DC-Trennung von Ricinusölfettsäure-Partialglyceriden

Thin-Layer Chromatographic Separation of Partial Glycerides of Castor Oil Fatty Acids Partial glycerides of castor oil fatty acids and hydrogenated castor oil fatty acids were prepared by esterification or glycerolysis and fractionated, together with commercial products, by TLC (especially by two-dimensional technique) on silicagel 60 precoated plates. By comparison of the two-dimensional chromatograms of the partial esters of castor oil fatty acids with synthetic standards, such as partial glycerides of ricinoleic, di- and tri-ricinoleic acids, estolides of castor oil fatty acids esterified to partial glycerides, and partial esters of castor oil fatty acids with 1,3-propanediol, the substances that could be identified were partial glycerides of ricinoleic, diricinoleic and triricinoleic and tetraricinoleic acids as well as partial glycerides, which contained, in addition to ricinoleic, diricinoleic and triricinoleic acids, fatty acids without hydroxyl groups as terminal estolide chain. The TLC enables an insight into the complex character of the glyceride composition of partial glycerides of castor oil fatty acids.     

Viscous,thermal and tribological characterization of oleic and ricinoleic acids-derived estolides and their blends with vegetable oils

This work deals with the viscous, thermal and tribological characterization of a variety of estolides, obtained from both oleic and ricinoleic acids, using different acid-catalysed synthesis protocols, and their blends with vegetable (high-oleic sunflower, HOSO, and castor, CO) oils. Estolides with molecular weights between 4.4 and 6.9 times higher than the originating fatty acids were obtained. Polymerization degree was larger when using the sulphuric acid-catalysed synthesis protocol. Estolides obtained from oleic acid displayed higher freezing temperatures than the fatty acid, whereas the crystallization process was delayed in estolides obtained from ricinoleic acid, yielding improved low-temperature properties. Ricinoleic acid-derived estolides showed much higher viscosity values than those prepared from the oleic acid, with values of kinematic viscosity up to around 6700 mm²/s. In general, viscosities were related to estolide molecular weight. Significant increments in HOSO and CO viscosities were found when they were blended with estolides, especially those prepared from the ricinoleic acid using the sulphuric and p-toluensulphonic acids-catalyzed methods. Relative increments in kinematic viscosities up to 1500% and 700% were obtained for HOSO and CO, respectively. HOSO's viscosity-temperature dependence was significantly improved when it was blended with different estolides, whereas CO/oleic acid-derived estolides blends showed a more moderate improvement of CO thermal dependence. The sulphuric acid-catalysed method influences friction and wear in the ball-on-plates contact lubricated with estolides. The addition of the different estolides to HOSO or CO does not modify their frictional behavior, resulting in just one single Stribeck curve for all samples, and significantly reduces wear.     

Decolorization of meadowfoam estolides using sodium borohydride

Estolides are condensed oligomers of fatty acids made by introducing an ester linkage at sites of unsaturation. Estolides made from meadowfoam (Limnanthes alba) oil fatty acids have positive effects in personal care formulations and a patent has been applied for. However, estolides prepared by acid catalysis had a color of 12 (Gardner scale) and industrial cooperators desired lower color to increase marketability of meadowfoam estolides. Hydrogen peroxide and hydrogenation did not lower the color of estolide but 1% w/w sodium borohydride at 80°C for 12 h reduced color to 7 on the Gardner scale which was acceptable to the industrial partners for further development. Sodium borohydride decolorization gives a product with good color at a reasonable cost. The sodium borohydride does not have to be used in concentrations higher than 1% w/w and the product loss, which can be several percent with a clay-based process, is negligible using sodium borohydride.     

Synthesis and Characterization of Polyethylene Glycol Diesters from Estolides Containing Epoxides and Diols

Estolides from oleic acid, 12-hydroxystearic acid, and methyl ricinoleate were synthesized and converted to polyethylene glycol (PEG) diesters. Oleic estolide was synthesized from oleic acid as a homo-oligomeric material using perchloric acid in 68.8% yield and an estolide number (EN) value of 1.29. Estolides from 12-hydroxystearic acid were homo-oligomers made by heating under vacuum at 150 °C for 24 hours to give a quantitative yield of estolide with an EN value of 2.55. Oleic acid-based estolides and 12-hydroxystearic acid-based estolide were esterified with PEG-200 diol to form PEG 200 diesters. Ricinoleate estolides was capped with lauric acid or 12-hydroxystearic estolide by reacting methyl ricinoleate with the corresponding fatty acids at 150 °C using tin(II) octoate as a catalyst. The corresponding estolides were transesterified with PEG-200 diol to form the diesters. The residual olefin of ricinoleate was then epoxidized and underwent ring opening hydrolysis to form the corresponding diol. NMR spectroscopy (¹H, ¹³C, distortionless enhancement by polarization transfer, heteronuclear single quantum correlation, heteronuclear multiple bond correlation, and correlated spectroscopy) was used to characterize the products.     

