Esterification Of Myristic Acid Research Articles

Substrate specificity of commercial lipases activated by a hydration–aggregation pretreatment in anhydrous esterification reactions

Substrate specificity in non-aqueous esterification catalyzed by commercial lipases activated by hydration–aggregation pretreatment was investigated. Four microbial lipases from Rhizopus japonicus, Burkholderia cepacia, Rhizomucor miehei, and Candida antarctica (fraction B) were used to study the effect of the carbon chain length of saturated fatty acid substrates on the esterification activity with methanol in n-hexane. Hydration–aggregation pretreatment had an activation effect on all lipases used, and different chain length dependencies of esterification activity for lipases from different origins were demonstrated. The effects of various acidic substrates with different degrees of unsaturation, aromatic rings, and alcohol substrates with different carbon chain lengths on esterification activity were examined using R. japonicus lipase, which demonstrated the most remarkable activity enhancement after hydration–aggregation pretreatment. Furthermore, in the esterification of myristic acid with methanol catalyzed by the hydrated–aggregated R. japonicus lipase, maximum reaction rate (5.43 × 10−5 mmol/(mg-biocat min)) and Michaelis constants for each substrate (48.5 mM for myristic acid, 24.7 mM for methanol) were determined by kinetic analysis based on the two-substrate Michaelis-Menten model.

Fatty alcohol synthesis from fatty acids at mild temperature by subsequent enzymatic esterification and metal-catalyzed hydrogenation.

Fatty alcohols are important products in chemical industry to be used in the formulation of surfactants and lubricants. This work describes a two step approach for the production of myristyl alcohol under neat conditions by combining a lipase catalyzed esterification of myristic acid and myristyl alcohol with a ruthenium catalyzed hydrogenation of the intermediate myristyl myristate. The esterification was carried out in a bubble column reactor with the commercial immobilized lipase B from Candida antarctica as a biocatalyst, while the hydrogenation was conducted under pressurized conditions being catalyzed by the homogeneous chemocatalyst Ru-Macho-BH. By investigating the reaction steps separately, comparable reaction rates were found for the esterification of short chain and long chain alcohols. Additionally, the hydrogen pressure could be reduced to 35 bar compared to the current industrial Lurgi process. Characterization of cross interactions by the reactants myristic acid and sodium myristate in the hydrogenation demonstrates that the metal catalyst was completely deactivated, even at a low amount of 0.5 mol% of myristic acid. Complete conversion of myristic acid in the esterification with equal amounts of myristic acid and myristyl alcohol was obtained, overcoming any limitation in the hydrogenation. In comparison to the Lurgi process starting also from fatty acid and fatty alcohols, the chemoenzymatic two step reaction sequence could be realized at lower reaction temperatures of 60 and 100 °C as well as lower hydrogen pressures of 35 bar.

Reaction kinetics for synthesis of isopropyl myristate catalyzed by sulfated titania

Sulfated titania (SO42−/TiO2) was prepared and characterized by nitrogen adsorption-desorption, FT-IR, thermostability analyzer, XRD and particle size analyzer. The esterification of myristic acid (MA) with isopropanol (IPOH) catalyzed by the solid super acid SO42−/TiO2 was studied. The effect of reaction kinetics conditions such as temperature, stirrer speed, initial mole ratio of alcohol to acid, and catalyst loading on the conversion of myristic acid was investigated. A second-order pseudo-homogeneous model was developed to calculate the rate of the reaction, and then the kinetic parameters were estimated. The calculated values were in agreement with experimental data.

