Metathesis of Unsaturated Fatty Esters

The development of a homogeneous catalyst (WCl₆Sn(CH₃)₄) for the metathesis of unsaturated fatty esters encloses new routes in fat chemistry. By these reactions an exchange of alkylidene moities takes place, thus methyl oleate is converted into 9-octadecene and 9-octadecenedioic dimethyl ester. The metathesis of poly-unsaturated esters leads to a much larger number of products, namely polyenes, mono- and dicarboxylic esters, and cyclopolyenes. Specially the formation of 1,4-cyclohexadiene is of great interest. The metathesis of unsaturated fatty oils and the cometathesis with alkenes are also possible. Reactants of technical purity with a low acid value (< 0.1) can undergo metathesis. The reaction is essentially thermoneutral; the distribution of products is statistical and no completion of the reaction occurs in one way or an other. Thus separation of reaction products and unconverted material is necessary. By the metathesis of mono-unsaturated esters this can be done by fractional crystallization. A review is given of these and other applications on account of the latest research development.     

Magnetic Nanoparticle Supported Second Generation Hoveyda–Grubbs Catalyst for Metathesis of Unsaturated Fatty Acid Esters

The Hoveyda–Grubbs catalyst has been successfully immobilized on surface‐modified magnetic nanoparticles with a loading amount of 0.28 mmol ruthenium/g (magnetic support). The supported catalysts were active for the self‐metathesis of methyl oleate and macro‐monomer in a quantitative conversion, respectively. In addition, the catalyst can be easily separated by using a magnet and reused several times with sustained activity.     

Platinum‐Catalysed Hydrosilylation of Unsaturated Fatty Acid Esters

Different Pt(IV), Pt(II) and Pt(0) catalysts were screened for the hydrosilylation of fatty acid esters containing terminal as well as internal double bonds. The reaction of terminally unsaturated fatty acid esters proceeded smoothly with short reaction times for nearly all examined catalysts, whereas Pt(IV) species and Pt(II) or Pt(0) species with labile ligands were sufficiently active in the reaction of internally unsaturated compounds. For methyl linoleate, a conjugation of the two internal double bonds before the hydrosilylation was observed. The reaction was carried out in substance as well as in solvent systems permitting a catalyst recycling and reuse. In these systems, however, hydrogenation and double bond isomerisation were found as side reactions.     

不饱和脂肪酸甲酯环氧化工艺的研究进展

以催化剂体系为主线,综述了近年来化学法和脂肪酶法制备无毒增塑剂环氧脂肪酸甲酯的研究现状。对杂多酸和离子液体等化学催化体系和酶催化体系的优缺点进行了评述;集中讨论了脂肪酶催化法中氧载体、底物物质的量比、H2O2滴加速度、反应温度等因素对不饱和脂肪酸甲酯环氧化过程的影响规律;分析了脂肪酶的固载化技术以及存在的相关问题。指出寻找合适载体固载脂肪酶、提高脂肪酶的活性和稳定性、探寻适宜的环氧化工艺条件、提高脂肪酶的利用率是下一步的开发方向。     

Reaction of Maleic Anhydride with cis-Isolated Unsaturated Fatty Acid Esters

The structures of maleic anhydride adducts of essentially pure oleic, linoleic and linolenic methyl esters have been determined. The cleavage of the methyl oleate adduct yields a product with a succinyl structure, with or without shift of the double bond; four isomeric structures are possible. The first adduct of maleic anhydride with methyl linoleate is a succinyl derivative followed by a shift into the conjugated isomer with which the second maleic anhydride reacts via a 1–4 Diels Alder addition to yield a second adduct having a cyclohexene structure. The first two moles of maleic anhydride add to methyl linolenate to form di-succinyl derivatives followed by a shift into conjugated diene and triene. The third maleic anhydride adds via a 1–4 addition to yield a disuccinyl and one 1–4 adduct. A number of isomers are possible for the linoleate and linolenate adduct.     