Fatty Acid Estolides: A Review

Estolides are bio-based oils synthesized from fatty acids or from the reaction of fatty acids with vegetable oils. Estolides have many advantages as lubricant base oils, including excellent biodegradability and cold flow properties. Promising applications for estolides include bio-lubricant base oils and in cosmetics. In this review, the synthesis of estolides from fatty acids using four different types of catalysts, namely, mineral acids, solid acids, lipases, and ionic liquids, is summarized. The summary includes the yield of estolide obtained from varying synthetic conditions (time, temperature, catalyst). Also reviewed are studies comparing the physical properties of estolides synthesized from refined fatty acids against those synthesized from fatty acid mixtures obtained from vegetable oils such as coconut, castor, Physaria, etc. By varying the structure of the fatty acids, estolides with a wide range of pour point, cloud point, and viscosity are synthesized to meet a wide range of application requirements. Currently, estolide products are being commercialized for personal care and lubricant base oils for automotive, industrial, and marine applications. The application areas and the demand for estolides is expected to grow as the drive for switching from petroleum to bio-based products keeps growing.     

Methods for increasing estolide yields in a batch reactor

Estolides are formed when the carboxylic acid group of one fatty acid forms an ester link at the site of unsaturation of another fatty acid. These compounds have the potential to be used in a variety of applications, such as lubricants, greases, plastics, inks, cosmetics, and surfactants. By manipulating the reaction equilibrium, yields of 20% estolide in clay-catalyzed estolide reactions have been increased to 30%. Reactions conducted at 180°C, where water was vented out of the reactor at specific times, not only gave dimer-free estolides but also yields up to 30%. Steam has also been used instead of water with similar results. Estolides were quite stable at temperatures up to 250°C, even when they were exposed to air.     

Estolides from meadowfoam oil fatty acids and other monounsaturated fatty acids

The formation of estolides was detected during the studies on dimerization of meadowfoam oil fatty acids. By adjusting the reaction conditions, it was possible to produce monoestolides with little dimer or trimer formations. Estolides have potential use in lubricant, cosmetic and ink formulations and in plasticizers. This paper reports the conditions for production of estolides from mixed meadow-foam fatty acids, commercial oleic acid, high-oleic sun-flower oil fatty acids,cis-5,cis-13-docosadienoic acid, petroselinic acid and linoleic acid.     

Features of the enzymatic hydrolysis of castor oil

Ricinoleic acid, which is used in medicine and veterinary science and is the initial material in the organic synthesis of various valuable products, is obtained via the hydrolysis of castor oil. The enzymatic hydrolysis of castor oil, which allows us to conduct the process under mild conditions (in the temperature range of 35–45°C and without high pressures) is a promising method for obtaining ricinoleic acid. This work demonstrates the feasibility of the enzymatic hydrolysis of castor oil with lipase from Candida rugosa in oil-water systems without an emulsifier. We propose a method for hydrolysis without emulsifiers, simplifying the process of isolating the target product (a mixture of free fatty acids in which ricinoleic acid predominates) and thus the relevant technology. The catalyst that we use ensures the environmental friendliness of the process. Our selection of the experimental conditions for hydrolysis resulted in a 47% yield of fatty acids.     

