Esterification, of fatty acids

The viscous fatty acid chloride is mixed with soHd sodium isothionate and is heated under vacuum and agitation without water or solvent HCl is evolved, leaving the product as a finely divided powder. The direct esterification of fatty acid and sodium isethionate has been patented (69). 

Eatty acid ethoxylates are used extensively in the textile industry as emulsifiers for processing oils, antistatic agents (qv), softeners, and fiber lubricants, and as detergents in scouring operations. They also find appHcation as emulsifiers in cosmetic preparations and pesticide formulations. Eatty acid ethoxylates are manufactured either by alkaH-catalyzed reaction of fatty acids with ethylene oxide or by acid-catalyzed esterification of fatty acids with preformed poly(ethylene glycol). Deodorization steps are commonly incorporated into the manufacturing process. 

Sorbitol is the most important higher polyol used in direct esterification of fatty acids. Esters of sorbitans and sorbitans modified with ethylene oxide are extensively used as surface-active agents. Interesteritication of fatty acid methyl esters with sucrose yields biodegradable detergents, and with starch yields thermoplastic polymers (36). 

Transesterification of fat triglycerides is the predominant method for manufacture of mixed fatty acid methyl esters, and direct esterification of fatty acids (FA) is practiced if very selective cuts of product, in general as an intermediate detergent range alcohol, are desired. Methyl cocoate is a mobile, oily liquid above 25 °C with a yellow tint and a characteristic fatty pungent odor. FAME sulfonation to FAMES is technically possible but been rarely applied up to now (1990) (Table 13). 

Adipose tissue Storage and breakdown of triacylglyc-erol Esterification of fatty acids and lipolysis lipogenesis Glucose, lipoprotein triacylglycerol Free fatty acids, glycerol Lipoprotein lipase, hormone-sensitive lipase... 

Lycopene was dispersed in medium-chain triglyceride oil derived from esterification of fatty acids and glycerol composition was stable for 3 mo at 25°C, compared with dispersion on soybean oil... 

Very recently, Nolan et al. studied several acidic polymeric catalysts for the esterification of fatty acids. The highest FFA conversion (45.7%) was obtained over strong acidic macroreticular polymer catalysts AmberlysH 15 at 60°C compared with Amberlyst 35, Amberlyst 16, and Dowex HCR-W2. 

Out of the metal oxides, sulfated titania and tin oxide performed slightly better than the sulfated zirconia (SZ) catalyst and niobic acid (Nb205). However, SZ is cheaper and readily available on an industrial scale. Moreover, it is already applied in several industrial processes (7,8). Zirconia can be modified with sulfate ions to form a superacidic catalyst, depending on the treatment conditions (11-16). In our experiments, SZ showed high activity and selectivity for the esterification of fatty acids with a variety of alcohols, from 2-ethylhexanol to methanol. Increasing... 

Usually, the cost of pure vegetable oils is very high and can dramatically affect the overall economics of the synthesis process. Waste vegetable oils or mixed streams of fatty acids can also be used as a starting raw material for synthesis. Kelkar et al. [14] have investigated the esterification of Fatty acid (FA) odour cut (Cg-Cio) with methanol in the presence of concentrated H2SO4 as a catalyst using hydrodynamic... 

As a historical note, SAI for Dove was made by this acyl chloride process until a commercial process for direct esterification of fatty acid and sodium isethionate was developed by Lever Brothers Co. in the late 1950 s. The SAI made by direct esterification is generally termed DEFI, an acronym for directly esterified fatty isethionate . The DEFI reaction is follows ... 

Fatty Acid Esters and Fatty Alcohols Fatty acid esters are obtained by transesterification of triglycerides (vegetable oils) or by esterification of fatty acid with alcohol or polyols. Fatty alcohols are obtained by hydrogenation of esters on metal catalysts. Fatty acid esters and fatty alcohols are useful platform molecules to prepare surfactants, emulsifier, lubricants and polymers. 

Fatty acid esters of sugars are also very important biodegradable and biocompatible surfactants that are prepared either by transesterification of methyl ester with sugar on basic catalysts or by esterification of fatty acids with sugar on acidic catalysts. Liquid acids and bases have been replaced by enzymatic catalysis with lipase, giving a higher yield of monoester [43, 44], but solid catalysts have not been used extensively so far. 

It, thus, appears that the capacity to catalyze reactions of transesterification and esterification is a characteristic of various hydrolases (Chapt. 3). Apart from the carboxylesterases discussed here, lipoprotein lipase has the capacity to synthesize fatty acid ethyl esters from ethanol and triglycerides, or even fatty acids [127]. Ethanol, 2-chloroethanol, and other primary alcohols serve to esterify endogenous fatty acids and a number of xenobiotic acids [128-130]. In this context, it is interesting to note that the same human liver carboxylesterase was able to catalyze the hydrolysis of cocaine to benzoylecgonine, the transesterification of cocaine, and the ethyl esterification of fatty acids [131]. 

G. P. Carlson, In vitro Esterification of Fatty Acids by Various Alcohols in Rats and Rabbits , Toxicol. Lett. 1994, 70, 57-61. 

Sugar The hydrolysis of sucrose in the intestine produces both glucose and fructose, which are transported across the epithelial cells by specific carrier proteins. The fructose is taken up solely by the liver. Fructose is metabolised in the liver to the triose phosphates, dihydroxy-acetone and glycer-aldehyde phosphates. These can be converted either to glucose or to acetyl-CoA for lipid synthesis. In addition, they can be converted to glycerol 3-phosphate which is required for, and stimulates, esterification of fatty acids. The resulting triacylglycerol is incorporated into the VLDL which is then secreted. In this way, fructose increases the blood level of VLDL (Chapter 11). 

