Conversion of methyl ricinoleate to methyl 12-ketostearate with Raney nickel

A convenient laboratory preparation of methyl 12-ketostearate is described. Methyl ricinoleate is converted to methyl 12-ketostearate in 70–75% yield by Raney nickel. The type and quantity of Raney nickel have a marked influence on the yield as well as on the time and temp required for the conversion. The reaction is not a direct isomerization as previously assumed but appears to be a two-step process. Methyl ricinoleate is hydrogenated rapidly to methyl 12-hydroxystearate which is then dehydrogenated slowly to the product. Hydrogenolysis of the alcohol function is a competing reaction which is minimized by the proper choice of reaction conditions. A laboratory of the W. Utiliz. Res. & Dev. Div., ARS, USDA.     

蓖麻油酸甲酯合成和高温裂解反应条件优化

先用蓖麻油和甲醇酯交换合成蓖麻油酸甲酯,再对蓖麻油酸甲酯进行高温裂解制备十一碳烯酸,探讨各种因素对蓖麻油酸甲酯合成和裂解的影响,得到较为适宜的反应条件。合成蓖麻油酸甲酯适宜的条件为:系统真空度0.095 MPa,反应时间4 h,甲醇钠催化剂质量为蓖麻油质量的3.00%,反应温度35 ℃,醇油物质的量比18∶1,该条件下,蓖麻油酸甲酯收率为86.4%;550 ℃裂解蓖麻油酸甲酯为最佳温度,十一碳烯酸收率为44.15%。     

Ultrasound in lipid chemistry,cyclopropanation of unsaturated fatty esters and triglycerides

Concomitant ultrasonic irradiation during the Simmons-Smith reaction facilitated the cyclopropanation of ethylenic fatty esters and triglycerides. Methyl ricinoleate furnished predominantly the corresponding hydroxy cyclopropanoid ester when the reaction was carried out at 85–95 C under ultrasound in the presence of zinc, while a C₁₈ furanoid fatty ester gave a novel tricyclo derivative (methyl 9,12-epoxy-9,10;11,12-dimethanooctadecanoate).     

Organoselenium-mediated cyclization of hydroxyolefinic fatty acids and m-CPBA oxidation of selenium-containing 1,4-epoxy acids

Chlorophenylselenenylation methodology is shown to cause cyclization of naturally occurring β- and γ-hydroxyolefinic acids. The phenylseleno-substituted 1,4-epoxides (tetrahydrofurans) thus obtained are oxidized by m-chloroperbenzoic acid (m-CPBA). Reaction of phenylselenenyl chloride with methyl 12-hydroxyoctadec-cis-9-enoate (methyl ricinoleate) gave methyl 9,12-epoxy-10-phenylselenenyloctadecanoate in useful yields. A similar reaction of phenylselenenyl chloride with methyl 9-hydroxyoctadec-cis-12-enoate afforded a quantitative yield of methyl 9,12-epoxy-13-phenylselenenyloctadecanoate. Oxidation of selenium-containing 1,4-epoxy esters by m-chloroperbenzoic acid (1 equivalent) yielded the respective olefinic 1,4-epoxy esters, while 5 equivalent m-CPBA afforded the corresponding oxirane esters of epoxytetrahydrofurans in high yields. The structure of the individual reaction products have been established from analytical and spectral data and corroborated by a study of their mass spectra.     

