation of state (BWRS EoS) using a least square optimization. Statistical values to evaluate the different correlations were reported. Published densities of 1-butanol and 2-butanol are compared with values calculated with the BWRS EoS using the parameters obtained in this work. The experimental data determined here are also compared with available correlations for 1-butanol and 2-butanol.     

Esterification of (RS)-Ibuprofen by native and commercial lipases in a two-phase system containing ionic liquids

Four commercially available lipases and two native lipases from Aspergillus niger AC-54 and Aspergillus terreus AC-430 were used for the resolution of (RS)-Ibuprofen in systems containing the ionic liquids [BMIM][PF₆] and [BMIM][BF₄]. The lipases showed higher conversion in a two-phase system using [BMIM][PF₆] and isooctane compared to that in pure isooctane. Although the best enzyme was a commercially available lipase from Candida rugosa (E = 8.5), another native lipase, produced in our laboratory, from A. niger gave better enantioselectivity (E = 4.6) than the other lipases tested (E = 1.9–3.3.). After thorough optimization of several reaction conditions (type and ratios of isooctane/ionic liquid, amount of enzyme, and reaction time), the E-value of A. niger lipase (15% w/v) could be duplicated (E = 9.2) in a solvent system composed of [BMIM][PF₆] and isooctane (1:1) after 96 h of reaction.     

Synthesis,characterization and thermochemistry of Cs(ASP) · nH2O (n = 0, 1)

New compounds of aspartic acid Cs(ASP) · nH₂O (n = 0, 1) have been synthesized and characterized by XRD, IR and Raman spectroscopy as well as TG. The structural formula of this new compound was Cs(ASP) · nH₂O (n = 0, 1). The enthalpy of solution of Cs(ASP) · nH₂O (n = 0, 1) in water were determined. With the incorporation of the standard molar enthalpies of formation of CsOH(aq) and ASP(s), the standard molar enthalpy of formation of −(1202.9 ± 0.2) kJ · mol⁻¹ of Cs(ASP) and −(1490.7 ± 0.2) kJ · mol⁻¹ of Cs(ASP) · H₂O were obtained.     

Properties of pure 1-methylimidazolium acetate ionic liquid and its binary mixtures with alcohols

Densities and viscosities of the pure ionic liquid 1-methylimidazolium acetate ([Mim]Ac) and its binary mixtures with methanol, ethanol, 1-propanol, and 1-butanol were measured at temperature ranging from T = (293.15 to 313.15) K. The thermal expansion coefficient, molecular volume, standard entropy, and lattice energy of [Mim]Ac were deduced from the experimental density results. A simple linear equation was used to correlate the variation of viscosity of [Mim]Ac with temperature. Excess molar volumes V^E and viscosity deviations Δη for the binary mixtures at above mentioned temperature were calculated and fitted to the Redlich–Kister equation with satisfactory results. Excess molar volumes for {[Mim]Ac + 1-butanol} mixture have an S shape, while those for other mixtures have a negative deviation from ideal behaviour over the entire mole fraction range. Viscosity deviations are all negative deviation for {[Mim]Ac + alcohol} mixtures. The results were interpreted in terms of interactions and structural factors of binary mixtures.     

Densities,speeds of sound,and refractive indices of the ternary mixtures (toluene + methyl acetate + butyl acetate) and (toluene + methyl acetate + methyl heptanoate) at 298.15 K

Density, ρ, speed of sound, u, and refractive index, n_D, at 298.15 K and atmospheric pressure have been measured over the entire composition range for (toluene + methyl acetate + butyl acetate) and (toluene + methyl acetate + methyl heptanoate) systems. Excess molar volumes, V^E, isentropic compressibility, κ_s, isentropic compressibility deviations, Δκ_s, and changes of refractive index on mixing, Δn_D, for the above systems, have been calculated from experimental data and fitted to Cibulka, Singh et al., and Nagata and Sakura equations, standard deviations from the regression lines are shown. Geometrical solution models, Tsao and Smith, Kholer, Jacob and Fitzner, Rastogi et al. were also applied to predict ternary properties from binary contributions.     

Isobaric vapor–liquid phase equilibria for the binary systems of tert-butanol + 2-ethyl-1-hexanol and n-butanol + 2-ethyl-1-hexanol

Isobaric vapor–liquid equilibria for the binary mixtures of tert-butanol (TBA) + 2-ethyl-1-hexanol and n-butanol (NBA) + 2-ethyl-1-hexanol were experimentally investigated at atmospheric pressure in the temperature range of 353.2–458.2 K. The raw experimental data were correlated using the UNIQUAC and NRTL models and used to estimate the interaction parameters between each pair of components in the systems. The experimental activity coefficients were obtained using the gas chromatographic method and compared with the calculated data obtained from these equilibrium models. The results show that UNIQUAC model gives better correlation than NRTL for these binary systems. The liquid–liquid extraction of TBA from aqueous solution using 2-ethyl-1-hexanol was demonstrated by simulation and the variation of separation factor of TBA at several temperatures was reported.     

Excess molar volumes and partial molar volumes for (propionitrile + an alkanol) at T = 298.15 K and p = 0.1 MPa

The excess molar volumes and the partial molar volumes for (propionitrile + an alkanol) at T = 298.15 K and at atmospheric pressure are reported. The hydrogen bonding between the OH⋯NC groups are discussed in terms of the chain length of the alkanol. The alkanols studied are (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and 1-pentanol).The excess molar volume data was fitted to the Redlich–Kister equation The partial molar volumes were calculated from the Redlich–Kister coefficients.