不饱和脂肪酸甲酯的绿色催化环氧化研究

选用氧化钼/叔丁基过氧化氢/阴离子离子液体{MoO3/TBHP/[bmimPF6]}(I)和氧化钼/过氧化氢/阴离子离子液体{MoO3/H2O2/[bmimBF4]}(II)两种绿色催化体系,探索了反应时间、反应温度、氧化剂/不饱和双键摩尔比和催化剂/不饱和双键摩尔比4个因素对不饱和脂肪酸甲酯环氧化转化率的影响。研究表明,实验条件下催化体系Ⅰ比催化体系Ⅱ具有更高的活性,MoO3可重复使用3次。     

Thermal Stability of Rapeseed Oil Fortified with Unsaturated Fatty Acid Sterol Esters

The thermal stability of rapeseed oil fortified with 3 % sterol linolenate, sterol linoleate, and sterol oleate was investigated using the Rancimat accelerated oxidation method. The results indicated that the sterol ester content in fortified oil displayed positive correlations (P < 0.05) with total phenols and tocopherols and significant negative correlations (P < 0.05) with acid value (AV), peroxide value (POV), conjugated diene value, \(\varDelta E\) value, viscosity, and polyphenols and γ-tocopherol levels. The sterol ester content in fortified oil was found to significantly decrease when the oil was heated at 110 °C. The rate of increase of the AV, POV, \(\varDelta E\) value, and viscosity, and the rate of decrease of polyunsaturated fatty acid, tocopherol, and polyphenol contents were accelerated with the increase of the degree of unsaturation of fatty acid sterol esters in rapeseed oil during heating. Therefore, the oxidative stability is further reduced by increasing the degree of unsaturation, as the instability of fortified oil is mainly due to the decomposition of unsaturated fatty acid sterol esters. The addition of lipid-soluble polyphenols is an effective method to improve the stability of rapeseed oil fortified with unsaturated fatty acid sterol esters.     

脲包法分离不饱和脂肪酸甲酯的研究

以混合脂肪酸甲酯为原料,采用尿素包合法（脲包法）分离不饱和脂肪酸甲酯。通过正交试验,得到了最佳工艺条件：混合脂肪酸甲酯（w）：尿素（w）：甲醇（v）为1：2．09：8．36,包合温度-10℃,包合时间18h。经过一次包合,不饱和脂肪酸甲酯的含量由原来的47．69％提高到86．74％,收率54．19％。     

A Highly Efficient Olefin Metathesis Process for the Synthesis of Terminal Alkenes from Fatty Acid Esters

Recently, considerable attention has been focused on the use of olefin metathesis to convert oleochemicals into value-added products such as the bifunctional molecule methyl 9-decenoate, but the implementation of this process has been hampered by low ethenolysis efficiencies. We report herein the use of alpha olefins as ethylene surrogates in cross metathesis reactions with methyl oleate and soybean oil fatty acid methyl esters (soy FAME) resulting in considerable increases in catalyst efficiencies in the production of this promising chemical product. Additional gains in efficiency were realized by using a peroxide-scavenging feedstock pretreatment.     

不饱和脂肪酸甲酯加氢Cu-Ni/SiO2催化剂的研究

针对铜镍二元催化剂活性低、难过滤及容易造成金属在加氢产物中残存等问题,开展了用于不饱和脂肪酸甲酯加氢的高活性、易过滤、低金属残存Cu Ni/SiO2催化剂的研究。以特制的、具有固定物性参数的SiO2做载体,是本催化剂的特点。通过控制铜镍比和不陈化解决了金属残存问题,且红外光谱表明,产物不发生异构。催化剂制备方法和条件为:并流沉淀,趁热过滤;铜镍总量与SiO2质量比为4∶1;铜镍质量比为1∶2 5;焙烧温度350℃左右,焙烧时间3h。该催化剂优点为:不需单独还原易于保存,反应速率快,加氢活性高,催化剂用量为甲酯质量的0 5%,1MPa氢压,反应30min条件下,产物碘值可由110降到5以下。     

Hydroxy Sulfonated Fatty Acid Esters as Surface Active Agents II: Surfactants from Individual Saturated and Unsaturated Fatty Acids

Hydroxy sulfonated fatty acid ester surfactants, having the general formula RCOOCH₂CHOHCH₂SO₃M (where M is alkali or other metal) have been synthesized from four saturated (C₁₂ to C₁₈) and four unsaturated (C₁₈?, C₁₈²?, C₁₈³? and ricinoleic) fatty acids. Comparative evaluation of their surface active properties as well as some analytical methods for determining their composition and their identification and separation have been described.     