Preparation of Sebacic Acid via Alkali Fusion of Castor Oil and its Several Derivatives

Castor oil and its three derivatives including methyl ricinoleate, sodium ricinoleate and ricinoleic acid were used as the raw material for alkali fusion to prepare sebacic acid. The reaction parameters including catalyst, ratio of oleochemicals/NaOH, reaction time and reaction temperature were optimized. It was found that Pb₃O₄ (1%) showed the best catalytic performance, and 553 K was considered as the most suitable reaction temperature. The oleochemicals/NaOH ratios of 15:14, 15:14, 15:12 and 15:14 were determined as the optimal ratio for alkali fusion of castor oil, methyl ricinoleate, sodium ricinoleate and ricinoleic acid, respectively. In addition, the optimal reaction time of alkali fusion of castor oil was 5 hours, and that of its derivatives was 3 hours. The maximum yield in sebacic acid of 68.8%, 77.7%, 80.1%, 78.6% can be obtained by using castor oil, methyl ricinoleate, sodium ricinoleate and ricinoleic acid as the raw material, respectively. High purity of sebacic acid was confirmed by GC and melting point analysis. ICP-OES results illustrated that the content of Pb in sebcic acid was less than 1 mg kg⁻¹. Separating glycerol from castor oil was beneficial for alkali fusion, by which, the yield of sebacic acid was increased of approximately 10%, and the reaction time was reduced from 5 to 3 hours. This study provided guiding significance for the future industrial production of sebacic acid.     

Saturated keto esters from lesquerolic,dimorphecolic, and densipolic acids

Summary The naturally occurring, unsaturated, hydroxy fatty esters, methyl lesquerolate (methyl 14-hydroxy-cis-11-eicosenoate), methyl dimorphecolate (methyl 9-hydroxy-trans, trans-10,12-octadecadienoate), and methyl densipolate (methyl 12-hydroxy-cis,cis-9,15-octadecadienoate) have been converted to the corresponding saturated keto esters by tow routes. The unsaturated esters were subjected to a hydrogenation-dehydrogenation reaction in the presence of Raney nickel or their saturated derivatives were dehydrogenated by copper chromite catalysis. Yields of the keto esters are 65–82% in the nickel-catalyzed reactions, and 71–94% by copper chromite-catalyzed dehydrogenation. In the hydrogenation-dehydrogenation system the order of reactivity is: methyl lesquerolate>methyl dimorphecolate>methyl densipolate. Relationships between structure and reactivity of these compounds, methyl 12-hydroxystearate, and methyl ricinoleate are discussed. W. Utiliz. Res. Dev. Div., ARS, USDA.     

Preparation and properties ofgem-dichlorocyclopropane derivatives of long-chain fatty esters

Methyl oleate (18∶1) and linoleate (18∶2) were readily transformed to the correspondinggem-dichlorocyclopropane derivatives in high yield, using triethylbenzylammonium chloride as the phase-transfer catalyst in the presence of aqueous NaOH and CHCl₃. Reaction of dichlorocarbene with methyl 12-hydroxystearate furnished methyl 12-chlorostearate (49%) and 12-O-formylstearate (19%). The hydroxy group in methyl ricinoleate was protected (O-tetrahydropyran-2′-yl) prior to dichlorocyclopropanation of the ethylenic bond. Removal of the protecting group allowed the hydroxy group to be converted to a chloride,O-acetyl, azido orO-formyl function. Treatment of methyl ricinoleate with thionyl chloride, followed by the reaction with dichlorocarbene gave the corresponding 12-chloro-dichlorocyclopropane derivative. The dichlorocyclopropane derivative of oleic acid was transformed to a C₁₉ allenic fatty acid when treated witht-butyl lithium. However, the remaining dichlorocyclopropane derivatives, containing an additional functional group in the alkyl chain, failed to yield the corresponding allenic derivatives. All derivatives were characterized by a combination of spectroscopic and chromatographic techniques, including infrared,¹H nuclear magnetic resonance (NMR), and¹³C NMR spectroscopy.     

