Compendium of the most significant studies with reference to properties, intake, effects.

Albro, P. W., & Thomas, R. O. (1973). Enzymatic hydrolysis of di-(2-ethylhexyl) phthalate by lipases. Biochimica et Biophysica Acta (BBA)-Lipids and Lipid Metabolism, 306(3), 380-390.

Abstract. Di-(2-ethylhexyl) phthalate was hydrolyzed by lipases from a variety of rat tissues. Of the preparations studied, only glycerol-ester hydrolase (pancreatic lipase, EC 3.1.1.3) and sterol-ester -hydrolase (cholesteryl ester hydrolase, EC 3.1.1.13) were unable to hydrolyze the phthalate diester. However, out of 15 different tissue preparations, only the liver alkaline lipase preparation could hydrolyze mono-(2-ethylhexyl) phthalate at a significant rate....

Gawas SD, Rathod VK. Ultrasound Assisted Green Synthesis of 2-Ethylhexyl Stearate: A Cosmetic Bio-lubricant. J Oleo Sci. 2020 Sep 2;69(9):1043-1049. doi: 10.5650/jos.ess19322.

Abstract. The 2-ethylhexyl stearate is used as a bio-lubricant in various cosmetic products. The present study is focused on the biocatalyzed esterification of 2-ethylhexanol and stearic acid to form 2-ethylhexyl stearate catalyzed by Fermase CALB 10000 in the presence of ultrasound treatment. The maximum conversion (95.87%) was obtained at molar ratio of 2-ethylhexanol to stearic acid 2:1, enzyme amount of 2 % (w/w), power 80 W, duty cycle 50 % and temperature 50°C in comparatively short reaction time (3 h) in the presence of Fermase as a catalyst. At optimum conditions, it is observed that in the presence of ultrasound; the reaction time minimizes up to 4 h as compared to mechanical stirring method (7 h). The physiochemical properties for the 2-ethylhexyl palmitate were also evaluated.

Richetti A, Leite SG, Antunes OA, Lerin LA, Dallago RM, Emmerich D, Di Luccio M, Vladimir Oliveira J, Treichel H, de Oliveira D. Assessment of process variables on 2-ethylhexyl palmitate production using Novozym 435 as catalyst in a solvent-free system. Bioprocess Biosyst Eng. 2010 Mar;33(3):331-7. doi: 10.1007/s00449-009-0328-7. 

Abstract. This work reports the optimization of 2-ethylhexyl palmitate production by esterification reaction in a solvent-free system using a commercial lipase as catalyst. For this, a sequential strategy was performed applying three experimental designs. An empirical model was built so as to assess the effects of process variables on the reaction conversion. Afterward, the operating conditions that optimized 2-ethylhexyl palmitate production were determined to be acid to alcohol molar ratio of 1:5.5, 70 degrees C, 150 rpm and 10.5 wt% of enzyme, leading to a reaction conversion as high as 93%. From this point, a kinetic study was carried out evaluating the influence of acid to alcohol molar ratio, enzyme concentration and temperature on product yield. Results obtained in this step allow to conclude that an excess of alcohol (acid to alcohol molar ratio of 1:6), relatively low enzyme concentration (10 wt%) and temperature of 70 degrees C led to nearly complete reaction conversion.

Xu, J., Zhang, R., Liu, C., Yu, Y., Wang, F., & Deng, L. (2021). High Efficient Biosynthesis 2-Ethylhexyl Palmitate in a Rotating Packed Bed Reactor. Applied biochemistry and biotechnology, 193(8), 2420-2429.

Abstract. 2-Ethylhexyl palmitate (2-EHP) is one of the important chemical products. Normally, 2-EHP is produced through the esterification. Since 2-EHP has a high viscosity, the mass transfer is significantly influenced with the product accumulation. In this work, a rotating packed bed reactor with intensive mixing was employed to solve the problem in the mass transfer during the enzymatic reaction. Under the optimal conditions, compared with the traditional continuous stirred-tank reactor (CSTR), the RPB reactor enhanced the final yield of 2-EHP, and shortened the reaction time to 1 h. In addition, the enzyme has a longer life-time in the RPB reactor, with production yield of closing to 99% after 9 batches. The results of this research indicated that the RPB has a great potential to be applied in the enzymatic production of 2-EHP.

Albro, P. W., & Thomas, R. O. (1973). Enzymatic hydrolysis of di-(2-ethylhexyl) phthalate by lipases. Biochimica et Biophysica Acta (BBA)-Lipids and Lipid Metabolism, 306(3), 380-390.

Abstract. Di-(2-ethylhexyl) phthalate was hydrolyzed by lipases from a variety of rat tissues. Of the preparations studied, only glycerol-ester hydrolase (pancreatic lipase, EC 3.1.1.3) and sterol-ester -hydrolase (cholesteryl ester hydrolase, EC 3.1.1.13) were unable to hydrolyze the phthalate diester. However, out of 15 different tissue preparations, only the liver alkaline lipase preparation could hydrolyze mono-(2-ethylhexyl) phthalate at a significant rate.

He, X. L., Chen, B. Q., & Tan, T. W. (2002). Enzymatic synthesis of 2-ethylhexyl esters of fatty acids by immobilized lipase from Candida sp. 99–125. Journal of Molecular Catalysis B: Enzymatic, 18(4-6), 333-339.

Abstract. The 2-ethylhexyl esters of fatty acids were synthesized by immobilized lipase from Candida sp. 99–125. The reuse stability of immobilized lipase was at least four batches. The conditions of enzymatic synthesis of 2-ethylhexyl palmitate were optimized. In the system of petroleum ether, 10% (w/w) immobilized lipase was used in the esterfication of 2-ethyl hexanol (7.8 mmol) and palmitic acid (7.8 mmol) at 40 °C with silica gel as the water absorbent. The esterification degree was 91% under these conditions. The purity of 2-ethylhexyl palmitate was 98% after purification consisting washing by water and evaporation to remove the organic solvent.

Choi, S., Kim, B. H., Yoon, S. W., Lee, M. W., Im, D. J., & Kim, I. H. (2022). Lipase-catalyzed synthesis of 2-ethylhexyl palmitate in a solvent free system using step changes in temperature. Biochemical Engineering Journal, 177, 108261.

 Abstract. Lipase-catalyzed synthesis of 2-ethylhexyl palmitate (2-EHP) from 2-ethylhexyl alcohol and palmitic acid was carried out in a solvent-free system. A commercial liquid lipase (Eversa Transform 2.0, Novozymes) from Thermomyces lanuginosus was immobilized on Lewatit VP OC 1600, a macroporous hydrophobic carrier. The efficacy of this Eversa immobilized lipase prepared in this study was evaluated on the synthesis of 2-EHP compared with that of Novozym 435 (from Candida antarctica), Lipozyme RM IM (from Rhizomucor miehei), Lipozyme TL IM (from Thermomyces lanuginosus), and the liquid Eversa lipase (commercial name: Eversa Transform 2.0). Among these lipases, the Eversa immobilized lipase was the most effective for the synthesis of 2-EHP. Optimum conditions for the synthesis of 2-EHP using this enzyme were a temperature of 55 °C and enzyme loading of 2% (based on the total weight of substrate). The conversion of 97% was achieved under these optimum conditions. Finally, as a cost-saving strategy, a step change in the reaction temperature was introduced. When a step change in the reaction temperature between 55 °C and 45 °C used, an identical degree of conversion was achieved compared to a constant reaction temperature of 55 °C throughout the reaction.