Carboxylic acid esters glycerides

Fats are sometimes converted by transesterification into the methyl esters of carboxylic acids the glycerides are allowed to react with methanol in the presence of a basic or acidic catalyst. The mixture of methyl esters can be separated by... 

Fatty acids are aliphatic mono carboxylic acids, many of which occur as esters of glycerin (glycerides) in natural fats and oils. For example, acetic, butyric, propionic, lauric,... 

Butyric acid is a carboxylic acid also classified as a fatty acid. It exists in two isomeric forms as shown previously, but this entry focuses on n-butyric acid or butanoic acid. It is a colorless, viscous, rancid-smelling liquid that is present as esters in animal fats and plant oils. Butyric acid exists as a glyceride in butter, with a concentration of about 4% dairy and egg products are a primary source of butyric acid. When butter or other food products go rancid, free butyric acid is liberated by hydrolysis, producing the rancid smell. It also occurs in animal fat and plant oils. Butyric acid gets its name from the Latin butyrum, or butter. It was discovered by Adolf Lieben (1836—1914) and Antonio Rossi in 1869. 

Complex lipids are those that are easily hydrolyzed to simpler constituents. Most complex lipids are esters of long-chain carboxylic acids called fatty acids. The two major groups of fatty acid esters are waxes and glycerides. Waxes are esters of long-chain alcohols, and glycerides are esters of glycerol. 

Lipases catalyze the hydrolytic cleavage of triglycerides into fatty acids and glycerol, or into fatty acids and mono or di-glycerides, at oil interfaces in nature. However, this hydrolytic reaction can be reversed and transformed into reactions of esterification (inter or transesterification), alcoholysis or aminolysis by engineering the medium polarity or the water content of the medium. Therefore, substrates for lipases can be esters, like the natural triglyceride substrates in hydrolytic reactions or, if the reaction is reversed, carboxylic acids, alcohols, amines or esters. The reaction medium not only determines the direction of the reaction (hydrolytic or synthetic), but also determines the solubility and stability of lipase substrates. Therefore, lipase activity and selectivity are strongly influenced by reaction medium. 

Com acid Com glycerides Corn oil PEG-6 esters C9-11 pareth-2 C9-11 pareth-3 C9-11 pareth-6 C9-11 pareth-8 C9-11 pareth-10 C9-11 pareth-12 CIO-12 pareth-3 C11-15 pareth-3 C11-15 pareth-5 C11-15 pareth-7 Cl 1-15 pareth-12 Cl 1-15 pareth-15 C11-15 pareth-20 C11-15 pareth-30 C11-21 pareth-3 Cl 1-21 pareth-10 Cl 2-13 pareth-3 Cl 2-13 pareth-4 Cl 2-13 pareth-9 Cl 2-13 pareth-10 Cl 2-13 pareth-15 Cl 2-14 pareth-5 C12-14 pareth-8 C12-14 pareth-11 C12-14 pareth-12 Cl 2-14 pareth-17 Cl 2-14 pareth-22 Cl 2-15 pareth-2 Cl 2-15 pareth-4 Cl 2-15 pareth-5 Cl 2-15 pareth-6 Cl 2-15 pareth-7 Cl 2-15 pareth-9 Cl 2-15 pareth-10 Cl 2-15 pareth-11 Cl 2-15 pareth-12 Cl 2-15 pareth-15 Cl 2-15 pareth-20 Cl 2-15 pareth-23 Cl 3-15 pareth-20 Cl 4-15 pareth-13 C20-40 pareth-3 C20-40 pareth-40 C22-24 pareth-33 C30-50 pareth-10 C30-50 pareth-40 C40-60 pareth-10 Cl 1-15 pareth-7 carboxylic acid Cl2-13 pareth-8 carboxylic acid Cl2-15 pareth-8 carboxylic... 

This less common process involves the interaction of ester and carboxylic acid in the presence of sulphuric acid, a metal oxide (zinc, calcium, magnesium, aluminium) or mercuric sulphate at about 150 °C. Applied to natural glycerides and lauric acid, for example, Ci6 and C q acids are replaced by the C12 acid. 

The Chemical Synthesis of Peptides Carboxylic acids and acyl derivatives of the carboxyl functional group are very important in biochemistry. For example, the carboxylic acid functional group is present in the femily of lipids called fatty acids. Lipids called glycerides contain the ester functional group, a derivative of carboxylic acids. Furthermore, the entire class of biopolymers called proteins contain repeating amide functional group linkages. Amides are also derivatives of carboxylic acids. Both laboratory and biochemical syntheses of proteins require reactions that involve substitution at activated acyl carbons. 

Each OH function of glycerol can react with the -COOH group of a fatty acid, leading to an ester derivative called glyceride. An ester results from the condensation of a carboxylic acid and an alcohol (Fig. 1.11). 

A final class of sulfated alkyl surfactants is that of the sulfated fats and oils in which the sulfate esters are obtained by the treatment of a variety of hydroxylated or unsaturated natural fats and oils with sulfuric or chlorosulfonic acids. These materials represent the oldest types of commercial synthetic surfactants, dating back to the original turkey red oils. Because of the nature of the starting materials and preparation processes, the sulfated fats and oils are chemically heterogeneous materials whose properties are very sensitive to their history. In fact, the preparation of such materials may correctly be considered to be more art than science. They will contain not only sulfated glycerides similar to those discussed above but also sulfated carboxylic acids and hydroxycarboxylic acids produced by hydrolysis of the starting materials. With the increased availability of more chemically pure surfactant materials, the use of the sulfated fatty oils has decreased considerably. They do still have their uses, however, especially where purity is not a major concern and cost is important. 

Q Predict the reactions of lipids under basic hydrolysis and with standard organic reagents. Show the reactions of the ester and olefinic groups of glycerides and the carboxyl groups of fatty acids. Problems 25-16,17,18,19,20,21, 23, and 24... 

The selection of this reagent was based partly on the observation [209] that, because various quaternary ammonium carboxylates undergo thermal decomposition to methyl esters, such esters could be formed in situ in good yield by the simple injection of a methanolic solution of the quaternary ammonium carboxylate above 250°C. Thus, the use of the quaternary ammonium hydroxide in the transesterification scheme described above permits the simultaneous conversion of both glycerides and fatty acids to methyl esters. 

Biodiesel, a mixture of fatty acid methyl esters, is manufactured by transesterification of natural glycerides by MeOH. Zinc laurate, palmitate, and stearate are effective catalysts in this process and a theoretical and experimental study showed that the mechanism involves initial coordination of MeOH followed by a carboxylate ion acting as a general base to generate an incipient alkoxide-like moiety that attacked the coordinated triglyceride. ... 

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