Formation of Furan Fatty Alkyl Esters from their Bis‐Epoxide Fatty Esters

Reactions of epoxidized alkyl soyate with four different alcohols: ethanol, isopropyl alcohol, 2‐ethylhexanol, benzyl alcohol, in the presence of Brønsted acid catalyst, were investigated. Products, not reported in prior studies of similar reactions, were found. These were furan fatty acid alkyl esters (FFE, mixture of alkyl 8‐(5‐hexyl‐2‐furyl) octanoate and alkyl 9‐(5‐pentyl‐2‐furyl)nonanoate) which were unambiguously identified by means of GC–MS and two‐dimensional NMR. Evidence suggests that the FFE are formed by an acid‐catalyzed rearrangement of the epoxidized linoleates. The FFE were formed in presence of all four alcohols tested and in the presence of either sulfuric acid or Amberlyst 15 catalyst. Yields of up to 13 %, as quantified by GC and NMR spectroscopies, were observed.     

Heats of Combustion of Fatty Acids and Fatty Acid Esters

The military uses JP-8, a kerosene type hydrocarbon, to fuel most of its vehicles and is seeking a renewable alternative fuel that meets strict JP-8 specifications. Biodiesel is typically a mixture of different alkyl esters produced from the transesterification of triglycerides readily available in plant oils and used cooking oil. To date, no traditional biodiesel meets the requirements for heat of combustion, freezing point, viscosity and oxidative stability to be a stand-alone replacement for JP-8. This work is a fundamental survey of the heat of combustion of single fatty acid esters and a predictive model for estimating the heat of combustion given a known molecular structure. The gross heat of combustion of various C6–C18 fatty acids and the methyl, propyl and isopropyl esters of these fatty acids was measured. This study sought to relate the effect of chain length, degree of unsaturation and branching to the critical fuel property of the gross heat of combustion (H _c). It was found that H _c (kJ/g) increased with chain length. A nearly linear relationship was found between wt% carbon and hydrogen, and H _c. Group contribution models previously published for hydrocarbons and polymers were modified to more accurately predict the heat of combustion of the fatty acids and esters. Modification of the molar heat values of carboxylic acid, methyl, and methylene groups improved correlation of the model with the experimental results.     

Crystallization Behavior of Fatty Acid Methyl Esters

Biodiesel from most agricultural feedstocks has flow properties that are prone to startup and operability problems during cold weather. Biodiesel from soybean oil is generally a mixture of long-chain fatty acid alkyl esters composed of 0.15–0.20 mass fraction saturated esters (melting point [MP] ≫ 0 °C) mixed with unsaturated esters (MP < 0 °C). This work investigates the crystallization properties of two saturated fatty acid methyl esters (FAME) commonly found in biodiesel from soybean oil. Differential scanning calorimetry (DSC) heating and cooling scans of methyl palmitate (MeC16), methyl stearate (MeC18) and methyl oleate (MeC18:1) in pure form were analyzed. Crystallization behavior in ternary FAME mixtures was inferred by the application of thermodynamic models based on ideal solution and freezing-point depression theories. Activity coefficients for MeC16 and MeC18 in MeC18:1 solvent were determined by analyzing DSC cooling curves for binary FAME mixtures. Eutectic points were predicted by both models. Crystallization onset temperatures inferred from freezing point depression theory were more accurate than those for ideal solutions with respect to a direct DSC cooling curve analysis of corresponding ternary mixtures. This work shows that the crystallization onset temperature (cloud point) of biodiesel may be predicted by freezing-point depression theory if the activity coefficients of the component FAME are known. The use of trade, firm, or corporation names in this publication is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by USDA or ARS of any product or service to the exclusion of others that may be suitable.     