Green synthesis of isopropyl myristate in novel single phase medium Part II: Packed bed reactor (PBR) studies

Isopropyl myristate is a useful functional molecule responding to the requirements of numerous fields of application in cosmetic, pharmaceutical and food industry. In the present work, lipase-catalyzed production of isopropyl myristate by esterification of myristic acid with isopropyl alcohol (molar ratio of 1:15) in the homogenous reaction medium was performed on a bench-scale packed bed reactors, in order to obtain suitable reaction performance data for upscaling. An immobilized lipase B from Candida antartica was used as the biocatalyst based on our previous study. The process intensification resulted in a clean and green synthesis process comprising a series of packed bed reactors of immobilized enzyme and water dehydrant. In addition, use of the single phase reaction system facilitates efficient recovery of the product with no effluent generated and recyclability of unreacted substrates. The single phase reaction system coupled with a continuous operating bioreactor ensures a stable operational life for the enzyme.

Simultaneous transesterification and esterification for biodiesel production with and without a sulphated zirconia catalyst

Simultaneous catalysed transesterification of rapeseed oil and esterification of 10wt% myristic acid with methanol was studied using sulphated zirconia and in the absence of catalyst. The maximum total FAME content of 86% was obtained at a catalyst loading of 3wt%, temperature of 170°C, pressure of 22 bars, molar ratio of oil to methanol of 1:20 and stirring rate of 600rpm for 60min. At these conditions, FFA was observed to reach 2.95% (2.94mg/ml sol.). Thermo/catalytic cracking and hydrolysis of triglyceride was presumed to form the FFA. Water was also formed: dehydration of methanol is likely to be the principal source. Three sets of main reactions occurred at distinctly different rates. Esterification of myristic acid was the most rapid reaction. Direct transesterification of triglyceride and side-reactions of thermo/catalytic cracking of triglyceride followed by esterification of fatty acid and hydrolysis of triglyceride followed by esterification of fatty acid occurred afterward. Dehydration of methanol was observed throughout the reaction, producing a constant supply of water, thereby facilitating hydrolysis reactions.

Kinetic of myristic acid esterification with methanol in the presence of triglycerides over sulfated zirconia

The esterification of myristic acid with methanol in presence of triglycerides using sulfated zirconia prepared by solvent-free method as the heterogeneous catalyst was studied. The effects of reaction temperature (393–443 K), catalyst loading (1–3 %wt) and molar ratio of oil to methanol (1:4–1:20) on the conversion of myristic acid were investigated. The experimental data was interpreted with a second order pseudo-homogeneous kinetic model. The kinetic parameters were obtained. A good agreement between the experimental data and the model was observed. Sulfated zirconia prepared by solvent-free method exhibited high catalytic activity for this reaction. Low activation energy of 22.51 kJ mol −1 was obtained in the range of temperature of 393–443 K.

Enzymatic synthesis of isopropyl myristate using immobilized lipase fromBacillus cereusMTCC 8372

A purified alkaline thermo-tolerant bacterial lipase from Bacillus cereus MTCC 8372 was immobilized on a Poly (MAc-co-DMA-cl-MBAm) hydrogel. The hydrogel showed approximately 94% binding capacity for lipase. The immobilized lipase (2.36 IU) was used to achieve esterification ofmyristic acid and isopropanol in n-heptane at 65 degrees C under continuous shaking. The myristic acid and isopropanol when used at a concentration of 100 mM each in n-heptane resulted in formation of isopropyl myristate (66.0 +/- 0.3 mM) in 15 h. The reaction temperature below or higher than 65 degrees C markedly reduced the formation of isopropyl myristate. Addition of a molecular sieve (3 A x 1.5 mm) to the reaction mixture drastically reduced the ester formation. The hydrogel bound lipase when repetitively used to perform esterification under optimized conditions resulted in 38.0 +/- 0.2 mM isopropyl myristate after the 3rd cycle of esterification.

