Fatty acids with

C22H34O2. A straight-chain fatty acid with 5 double bonds. A major component of fish oils and the oils of marine animals, clupeine Protamine class protein found in the sperm and testicles of the herring. On hydrolysis it gives about 90% of argenine. 

There also exist natural fatty acids with four or more double bonds, fatty acids with hydroxy groups in the molecule, and certain cyclic fatty acids. 

CH3-[CHi]5.CH CH-[CH2]g-C02H. A white solid, m.p. 43-44°C, which is present in small quantities in animal fats and in milk. It is the only naturally occurring fatty acid with the trans configuration. 

Mixing fatty acids with fatty bases can dissolve films as the resulting complexes become water-soluble however, in some cases the mixed Langmuir film is stabilized [128]. The application of an electric field to a mixed lipid monolayer can drive phase separation [129]. 

The term fat is applied to solid esters of fatty acids with glycerol (glycerides) if the fat is liquid at the ordinary temperature, it is conventionally called a fatty oil, vegetable oil or animal oil. The acids which occur most abundantly are palmitic ticid CH3(CHj),4COOH, stearic acid CH3(CH2)isCOOH and oleic acid CH3(CH2),CH=CH(CH2),C00H. Upon hydrolysis, fats yield glycerol and the alkali salts of these acids (soaps) ... 

The free acids are obtained upon acidification. Fata usually consist of mixtures of glycerides. The term wax is usually applied to esters of fatty acids with other alcohols such as cetyl alcohol CH3(CH2),4CHjOH and oleyl alcohol CH3(CHj),CH=CH(CHj),CH30H. 

A few fatty acids with trans double bonds (trans fatty acids) occur naturally but the major source of trans fats comes from partial hydrogenation of vegetable oils m for example the preparation of margarine However the same catalysts that catalyze the... 

Fats and oils are one of the oldest classes of chemical compounds used by humans. Animal fats were prized for edibiUty, candles, lamp oils, and conversion to soap. Fats and oils are composed primarily of triglycerides (1), esters of glycerol and fatty acids. However, some oils such as sperm whale (1), jojoba (2), and orange roughy (3) are largely composed of wax esters (2). Waxes (qv) are esters of fatty acids with long-chain aUphatic alcohols, sterols, tocopherols, or similar materials. 

Detergents may be produced by the chemical reaction of fats and fatty acids with polar materials such as sulfuric or phosphoric acid or ethylene oxide. Detergents emulsify oil and grease because of their abiUty to reduce the surface tension and contact angle of water as well as the interfacial tension between water and oil. Recent trends in detergents have been to lower phosphate content to prevent eutrification of lakes when detergents are disposed of in municipal waste. 

Hlkanolamides. The fatty acid alkanolamides are used widely ia shampoo formulations as viscosity and lather builders. They are formed by the condensation of a fatty acid with a primary or secondary alkanolamine. The early amides were compositions of 2 1 alkanolamine to fatty acid. Available technology allows the formation of amides with a 1 1 ratio of these additives. These amides are classified as superamide types. The typical amide used ia shampoo preparations usually contains the mono- or diethanolamine adduct, eg, lauric diethanolamide [120-40-1] (see Amides, fatty acid). 

The primary products used are fatty acids with 12—18 carboa atoms and fatty alcohols, or esters of fatty acids such as the glycerides of rapeseed and lard oil (18). Eatty acid amines and amides are used ia metal working, particularly ia emulsions (18). 

Based on C18 fatty acids with average eq wt of 280. If the average eq wt of the monobasic acids is significantly different, adjustment is necessary. 

Unsubstituted Amides. The most widely used synthetic route for primary amides is the reaction of fatty acid with anhydrous ammonia (11). Fatty acid and ammonia are allowed to react at approximately 200°C for 10 to 12 h under a constant vent of excess ammonia and water by-product. A pressure of 345—690 kPa (50—100 psi) is maintained by the addition of ammonia while the venting of water faciUtates the completion of the reaction. 

Alkanolamides, a special subclass of substituted amides used as surfactants, are produced by three principal methods the reaction of fatty amides with formaldehyde, fatty acids with hydroxyalkylamines, and fatty esters with hydroxyalkylamines (37). A fatty amide and formalin can be heated in the presence of sodium hydroxide to yield 70—95% substituted alkanolamides (38,39). 

In recent years, especially in the USSR and Europe, synthetic fatty acids, prepared via hydrocarbon oxidation, have been used to prepare fatty amines (2,9). In 1978 Eastern Europeans produced an estimated 0.55 biUion kg of synthetic fatty acids with odd and even numbers of carbon atoms, whereas in the United States, production of natural fatty acids with even carbon atom chain-length acids was 435 million kg. To date, there has been no significant production of synthetic fatty acids in the United States. 

Saponification can proceed direcdy as a one-step reaction as shown above, or it can be achieved indirectly by a two-step reaction where the intermediate step generates fatty acids through simple hydrolysis of the fats and oils and the finishing step forms soap through the neutralization of the fatty acid with caustic soda. There are practical considerations which must be addressed when performing this reaction on a commercial scale. 

Fatty Acid Neutralization. Another approach to produce soap is through the neutralization of fatty acids with caustic. This approach requires a stepwise process where fatty acids are produced through the hydrolysis of fats and oils by water, followed by subsequent neutralization with appropriate caustics. This approach has a number of inherent benefits over the saponification process. 

