Evaluation of factors influencing the enantioselective enzymatic esterification of lactic acid in ionic liquid

Abstract

In this paper esterification of ethanol and lactic acid catalyzed by Candida antarctica B (Novozyme 435) in ionic liquid (Cyphos 104) was studied. The influence of different variables on lipase enantioselectivity and lactic acid conversion was investigated. The variables investigated were ionic liquid mass/lipase mass ratio, water content, alcohol excess and temperature. Using the Design Expert software 2(3) factorial experimental plan (two levels, three factors) was performed to ascertain the effect of selected variables and their interactions on the ethyl lactate enantiomeric excess and lactic acid conversion. The results of the experiments and statistical processing suggest that temperature and alcohol excess have the highest effect on the ethyl lactate enantiomeric excess, while temperature and water content have the highest influence on the lactic acid conversion. The statistical mathematical model developed on the basis of the experimental data showed that the highest enantiomeric excess achieved in the investigated variable range is 34.3%, and the highest conversion is 63.8% at the initial conditions of water content at 8%; 11-fold molar excess of alcohol and temperature at 30 °C.

Application of Chemical Engineering Methodology in Process Development: A Case Study of MenD-catalyzed Synthesis of 6-Cyano-4-oxohexanoic Acid

“…For further growth and development of biocatalysis, biochemical-engineering approaches can be very beneficial. They include the use of mo-deling techniques 10,11 , process optimization tools [12][13][14] , as well as the use of early-stage economic assessment tool 1,15 . A model-based methodology can be used to define the process design search-space within which the optimal solution can be found; it can save development time and money as simulations increase the process understanding 11 , and it can have a favorable impact on product quality 16 .…”

Enzyme activation using dynamic manipulation of process variables.

“…Published articles generally study enzymatic reactions through experimental designs based on the final yield of the reaction and invariably conclude that temperature is the most important variable for the studied system [7,10,16,23]. However, this variable trend of influence has a divergent behavior between these studies, even though they used similar temperature ranges.…”

“…The main goal of including the latter variable in the experimental design is to reduce the reaction time seeking to maintain the response variable optimized, as shown in several studies in the literature [4][5][6][7][8][9]. Usually, these studies conclude that maximal response occurs at the highest level studied [10][11][12][13]. Additionally, it was verified that the process is not always controlled by the same variables, even for similar studies with similar levels [9,[14][15][16][17].…”

“…The amount of lipase in the reaction medium, in most studies, is identified as an important variable in the process [10,16,23] and, in all studies reviewed, the effect of increasing lipase concentration is either an increase in the response variable or a tendency to lower the time for the system to reach equilibrium [16,37]. In fact, the greater the relative amount of biocatalyst, the higher is the reaction rate in the same period of time, leading to one of two consequences: either shorter time to reach chemical equilibrium or increased yield, depending on whether the reaction time was sufficient to reach equilibrium.…”

Rhizomucor miehei Lipase-Immobilized Sodium Alginate Membrane Preparation and Usage in a Pervaporation Biocatalytic Membrane Reactor

“…In most of these studies, lipase has been used as a free catalyst or as immobilized beads in a classical reactor. Findrik et al studied the ethanol-lactic acid esterification reaction by means of a commercial immobilized enzyme (immobilized Candida antarctica B) and obtained 0.59 lactic acid conversion within 5 hours in a batch reactor 37 . Koutinas et al studied the same reaction with a Novazyme 435 immobilized enzyme and reported 0.33 lactic acid conversion in a batch reactor 38 .…”