Carotenoids from red palm methyl esters by nanofiltration

Palm oil contains high concentrations of carotenoids and tocopherols that can be recovered by first converting them to methyl esters and then applying membrane technology to separate the carotenoids from the methyl esters. Several solvent-stable nanofiltration membranes were investigated for this application. Flux with a model red palm methyl ester solution ranged from 0.5 to 10 Lm⁻²h⁻¹, and rejection of β-carotene was 60–80% at a transmembrane pressure of 2.76 MPa and 40°C. A multistage membrane process was designed for continuous production of palm carotene concentrate and decolorized methyl esters. With a feed rate of 10 tons per hour of red palm methyl esters containing 0.5 gL⁻¹ β-carotene, the process could produce 3611 L·h⁻¹ of carotene concentrate containing 1.19 gL⁻¹ carotene and 7500 Lh⁻¹ of decolorized methyl esters containing less than 0.1 gL⁻¹ β-carotene. The economics of this process is promising.     

Formation and growth of dispersed carbon particles during pyrolysis of ethylene,benzene, and naphthalene in a reflected shock wave

The formation and growth rates of dispersed carbon particles were determined experimentally for pyrolysis of ethylene, benzene, and naphthalene in a reflected shock wave at temperatures of 1920–2560 K and hydrocarbon concentrations in argon of 1.8–20%. The diameter of the particles formed was estimated (30–600 Å). The maximum rate of particle formation at various temperatures [(0.7–96) · 10¹⁶ cm⁻³·sec⁻¹] and the particle growth rate (0.002–0.036 cm · sec⁻¹) were determined from results of measurements of reaction (residence) times. For pyrolysis of benzene, the activation energy of the overall process of particle formation is 410 kJ/mole, and for all hydrocarbons studied, the activation energy of the overall process of particle growth is 5–50 kJ/mole. The surface average particle diameter increases with increasing concentration of the initial hydrocarbon at a constant temperature. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 4, pp. 82–89, July–August, 2007.     

Dimer acid esters by simultaneous dehydration and polymerization of technical methyl ricinoleate

Filtrol 13 may be used to dehydrate methyl ricinoleate with simultaneous dimerization and polymerization of the linoleate esters formed. Hydrolysis of the ester group is avoided by the use of xylene as an azeotroping solvent and the preferred method of reaction is the dropwise addition of the ester to a stirred suspension of catalyst in xylene. Products prepared by this technique had a dimer/polymer ratio of about 5 when the yield was 50%. The acid value of the polymer was 7 and of the recovered monomer 3–4.     

蓖麻油酸基聚酯多元醇的合成研究

以可再生资源蓖麻油制备的蓖麻油甲酯、己二酸、乙二醇为原料,钛酸四正丁酯为催化剂,经酯化、缩聚合成蓖麻油酸基聚酯多元醇,考察了反应时间、催化剂、蓖麻油甲酯对聚酯多元醇热稳定性能的影响,采用凝胶色谱(GPC)、红外光谱仪(IR)、示差扫描量热仪(DSC)对蓖麻油酸基聚酯多元醇的相对分子质量、结构、热稳定性进行了系统的表征。实验表明,在醇酸(己二酸∶乙二醇)比为1.15、催化剂质量分数0.04%～0.05%、温度180℃,真空缩聚2h的条件下,制得相对分子质量为2600～3800、分布指数(PDI)为1.89～2.44的不同蓖麻油酸含量的聚酯多元醇,蓖麻油酸基聚酯多元醇的熔点随着蓖麻油酸含量的增加而降低。     

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.     

Hydrolysis of mono- and diepoxyoctadecanoates by alumina

In this study it is shown that the epoxide derivative of oleic acid, methyl 9,10-epoxyoctadecanoate, is readily hydrolyzed to a diol when exposed to a commercial preparation of neutral alumina. Comparison of ¹H and ¹³C NMR spectra of the diol with those of standards showed that the product was the threo isomer. When methyl 9, 10–12,13-diepoxyocta-decanoate was treated with alumina, a mixture of dihydroxy-tetrahydrofuran regioisomers, methyl 9,12-epoxy-10,13-dihydroxystearate and methyl 10,13-epoxy-9,12-dihydroxystearate, was obtained. These results show that alumina is an unsuitable support for epoxidation catalysts. However, alumina-catalyzed hydrolysis of fatty epoxides is an efficient way to synthesize polyhydroxy materials, and these materials are suitable for several industrial applications.     

