Transesterification of fats and oils

In addition to their transformation into linear alcohols by hydrogenation, methyl esters obtained in the transesterification of fats and oils can also be used as raw materials for sulfonation, yielding a family of derivatives known as methyl ester sulfonates (MES). These products are only significant in some southeast Asian markets, Japan and to a much lesser extent in other markets such as the US. 

Schuchardt, U. and Lopes, O.C. 1988. Tetramethyl-guanidine catalyzed transesterification of fats and oils A new method for rapid determination of their composition. JAOCS 65 1940-1941. 

Methyl Ester-Based Processes. The fatty methyl esters are produced predominantly by the transesterification of fats and oils with methanol in the presence of an alkaline catalyst under very mild reaction conditions.l5a,b They are used in the production of lauric-type (Cl2) alcohols. The short-chain fatty methyl esters (C8-Cl0), produced as by-products via the fractional distillation of crude lauric-type (coconut, palm kernel) methyl esters, are converted to fatty acids via acidic or alkaline hydrolysis (Fig. 36.12). The hydrolysis of short-chain fatty methyl esters by stream splitting or Twitchell-type processes is not very efficient because of unfavorable equilibrium constants.16a,b... 

Transesterification Processes. Transesterification of fats and oils is the most commonly used process for the manufacture of methyl esters, except in cases where methyl esters of specific fatty acids are needed. 

Fatty acid esters are generally obtained from the transesterification of fats and oils with a lower alcohol, e.g. methanol, along with glycerol. More than 90% of all oleochemical reactions (conversion into fatty alcohols and fatty amines) of fatty acid esters (or acids) are carried out at the carboxy functionality. However, transformation of unsaturated fatty acid esters by reactions of the carbon-carbon double bond, such as hydrogenation, epoxidation, ozonolysis, and dimerization, are becoming increasingly of industrial importance. Here we will discuss another catalytic reaction of the carbon-carbon double bond, viz. the olefin metathesis reaction, in which olefins are converted into new products via the rupture and reformation of carbon-carbon double bonds [2]. Metathesis of unsaturated fatty acid esters provides a convenient route to various chemical products in only a few reaction steps. 

The presence of a membrane in biodiesel production plays two main roles the first one is transesterification of fats and oils to produce biodiesel, and the second one is to separate impurities such as GLY, alcohol, and catalyst from the FAME product stream without using water, solvents acids, or absorbents. 

Matsuo, T., Sawamura, N., Hashimoto, Y. and Hasido, W. (1980) Producing a cocoa butter substitute by transesterification of fats and oils, UK Patent Application 2035A, Fuji Oil Company Ltd., Japan. 

Sawamura, N. (1988) Transesterification of fats and oils, in Enzyme Engineering 9. Annals of the New York Academy of Sciences, eds. H.W. Blanch and A.M. Klibanov, New York, pp. 266-269. 

Warwel et al. applied catalytic methods of olefin chemistry to achieve polymer building blocks as well as polymers like functionalized polyolefins, polyesters, polyethers, polyamides as well as sugar-based surfactants [4]. The fundamental approach was the polymer synthesis based on unsaturated fatty acid methyl esters, which are available by industrially applied transesterification of fats and oils with methanol. In Figure 18 is reported a schematic representation of the potential of plant oil components in the preparation of different polymeric materials. 

P. are made by - esterification of polyglyeerol with - fatty acids or by transesterification of - fats and oils with polyglycerol. 

The transesterification of fats and fatty oils by methanol into fatty acid methyl esters proceeds at 50-70°C without pressure. The deacidified fat is stirred for a short period with an excess of methanol and 0.1-0.5% caustic alkali as catalyst. On standing the reaction mixture separates forming a bottom layer of glycerin and a top layer of fatty acid esters. 

For technical applications, the production of ester sulfonates from the (purified) sulfo fatty acids involves too much effort, especially because the relevant fatty acid esters can be produced directly from the triglycerides of fats and oils by transesterification. The only possible way to produce ester sulfonates is the sulfonation of fatty acid esters. 

Aston [141] selected for the preparation of butyl esters transesterification with the aid of2N KOH in /7-butanol (5 min at room temperature). He evaluated the analyses of fats and oils by computer using a Fortran program. 

