脂肪酸酯的技术与市场发展动向

论述了脂肪酸一元醇酯,多元醇酯的特性、合成及用途,并介绍了由脂肪酸酯开发“绿色”表面活性剂的最新技术动向。     

Enzymatic synthesis of monosaccharide fatty acid esters and their comparison with conventional products

5-O-Acyl-1,2-O-isopropylidene-D-xylofuranose and 6-O-acyl1,2∶3,4-di-O-isopropylidene-D-galactopyranose were enzymatically prepared from the corresponding monosaccharide acetals and commercial (crude) fatty acid mixtures. Subsequent acid-catalyzed hydrolysis of the isopropylidene group(s) gave monosaccharide esters with overall yields of 59–88%, where the monoester content was at least 80% (galactose oleate) and typically 90% for the other preparations. In contrast to sugar fatty acid esters prepared by conventional, high-temperature (trans)esterification, the enzymatically obtained monosaccharide esters contained no appreciable quantities of undersirable side products, and the only contaminants were monosaccharides and fatty acids.     

Convenient preparation of picolinyl derivatives from fatty acid esters

It is essential to have simple rapid methods for the determination of fatty acid structures. Traditionally, fatty acids are analysed by gas chromatography using their methyl ester derivatives (FAME). However, their corresponding mass spectra exhibit molecular ions but are usually devoid of ions indicative of structural features and, notably, the position of double bounds on the aliphatic chains [1]. In the most useful approach to structure determination, the carboxyl group is derivatised with a reagent containing a nitrogen atom. Recently, a convenient method for preparing picolinyl esters from intact lipids has been published [2]. However, some problems occurred in our laboratory when this method was used, leading to some modifications and optimisation. Thus, hexane and water have been added while sodium bicarbonate has been removed in order to lower contamination. Temperature and length of the reaction have then been optimised in order to get 100% derivatisation for different kinds of lipids (45 °C and 45 min for FAME). Finally, a comparison of the response factors has confirmed the better sensitivity of the picolinyl derivative against FAME (five times more).     

Chemo-enzymatic synthesis of disaccharide fatty acid esters

A novel enzymatic method for the synthesis of disaccharide fatty acid esters was developed with immobilizedMucor miehei lipase (Lipozyme IM-60; Novo Nordisk, Bagsvaerd, Denmark) as a catalyst. A range of lactose and maltose monoesters was prepared in overall yields of 48–77% from the corresponding sugar acetals and fatty acids.     

柠檬酸甘油单,二酸酯合成过程中沉淀物的分析

对柠檬酸和单甘酯酯化反应制取柠檬酸甘油单、二酸酯过程中产生的沉淀进行了红外光谱分析,并对沉淀产物的原因提出了合理的解析。     

Anomalous viscosity behavior of fatty acid esters in solution

Solution viscosity of oils of melonseed(Colocynthis vulgaris Schrad.), soyabean [Glycine max (L). Merr], and rubberseed [Hevea brasiliensis (Kunth) Muell.] were determined in different solvents at various concentrations. Reduced viscosity(_{η red}) vs concentration (C) plots showed three types of behavior:_{η red} increased linearly with C (2–30 g/dl);_{η red} levelled off with C (2–1.2 g/dl); and_{η red} rose steeply with decrease in C (below 1.2 g/dl), the latter behavior is anomalous. Similar viscosity behavior was observed for the methyl ester of melonseed oil, methyl palmitate and n-butyl acetate. Molecular cluster formation was believed to cause the observed anomalous viscosity behavior, the extent of which varied, depending on the nature of the fatty acid ester and the solvent.     