Two important widely used sulfonic acids are known as TwitcheU s reagents, or as in Russia, the Petrov catalysts. These reagents are based on benzene or naphthalene ( ) and (12), [3055-92-3] and [82415-39-2] respectively. The materials are typically made by the coupling of an unsaturated fatty acid with benzene or naphthalene in the presence of concentrated sulfuric acid (128). These sulfonic acids have been used extensively in the hydrolysis of fats and oils, such as beef tallow (129), coconut oil (130,131), fatty methyl esters (132), and various other fats and oils (133—135). TwitcheU reagents have also found use as acidic esterification catalysts (136) and dispersing agents (137). 

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. 

Regular fatty acid diethanolamides are prepared by heating fatty acid with diethanolamine at 160—180°C for 2—4 h. Superamides are prepared by heating a fatty acid methyl ester with an equimolar amount of diethanolamine at 100—110°C for 2—4 h the methanol formed is distilled off (Table 23). 

Black Liquor Soap Recovery. Black Hquor soap consists of the sodium salts of the resin and fatty acids with small amounts of unsaponifiables. The soap is most easily separated from the black Hquor by skimming at an intermediate stage, when the black Hquor is evaporated to 25% soHds (7). At this soHds level, the soap rises in the skimmer at a rate of 0.76 m/h. At higher soHds concentrations, the tall oil soap is less soluble, but higher viscosity lowers the soap rise rate and increases the necessary residence times in the soap skimmer beyond 3—4 hours. The time required for soap recovery can be reduced by installing baffles, by the use of chemical flocculants (8,9), and by air injection into the suction side of the soap skimmer feed pump. Soap density is controUed by the rate of air injection. Optimum results (70% skimmer efficiency) are obtained at a soap density of 0.84 kg/L (7 lb/gal). This soap has a minimum residual black Hquor content of 15% (10—12). 

Higher grade fatty acids with less than 2% rosin are obtained by further distiUation. Union Camp uses two columns to achieve this. The first column is used to separate light ends and the second column to separate a mixture of rosin and higher boiling fatty acids. This mixture with about 40% rosin is sold as DistiUed TaU Oil (DTO). Standard specifications for TOFA grades have been estabHshed by ASTM (25) as shown in Table 3. Also, the Pulp Chemicals Association provides specifications on TOFA having either more or less than 2% rosin. 

A series of sorbitol-based nonionic surfactants are used ia foods as water-ia-oil emulsifiers and defoamers. They are produced by reaction of fatty acids with sorbitol. During reaction, cycHc dehydration as well as esterification (primary hydroxyl group) occurs so that the hydrophilic portion is not only sorbitol but also its mono- and dianhydride. The product known as sorbitan monostearate [1338-41 -6] for example, is a mixture of partial stearic and palmitic acid esters (sorbitan monopalmitate [26266-57-9]) of sorbitol, 1,5-anhydro-D-glucitol [154-58-8] 1,4-sorbitan [27299-12-3] and isosorbide [652-67-5]. Sorbitan esters, such as the foregoing and also sorbitan monolaurate [1338-39-2] and sorbitan monooleate [1338-43-8], can be further modified by reaction with ethylene oxide to produce ethoxylated sorbitan esters, also nonionic detergents FDA approved for food use. 

Many substituted, ie, branched, fatty acids, particularly methacryUc, 2-ethylhexanoic, and ricinoleic acids, are commercially significant. Several substituted fatty acids exist naturally (Table 5). Fatty acids with a methyl group in the penultimate position are called iso acids, and those with a methyl group in the antepenultimate position are called anteiso acids (1) (see Carboxylic acids, branched-CHAIN acids). However, the term iso is often used in a broader sense to mean branched or mixtures of branched-chain industrial acids. 

Table 6. Some Fatty Acids with Alicyclic Substituents...

The prostaglandins (qv) constitute another class of fatty acids with aUcycHc structures. These are of great biological importance and are formed by i vivo oxidation of 20-carbon polyunsaturated fatty acids, particularly arachidonic acid [27400-91-5]. Several prostaglandins, eg, PGE [745-65-3] have different degrees of unsaturation and oxidation when compared to the parent compound, prostanoic acid [25151 -18-9]. 

Vinyl esters are prepared by the reaction of a fatty acid with either acetjfene in direct condensation or vinyl acetate by acidolysis. 

Z,Z,Z,)-9,12,15-octadecatrienoic acid). Fish oils contain esters of eicosanoic and docosanoic acids with four to six double bonds separated by single methylene groups, eg, (i7//-Z)-4,7,10,13,16,19-docosahexaenoic acid [6217-54-5] in menhaden oil (4). The fatty acid with conjugated double bonds in tung oil is a-eleostearic acid [506-23-0] ((F,Z,F)-9,ll,13-octadecatrienoic acid) the predominant fatty acid in oiticica oil is licanic acid [17699-20-6] (4-oxo-(F,Z,F)-9,ll,13-octadecatrienoic acid). In all oils, other fatty acids including palmitic acid [57-10-3] (hexadecanoic acid), stearic acid [57-11-4] (octadecanoic acid), and oleic acid [112-80-1] ((Z)-9-octadecenoic acid) also are present. 

Synthetic Conjugated Oils. Tung oil dries rapidly, but is expensive, and its films discolor rapidly due to the presence of three double bonds. These defects led to efforts to synthesi2e conjugated oils, especially those containing esters of fatty acids with two conjugated double bonds. 

Lipophilic dyes in aqueous alcoholic solutions can be employed in an analogous manner [92, 93]. They are enriched at the zones of lipophilic substances, so that these appear deeply colored on a pale background. This does not apply to fatty acids with less than 12 C atoms [94]. 

Acids can also be converted to fluorescent dansyl derivatives The reaction of Cg to C24 fatty acids with dansyl semipiperazide or semicadavende provides an excellent example (Fig 34) [87] Odd-numbered and unsaturated fatty acids [88] and propionic, sorbic and benzoic acid [89] can be detected in the same manner... 

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