Identification of α-parinaric acid in the seed oil ofSebastiana brasiliensis sprengel (Euphorbiaceae)

Besides some usual fatty acids, the seed oil ofSabastiana brasiliensis (Euphorbiaceae) contains up to 39% (estimated by ultraviolet spectroscopy) of α-parinaric acid (cis, trans, trans, cis-9, 11, 13, 15-octadecatetraenoic acid). The fatty acids were analyzed by gas chromatography and gas chromatography/mass spectrometry as their methyl esters. The structure of α-parinaric acid was proven by a combination of chemical and spectroscopic methods, conducted with the crude oil, the methyl ester mixture, and the isolated fatty acid methyl ester. Complete assignment of the¹H and¹³C nuclear magnetic resonance (NMR) shifts of α-parinaric acid was carried out by two-dimensional NMR experiments Presented in part at the 21st world Congress and Exhibition of the International Society for Fat Research (ISF), October 1–6, 1995, The Hague, The Netherlands.     

Preparation of malvalic and sterculic acid methyl esters from Bombax munguba and Sterculia foetida seed oils

A method has been developed for the preparation of highly pure malvalic (cis-8,9-methyleneheptadec-8-enoic) and sterculic (cis-9,10-methyleneoctadec-9-enoic) acid methyl esters starting from Bombax munguba and Sterculia foetida seed oils. The methyl esters of these oils were prepared by sodium methylate-catalyzed transmethylation followed by cooling (6°C) the hexane solution of crude methyl esters and separation of insoluble fatty acid methyl esters by centrifugation in the case of B. munguba and by column chromatography in the case of S. foetida. Subsequently, the saturated straight-chain fatty acid methyl esters were almost quantitatively removed by urea adduct formation. Finally, methyl malvalate and methyl sterculate were separated from the remaining unsaturated fatty acid methyl esters, in particular methyl oleate and methyl linoleate, by preparative high-performance liquid chromatography on C₁₈ reversed-phase using acetonitrile isocratically. Methyl malvalate and methyl sterculate were obtained with purities of 95–97 and 95–98%, respectively.     

尿素包合法分离棕榈油甲酯化产物中C_(16)和C_(18)脂肪酸甲酯

采用尿素包合法分离棕榈油甲酯化物中不同碳链长度的脂肪酸甲酯,为农产品涂膜保鲜材料的开发提供原料。重点考察了尿素用量、溶剂用量、包合时间和包合温度对分离效果的影响,并以尿素用量、95%乙醇用量、包合温度为三因素,C16脂肪酸甲酯和C18脂肪酸甲酯的纯度为二指标,根据Box-Benhnken中心组合试验设计原理,利用Designexpert7.0.1软件分析优化了分离的工艺条件并建立了回归模型。优化的最佳工艺条件如下:在棕榈油甲酯化物用量为20g,尿素用量为35g,95%乙醇用量为120mL,包合温度为5℃,包合时间为16h的条件下,饱和脂肪酸甲酯相中C16脂肪酸甲酯的含量达78.5%,不饱和脂肪酸甲酯相中C18脂肪酸甲酯的含量达93.1%,分别比原料提高36.4%和40.8%。     

Performance and physicochemical properties of α-sulfo fatty acid methyl esters

The detergency properties of α-sulfonated fatty acid methyl esters (α-SFMe) were evaluated and compared to those of conventional anionic surfactants by using a model heavy-duty detergent formulation. Several physicochemical properties of surfactants were measured to investigate the effective factors on detergency. α-SFMe showed good detergency performance under various washing conditions. These results were considered to correlate well with the good adsorption behavior on oils and dispersing capabilities for particles, as well as with the good solubilization capacity. Solubilization behavior of α-SFMe is discussed in relation to micelle properties. It is suggested that α-SFMe can form suitable micelles for solubilizing polar oils advantageously, due to its bulky hydrophilic group.     

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.     

Lipase-catalyzed synthesis of lesquerolic acid wax and diol esters and their properties

Lesquerolic acid was and α,Ω-diol esters were synthesized via immobilizedRhizomucor miehei lipase-(Lipozyme) catalyzed esterification of lesquerolic acid and alcoholysis of lesquerella oil. For each wax ester synthesis, when alcohol substrate was present at a slight (ca. 20%) stoichiometric excess and water content was kept low, over 94% of the hydroxy acyl groups were esterified. The extent of reaction and the ratio of monoester to diester produced for α,Ω-diol reactions was controlled by the solubility of diol in the medium. This latter quantity increased as alcoholysis proceeded due to the formation of partial glycerides and monoesters, which increased the polarity of the medium. Alcoholysis reactions were significantly slower when the medium diol content was above saturation. As the diol chainlength increased, diol solubilization decreased, the ratio of monoester to diester decreased, and the extent of hydrolysis increased. Alcoholysis reactions involving either fatty alcohols or diols suffered from acyl migration, which lowered the purity of lesquerolic acid esters. Several lesquerolic acid esters, synthesized on a preparative scale and purified via column chromatography, were evaluated for their properties: density, viscosity, and melting point. Potential applications for lesquerolic acid esters are discussed.     