Produkte der Dimerisierung ungesättigter Fettsäuren X: Identifizierung von Estoliden in der Anfangsphase der Dimerisierung

Products of the Dimerisation of Unsaturated Fatty Acids X: Identification of Estolides in Early Phase of the Dimerisation Dimeric fatty acids, obtained by dimerisation of the conjugated fatty acid (mixture of 9,11-Octadecadienoic acid and 10,12-Octadecadienoic acid) in presence of the catalyst molybdenum pentachloride and tin dichloride, could be separated after methylation with diazomethane. The isolated fraction of methyl-9-octadecanoyloxy-octadecanoat resp. methyl-10-octadecanoyloxy-octadecanoat and methyl-9-octadec-9-enoyloxy-octadecanoat resp. methyl-10-octadec-9-enoyloxy-octadecanoat was characterized. It could be shown that these estolides can be saponified to stearic acid, oleic acid and 9- resp. 10-hydroxyoctadecanoic acid. Thus saponification can serve as an unambiguous proof of estolide components. Analogous estolides could be identified in the early phase of the clay-catalyzed dimerisation of oleic and linoleic acid. The detection of estolides shows that at low dimerisation temperature at first hydroxy fatty acids are formed which are subsequently esterified with unsaturated fatty acids. In the final products of the dimerisation estolides are absent, because their formation is suppressed by higher temperatures.     

Studies on castor oil. II. Hydrogenation of castor oil

1. Products of low iodine value (<10.0) and hydroxyl value (35–40) can be readily obtained by hydrogenating castor oil at atmospheric pressure and at temperatures of the order of 220°, using 1.0% Raney nickel.
2. Dehydration of ricinoleic acid and subsequent hydrogenation of the resulting double bond as also simple saturation of ricinoleic acid are the main reactions occurring during the hydrogenation of castor oil under ordinary conditions.
3. Increase in the amount of catalyst favors more the hydrogenation of double bond at lower temperatures and both dehydration and hydrogenation at about 220°, which seems to be the optimum temperature for the maximum conversion of ricinoleic acid into nonhydroxy acids with both Raney and dryreduced nickel at atmospheric pressures.
4. Higher proportions of catalyst, addition of catalyst stepwise, and higher temperature of hydrogenation cause considerable splitting and estolide formation.
5. When hydrogenation is carried out at room temperature, under a pressure of 40 p.s.i. with alcohol as solvent, a product rich in monohydroxy stearic acid is obtained.
6. True unsaturation of hydrogenated castor oil is measured by the Wijs method at 15–20°C.

     

Chemical derivatives of castor oil

The chemistry of castor oil and its derivatives is reviewed with particular reference to work done in India in general and at the Regional Research Laboratory in Hyderabad in particular. Topics covered are the structure of castor oil, preparation of ricinoleic acid and its glycerides, monoglycerides, surfactants from castor oil, diverse hydrogenations, dehydration, preparation and properties of estolides, alkali fusion or oxidation to dibasic acids, hydroxylation and acetoxy-epoxies, urethanes and polymerisable monomers. Presented at the Plenary Session of the ISF-AOCS World Congress, Chicago, September 1970.     

Synthesis of triglyceride estolides from lesquerella and castor oils

Triglyceride (TG) estolides were synthesized from the hydroxy moieties of lesquerella and castor oils with oleic acid. Complete esterification of the hydroxy oils was possible when a slight excess of oleic acid was employed (1 to 1.5 mole equivalents). The estolides could be formed in the absence of catalyst at 175 to 250°C under vacuum or a nitrogen atmosphere. The optimal reaction conditions were found to be under vacuum at 200°C for 12 h for lesquerella and 24 h for castor oil. The lesquerella esterification reaction was completed in half the time of the for castor and with lower equivalents of oleic acid due to the difunctional hydroxy nature of lesquerella TG compared to the trifunctional nature of castor TG. Interesterification or dehydration of the resulting estolides to conjugated FA was not a significant side reaction, with only a slight amount of dehydration occurring at the highest temperature studied, 250°C. Use of a mineral-or Lewis-acid catalyst increased the rate of TG-estolide formation at 75°C but resulted in the formation of a dark oil, and the reaction did not go to completion in 24 h. Estolide numbers (i.e., degree of estolide formation) for the reaction and characterization of the products were made by ¹H NMR and ¹³C NMR. The decrease in the hydroxy methine signal at 3.55 ppm was used to quantify the degree of esterification by comparing this integral to the integral of the alpha methylene protons on the glycerine at 4.28 and 4.13 ppm.     