Kinetics of transesterification of palm-based methyl esters with trimethylolpropane

Kinetics of transesterification of palm-based methyl esters (POME) with trimethylolpropane (TMP) to polyol esters was investigated. A kinetic model of reaction was obtained by assuming a series of irreversible elementary reactions at various temperatures. The reaction rate constants were determined under limited conditions. The optimal ratios for k ₂/k ₁ and k ₃/k ₁ were 0.70–0.80 and 0.21–0.25, respectively. Both palm oil methyl esters (PPOME) and palm-kernel oil methyl esters (PKOME) were reacted with TMP by using sodium methoxide as catalyst. The POME-to-TMP molar ratio and catalyst weight percentage were held constant at 10∶1 and 0.4%, respectively. The effects of temperature (70–110°C) and raw materials (PKOME and PPOME) were investigated and found to have a significant impact on the reaction kinetics. When using a large excess of POME and continual withdrawal of methanol via vacuum, the reaction reached completion in less than 20 min at 80°C. After removal of unreacted POME, the final product contained apprximately 98 wt% triesters.     

Biodiesel production by the transesterification of cottonseed oil by solid acid catalysts

Methyl esters (biodiesel) were produced by the transesterification of cottonseed oil with methanol in the presence of solid acids as heterogeneous catalysts. The solid acids were prepared by mounting H₂SO₄ on TiO₂ · nH₂O and Zr(OH)₄, respectively, followed by calcining at 823K. TiO₂-SO₄ ²⁻ and ZrO₂-SO₄ ²⁻ showed high activity for the transesterification. The yield of methyl esters was over 90% under the conditions of 230°C, methanol/oil mole ratio of 12:1, reaction time 8 h and catalyst amount (catalyst/oil) of 2% (w). The solid acid catalysts showed more better adaptability than solid base catalysts when the oil has high acidity. IR spectral analysis of absorbed pyridine on the samples showed that there were Lewis and Br?nsted acid sites on the catalysts. Translated from The Chinese Journal of Process Engineering, 2006, 6(4): 571–575 [译自: 过程工程学报]     

Production,chemistry, and commercial applications of various chemicals from castor oil

The presence of a hydroxyl group, in addition to an olefinic linkage, in the predominating fatty acid of castor oil gives this vegetable oil many unique and interesting properties. Castor oil consists largely of glycerides of ricinoleic acid or 12-hydroxy octadecenoic acid. The chemical reactions of castor oil, undecylenic acid, 12-hydroxylstearic acid, sebacic acid, and nylon 11, depict the uniqueness of this agricultural oil. By dehydration, castor oil is converted to a conjugated acid oil similar to tung or oiticica oil. The catalytic dehydration results in the formation of a new double bond in the fatty acid chain. The dehydrated castor oil imparts good flexibility, rapid dry, excellent color retention, and water resistance to protective coatings. The pyrolysis of castor oil cleaves the molecule to produce undecylenic acid and heptaldehyde. The pyrolysis of the methyl ester at 450–550 C results in the formation of methyl 10-undecylenate. Hydrolysis of the methyl ester gives 10-undecylenic acid. Hydrogen bromide is added to form 11-bromo undecanoic, which is ammoniated and condensed to form a nylon polymer. When castor oil is added slowly to an 80% caustic solution, the sodium ricinoleate formed splits to form sodium sebacate and capryl alcohol. Sebacic acid is condensed with hexamethylene diamine to form nylon 6,10. The commercial application of castor oil derivatives in urethanes, starch gel modifiers, medium chain triglycerides, and thixotropic additives is reviewed briefly. One of 12 papers presented in the symposium “Novel Uses of Agricultural Oils” at the AOCS Spring Meeting, New Orleans, April 1973.     