α-Sulfonated fatty acid esters: I. Structural effects of sodium α-sulfonated fatty acid higher alcohol esters on surface-active properties and emulsification ability

The surface-active properties and emulsification ability of sodium α-sulfonated fatty acid esters, C_mH_2m+1CH-(SO₃Na)COOC_nH_2n+1, were studied as a function of the hydrophobic alkyl chainlength in the fatty acid (m=8−16) and the alcohol (n=8−18). As a result, it was discovered that sodium α-sulfonated fatty acid esters have a structural effect on the Krafft point different from that of amphiphiles with short alkyl chains. Moreover, some of the α-sulfonated fatty acid esters have quite low interfacial tensions, as well as non-foaming properties, which depend upon the total (m+n) number of carbon atoms in the alkyl chains.     

Structural Analyses of Hydrated Crystals in Mixed Green Surfactant Systems: α‐Sulfonated Fatty Acid Methyl Ester Salt and Fatty Acid Soap Mixtures

α‐Sulfonated fatty acid methyl ester salts (MES), synthesized from renewable plant resources, are an example of green surfactants used in eco‐friendly washing detergents because of their excellent detergent properties, biodegradability, and enzyme stability. Although various physicochemical properties of MES crystals and micelles have been studied, mixed systems composed of MES and other surfactants have not been well studied. We investigated the crystalline structures of hydrated solids in mixed systems containing MES and soaps, which have been utilized as detergents, using small‐ and wide‐angle X‐ray scattering (SWAXS), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy techniques. The minimum dissolution temperature, determined by visual observation, of a 4:1 M ratio of the sodium salt of α‐sulfonated palmitic acid methyl ester (C₁₆MES‐Na) and sodium palmitate (C₁₆‐Na), is indicative of a eutectic mixture. SWAXS measurements reveal that C₁₆MES‐Na and C₁₆‐Na crystals are formed separately in this system. Eutectic mixtures were also observed for the C₁₆MES‐Na/C₁₆MES‐K (α‐sulfonated palmitic acid methyl ester potassium salt) system and in the C₁₆MES‐K/C₁₆‐Na system. Furthermore, in addition to C₁₆MES‐K and C₁₆‐Na crystals, C₁₆MES‐Na crystals were also formed in the C₁₆MES‐K/C₁₆‐Na system, through counterion exchange during crystallization.     

Determination of the identity of by-products in the industrial production of saturated fatty acids

A technical product of saturated fatty acids has been analyzed to determine the structure of by-products found in the C_20–22 fatty acids manufactured from fish oil. Short-path distillation of the weakly colored product provided a residue, which was extracted either by supercritical carbon dioxide or by acetone. Extracts and residues were analyzed by size-exclusion chromatography, supercritical fluid chromatography, and by gas chromatography, the latter combined with mass spectrometry and Fourier-transform infrared spectroscopy, and by nuclear magnetic resonance spectrometry. A series of homologs of fatty acid dimers was identified as lactone esters. Each homolog also contained several isomers with a varying number of carbon atoms in the two hydrocarbon chains of the dimers. Trimers, containing yellow components, were also present in small amounts, but the structure of the trimers has not been determined yet.     

Sugar fatty acid ester surfactants: Structure and ultimate aerobic biodegradability

Ultimate aerobic biodegradabilities of an array of sugar ester surfactants were determined by International Standards Organisation method 7827, “Water Quality—Evaluation in an Aqueous Medium of the Aerobic Biodegradability of Organic Compounds, Method by Dissolved Organic Carbon” (1984). The surfactants were nonionic sugar esters with different-sized sugar head groups (formed from glucose, sucrose, or raffinose) and different lengths and numbers of alkyl chains [formed from lauric (C₁₂) or palmitic (C₁₆) acid]. Analogous anionic sugar ester surfactants, formed by attaching an α-sulfonyl group adjacent to the ester bond, and sugar esters with α-alkyl substituents were also studied. It was found that variations in sugar head group size or in alkyl chain length and number do not significantly affect biodegradability. In contrast, the biodegradation rate of sugar esters with α-sulfonyl or α-alkyl groups, although sufficient for them to be classified as readily biodegradable, was dramatically reduced compared to that of the unsubstituted sugar esters. An understanding of the relationship between structure and biodegradability provided by the results of this study will aid the targeted design of readily biodegradable sugar ester surfactants for use in consumer products.     