Esterification of myristic acid in supercritical carbon dioxide

The esterification of myristic acid with ethanol was studied with a commercial lipase (crude Hog pancreas lipase, HPL). The reaction was investigated in solvent-free conditions and in two solvents: supercritical carbon dioxide (SCCO 2) and acetonitrile. Conversions of up to 76% were obtained under solvent-free conditions while conversions of only up to 37 and 4% were obtained in SCCO 2 and acetonitrile, respectively. However, for similar enzyme concentrations, 37% of the myristic acid was converted to ester in SCCO 2 but only 4% was converted in acetonitrile and solvent-free conditions. Various parameters like temperature, water and ethanol concentrations that influenced the reaction were also investigated. Ethanol was found inhibitory for the reaction in SCCO 2. Addition of water led to sharp reduction in the conversions of myristic acid.

Multiple mutagenesis of non-universal serine codons of the Candida rugosa LIP2 gene and biochemical characterization of purified recombinant LIP2 lipase overexpressed in Pichia pastoris.

The 17 non-universal serine codons (CTG) in the Candida rugosa LIP2 gene have been converted into universal serine codons (TCT) by overlap extension PCR-based multiple site-directed mutagenesis. An active recombinant LIP2 lipase was overexpressed in Pichia pastoris and secreted into the culture medium. The recombinant LIP2 showed distinguishing catalytic activities when compared with recombinant LIP4 and commercial C. rugosa lipase. The purified enzyme showed optimum activity at pH 7 and a broad temperature optimum in the range 30-50 degrees C. The enzyme retained 80% of residual activity after being heated at 70 degrees C for 10 min. Recombinant LIP2 demonstrated high esterase activity towards long-chain (C12-C16) p-nitrophenyl esters. Tributyrin was the preferred substrate among all triacylglycerols tested for lipolysis. Among cholesteryl esters, LIP2 showed highest lipolytic activity towards cholesteryl laurate. The esterification of myristic acid with alcohols of various chain lengths showed that the long-chain n-octadecanol (C18) was the preferred substrate. In contrast, the esterification of n-propanol with fatty acids of various chain lengths showed that the short-chain butyric acid was the best substrate. From comparative modelling analysis, it appears that several amino acid substitutions resulting in greater hydrophobicity in the substrate-binding site might play an important role in the substrate specificity of LIP2.

Design and control of a reaction distillation column including the recovery system

A complex dynamic model for reactive distillation, which includes control systems and the capability of coupling additional columns is derived. On this basis, a typical reactive distillation column coupled with a recovery column is investigated and optimized. In this paper, the esterification of myristic acid in a reaction column as a typical example is optimized through simulations. To guarantee an almost complete conversion of the acid and a high purity of the reaction by product water, the reaction column is coupled with a recovery column. Both columns are designed based on steady state simulations. To develop a control structure, the reaction column's steady state and dynamic sensitivity of possible disturbances and manipulated variables are analyzed. It is shown, that in this reaction column there is no direct relationship between temperature and purity as is usual in common distillation columns. The influence of the reaction on the temperature profile within the reaction column has to be known, when the temperature is used as a reference variable for the purity. The recovery does not lead to an instability of the system. With this knowledge an efficient control structure is presented for this strongly non-linear coupled system. The purities of the product streams can be guaranteed

Internal Mass Transfer Limitation During Enzymatic Esterification in Supercritical Carbon Dioxide and Hexane

A kinetic study of ethyl myristate formation by esterification of myristic acid with ethanol catalysed by a lipase from Mucor miehei immobilized on Duolite A 568, has been carried out.The reaction was done in a two liquid phase system in which the non-aqueous solvent was supercritical carbon dioxide (P= 12.5 MPa, T = 323 K) or n-hexane (P = 0.1 MPa, T = 323K). In heteregenous catalysis, it is important to study the internal mass transfer limitation. For this, the support was sieved into different size series (from 300 to 600 mm) and the reaction was carried out for each size series. The samples were analyzed by gas chromatography and the esterification was shown to follow Ping Pong Bi Bi kinetics with competitive substrate inhibition. The Thiele modulus values show that there is, in the hexane case, a diffusional control while in SCCO2 media, we obtained an intermediate rate between reactional and diffusional rates.