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| 离子液体中酶法酯化选择性富集单甘酯的研究 |
| Selective enrichment of monoglycerides in ionic liquids bylipase-catalyzed esterification |
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| DOI： |
| 中文关键词: 离子液体 单甘酯 选择性富集 脂肪酶 溶剂性质 极性 |
| 英文关键词:ionic liquid monoglycerides selective enrichment lipase solvent property polarity |
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| 中文摘要: |
| 系统地探究了离子液体的溶剂性质对酶法酯化反应中选择性富集单甘酯的影响。结果表明，离子液体的极性和氢键性质是影响选择性富集单甘酯的决定因素。在[Tf2N]-类离子液体中，ETN值与单甘酯选择性呈现明显的正相关性。具有羟基功能基团的离子液体[HO(CH2)2MIM]Tf2N以及具有强氢键碱性的阴离子离子液体[BMIM]N(CN)2有很高的单甘酯选择性。[PF6]-和[Tf2N]-类离子液体由于具有较高的log P值和较低β值，因此具有较高的脂肪酸转化率。[PF6]-离子液体过高的黏度提高了反应的传质阻力，使脂肪酸转化率降低，单甘酯选择性升高，呈现与极性规律相反的规律。选择[HO(CH2)2MIM]Tf2N作为反应溶剂，得到合成单甘酯的最佳工艺条件为底物（甘油与油酸）摩尔比4∶1、反应时间8 h、脂肪酶添加量4%、离子液体添加量30%、反应温度50?℃。在最佳条件下脂肪酸转化率为93.6%，单甘酯含量为61.1%，单甘酯选择性为64.5%。 |
| 英文摘要: |
| The lipase-catalyzed esterification was studied in ionic liquids(ILs) in order to deduce the effects of solvent properties on selective enrichment of monoglycerides (MAG). The results showed that polarity and Kamlet-Taft parameters of ILs were the decisive factors for selective enrichment of MAG. Especially for [Tf2N\]-based ILs, ETN values had a significantly positive correlation with MAG selectivity. ILs with higher polarity and hydroxyl group could form the hydrogen-bond with MAG and resulted in higher MAG selectivity such as [HO(CH2)2MIM]Tf2N and [BMIM]N(CN)2. ILs with higher log P and lowerβ, such as [Tf2N]-/sup> and [PF6]-based ILs, resulted in higher fatty acid (FFA) conversion. Viscosity might reduce the reaction rate, which could decrease the FFA conversion and increase MAG selectivity in some high viscous ILs especially for [PF6]- based ILs, and it appeared contrary to the law of polarity. Choosing [HO(CH-)-MIM]Tf-N as the solvent, the optimal preparation conditions of MAG were obtained as follows: reaction time 8 h, reaction temperature 50?℃，substrate(glycerol and oleic acid) molar ratio 4∶1，lipase dosage 4%，ILs dosage 30%. Under the optimal conditions, FFA conversion, MAG content and MAG selectivity were 93.6%, 61.1% and 64.5% repectively. |
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