Characterization of triglycerides isolated from jojoba oil

Triglyceride compounds isolated from jojoba seed oil by column chromatography were composed predominantly of C_18′ C_20′ C_22′ and C₂₄ n−9 fatty acids with minor amounts of saturated C₁₆. Chain length and double-bond positions were determined by gas-liquid chromatography and gas-liquid chromatography-mass spectrometry of the corresponding methyl ester and picolinyl ester derivatives. Triglyceride structures were analyzed directly by ion trap mass spectrometry. The analysis of minor compounds, can provide highly specific information about the identity of an oil.     

脂肪酸甲酯磺酸钠盐的纯化

二步溶剂结晶法纯化了脂肪酸甲酯磺酸钠盐表面活性剂。将每10 gα-磺酸脂肪酸甲酯工业品用NaOH的无水乙醇溶液中和至pH=7.0,再加入无水乙醇定容至80 mL,60℃过滤,得到的滤液加无水乙醇定容至80 mL,在10℃结晶2 h,所得晶体中α-磺酸脂肪酸甲酯钠盐、α-磺酸脂肪酸二钠盐和脂肪酸钠皂的质量分数分别由74.38%、16.30%和8.83%改善为94.74%、1.12%和4.01%。同时,黑色的脂肪酸甲酯磺酸钠盐工业品纯化为浅黄色的晶体,收率为48.03%。纯化前后脂肪酸甲酯磺酸钠盐在30℃时的临界胶束浓度由6.47×10-3mol/L降低到6.68×10-4mol/L,c20由2.14×10-4mol/L降低到9.48×10-5mol/L。     

环氧脂肪酸甲酯合成的研究进展

介绍以不饱和脂肪酸甲酯为原料,在不同给氧体作用下经环氧化,合成新型环保增塑剂—环氧脂肪酸甲酯的方法.评价了不同给氧体与催化体系对不饱和脂肪酸甲酯环氧化过程和产品性能的影响,并对催化环氧化法制备环氧脂肪酸甲酯进行了展望.     

Direct ethoxylation of fatty methyl ester over Al-Mg composite oxide catalyst

For the purpose of estimating the reaction mechanism of the direct ethoxylation of a fatty ester in the presence of an Al-Mg composite oxide catalyst, a labeled fatty methyl ester C₁₁H₂₃CO¹⁸OCH₃ containing ¹⁸O isotope was synthesized and directly ethoxylated. The product was evaluated by gas chromatography-mass spectrometry (GC-MS). The GC-MS spectra showed that the ¹⁸O isotope label was present only in the methoxy group at the molecular end of the ethoxylated fatty methyl ester. This supports the reaction mechanism of coordination anionic polymerization where the bond between the acyl and methoxy groups of the fatty methyl ester molecule was broken, caused by the bifunctional effect of the acid-base active sites; an intermediate chemisorption species was formed; and then ethylene oxide was addition-polymerized sequentially, in parallel.     

Methyl ester ethoxylates

Conventional ethoxylation of fatty methyl esters, or other fatty-fatty esters or diesters, produces poor yields of the desired ethoxylated ester. A proprietary ethoxylation catalyst, currently in use to produce “peaked” or “narrow-range” alcohol ethoxylates, has been found to successfully insert ethylene oxide into the ester linkage of fatty esters. The mechanism for this insertion likely involves an ethoxylation-transesterification step in the ethoxylation process. Physical, performance, and environmental/human safety properties were evaluated. Results, in general, show that methyl ester ethoxylates behave similarly to alcohol ethoxylates with the exception of having a lower foam profile and being less irritating. Presented at the Annual Meeting of the American Oil Chemists’ Society, Indianapolis, Indiana.     

脂肪酸甲酯磺酸盐制备和分析方法的研究进展

介绍了SO3磺化法和磺氧化法两种制备脂肪酸甲酯磺酸盐(MES)的方法,重点介绍了MES产品中形成深色杂质的原因及MES主要成分的基本分析方法,如薄层色谱、毛细管电泳、色质联用、容量分析等;同时从原料、反应设备、反应过程、成色机理等方面阐述了几种不同的抑制MES产品中形成深色杂质的方法,并对MES的发展前景进行了展望.     

