An efficient reaction protocol for the ruthenium‐catalysed epoxidation of methyl oleate

The transition metal catalysed epoxidation of methyl oleate 1 by hydrogen peroxide was investigated using Ru(acac)₃/dipicolinic acid as catalyst. Under optimised reaction conditions, the epoxidised methyl oleate 2 was obtained with a quantitative yield in short reaction time and under mild reaction conditions. Practical applications: Epoxidised fatty acids and their derivatives are produced by the Prilezhaev reaction and used in various applications in the chemical industry. Due to the known drawbacks of epoxidation with peroxy acids, such as hazardous handling of peracids in large quantities or the decrease of epoxide selectivity due to the formation of undesired by‐products in the acidic medium, the epoxidation of fatty acid derivatives using more convenient oxidants is still a subject of research interest. Herein, we present a simple procedure for the transition metal catalysed epoxidation of methyl oleate 1 by hydrogen peroxide in quantitative yields, and under mild reaction conditions, as a potential alternative for the production of epoxidised fatty acid derivatives.     

Extraction of a Homogeneous Rhodium Catalyst from Saturated Branched Fatty Derivatives

Saturated branched fatty derivatives are of great interest for the lubricants and cosmetics industry due to their improved temperature and viscosity behavior compared to the corresponding linear homologues. One way to produce saturated branched derivatives is the homogeneous rhodium‐catalyzed conjugation and co‐oligomerization of linoleic compounds based on renewable resources, e.g., sunflower oil, with ethene. The catalyst extraction behavior of the homogeneous rhodium catalyst RhCl₃·3H₂O from saturated branched fatty derivatives for catalyst recycling was studied. Investigation of the extraction parameters was performed using the model substance isostearic acid. Additionally, extraction of rhodium from co‐oligomer mixtures with different grade of saturation was carried out successfully. Also, the influence of solvent residues from prior reaction steps was evaluated.     

Hydroaminomethylation of fatty acids with primary and secondary amines — A new route to interesting surfactant substrates

The rhodium catalysed hydroaminomethylation of the unsaturated fatty acid derivatives oleic acid ethyl ester (1) and oleyl alcohol (2) with the primary amines hexylamine (3) , benzylamine (4) , aspartic acid diethyl ester (5) and valinol (6) , and with the secondary amine morpholine (7) , respectively, proceeds with good to excellent yields. Using primary amines the structure of the reaction products depends on the stoichiometry of the reactants. Performing the reaction of (1) with (3) with an excess of the amine compound the corresponding secondary amine (9) (1:1‐adduct) was observed. Working with a 2‐fold excess of (1) the tertiary amine (16) (2:1‐adduct) was the main product.     

Ionic Liquids as Surfactants in Aqueous Multiphase Systems for the Pd-Catalyzed Hydrocarboxylation

The suitability of ionic liquids (alkylmethylimidazolium bromides) as surfactants in an aqueous multiphase system for the Pd-catalyzed hydrocarboxylation of 1-dodecene is discussed. Attention is paid to the influence of these ionic liquids on the reaction performance and the phase separation. All tested ionic liquids are suitable as surfactants, but their concentration has a strong impact on the reaction performance. The resulting product concentrations are crucial for the phase behavior and so for the phase separation. In recycling experiments, the Pd-catalyst is successfully separated and reused.     

Unique adhesive properties of pressure sensitive adhesives from plant oils

We report novel insights into the adhesive performance of bio-based pressure sensitive adhesives (PSAs). Three different homopolymers based on renewable fatty acid methyl esters were characterized in terms of their mechanical and adhesive properties. The polymers display the typical dependence of adhesive properties on molecular weight and degree of crosslinking, as quantified by shear modulus, tack and peel measurements. The absolute values of characteristic adhesion parameters are in the range of commercially available petrochemical PSAs. Curing of applied PSA films at elevated temperature results in a pronounced maximum in tack and peel strength at a critical curing time, which corresponds to a change from cohesive to adhesive failure. Thus, demand-oriented tailoring of adhesive properties can be achieved via an appropriate choice of curing time. Moreover, these bio-based adhesives offer improved adhesion on hydrophobic substrates and high water-resistance without any whitening, thus rendering them an attractive alternative to conventional petroleum-based products. These peculiar features are attributed to the high hydrophobicity of the used monomers.     

Recycling and Oligomerization Activity of Ni/Al Catalyst in a Biphasic System with Ionic Liquids

The catalyst decomposition in homogeneously catalyzed reactions is a very important factor that has been studied for the oligomerization of n‐butenes in a system of two liquid phases. A highly active catalyst [NiCl₂(PMe₃)₂] was investigated with an emphasis on the long‐term catalyst activity using N‐methylpyrrole as a buffer. The recycling experiments indicated that this catalyst is viable for five runs. Furthermore, introducing aluminum chloride or an ionic liquid in small concentrations led to increased stability, though fine adjustments were necessary to arrive at optimal results.     

