T. Garcia

Enzymatic synthesis of fatty esters. Part I. Kinetic approach

A kinetic study of palmitic acid esterification reaction catalyzed by immobilized lipase Novozym 435 (from Candida antarctica) has been made in a range of 65–75°C temperature and 3–7% of initial catalyst concentration and atmospheric pressure. Influence of operating variables also was studied. Different values of temperature, initial lipase concentration, acid/alcohol molar ratio, and products concentrations were tested. Experiments were carried out in a stirred batch reactor equipped with adequate control systems. Evolution of concentration of the species involved was found by using gas-liquid chromatography. The kinetic characteristics observed in the esterification reaction with isopropanol were found to follow an ordered bi-bi mechanism with competitive inhibition by reactants and products. According to the mechanism maximum reaction rate, Michaelis–Menten constants and inhibition constants were determined. A good quality of fit was observed by fitting experimental rate data to the kinetic model with an average error beneath the 15%. Kinetic constants, as well as enthalpy and entropy values, have been determined for the model proposed for the esterification reaction within the experimental range studied.

Enzymatic synthesis of fatty esters : Part II. optimization studies☆

The synthesis of isopropyl palmitate over an enzymatic catalyst has been developed and optimized following the Factorial Design and Response Surface Methodology. A full two-factorial design has proved effective in the study of the influence of the variables (selected for the present study temperature and enzyme concentration) on the process. The range studied was 62.9°C and 77°C for temperature, and 2.2%wt and 7.83%wt for the catalyst concentration. Catalyst concentration has been found to be the most significant factor on the esterification process and its influence is positive. The Response Surface model obtained, representing the yield on ester, has been found to describe adequately the experimental results obtained.

Kinetic modelling of esterification reactions catalysed by immobilized lipases

The kinetics of the synthesis of several esters of different chain length and physical properties was studied. A commercial Candida antarctica lipase was used as catalyst for the synthesis of oleyl oleate, isopropyl oleate, isopropyl palmitate, myristyl myristate, cetyl oleate, and oleyl 2-methylbutyrate. A general kinetic model was derived and tested experimentally for the synthesis of the above esters. The general kinetic model took a different shape for each particular esterification reaction, depending on the significance of the different terms. The corresponding parameters were calculated by non-linear regression. The kinetic models were found to describe the experimental values adequately.

Enzymatic synthesis of an analogue of jojoba oil: Optimization by statistical analysis

The optimization of the enzymatic synthesis of an analogue of jojoba oil from easily available materials in Spain was achieved. A full 23 factorial design at two levels was applied. The variables chosen were temperature, enzyme concentration, and presure. A response equation was found to determine the yield of ester.

Enzymatic Synthesis of Myristyl Myristate. Estimation of Parameters and Optimization Of the Process

The optimization of the operating variables in the enzymatic synthesis of myristyl myristate ester was carried out by factorial design and analysis of experiments. A fungal lipase from Candida antarctica, E.C. 3.1.1.3 triacylglycerol hydrolase, was used as catalyst. Reaction parameters such as temperature, pressure and initial catalyst concentration were considered as determinant factors in the factorial design. The response considered was ester yield at two hours of reaction. Working pressure was the most significant factor in the esterification process and its influence was negative. Temperature and initial catalyst concentration had positive influences on the process. Depending on the pressure value the influence of the interactions can be more important than that of the other two main effects, temperature and concentration of lipase. Response surface models have been found adequate to represent the ester yield. The results obtained can be considered as a starting point for the future industrial-scale ...

Optimization of the synthesis of a sperm whale oil analogue

Abstract The development and optimization of the synthesis of an analogue of sperm whale oil have been carried out. The product is an ester with similar characteristics to those of natural oils, and can be used as a substitute for these. A Factorial Design of Experiments and a Central Composite Design have been used in the synthesis of this fine chemical. The variables chosen were temperature and initial catalyst concentration. Response surface models have been found to represent the yield of ester.

Regioselective synthesis of monoglycerides. Kinetic modelling

Abstract A kinetic study of ricinoleic acid and glycerol esterification reaction catalyzed by immobilized lipase from Candida antarctica (E.C.3.1.1.3) has been made in a range of 70 – 80°C. The best operating conditions were found at vacuum conditions, which permits the study of esterification reaction as irreversible process. High selectivities for monoglyceride were obtained by controlling the initial concentration of catalyst on the reaction medium. The kinetic characteristics were found to conform to an ordered bi-bi mechanism with competitive inhibition by reactants and products. Michaelis Menten constants and inhibition constants were determined according to the mechanism maximum reaction rate. A good quality of fit was observed by fitting experimental rate data to the kinetic model.