Enzymatic synthesis of acetylated glucose fatty acid esters in organic solvent

Two immobilized lipases fromCandida antarctica (SP 382) andC. cylindraceae, nowrugosa (2001), catalyzed the synthesis of novel acetylated glucose fatty acid esters with glucose pentaacetate (GP) and Trisun 80 (80% oleic) vegetable oil or methyl oleate as substrates in organic solvents. The relative yield was between 6.4–52%, and the incorporation of oleic acid onto the glucose was between 31–100%. In addition, these enzymes were able to catalyze the synthesis of glucose fatty acid esters with free glucose as the sugar substrate. The highest oleic acid incorporation (100%) was obtained in benzene with SP 382 lipase and Trisun 80 as the acyl donor. With methyl oleate as the acyl donor, greater incorporation was obtained in benzene (90.5%) compared to 75% in isooctane. The 2001 lipase was better in benzene/pyridine (2∶1 vol/vol) 74%) and chloroform (61%) compared to benzene and isooctane. However, with free glucose and Trisun 80 as substrates, both enzymes gave acceptable levels of oleic acid incorporation (82–100%) in benzene, benzene/pyridine and pyridine. The best conditions for the ester interchange reaction reported are: lipase (10% by weight of substrate); incubation time 48 h; molar ratio of Trisun/GP 1∶2; 3 mL solvent and 3% added water. These glucose esters have potential applications as emulsifiers in food, cosmetics and pharmaceutical formulations.     

Hydrogenation of fatty acid methyl esters to fatty alcohols at supercritical conditions

Extremely rapid hydrogenation of fatty acid methyl esters (FAME) to fatty alcohols (FOH) occurs when the reaction is conducted in a substantially homogeneous supercritical phase, using propane as a solvent, over a solid catalyst. At these conditions, the limitations of hydrogen transport are eliminated. At temperatures above 240°C, complete conversion of the starting material was reached at residence times of 2 to 3 s, which is several orders of magnitude shorter than reported in the literature. Furthermore, formation of by-products, i.e., hydrocarbons, could be prevented by choosing the right process settings. Hydrogen concentration turned out to be the key parameter for achieving the above two goals. As a result of the supercritical conditions, we could control the hydrogen concentration at the catalyst surface independently of the other process parameters. When methylated rapeseed oil was used as a substrate, the hydrogenation catalyst was deactivated rapidly. However, by using methylated sunflower oil, a catalyst life similar to that obtained in industrial processes was achieved. Our results showed that the hydrogenation of FAME to FOH at supercritical conditions is a much more efficient method than any other published process.     

Geometrical isomerisation of double bonds in acid‐catalysed preparation of fatty acid methyl esters

Acid‐catalysed methylation is frequently applied for the preparation of fatty acid methyl esters used for gas chromatographic analysis of fatty acids. A series of artefacts were observed in hydrochloric acid‐catalysed direct methylation of herring (Clupea harengus L.) muscle. The artefacts were identified as trans isomers of eicosapentaenoic and docosahexaenoic acid, and their levels increased with reaction time. The isomers were not found after methylation of a lipid extract of the herring muscle, even after extreme reaction times. In general, the trans isomers are only observed after methylation of certain marine tissues, indicating catalytic activity in these samples. Based on these results, it is recommended that direct methylation procedures are thoroughly validated with each matrix type analysed, and that reaction times should not be longer than necessary to complete the methylation.     

Separation of fatty acid esters from cholesterol in esterified natural and synthetic mixtures by supercritical carbon dioxide

The solubility of cholesterol in supercritical carbon dioxide was determined by a continuous flow method. The solubility of cholesterol increased with increasing pressure and exhibited retrograde behavior. The Chrastil equation was used to describe the relationship between solubility and the density of carbon dioxide. A model mixture was made by adding cholesterol and fatty acid esters together. Squid visceral oil was esterified as the feed material. Both the model mixture and esterified squid visceral oil were extracted by supercritical carbon dioxide. The experimental results showed that cholesterol could be removed from a model mixture and from esterified squid visceral oil at low pressure (1500 psig) and high temperature (328.2°K). Under these conditions, cholesterol content in the extract was reduced from 2867 mg/100 g to 14.1 mg/100 g.     

