Optimization of Lipase‐Catalyzed Synthesis of Cetyl Octanoate in Supercritical Carbon Dioxide

Abstract

Cetyl octanoate, a wax ester of 24 carbons, is widely used in the cosmetic industry as a base oil. The current work focuses on lipase-catalyzed synthesis of cetyl octanoate in supercritical carbon dioxide (SC-CO2) by esterification of cetyl alcohol and octanoic acid. Three immobilized lipases were screened, and 15 reaction conditions were tested in order to find the combination for maximal yield. The results showed that Novozym 435 was the best catalyst for the synthesis, and a reaction time of 20 min was adequate for a maximal yield. Response surface methodology (RSM) with a 3-factor- 3-level Box-Behnken design was employed to evaluate the effects of synthesis parameters, including reaction temperature (35–75 C), pressure (8.27–12.41 MPa), and enzyme amount (5–15% wt of cetyl alcohol). A model for the synthesis was developed and the optimum conditions could be predicted to be reaction pressure of 10.22 MPa, reaction temperature of 63.70 C, and enzyme amount of 11.20%. An experiment was performed under this optimum condition and a yield of 99.5% was obtained. This experimental yield correlated well with the predicted value of yield (97.6%). We concluded that, in a SC-CO2 system, nearly 100% molar conversion of cetyl octanoate could be obtained by immobilized Novozym 435 in a short reaction time (20 min) under the predicted optimal conditions

High Yield of Wax Ester Synthesized from Cetyl Alcohol and Octanoic Acid by Lipozyme RMIM and Novozym 435

“…The esterification reaction was carried out in an orbital shaking water bath (200 rpm) under various reaction temperatures and reaction times as shown in Table 1 . The yield % was defined as (mmol of cetyl octanoate/mmol of initial cetyl alcohol) × 100% and was determined using GC method [ 15 ].…”

One‐Step Solvent‐Free Production of a Spermaceti Analogue Using Commercial Immobilized Lipases

“…These reactions should be performed with a very low presence of water in reaction media, in order to push the chemical equilibrium towards the synthesis. In this way, organic solvents, ionic liquids, and supercritical fluids have been employed, but either for the unnecessary severe operation conditions or for the risk of finding traces of the reaction media on the product, these methods are unsuitable for obtaining cosmetic or pharmaceutical compounds. Therefore, the enzymatic synthesis of these products can be faced with great success by operating under vacuum using a solvent‐free system, as it requires mild reaction conditions and purification steps are considerably reduced ,…”

Supercritical CO2 as a Valuable Tool for Aroma Technology

“…While some studies suggest that such reactions should occur at reduced pressures (near the critical point), others claim no activity loss at higher pressures. − Thus, the study of the pressure effect must be performed on a case-by-case basis and is strongly dependent on the enzyme involved and other reaction conditions . For the effect of temperature, studies show that in nonaqueous and supercritical media, enzymes have greater thermal resistance than aqueous media. , Lipase-catalyzed esterifications (for volatile ester production in a SC-CO 2 system) should operate at a temperature range of 35 to 65 °C since the aroma esters are volatile and stable in this temperature range. − Thus, there is no benefit in working at higher temperatures. , Consequently, the studies regarding the production of aroma esters, as the examples described next, usually evaluate the effect of pressure and temperature on the esterification reaction.…”