Identification of Minor Acylglycerols Less Polar than Triricinolein in Castor Oil by Mass Spectrometry

Acylglycerols in castor oil less polar than triricinolein were identified by electrospray ionization–mass spectrometry using the lithium adducts of the acylglycerols in the HPLC fractions of castor oil. Thirty four new molecular species of acylglycerols containing hydroxy fatty acids in castor oil were identified by MS. The chain lengths of fatty acid substituents were C16, C18, C20, C22 and C23. The numbers of double bonds of the fatty acids were from zero to three. The numbers of hydroxyl groups on the fatty acid chains were from zero to three as previously reported. The structure of fatty acid, OH18:2, was proposed as 12-hydroxy-9,13-octadecadienoic acid. An unusual odd-numbered long-chain fatty acid, 23:0 (tricosanoic acid), was identified. Some new estolides and tetraacylglycerols, were identified as (12-ricinoleoylricinoleoyl)-ricinoleoyl-linoleoyl-glycerol (RRRL), (12-ricinoleoylricinoleoyl)-ricinoleoyl-oleoyl-glycerol (RRRO), (12-ricinoleoylricinoleoyl)-ricinoleoyl-palmitoyl-glycerol (RRRP), (12-ricinoleoylricinoleoyl)-ricinoleoyl-stearoyl-glycerol (RRRS) and (12-ricinoleoylricinoleoyl)-ricinoleoyl-linolenoyl-glycerol (RRRLn). The normal fatty acid (non-hydroxylated) of these tetraacylglycerols were directly attached to the glycerol backbone. The biosynthetic pathway of castor oil is proposed.     

Synthesis of estolides from oleic and saturated fatty acids

Oleic acid and various saturated fatty acids, butyric through stearic, were treated with 0.4 equivalents of perchloric acid at either 45 or 55°C to produce complex estolides. Yields varied between 45 and 65% after Kugelrohr distillation. The estolide number (EN), i.e., the average number of fatty acid units added to a base fatty acid, varied as a function of temperature and saturated fatty acid. The shorter-chain saturated fatty acids, i.e., butyric and hexanoic, provided material with higher degrees of oligomerization (EN=3.31) than stearic acid (EN=1.36). The individual, saturated fatty acid estolides each have very different characteristics, such as color and type of by-products. The higher-temperature reactions occurred at faster rates at the expense of yield, and lactones were the predominant side products. At 55°C, lactone yields increased, but the δ-γ-lactone ratio decreased; this led to lower estolide yields. The opposite trend was observed for the 45°C reaction. The saturate-capped, oleic estolides were then esterified with 2-ethylhexyl alcohol, and the chemical composition of these new estolides remained consistent throughout the course of the reaction.     

Enzymatic preparation of polyethylene glycol esters of castor oil fatty acids and their surface-active properties

This study concerns the preparation and evaluation of nonionic surfactants prepared from polyethylene glycol (PEG) esters of castor oil fatty acid, a source of hydroxy fatty acid. A lipase-catalyzed esterification reaction has been employed to prepare PEG esters of hydroxy acid to overcome problems associated with chemical processes. Castor oil fatty acid (85% ricinoleic acid) was mixed with PEG of different molecular weight. Rhizomucor miehei lipase was added as catalyst (10% level) and the reaction was continued at 60°C under 2 mm Hg pressure for 360 min. Conversion of PEG to esters was in the range of 86–94%, depending on the molecular size of PEG. The products were isolated and examined for surface activity by surface tension measurement. Surface tension values measured at 25°C were about 36–37 dynes/cm.     

Soybean Oil Fatty Acid Ester Estolides as Potential Plasticizers

Fatty acid ester estolides were synthesized from soybean oil and evaluated for plasticizer functionality in poly(vinyl chloride) (PVC). The plasticization ability of the fatty acid ester estolides depends upon the molecular features such as polarity, molecular weight, and branching. The structure of the fatty acid derivatives was modified at the ester head group with various alcohols and the estolide branch was created at the site of unsaturation. Soy fatty acid esters of methanol, iso-butanol, 2-ethylhexanol, and glycerol were prepared to vary the size and polarity at the ester head group. Estolides of these fatty acid esters were prepared using two synthetic routes. In the first route, the fatty acid ester was condensed with an aliphatic acid at the site of unsaturation in the presence of a strong mineral acid. In the second route, the fatty acid ester double bonds were converted to epoxy groups, which were ring opened and acetylated to form acetate estolides. The first synthetic route resulted in low-average estolide content per fatty acid chain while the second route resulted in a higher estolide content per fatty acid chain. The fatty acid ester estolides compounded with PVC showed good plasticizer properties as evidenced by the rheological properties and reduction in glass transition temperature. The fatty acid ester estolides with a higher estolide content had better plasticizer functionality, comparable to commercial controls.     