Figure 16.1 The glucose/fatty add cycle. The dotted Lines represent regulation. Glucose in adipose tissue produces glycerol 3-phosphate which enhances esterification of fatty acids, so that less are available for release. The effect is, therefore, tantamount to inhibition of lipolysis. Fatty acid oxidation inhibits pyruvate dehydrogenase, phosphofructokinase and glucose transport in muscle (Chapters 6 and 7) (Randle et al. 1963).

As discussed above, insulin suppresses the breakdown of triglyceride within fat cells in the post-prandial period, preventing release of fatty acids from adipocytes in healthy individuals. Insulin also stimulates triglyceride clearance from triglyceride-rich lipoprotein particles and the esterification of fatty acids to form the intra-adipocyte triglyceride store. 

In this chapter, we report just a few selected examples of heterogeneous catalytic systems for the esterification of fatty acids and for the simultaneous esterification and transesterification of acidic oils and fats, and we discuss the use of selective hydrogenation as a tool for the production of high-quality biodiesel from non-edible raw materials. 

Currently, the esterification of fatty acids with alcohols is achieved commercially using liquid catalysts, such as sulfuric acid, hydrochloric acid and p-toluenesulfonic acid (Figure 10.4). 

Functionalized mesoporous materials with organosulfonic groups have also been used in the esterification of fatty acids with alcohols." " The increased hydrophobic character of the catalyst surface resulted in high catalytic activity... 

Ester synthesis of fatty acid ethyl ester. The lipase-catalyzed esterification of fatty acid and alcohol is well-known. It was also favorable for the esterification of poly unsaturated fatty acids under mild conditions with the enzyme. However, the activity of native lipase is lower in polar organic solvents, i.e. ethanol and methanol. The synthesis of Ae fatty acid ethyl ester was carried out in ethanol using the palmitic acid-modified lipase. As shown in Figure 7, the reactivity of the modified lipase in this system was much higher than that of the unmoditied lipase. 

Glucose transport into cell provides glycerol phosphate to permit esterification of fatty acids supplied by lipoprotein transport... 

Esterification of fatty acids is not random C12-C16 are esterified principally at the sn-2 position while C4 and C6 are esterified principally at the sn-3 position (Table 3.8). The concentrations of C4 and C18 appear to be rate-limiting because of the need to keep the lipid liquid at body temperature. Some features of the structures are notable ... 

The esterification of fatty acids in the mammary cell has been reported as a function of the microsomes and mitochondria (Bauman and Davis 1974 Moore and Christie 1978). While both microsomes and mitochondria may have acyltransferase activity, it has been observed to be 10 times greater in the microsomal fraction of the rat mammary cell (Tanioka et al. 1974). Based on autoradiographic studies, it appears that most synthesis of milk TG occurs in the rough endoplasmic reticulum of mouse mammary tissue (Stein and Stein 1971). 

Schlenk. H. and Gellerman, J. L. 1960. Esterification of fatty acids with diazomethane on a small scale. Anal. Chem. 32 1412-1414. 

Yoon, S. H. Nakaya, H. Ito, O. Miyawaki, O. Park, K. H. Nakamura, K. Effects of Substrate Solubility in Interesterification with Riolein by Immobilized Lipase in Supercritical Carbon Dioxide. Biosci. Biotechnol. Biochem. 1998, 62, 170-172. Yu, Z. R. Rizvi, S. S. H. Zollweg, J. A. Enzymatic Esterification of Fatty Acid Mixtures from Milk Fat and Anhydrous Milk Fat with Canola Oil in Supercritical Carbon Dioxide. Biotechnol. Prog. 1992, 8, 508-513. 

This reaction offers several advantages when compared to esterification of fatty acids, mainly owing to the possibility of using vegetable oils as substrates. In this case, a vegetable oil and an alcohol are used as substrates in the production of glycerol and fatty acid alkyl esters. Conventionally, acid and basic catalysts have been used (4,5). However, the use of acid catalysts usually results in low conversions. The use of basic catalysts require the utilization of vegetable oils with low free fatty acid con-... 

Methyl esterification of fatty acids with methanol is generally conducted in the presence of acid catalyst at an elevated temperature close to the boiling point of methanol. Recently, we found that fatty acids could be successfully methyl esterified in supercritical methanol without the use of a catalyst (10). In addition, from a comparative study between transesterification of vegetable oil and alkyl esterification of fatty acids with supercritical alcohols at 300°C in a batch-type reaction system, the reaction rates of alkyl esterification were found to be faster than those of transesterification (11). An additional finding was that alkyl esterification of fatty acids could be performed at a lower reaction temperature than transesterification. 

The same procedure and equipment for hydrolysis were used in the second step methyl esterification of fatty acids by supercritical methanol treatment. Authentic fatty acids as well as fatty acids prepared by hydrolysis (the products of subcritical water treatment) and methanol were charged into the reaction vessel at a molar ratio of 42 in methanol for all runs. 

Methyl Esterification of Fatty Acids with Supercritical Methanol... 

The second part of the present work deal with methyl esterification of fatty acids, the hydrolyzed products of triglycerides, in supercritical methanol treatment. We investigated the methyl esterification of several fatty acids present in rapeseed oil such as palmitic, oleic, linoleic and lino-lenic acids by supercritical methanol at 270°C and 17 MPa. Figure 4 shows... 

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