Fatty acid-soap mixtures

Fatty Acids, Soaps, and Fatty Acid-Soap Mixtures... 

Since saturated fatty acids are insoluble in bile acid solutions, and since saturated fatty acid soaps are only soluble in terms of the mole fraction of a soap-bile acid mixture having a critical micellar temperature of 37° C, one would anticipate saturated fatty acid-soap mixtures to have negligible solubility in bile acid solutions. Some years ago, we compared the behavior of sodium, palmitate, and stearate at pH 5.8, 6.2, 6.6, and 7.0 in buffer or buffer containing bile acid. In the absence of bile acid, the saturated fatty acids remained as unwetted crystals. When bile acid was added, the solubility increased measurably but only very slightly. 

Tall oil rosin is a by-product of paper manufacturing. Raw wood chips are digested under heat and pressure with a mixture of sodium hydroxide and sodium sulfide. Soluble sodium salts of lignin, rosin, and fatty acids are formed, which are removed from the wood pulp as a dark solution. The soaps of the rosin and fatty acids float to the top of the mixture, where they are skimmed off and treated with sulfuric acid to free the rosin and fatty acids. This mixture, known as cmde tall oil (CTO), is refined further to remove color and odor bodies fractional distillation separates the tall oil rosin acids from the fatty acids (see Tall oil). 

Near the surfactant region the crystalline or lamellar phase is found. This is the region one finds in hand soaps. The ordinary hand soap is mainly the salt of fatty acid (coconut oil fatty acids or mixtures [85%] plus water [15%] and some salts. X-ray analyses have shown that the crystalline structure consists of a layer of soap separated by a water layer (with salts). The hand soap is produced by extruding under high pressure. This process aligns the lamellar crystalline structure lengthwise. If the degree of expansion versus temperature is measured, the expansion will be found... 

This last case is a combination of the two previous ones, in which the pH has an opposite effect on two surfactants. As shown in Fig. 17 (upper part) and discussed in Sect. 5.2 an increase in pH increases the ionization of the fatty acid, i.e., the proportion of the ionized hydrophilic soap, and hence the hy-drophilicity of the acid-soap mixture in the water phase and consequently at the interface. At low pH, the acid, i.e., a lipophilic nonionic surfactant, prevails, whereas at high pH, it is the hydrophilic soap that dominates the formulation. The pH at which about half of the interfacial mixture is acid and half soap, i.e., the pH at which the interfacial mixture is at optimum formulation (and three-phase behavior is exhibited), is called pH in Fig. 17. 

Explosive Mixtures of High Density. A method of prepn, patented by Cook 8i Davis, involves subjecting two solid chem compds, at least one of which is a nitrated org compd (such as a mixt of TNT, An and (other compds), to a temperature at which at least a portion of one of the compds is in molten condition. To this molten mass is added a dispersing agent (such as a Na alkyl naphthalene sulfonate or other suitable org sulfonate or fatty acid soap) and then, after thorough blending, the mass is cooled and solidified. Several examples with details are given... 

Mix Sodium Carbonate, Rhodafac RA-600, Igepal CO-710 and Tall Oil Fatty Acid Soap together until a uniform powdered mixture is obtained. 

A surfactant molecule is an amphiphile, which means it has a hydrophilic (water-soluble) moiety and a hydrophobic (water-insoluble) moiety separable by a mathematical surface. The hydrophobic tails of the most common surfactants are hydrocarbons. Fluorocarbon and perfluorocarbon tails are, however, not unusual. Because of the hydrophobic tail, a surfactant resists forming a molecular solution in water. The molecules will tend to migrate to any water-vapor interface available or, at sufficiently high concentration, the surfactant molecules will spontaneously aggregate into association colloids, i.e., into micelles or liquid crystals. Because of the hydrophilic head, a surfactant (with a hydrocarbon tail) will behave similarly when placed in oil or when put in solution with oil and water mixtures. Some common surfactants are sodium or potassium salts of long-chained fatty acids (soaps), sodium ethyl sulfates and sulfonates (detergents), alkyl polyethoxy alcohols, alkyl ammonium halides, and lecithins or phospholipids. 

Engblom, J., Engstrbm, S. and Fontell, K. The effect of the skin penetration enhancer Azone on fatty-acid soap-water mixtures. Journal of Controlled Release 33 299-305, 1995. 

Water-in-oil emulsions traditionally contain surfactants of natural origin such as cholesterol, wool fat, wool alcohols, lanolin, divalent salts of fatty acids soaps, calcium oleate and/or synthetic agents of low hydrophilic-lipophilic balance (HLB) (indicating high lipophilicity), such as Spans (fatty acid esters of sorbi-tan). An example of such a product is Oily Cream B.P. which consists of a 1 1 mixture of wool alcohols and water. 

The titre of a soap or a fat is the temperature at which its fatty acid solidifies. As a rule the melting points are not clearly defined because the fatty acids are mixtures. A few examples of titres are given below (°C) ... 

