- Enzymatic synthesis of 1,3-dicaproyglycerol by esterification of glycerol with capric acid in an organic solvent system
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In this work, the esterification of glycerol with capric acid catalyzed by an immobilized form of a 1,3-positionally selective lipase (Rhizomucor miehei) showed to be effective for the synthesis of 1,3-dicaprin in n-heptane as the reaction medium. The effects of the reaction parameters were studied using an experimental factorial design of three factors and three levels with two central points. The selected experimental variables were amount of glycerol adsorbed on silica gel (G), biocatalyst load (E) and reaction temperature (T), and the response variables were total conversion of capric acid, acylglycerol fractions, selectivity and yield of dicaprin, and acyl migration reaction. The range of each parameter was selected as follows: G = 50-250 mg, E = 20-40 mg and T = 40-60 C. At optimum conditions 73% capric acid conversion was achieved, with 76% dicaprin selectivity, and selectivity to the specific 1,3-dicaprin of 70% of total products. An adequate selection of the reaction conditions is necessary not only to maximize the conversion of capric acid, but also to minimize the acyl migration reaction and the generation of undesired products. Evidence of kinetically controlled enzymatic acyl migration from sn-3/sn-1 to sn-2 is presented.
- Sanchez, Daniel Alberto,Tonetto, Gabriela Marta,Ferreira, Maria Lujan
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- Separation of acylglycerides obtained by enzymatic esterification using solvent extraction
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New avenues to add value to glycerol are currently being explored. One of them is the synthesis of structured lipids through glycerol esterification. In this work we have analyzed the recovery and purification of dicaprin obtained by esterification of glycerol with capric acid (C) in heptane, mediated by Lipozyme RM IM. This is an intermediate step to obtain lipids MLM. In the first stage, the diglyceride synthesis MGM (being G a central HC-OH) was carried out. When M = C, the diglyceride is CGC. Recovery of the diglyceride CGC is required to carry out the esterification of the sn-2 position with palmitic acid (P), thus obtaining the triglyceride CPC. Different solvents were evaluated using Ecofac 1.0 (a molecular design software solvent) through a theoretical approach to explore the best solvents for the acylglycerides separation. Then, the performance of the selected solvents to separate dicaprin from mono and tricaprin was experimentally studied in a liquid-liquid extraction process. Previously, the remaining fatty acid had been neutralized. With liquid-liquid extraction in three simple steps, using ethanol/water, 94 % of the dicaprin obtained by enzymatic esterification was recovered with a purity of 89 % (wt%). It was also possible to obtain dicaprin with a purity of 97 % but with a yield of 56 %.
- Sanchez, Daniel Alberto,Tonetto, Gabriela Marta,Ferreira, Maria Lujan
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p. 261 - 270
(2014/03/21)
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- 1-O-Alkyl (di)glycerol ethers synthesis from methyl esters and triglycerides by two pathways: Catalytic reductive alkylation and transesterification/reduction
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From available and bio-sourced methyl esters, monoglycerides or oleic sunflower refined oil, the corresponding 1-O-alkyl (di)glycerol ethers were obtained in both high yields and selectivity by two different pathways. With methyl esters, a reductive alkylation with (di)glycerol was realized under 50 bar hydrogen pressure in the presence of 1 mol% of Pd/C and an acid co-catalyst. A second two step procedure was evaluated from methyl esters or triolein and consisted of a first transesterification to the corresponding monoglyceride with a BaO/Al2O3 catalyst, then its reduction to the desired glycerol monoether with a recyclable heterogeneous catalytic system Pd/C and Amberlyst 35 under H2 pressure. In addition, a mechanism for the reaction was also proposed.
- Sutter, Marc,Dayoub, Wissam,Metay, Estelle,Raoul, Yann,Lemaire, Marc
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supporting information
p. 786 - 797
(2013/04/24)
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- Enzymatic synthesis of symmetrical 1,3-diacylglycerols by direct esterification of glycerol in solvent-free system
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1,3-Diacylglycerols were synthesized by direct esterification of glycerol with free fatty acids in a solvent-free system. Free fatty acids with relatively low melting points (45°C) such as unsaturated and medium-chain saturated fatty acids were used. With stoichiometric ratios of the reactants and water removal by evaporation at 3 mm Hg vacuum applied at 1 h and thereafter, the maximal 1,3-diacylglycerol content in the reaction mixture was: 84.6% for 1,3-dicaprylin, 84.4% for 1,3-dicaprin, 74.3% for 1,3-dilinolein, 71.7% for 1,3-dieicosapentaenoin, 67.4% for 1,3-dilaurin, and 61.1% for 1,3-diolein. Some of the system's parameters (temperature, water removal, and molar ratio of the reactants) were optimized for the production of 1,3-dicaprylin, and the maximal yield reached 98%. The product was used for the chemical synthesis of 1,3-dicapryloyl-2-eicosapentaenoylglycerol. The yield after purification was 42%, and the purity of the triacylglycerol was 98% (both 1,3-dicapryloyl-2-eicosapentaenoylglycerol and 1,2-dicapryloyl-3-eicosapentaenoylglycerol included) by gas chromatographic analysis, of which 90% was the desired structured triacylglycerol (1,3-dicapryloyl-2-eicosapentaenoylglycerol) as determined by silver ion high-performance liquid chromatographic analysis.
- Rosu, Roxana,Yasui, Mamoru,Iwasaki, Yugo,Yamane, Tsuneo
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p. 839 - 843
(2007/10/03)
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- Glyceride synthesis in a solvent-free system
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Synthesis of partial glycerides in a solvent-free system has been investigated with various acyl donors and glycerol as substrates and a 1,3-specific immobilized lipase to catalyze the reaction. Capric acid was the most efficient acyl donor, compared with ethyl caprate and tricaprin. However, to obtain a high yield of dicaprin and a low amount of tricaprin, ethyl caprate was the acyl donor of choice. The composition of the product mixture was determined by the ratio of ethyl caprate to glycerol; a molar ratio of 3:1 was optimum for dicaprin synthesis. The water content in glycerol did not influence the final yield of dicaprin, but initial production of capric acid increased with increasing water content. The reaction was found to be controlled entirely by external mass transfer. The yield of diglyceride could be increased from 70 to 90% by lowering the reaction temperature, so that the diglyceride precipitated during the reaction.
- Fureby,Adlercreutz,Mattiasson
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p. 1489 - 1495
(2007/10/03)
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- Synthesis of medium-chain glycerides by lipase in organic solvent
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Using commercial lipases from various microbial origins, medium-chain glycerides, such as mono-, di-, and tri-caprin, were synthesized in isooctane from glycerol and capric acid. The enzyme reaction was performed with 0.35 M capric acid, 0.025 M glycerol, and 0.46 g silica gel to remove water in 5 mL of isooctane with 30 mg lyophilized lipase. Of the 21 kinds of lipases, 11 showed good synthetic activities. Lipases from Pseudomonas aeruginosa (Lipase PS), Rhizomucor miehei lipase and Chromobacterium viscosum lipase (Lipase CV) showed high activities for the production of tricaprin, while lipase OF-360 (from Candida rugosa) and lipase D (Rhizopus delemar) were good for dicaprin production. Lipases CC and MY from C. rugosa (C. cylindracea) also showed high activities for dicaprin and tricaprin. Some lipases, especially lipase PS, had high thermal stability over 60°C. The optimal lyophilization pH to dehydrate the lipase coincides with the optimal buffer solution pH for hydrolysis.
- Kwon, Dae Young,Song, Hyo Nam,Yoon, Suk Hoo
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p. 1521 - 1525
(2007/10/03)
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