A bulky phosphite-modified rhodium catalyst for the hydroformylation of unsaturated fatty acid esters

A series of hydroformylation experiments was performed with a high-grade and a technical-grade-derived methyl oleate (MO) and a rhodium catalyst modified by the bulky tris(2-tert-butyl-4-methylphenyl)phosphite. In the hydroformylation of pure methyl oleate, relatively high turnover numbers were obtained (400–500 mol/mol/h) under mild conditions (molar ratio MO/Rh=910, 80–100°C and 20 bar; CO/H₂=1:1, solvent toluene), leading to about 95% conversion in 3 h. Fast isomerization occurs under these conditions to produce the trans oleate. Trans oleate reacts more slowly than cis oleate. At temperatures below 50°C, isomerization does not occur. The use of technical-grade methyl oleate, containing 14% 9,12 diene, methyl linoleate (ML), results in lower reaction rates because dienes form stable π-allylic intermediates, which slowly undergo hydroformylation. More severe conditions were applied to obtain higher rates. The rate varied from 50 to 400 mol/mol/h, depending on conditions (molar ratio MO/Rh=910, T=50–120°C, P = 50–80 bar; CO/H₂=1:1–1:6, solvent, toluene). Several isomers of ML were formed during the reaction. Subsequent hydroformylation of these isomers results in a complicated mixture of products. The product mixture consists predominantly of methyl formylstearate, methyl formyloleate, methyl diformylstearate, and some yet unidentified side products. A comparison of the classic triphenylphosphine-modified catalyst and the bulky phosphite-modified catalyst has shown that the latter is several times more active.     

Preparation of fatty acid methyl esters for gas-chromatographic analysis of lipids in biological materials

Theoretically, preparation of fatty acid methyl esters (FAMEs) deals with reversible chemical reactions in a complex system. Methodologically, there are numerous ways, generally characterized by the type of catalysts used and steps involved. Although there are more than a half dozen common catalysts, the majority fall into either acidic (HCl, H₂SO₄ and BF₃) or alkaline types (NaOCH₃, KOH and NaOH), with each having its own catalytic capability and application limitations. In terms of steps, many conventional methods, including those officially recognized, consist of drying, digestion, extraction, purification, alkaline hydrolysis, transmethylation/methylation and postreaction work-up. Although these methods are capable of providing reliable estimates if some precautions are taken, they are cumbersome, time-consuming and cost-inefficient. A new approach has been to transmethylate lipidsin situ. Due to its simplicity, high sensitivity, comparable reliability and capability to determine total fatty acids, the method of direct transmethylation is finding a unique place in lipid determination. Regardless of which method is used, quantitative methylation requires chemists to take precautions at every step involved, particularly during FAME formation and subsequent recovery steps. Evidently, there is an urgent need for more systematic studies, guided by the chemical principle of reactions involved and physicochemical properties of regents and end products, into factors affecting these steps. Hopefully, this will lead to an improved method, which measures lipid composition in biological materials not only with high accuracy but also with high efficiency and minimum costs.     

聚甘油脂肪酸酯的表面性能研究

利用甘油聚合得到聚甘油,与一系列高级脂肪酸酯化合成聚甘油脂肪酸酯。分别测试和比较了合成产品的HLB值、表面张力、乳化性能、泡沫性能及钙皂分散性能,并讨论了合成影响因素,为研究聚甘油酯类产品应用性能提供了理论基础。     

Effects of epoxidation on the thermal oxidative stabilities of fatty acid esters derived from palm olein

A variety of esters from the reactions of monoalcohols with palm olein were prepared, epoxidized byin situ peroxyacid techniques, and some of their physical properties were compared. The thermal oxidative stabilities of these esters andbis(2-ethylhexyl) phthalate were studied. The esters were placed in an oven maintained at 120°C, and the loss of mass and acid, iodine, percent oxirane, hydroxyl, and peroxide values were monitored periodically. The epoxidized esters had higher densities and lower volatilities, and were more resistant toward oxidation than their unepoxidized counterparts. The stability of the oxirane was related to the initial acid value of the sample. Higher initial acid value resulted in a greater decrease in the oxirane content, indicating acid-catalyzed cleavage of the oxirane ring.     

