Melting points, fatty acids

Fatty acid Melting Point (°C) Fatty Acid Melting Point (°C)... 

The melting points of fatty acids. Melting points of both saturated and unsaturated fatty acids increase as the number of carbon atoms in the chain increases. The melting points of unsaturated fatty acids are lower than those of the corresponding saturated fatty acid with the same number of carbon atoms. Also, as the number of double bonds in the chain increases, the melting points decrease. 

Mixed Soap Crystals in Super-Fatted Formulations A small quantity of fatty acid, usually less than 10%, is added to normal soap to produce a super fatted soap. The fatty acid is added to the soap phase at temperatures above the fatty acid melting point and new solid crystalline and liquid crystalline phases are formed on cooling. 

The melting points of the pure saturated fatty acid-DETA derivatives were over 100°C and possessed low solubility in most organic solvents. The unsaturated fatty acid-diamides had much lower melting points. The industrial fatty-DETA derivatives with the exception of the product from hydrogenated tallow fatty acids melted at 60°C or below. 

Fig. 9. Phase equilibria for the bile salt (bile acid)-fatty acid-water system at constant water concentration in relation to temperature (see Fig. 5). Six mixtures varying in molar ratios of bile salt (bile acid) and palmitic acid with total concentration of micellar bile acid plus palmitic acid equal to 40 mM were examined. Fatty acid has a finite solubility in the micellar bile acid solution, the excess being crystalline at body temperature. At 50-60 C, there is a marked increase in micellar solubility, and the fatty acid melts. At higher fatty acid/bile acid ratios, the micellar solubility is exceeded, and an immiscible oil phase occurs. The melting point of fatty acid in the presence of water is nearly identical to that in the anhydrous state (38), in contrast to the behavior of monoglyceride (Table I). As shown in Fig. 3, the size of the micellar area decreases with increasing chain length. Unsaturated fatty acids (not shown) behave similarly to saturated fatty acids, but their micellar solubility is greater, and at most experimental temperatures a crystalline phase will not occur.

Fig. 6. Melting points of mono-, di-, and triglycerides, where H is fatty acid I, triglyceride 1,3-diglyceride and, 1-monoglyceride.

Fa.ts nd Oils. Eats and oils from rendering animal and fish offal and vegetable oilseeds provide nutritional by-products used as a source of energy, unsaturated fatty acids, and palatabiHty enhancement. Eats influence the texture in finished pet foods. The use and price of the various melting point fats is deterrnined by the type and appearance of the desired finished food appearance. 

The major components of camauba wax are aHphatic and aromatic esters of long-chain alcohols and acids, with smaller amounts of free fatty acids and alcohols, and resins. Camauba wax is very hard, with a penetration of 2 dmm at 25°C and only 3 dmm at 43.3°C. Camauba also has one of the higher melting points for the natural waxes at 84°C, with a viscosity of 3960 rare]/s at 98.9°C, an acid number of 8, and a saponification number of 80. 

Substituted Amide Waxes. The product of fatty acid amidation has unique waxlike properties (13). Probably the most widely produced material is N,1S7-distearylethylenediarnine [110-30-5] which has a melting point of ca 140°C, an acid number of ca 7, and a low melt viscosity. Because of its unusuaHy high melting point and unique functionaHty, it is used in additive quantities to raise the apparent melting point of themoplastic resins and asphalts, as an internal—external lubricant in the compounding of a variety of thermoplastic resins, and as a processing aid for elastomers. 

Properties are furthermore determined by the nature of the organic acid, the type of metal and its concentration, the presence of solvent and additives, and the method of manufacture. Higher melting points are characteristics of soaps made of high molecular-weight, straight-chain, saturated fatty acids. Branched-chain unsaturated fatty acids form soaps with lower melting points. Table 1 Hsts the properties of some soHd metal soaps. 

Fatty alcohols were sulfated with concentrated sulfuric acid before World War II, most frequently involving oleyl alcohols or alcohols derived from sperm and whale oil. Low temperatures were often suggested. Oleyl alcohol was sulfated by adding the alcohol to concentrated sulfuric acid, precooled to a temperature only slightly above the melting point of the alcohol [19], or by addition of cooled sulfuric acid (<95.12%) mixed with diethyl ether and phosphorus pentoxide to the alcohol, under constant stirring, for 3 h at 6-7°C, giving a yield of 98% [20]. Oleyl alcohol was also sulfated either by sulfuric acid or by oleum at 15°C [21]. 

Therefore a special N-containing ether carboxylate was developed [36] with a high melting point ( 90°C) with a good foam and low hard water sensibility. This is obtained by condensation of a fatty acid (e.g., lauric acid) with diglycolamine, followed by carboxymethylation with NaOH and SMCA, washing out of the reaction mixture with a aqueous solution of a strong acid, separation of the oil layer, and neutralization with NaOH or KOH. The result is an ether carboxylate with exactly 2 EO units with the structure ... 

It is unlikely in real tribological events that adsorbed mono-layers work solely to provide lubrication. Instead, adsorption and chemical reactions may occur simultaneously in most cases of boundary lubrication. For example, fatty acid is usually regarded as a friction modiher due to good adsorp-tivity, meanwhile its molecules can react with metal or a metal oxide surface to form metallic soap which provides protection to the surface at the temperature that is higher than its own melting point. 

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