柠檬酸酯合成用催化剂研究进展

介绍了近年来柠檬酸酯类化合物的合成方法及主要用途。对各类催化剂,如磺酸类、固体超强酸、杂多酸、无机盐等在合成柠檬酸酯上的应用进行了综述,并分析比较了各种催化剂的优缺点。介绍了固载交联、纳米、磁化、微波辐射等技术在催化剂改性上的应用,展望了柠檬酸酯合成的发展前景。     

Phenylethyl esters of fatty acids for the analytical resolution of petroselinate and oleate

2-Phenylethyl esters of fatty acids were prepared readily by esterification of free fatty acids or transesterification of other lipids. Compared with methyl esters, phenylethyl esters greatly improve the resolution of oleate and petroselinate by both gas and high-performance liquid chromatography, and the ultraviolet absorption of the phenylethyl esters facilitates detection of the derivatives by high-performance liquid chromatography (HPLC) ultraviolet detectors. The fatty acid compositions of corn and soybean oil obtained by analysis of phenylethyl esters agreed with those obtained with methyl esters. The phenylethyl esters were resolved and eluted on C-18 HPLC columns with much smaller solvent volumes than those reported for other aromatic esters.     

Monomer recycling for vulcanized silicone rubbers in the form of cyclosiloxane monomers. Role of acid buffers

The KOH-catalyzed depolymerization of vulcanized silicone rubbers to reproduce cyclosiloxane monomers was studied. First, the depolymerization was carried out in toluene with varying amounts of KOH to find that the yield of monomers first increased and then decreased with the increment of KOH, the highest yield was 65% at the molar ratio KOH/(Si–O) UNITS=0.08. At the molar ratio 0.13 in the absence of solvent, the monomers yield was 46%. However, when an acid buffer such as KH₂PO₄ and KCOOC₆H₄COOH was added after the KOH-catalyzed depolymerization was over, the product yield was increased remarkably to more than 80%.     

Characterization and carbonylic hydrogenation of methyl oleate over Ru-Sn/Al2O3: Effects of metal precursor and chlorine removal

Hydrogenation of methyl oleate to oleyl alcohol was evaluated over Ru-Sn/Al₂O₃ catalysts, prepared from different precursors, at 270 °C and 5.0 MPa. Two kinds of metal precursors were employed: chlorine-free precursors and inorganic chlorides. In addition, several methods for chlorine removal of metal-chloride-based catalysts were studied. Catalysts were characterized by EDX, XRF, DRX, BET and TPR analyses. Selectivity toward unsaturated alcohol was higher with the bimetallic catalyst based on chlorine-free precursors than with the catalyst based on metal chlorides, owing that chlorine avoids, at certain extent, an effective interaction between ruthenium and tin species. However, the most selective catalyst was the bimetallic one based on chloride precursors and reduced with NaBH₄, due to elimination of residual chlorine and higher dispersion of Ru-Sn species.     

A Comprehensive Evaluation of the Density of Neat Fatty Acids and Esters

Density is one of the most important physical properties of a chemical compound, affecting numerous applications. An application in the case of fatty acid esters (biodiesel) is that density is specified in some biodiesel standards. In the present work, the density of fatty acid methyl, ethyl, propyl, and butyl esters as well as triacylglycerols in the C₈–C₂₄ range was determined in the range of 15–40 °C with a densitometer utilizing the oscillating U-tube technique. Literature data on density are compiled and compared, showing that data for these compounds are incomplete with discrepancies existing in some cases. Besides known effects such as density decreasing with increasing chain length and increasing saturation, it is shown that trans fatty compounds exhibit lower density than cis fatty compounds. Density data for several saturated odd-numbered, C₁₈, as well as C₂₀ and C₂₂ polyunsaturated fatty esters are reported for the first time. The density contribution of compounds with high melting points is predicted. An equation is given for the calculation of the density of mixtures.     

Flame-ionization detector response to methyl, ethyl, propyl, and butyl esters of fatty acids

The concept of theoretical response factors is not directly applicable to methyl esters of short-chain fatty acids (FA), since their carbon deficiency is larger than expected from theory. Substituting the methyl group by an ethyl, propyl, or butyl group improved the flame-ionization efficiency of fatty acid esters gradually, up to the point where the empirical response factors of the butyl esters were identical within experimental error to the theoretical values. Butyl esters of FA have a uniform flame-ionization detection (FID) response irrespective of the number of carbon atoms contained in the FA. They exhibit a carbon deficiency of 1.0, i.e. the carbonyl carbon atom does not respond, as expected from theory. Compared to methyl esters, which have a carbon deficiency of 1.4–1.5 for short-chain FA, use of butyl esters has the advantage that a precalculation of the FID response enables the analyst to judge whether the analytical system employed works properly and the data produced are accurate and reliable. Both acid (BF₃ or H₂SO₄)-and alkali (butoxide)-catalyzed butyl ester preparation were equally effective, giving the analyst a choice of methods so that different analytical needs can be addressed efficiently. Computing response factors and comparing the theoretically expected values with those obtained experimentally gives the experimenter an indication whether the analytical system employed for FA profiling (transesterification plus the subsequent gasliquid chromatographic separation and quantitation by FID) works properly. This setup is particularly useful for an accurate analysis of the FA profile of milk fat.     