Indirect Method for Simultaneous Determinations of 3-Chloro-1,2-Propanediol Fatty Acid Esters and Glycidyl Fatty Acid Esters

Recent concerns about potential health risks associated with 3-chloro-1,2-propanediol fatty acid esters (3-MCPD esters) and glycidyl fatty acid esters (GEs) in refined vegetable oils and fats have led to development of various methods for quantitative determinations of these compounds. Among them, indirect methods, which determine total amount of 3-MCPD and glycidol after hydrolysis of the esters, have an advantage over direct methods, which require a reference standard for each of the many possible species of fatty acid esters to be quantified. The existing indirect methods, however, may yield unreliable results or require long hours of alkaline methanolysis. To overcome these shortcomings, the objective of this study was to develop a reliable and rapid indirect method for simultaneous determinations of 3-MCPD esters and GEs. By using Candida rugosa lipase and sodium bromide for a hydrolysis/bromination step, 3-MCPD esters and GEs were transformed within 30 min to 3-MCPD and 3-bromo-1,2-propanediol (3-MBPD), respectively, without interconversion. Gas chromatography–mass spectrometry (GC–MS) analysis of 3-MCPD and 3-MBPD derivatized with phenylboronic acid showed 89–108 % recovery of 3-MCPD-diesters, -monoesters, and GEs from various oils and fats spiked at 2 and 20 mg/kg. The method should be useful for routine analysis of 3-MCPD esters and GEs.     

Lewis Acid Induced Additions to Unsaturated Fatty Compounds III: Alkylaluminium Halide Induced Friedel-Crafts Acylations of Unsaturated Fatty Compounds

Alkylaluminium halide induced Friedel-Crafts acylations of unsaturated fatty compounds with acyl chlorides give the corresponding β,γ-unsaturated ketones. Acylation of oleic acid and 10-undecenoic acid with acetyl chloride yields (E)-9(10)-acetyloctadec-10(8)-enoic acid and 12-oxo-tridec-9-enoic acid, respectively. Acylation of 10-undecenoic acid with heptanoyl chloride followed by NaBH₄-reduction gives ricinelaidic acid. The very interesting β,γ-unsaturated ketodicarboxylic acid (E)-9(10)-(1-oxo-3-carboxy-propyl)octadec-10(8)-enoic acid is obtained by acylation of oleic acid with succinic anhydride.     

Unsaturated Fatty Acids as Synergists for Antioxidants

Both the double bond and the carboxyl group are found necessary for the marked synergism exhibited by oleic acid for phenolic antioxidants in vegetable fats. Compounds in which either function is blocked are ineffective as synergists. After considering various possibilities for the mechanism of the reaction, it is proposed that oleic acid hydroperoxides supply hydrogen atoms to the oxidised antioxidant, thus regenerating it.     

Transition-metal Catalyzed Oxidative Cleavage of Unsaturated Fatty Acids

The oxidative cleavage of the C? C-bond converts unsaturated fatty acids to carboxylic and dicarboxylic acids. The only method currently used in oleochemistry is ozonolysis. The high energy consumption of ozonolysis makes a transition-metal catalyzed alternative with a cheaper secondary oxidant attractive. Here we report new methods for ruthenium-, rhenium- and tungsten-catalyzed oxidations with peracetic acid and hydrogen peroxide. Whereas the direct oxidative cleavage of internal C? C-bonds still lacks selectivity, two-step reactions are feasible. The first possibility is to convert natural, internal unsaturated fatty acids to ω-unsaturated ones. These ω-unsaturated fatty acids can be cleaved by Ru/acac)₃/CH₃COOOH or Re₂O₇/H₂O₂ with yields up to 80 %. In the second two-step procedure the fatty acid first is hydroxylated and the diol is cleaved: the overall yield for this method is 80 %, too.