长链脂肪酸淀粉酯合成及应用研究进展

长链脂肪酸淀粉酯是一类具有特殊的热塑性、疏水性、乳化性和可生物降解性的变性淀粉,在食品、纺织、化妆品、医药等行业有着广泛的应用。本文系统地介绍了长链脂肪酸淀粉酯的性质、合成方法和应用领域;分析了各种制备方法的特点,并指出了今后研究方向和发展前景。     

An improved reversed-phase thin-layer chromatography method for separation of fatty acid methyl esters

Resolution of fatty acid methyl esters (FAME) by thin-layer chromatography often is complicated by co-migration of certain acyl-isomers in heterogeneous mixtures. However, a novel reversed-phase thin-layer chromatography method which employs 10% (wt/vol) silver nitrate in a mobile phase containing acetonitrile/1,4-dioxane/acetic acid (80:20:1, vol/vol/vol) allows one-dimensional resolution of a wide range of acyl-methyl esters. This innovation enables improved separation of saturated FAME ranging from C₁₂ to C₂₂, and geometric isomers of C₁₄ to C₂₂ unsaturated FAME by thin-layer chromatography.     

反丁烯二酸酯类物质结构与抑菌性能关系

采用密度泛函理论(DFT)考察反丁烯二酸酯类化合物结构与抑菌活性之间的定量构效关系(QSAR).在B3LYP/6-311++ G(d)基组下对13种反丁烯二酸酯类化合物进行几何构型优化和频率计算,选取最高占据轨道能量E_HOMO、最低空轨道能量E_LUMO及两者的绝对差值DE、偶极矩(μ)、零点能、平均分子极化率(p)等量化参数作为量子化学描述符,通过多元逐步回归分析筛选影响抑菌活性的主要因素并建立化合物量化参数和抑菌活性之间的QSAR模型方程,并用留一法交叉验证模型的稳定性及预测能力。结果表明反丁烯二酸酯类化合物抑制枯草芽孢杆菌性能与其结构参数DE、μ、ZPE之间存在着较高的线性关系,DE和μ越大,抑菌活性越大,相关系数R=0.957,此类化合物抑制枯草芽孢杆菌活性的理论值与实验值的相关性良好,表明该模型能较好的预测此类具有α,β-不饱和羰基母体结构的反丁烯二酸酯类化合物的抑菌活性。     

Integrated synthesis and extraction of short‐chain fatty acid esters by supercritical carbon dioxide

We developed an efficient, integrated reaction‐extraction process for the production of short‐chain fatty acid ethyl esters (FAEE) from milk fat, using carbon dioxide as the only processing solvent. FAEE were synthesized using a short‐chain fatty acid selective lipase. The expansion of the liquid mixture of reactants by dense carbon dioxide enhanced the apparent lipase selectivity. In situ extraction of FAEE by a continuous flow of supercritical carbon dioxide proved to increase the lipase production rate. When the integrated process was operated with alternated periods of synthesis and product removal, the overall selectivity for short‐chain FAEE increased as well, as a result of the combination of the selectivities of lipase and extraction solvent. A two‐fold increase of the lipase productivity was achieved at these conditions, compared to a single batch reaction. The developed process enables the synthesis and isolation of high‐value fatty acid derivatives from a natural source such as milk fat. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

The prediction of fatty acid structure from selected ions in electron impact mass spectra of fatty acid methyl esters

The possibility of fatty acid identification from ions in the mass region of 50–110 amu in electron impact mass spectra has been studied by application of various multivariate techniques. The focus has mainly been on the prediction of the number of double bonds in methylene‐interrupted polyunsaturated fatty acids isolated from marine lipids. The number of double bonds in these fatty acids could be predicted with high accuracy, both by partial least squares regression on all ions in this region, and by multiple linear regressions on selected subsets of 5–6 ions. The subsets with optimal predictive power have been found, and the ability to distinguish between methylene interrupted polyunsaturated fatty acids and other fatty acids have also been evaluated.     

从废弃油脂生物柴油中分离不饱和脂肪酸甲酯

以废弃油脂制生物柴油为原料,以95%醇为溶剂,采用尿素包合法提取不饱和脂肪酸甲酯,为生物柴油联产具有高附加值化工产品打下基础.重点考察了尿素用量、溶剂用量、包合时间和包合温度对不饱和脂肪酸甲酯分离效果的影响.结果表明,尿素包合法从生物柴油中分离不饱和脂肪酸甲酯的适宜工艺条件为:尿素,生物柴油质量比为1.4～1.7,溶剂/生物柴油质量比为4.6～6.0,包合温度为10℃,包合时间为18 h.在适宜条件下,不饱和脂肪酸甲酯含量可达93.5%,收率可达55.8%.