Chemoenzymatic epoxidation of unsaturated fatty acid esters and plant oils

In the presence of an immobilized lipase fromCandida antacrtica (Novozym 435^R) fatty acids are converted to peroxy acids by the reaction with hydrogen peroxide. In a similar reaction, fatty acid esters are perhydrolyzed to peroxy acids. Unsaturated fatty acid esters subsequently epoxidize themselves, and in this way epoxidized plant oils can be prepared with good yields (rapeseed oil 91%, sunflower oil 88%, linseed oil 80%). The hydrolysis of the plant oil to mono- and diglycerides can be suppressed by the addition of a small amount of free fatty acids. Rapeseed oil methyl ester can also be epoxidized; the conversion of C=C-bonds is 95%, and the composition of the epoxy fatty acid methyl esters corresponds to the composition of the unsaturated methyl esters in the substrate. Based partly on a lecture at the 86th AOCS Annual Meeting & Expo, San Antonio, Texas, May 7–11, 1995.     

Determining the blend level of mixtures of biodiesel with conventional diesel fuel by fiber-optic near-infrared spectroscopy and 1H nuclear magnetic resonance spectroscopy

Biodiesel, defined as the alkyl esters (usually methyl esters) of vegetable oils, is miscible with conventional diesel fuel at all blend levels. Until the present time, no rapid and reliable analytical method has existed for determining the blend level of biodiesel in conventional diesel fuel. In the present work, near-infrared (NIR) and nuclear magnetic resonance (NMR) spectroscopies were used to determine the blend level of biodiesel in conventional diesel fuel. Several regions in the NIR region (around 6005 cm⁻¹ and 4800–4600 cm⁻¹) are suitable for this purpose. The method is rapid and easy to use, and does not require any hardware changes when using the same instrument for monitoring the biodiesel-producing transesterification reaction and determining biodiesel fuel quality. In ¹H NMR spectroscopy, the integration values of the peaks of the methyl ester moiety and the aliphatic hydrocarbon protons in biodiesel and conventional diesel fuel were used for determining blend levels. The results of NIR and NMR blend level determinations are in good agreement.     

Reactions of dioxiranes with selected oleochemicals

Reaction of fatty acids with dimethyldioxirane in acetone produces ketoacids in 9–12% yields in which the ketone carbonyl is distributed along the fatty chain. The n-1 position appears to be preferred. Lactones of hydroxy fatty acids are oxidized by this reagent, but in low yields, to the corresponding ketoacids. Biphasic epoxidations with methylethyldioxirane in 2-butanone were conducted with methyl oleate and methyl ricinoleate to give the corresponding expoxides in high yield, and olive oil and tallow were cleanly epoxidized by this procedure as well.     

Technological aspects of heat resistance in carbon-ceramic composite refractories

A technology has been developed for making carbon-ceramic composite refractories by combining carbon fibers as reinforcing component with a mixture matrix, which allows one to make refractory components of various sizes and geometry, including thin-walled large constructions. The heat resistance of these composite refractories increases with the bulk silicization during ceramic production on a carbon-carbon substrate. The degree of silicization is determined by the volume of the open microporosity of transport type, which is formed by pyrolysis of a polymer coke-forming matrix in the initial carbon plastic. The transport micropores are produced by a modification of the phenol-formaldehyde resin additive treatment, which does not give rise to coke on pyrolysis. As a result, the content of open pores in the carbon framework attains 55%, which enables one to make a silicized composite refractory of density up to 2.7 g/cm³ with a compressive strength of 250 – 300 MPa, bending strength 120 – 140, and tensile strength 60 – 80 MPa, elastic modulus 120 – 140 GPa, linear expansion coefficient 3.5 × 10^–6 – 4.5 × 10^–6 K^–1, and thermal conductivity 6 – 8 W/(m ∙ K). These refractories are widely used in various branches of industry Translated from Novye Ogneupory, No. 4, pp. 132 – 135, April, 2009.