Fatty acids, soaps and fatty acid methyl esters are the most extensively used oleochemicals [13]. The free fatty acids are prepared by hydrolysis of oils and fats by alkalis. This procedure named saponification proceeds at high temperature and pressure and leads to crude soaps the acidification of which gives fatty acids. They are subjected to various purification procedures, and finally isolated individually or as mixtures of carboxylic acids of the general formula RCOOH or as soaps RCOOM. The carboxylic acid methyl esters can be produced in two ways by esterification of the isolated carboxylic acid with methanol or by low-temperature... 

In case of using mixtures of two and more collectors, the selective hydrophobisation is accomplished simultaneously both due to chemisorption and physical adsorption. It is shown in [69] that the simultaneous use of fatty acids and hydrocarbon oils for calcium phosphate flotation from quartz different processes are observed. Fatty acid soaps form chemical compounds on the surface of the material floated, after which the hydrocarbon oil physically adsorbs. It has been experimentally established that hydrocarbon oil is transferred from quartz particles to the surface of floated phosphate. When using mixtures of anionics and nonionics, hydrophobisation of particle surfaces is also accomplished both due to the formation of chemical compounds and physical adsorption which is confirmed by measurements of the zeta-potential of the particles floated [70]. 

Shinoda, K., The Effect of Alcohols on the Critical Micelle Concentrations of Fatty Acid Soaps and the Critical Micelle Concentrations of Soap Mixtures, J. Phys. Chem. 58 ... 

Fig. 10. Phase equilibria of the bile acid (as sodium salt)-fatty acid soap-water phase diagram at constant water concentration in relation to temperature. Mixtures with varying molar ratios of bile acid/sodium soap (total concentration 40 mM) were incubated, and the temperature at which the system became clear was plotted solutions were buffered top i 12. The curves indicate the critical micellar temperature of the system and have also been termed mixed Krafft points (46). The CMT of the bile acids is extremely low.

No studies have been carried out on mixtures of medium-chain fatty acid, soap, and monoglyceride. 

Soap s6p [ME sope, fr. OE sape akin to OHGr seifa soap] (before 12c) n. The detergent obtained by the formation of a sodium or potassium salt of a fatty acid or mixture of fatty acids. 

The fatty acid soap may be added as an alkali metal salt of fatty acids having 10-22 carbon atoms, or prepared in situ by adding alkali metal compounds to the reaction mixture, such as alkali metal hydroxides or salts of volatile organic acids. The quantity of soap can vary within wide limits, e.g.,10-80% by weight of the quantity of polyol. 

Anionic surfactants are the most commonly used type in the emulsion polymerization. These include sulfates (sodium lauryl sulfate), sulfonates (sodium dodecylbenzene sulfonate), fatty acid soaps (sodium or potassium stearate, laurate, palmitate), and the Aerosol series (sodium dialkyl sulphosuccinates) such as Aerosol OT (AOT, sodium bis(2-ethylhexyl) sulfosuccinate) and Aerosol MA (AMA, sodium dihexyl sulphosuccinates). The sulfates and sulfonates are useful for polymerization in acidic medium where fatty acid soaps are unstable or where the final product must be stable toward either acid or heavy-metal ions. The AOT is usually dissolved in organic solvents to form the thermodynamically stable reverse micelles. [22] Nonionic surfactants usually include the Brij type, Span-Tween 80 (a commercial mixture of sorbitol monooleate and polysorbate 80), TritonX-100[polyoxyethylene(9)4-(l,l,3,3-tetramethylbutyl)-phenyl... 

These questions also have a chemical component it would be helpful to understand the relationship between the chemical structure of the monomeric surfactant and the propensity to assemble to giant vesicles. It has been observed that, generally, a small amount of giant vesicles accompanies the formation of normal vesicles. However, this tendency varies strongly from surfactant to surfactant. This situation also occurs in the case of electroformation [2] some surfactants (e.g. fatty acids/soaps, phosphatidyl nucleosides) fail to give giant vesicles by the electro-formation method [3], and in fact the method seems to be restricted to phosphatidylcholine or to lipid mixtures containing phosphatidylcholine. It is fair to say that the relationship between the chemical structure and the propensity to form vesicles is still poorly understood. 

The composite soap is a mixture of a fatty acid soap and a monoglyceride sulfonate (9, 2-35%). 

The base lubricant is usually a petroleum oil while the thickener usually consists of a soap or soap mixture. In addition they may contain small amounts of free alkali, free fatty acid, glycerine, anti-oxidant, extreme-pressure agent, graphite or molybdenum disulphide. 

Calcium complex soap greases, obtained by the reaction of lime and a mixture of fatty acids and acetic acid. These greases offer good high temperature and anti-wear/extreme pressure properties related to the presence, in the soap, of calcium acetate that acts as solid lubricant they have good mechanical stability. 

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