Conversion of polyhydroxybutyrate (PHB) to methyl crotonate for the production of biobased monomers

Within the concept of the replacement of fossil with biobased resources, bacterial polyhydroxybutyrate (PHB) can be obtained from volatile fatty acids (VFAs) from agro‐food waste streams and used as an intermediate toward attractive chemicals. Here we address a crucial step in this process, the conversion of PHB to methyl crotonate (MC), which can be converted via cross‐metathesis with ethylene to methyl acrylate and propylene, two important monomers for the plastics industry. The conversion of PHB to MC proceeds via a thermolysis of PHB to crotonic acid (CA), followed by an esterification to MC. At pressures below 18 bar, the thermolysis of PHB to CA is the rate‐determining step, where above 18 bar, the esterification of CA to MC becomes rate limiting. At 200°C and 18 bar, a full conversion and 60% selectivity to MC is obtained. This conversion circumvents processing and application issues of PHB as a polymer and allows PHB to be used as an intermediate to produce biobased chemicals. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42462.     

Kinematic viscosity of fatty acid methyl esters: Prediction, calculated viscosity contribution of esters with unavailable data, and carbon–oxygen equivalents

Many properties of biodiesel, the mono-alkyl esters of vegetable oils, animal fats or other triacylglycerol-containing feedstocks, are largely determined by its major components, the fatty acid alkyl esters. Therefore, information on the properties of individual components and their interaction is essential to understanding and predicting the properties of biodiesel fuels. Viscosity, which affects flow and combustion of a fuel, is such a property. In previous literature, the effect of the structure of fatty esters on viscosity was discussed. However, these data are largely confined to esters with an even number of carbon atoms in the chain and that are liquid at 40 °C. To gain a better understanding of kinematic viscosity, this work additionally reports data on esters with an odd number of carbons in the fatty acid chain and some unsaturated fatty esters. Furthermore, the kinematic viscosity of some biodiesel fuels is affected by components that are solids at 40 °C. A method based on polynomial regression for determining the calculated viscosity contribution (CVC) of esters that are solid at 40 °C (saturated esters in the C₂₀–C₂₄ range) or esters that are liquids but not available in pure form is presented as these values are essential for predicting the kinematic viscosity of mixtures containing such esters. The kinematic viscosity data of esters are compared to those of aliphatic hydrocarbons in the C₆–C₁₈ range and those of dimethyl diesters. The increase of kinematic viscosity with increasing number of CH₂ groups in the chain is non-linear and depends on the terminal functional groups, chain length and double bonds. To illustrate this effect, carbon–oxygen equivalents (COE) are used in which the numbers of carbon and oxygen atoms are added. A straightforward equation, taking into account only the amounts and kinematic viscosity values of the individual neat components, suffices to predict the viscosity of mixtures of fatty esters (biodiesel) at a given temperature.     

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.     

In situ production of fatty acid methyl ester from low quality rice bran: An economical route for biodiesel production

Low quality rice bran was used to produce fatty acid methyl ester (FAME) via in situ extraction, esterification and transesterification process. The effects of the acid and alkaline catalysts on the ester yield, esterification and transesterification process were studied. When 75 ml of absolute methanol, 150 ml of petroleum ether, 0.75 g of concentrated sulfuric acid and 0.71 g of sodium hydroxyl were used, 16.69% (w_FAME/w_{rice bran}) of FAME was obtained. The esterification rate and the transesterification rate reached 98.83% and 80.47%. Based on the proposed route, the production process of FAME (biodiesel) could be simplified and the production cost could be reduced.     

Evidence of thermal decomposition of fatty acid methyl esters during the synthesis of biodiesel with supercritical methanol

New evidence on the thermal decomposition of fatty acid methyl esters during biodiesel synthesis in supercritical conditions is presented. Thermal decomposition products were detected chromatographically, by applying the UNE-EN 14105:2003 standard, as a broad single peak during the determination of glycerides in the reaction samples. These degradation products could be quantified chromatographically by the above standard because the area of the peak was proportional to the disappearance of the polyunsaturated fatty acid methyl esters, which contain two or more double bonds (methyl linoleate and linolenate), generated during biodiesel synthesis from soybean oil. In the experimental conditions tested, thermal decomposition reactions of these unsaturated fatty acid methyl esters began to appear at 300 °C/26 MPa, and were more intense as the temperature rose. For its part, the main saturated fatty acid methyl ester (methyl palmitate) generated during the reaction was hardly decomposed at all in the experimental conditions tested and only began to disappear at 350 °C/43 MPa.     

Undecylenic acid: A valuable renewable building block on route to Tyromycin A derivatives

A key intermediate for the synthesis of Tyromycin A, a C‐20 tetrachlorodicarboxylic acid, was produced in six steps starting with the dimerization of methyl 10‐undecenoate which was obtained from a renewable resource, e.g. castor oil. The acyloin condensation product was then oxidized, transformed to the diene, followed by ozonization, chlorination and finally oxidation to the corresponding tetrachlorodicarboxylic acid.