Transesterification of fats or oils with medium-chain alcohols may increase CN, a parameter that can influence ignition quality and exhaust emissions (Klopfenstein, 1985). On the other hand, increased branching in saturated hydrocarbon chains also decreases CN. Two studies comparing isopropyl... 

Use of Enzymes Lipases are widely used in the processing of fats and oils as catalysts of a number of important lipid reactions, such as hydrolysis, esterification, and transesterification reactions (174). There are a wide number of lipases obtained from different sources, which are available commercially in their free/ crude or immobilized form. However, enzymes with a higher tolerance of pressure would be welcomed, and more research is needed to hopefully develop such enzymes (i.e., genetic engineering or marine sources of the deep ocean). 

Mono- and diglycerides are important food emulsifiers. They can be made enzymatically by the glycerolysis of fats and oils.191 The reaction can be run continuously in a membrane reactor with an enzyme half-life of 3 weeks at 40°C. Higher concentrations of glycerol can be used if silica is present to prevent blockage of the enzyme by glycerol.192 Depending on the conditions and lipase chosen for transesterifications with ethanol, the product can be the 2-mono-... 

Uses Catalyst for transesterification and isomerization of fats and oils (food)... 

Lipases are used to catalyze hydrolytic, esterification and transesterification reactions. These reactions alter the physical properties of fats and oils and thereby produce a wide range of products (Mukherjee, 1990). Lipases have also been used for the kinetic resolution of Isomers of alcohols or fatty acids (Hills, et 1990). The lipases... 

G. lowers the freezing point of water with a maximum at -46.5 °C (66.7% g. and 33.3% water). This property was the basis for a major market as antifreeze for automotives for many years, which today has been completely substituted by ethylene glycol. G. is always the by-product of the ->splitting of - fats and oils, which contain -depending on the fatty acid composition- between 8 and 14% g. High-pressure - hydrolysis of - fats and oils is the main source and yields fatty acids and g. as a 15% solution in water. Their - transesterification, mainly with methanol, gives - fatty acid methyl esters and g. in a concentration of 90-92%. - Saponification was the traditional method to obtain g. but has been abandoned almost totally. 

Transesterification has a number of important commercial uses. Methyl esters of fatty acids are produced from fats and oils. Transesterification is also the basis of recycling technology to break up poly(ethylene terephthalate) [25038-59-9] to monomer for reuse (29) (see Recycling, plastics). Because vinyl alcohol does not exist, poly(vinyl alcohol) [9002-89-5] is produced commercially by base-cataly2ed alcoholysis of poly(vinyl acetate) [9003-20-7] (see Vinyl polymers). An industrial example of acidolysis is the reaction of poly(vinyl acetate) with butyric acid to form poly(vinyl butyrate) [24991-31-9]. 

Compared with the fatty alcohol sulfates, which are also oleochemically produced anionic surfactants, the ester sulfonates have the advantage that their raw materials are on a low and therefore cost-effective level of fat refinement. The ester sulfonates are produced directly from the fatty acid esters by sulfona-tion, whereas the fatty alcohols, which are the source materials of the fatty alcohol sulfates, have to be formed by the catalytic high-pressure hydrogenation of fatty acids esters [9]. The fatty acid esters are obtained directly from the fats and oils by transesterification of the triglycerides with alcohols [10]. 

The starting substances for the production of a-ester sulfonates are the triglycerides of animal and vegetable fats and oils. The transesterification of the glycerides with alcohol leads directly to fatty acid alkyl esters and glycerin [7]. 

Catalysts able to promote both transesterification of triglycerides and esterification of FFAs in an oil or fat are still rare and up to now none of them have found a commercial application. Thus far it seems that a moderate to high concentration of strongly acidic sites and a hydrophobic surface are mandatory to achieve good conversions in simultaneous esterification and transesterification reactions, but more research and creative thinking are still needed in this area. 

Naturally occurring fatty alcohols used in the fragrance industry are produced principally by reduction of the methyl esters of the corresponding carboxylic acids, which are obtained by transesterification of natural fats and oils with methanol. Industrial reduction processes include catalytic hydrogenation in the presence of copper-chromium oxide catalysts (Adkins catalysts) and reduction with sodium (Bouveault—Blanc reduction). Unsaturated alcohols can also be prepared by the latter method. Numerous alcohols used in flavor compositions are, meantime, produced by biotechnological processes [11]. Alcohols are starting materials for aldehydes and esters. 

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