Additive effects of acyl-binding site mutations on the fatty acid selectivity of Rhizopus delemar lipase

The fatty acid specificity and pH dependence of triacylglycerol hydrolysis by the Rhizopus delemar lipase acylbinding site mutant Val206Thr+Phe95Asp (Val, valine; Thr, threonine; Phe, phenylalanine; Asp, aspartic acid) were characterized. The activity of the double mutant prolipase was reduced by as much as 10-fold, compared to the wild-type prolipase. However, the fatty acid specificity profile of the enzyme was markedly sharpened and was dependent on the pH of the substrate emulsion. At neutral pH, strong preference (10-fold or greater) for hydrolysis of triacylglycerols of medium-chainlength fatty acids (C_8:0 to C_14:0) was displayed by the variant prolipase, with no hydrolysis of triacylglycerols of short-chain fatty acids (C_4:0 to C_6:0) and little activity manifested toward fatty acids with 16 or more carbons. At acidic pH values, the fatty acid selectivity profile of the double mutant prolipase expanded to include short-chain triacylglycerols (C_4:0, C_6:0). When assayed against a triacylglycerol mixture of tributyrin, tricaprylin and triolein, the Val206Thr+Phe95Asp prolipase displayed a high selectivity for caprylic acid and released this fatty acid at least 25-fold more efficiently than the others present in the substrate mixture. When presented a mixture of nine fatty acid methyl esters, the wild-type prolipase showed a broad substrate specificity profile, hydrolyzing the various methyl esters to a similar extent. Contrastingly, the double mutant prolipase displayed a narrowed substrate specificity profile, hydrolyzing caprylic methyl ester at nearly wild-type levels, while its activity against the other methyl esters examined was 2.5- to 5-fold lower then that observed for the wild-type enzyme.     

Producing Fatty Acid Methyl Esters from Free Fatty Acids with Ionic Liquids as Catalyst

Three Brønsted acidic imidazole dicationic ionic liquids (ILs) with different length of alkyl chains, [C_n(Mim)₂][HSO₄]₂ (n = 3, 6, 12), were prepared and used as catalyst for the esterification reaction of free fatty acids and methanol. Taking oleic acid as model acid, the catalytic performances of the synthesized ILs for the esterification were evaluated. The main physicochemical properties of the ILs, thermal stability, acidity, solubility in common solvents, and causticity on Austenitic stainless steel 316, were examined. [C₃(Mim)₂][HSO₄]₂ demonstrated the highest catalytic activity and enabled to assess the preliminary optimum esterification condition of oleic acid and methanol. Under optimized reaction conditions, the yield of oleic acid methyl ester was up to 95 %. The ILs have great potential as catalysts for producing fatty acid methyl esters from long‐chain free fatty acids.     

θ3 fatty acids in freshwater fish from south brazil

Lipid and fatty acid levels in the edible flesh of 17 freshwater fish from Brazil’s southern region were determined. Analyses of fatty acid methyl esters were performed by gas chromatography. Palmitic acid (C_16:0) was the predominant saturated fatty acid, accounting for 50–70% of total saturated acids. Oleic acid (C_18:1θ9) was the most abundant monounsaturated fatty acid. Linoleic acid (C_18:2θ6), linolenic acid (C_18:3θ3), and docosahexaenoic acid (C_22:6θ3) were the predominant polyunsaturated fatty acids (PUFA). The data revealed that species such as truta, barbado, and corvina were good sources of eicosapentaenoic acid (C_20:5θ3) and docosahexaenoic acid (C_22:6θ3), and that most freshwater fish examined were good sources of PUFA θ3.     

How is chemical interesterification initiated: Nucleophilic substitution or α-proton abstraction?

Esters of carboxylic acids including 2-methylhexanoic, 2-methylbutyric, 2,2-dimethyl-4-pentenoic, palmitic, and oleic acids were tested as substrates in methoxide-catalyzed interesterification and transesterification. The aliphatic acid esters participated in the ester-ester interchange upon addition of catalytic sodium methoxide. Their isopropyl esters also produced methyl esters on heating with sodium methoxide. The esters of α-methyl-substituted acids did not participate in the ester-ester interchange. Their isopropyl esters did not react with methoxide to produce methyl esters. However, upon addition of methanol with sodium methoxide, their methyl esters were produced. These results indicate that the first step in interesterification is possibly that methoxide abstracts the α-hydrogen of an ester to form a carbanion. Interesterification is then likely completed via a Claisen condensation mechanism involving the β-keto ester anion as the active intermediate. The β-keto ester anion contains positively charged ketone and acyl carbons that are active sites for nucleophilic attack by anions such as methoxide and glycerinate, which would produce a methyl ester or rearrange acyls randomly. On the other hand, transesterification is a nucleophilic substitution by methoxide at the acyl carbon in the presence of methanol.