Synthesis and characterization of hyperbranched and air drying fatty acid based resins

In this research four hyperbranched resins having fatty acid residues were synthesized. Dipentaerythritol, which was used as the core molecule of the resins, was twice esterified with dimethylol propionic acid. This resin was then esterified with the castor oil fatty acids. The hydroxyl group present in the ricinoleic acid which constitutes almost 87% of the castor oil fatty acids was then reacted with linseed oil fatty acids and benzoic acid. The linseed fatty acids were incorporated into the structure to esterify 0, 15, and 70% of the ricinoleic acid on mole basis. These resins were named as HBR-1, 2, and 3. A fourth resin (e.g. HBR-4) was synthesized by the incorporation of ‘15% linseed fatty acids + 55% benzoic acid’. The chemical characterization of the resins was achieved by FTIR spectroscopy and the thermal properties were determined by DSC. The physical and the mechanical properties of the resins were determined. The hardness value of the resins was measured as 24, 27, 25, and 68 Persoz for HBR-1, 2, 3, and 4, respectively. The viscosity of the resins was measured as 17.3, 9.7, 5.8, and 17.5 Pa·s at a shear rate of 200 s⁻¹. The increase in the amount of the linseed fatty acids increased the hardness, and decreased the viscosity of the resins. All resins showed excellent adhesion, gloss, and flexibility.     

Some physical properties of castor oil esters and hydrogenated castor oil esters

Esters of castor oil and hydrogenated castor oil were prepared with C₆, C₁₂, C₁₆, C₁₈ fatty acids, using tetra‐n‐butyl titanate as a catalyst and n‐butyl benzene as a water entrainer. Physical properties such as melting point, refractive index, viscosity, and specific gravity of these esters were measured. Slip melting points of the esters were very low in both cases. These esters did not crystallize even at low temperature. The highest slip melting point obtained was 21 °C with stearoyl hydrogenated castor oil ester and lowest slip melting point obtained was —6 °C with hexanoyl castor oil ester.     

Biocatalytic production of ricinoleic acid from castor oil: augmentation by ionic liquid

Abstract

In present study involving castor oil hydrolysis catalyzed by porcine pancreas lipase, organic solvent, and ionic liquid were applied to augment production of ricinoleic acid. Toluene was the best organic solvent (30.18% hydrolysis in 2?h). In presence of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF₆]), an ionic liquid, the optimal conditions were, 0.12?g ionic liquid/g oil, 4?mg enzyme/g oil, 2?g buffer/g oil, pH of 8, and 2.5?h. Under this condition, ricinoleic acid recovery was 43.41 and 52% at 25?°C and 35?°C, respectively. Organic solvent concentration, enzyme concentration, buffer concentration and time had significant impacts on lipase catalyzed hydrolysis in the presence of organic liquid; whereas, pH and speed remained insignificant. In hydrolysis involving ionic liquid, time had most important effect on ricinoleic acid production. Interaction between enzyme and buffer concentration was most significant. Interactions of ionic liquid concentration with all other variables were also significant besides buffer concentration–time interaction.     

A novel technique for the preparation of secondary fatty amides II: The preparation of ricinoleamide from castor oil

The butyl amide of ricinoleic acid (N-n-butyl-12-hydroxy-(9Z)-octadecenamide) was prepared from a neat mixture of castor oil andn-butylamine (fatty ester/amine molar ratio, 1:1.3). No catalyst was required. The identity and purity of the amide was assessed by thin-layer chromatography and confirmed by elemental analysis and by infrared and C¹³ nuclear magnetic resonance spectroscopy. High product yields were achieved at 45 and 65°C in 48 and 20 h, respectively. The reaction was inhibited by the addition of trimethylpentane and dioxane, but not by water. An attempt was made to prepare the amide from methyl ricinoleate, rather than castor oil; even after 10 d only partial conversion was achieved. Attempts to prepare the amide from methyl-n-butylamine, rather thann-butylamine, were also unsuccessful. The ease with which secondary fatty amides can be produced from an oil that consists primarily of the glycerol esters of hydroxylated fatty acids indicates that the described procedure has industrial utility.