The Solubilities of the Normal Saturated Fatty Acids in Water

Abstract

Solubilities of saturated fatty acids in water reported by John and McBain (1) are one-fifth to one-tenth of those reported by Ralston and Hoerr (2). As a result of these discrepancies, it was decided to reopen the study.EXPERIMENTAL Preparation of Materials. The fatty acids used in this work were highly purified samples prepared by Mr. R. S. Sedgwick. Freezing points of the acids were as follows: octanoic, 16.63°; nonanoic, 12.52°; decanoic, 31.49°; hendecanoic, 28.59°; dodecanoic, 44.16°; tetradecanoic, 54.25°. Water with a conductivity of 1 micromho was used in making up all solutions.Procedure. Most of the determinations were made on fatty-acid solutions saturated by heating to 100°, shaking, then placing in a constant-temperature bath with a regulation range of ±0.05°. In several cases, saturation was also approached from a lower temperature, and in all such runs identical values were obtained. The minimum saturation time at the desired temperature was 16 hours. This time was checked in some cases by starting from an over-or under-saturated state, and was found to be adequate. During the saturation period, the solution was stirred by bubbling purified nitrogen through it. The nitrogen had previously been led through soda-lima and then water.To measure a volume of solution for analysis, a pipet of 149.4 cc. capacity was built into the constant-temperature bath in such a way that most of the path for transporting the solution from the saturation flask to the pipet was in the water-bath. This system was so arranged that the solution was exposed only to the purified-nitrogen atmosphere.The cell consisted of unplatinized platinum electrodes built into a 300-ec. round flask. The constant was approximately 0.

Ecophysiology of syntrophic communities that degrade saturated and unsaturated long-chain fatty acids

“…When a hydrocarbon radical is large, the strength of the carboxyl group is not enough to bring the molecule of acid to the solution. Solubility of palmitic (C16:0) and stearic (C18:0) acids at 20 °C is 0.72 and 0.29 mg LCFA per 100 g of water; shorter chain fatty acids have higher solubility, for example 79.0 mg of caprylic acid (C8:0) can be dissolved in 100 g of water at 30 °C (Eggenberger et al , 1949). Unsaturated LCFA, have slightly higher solubilities; for example, linoleic acid (C18:2) solubility in 6.7 °C water is 16 mg LCFA per 100 mL of water (Mabrouk & Dugan, 1961).…”

Solubility of Saturated Fatty Acids in Water at Elevated Temperatures

“…The solubility of oil, fat and fatty acids in water would be an important and basic parameter. However, there are only a few reports on such solubility at temperatures lower than 609 C. [12][13][14] In this context, we measured the solubility of fatty acids with even carbon numbers of 8 to 18 in water at 609 C to 2309 C under pressures of 5 and 15 MPa.…”

Method of creating starch‐like ultra‐fine rice flour and effect of spray drying on formation of free fatty acid

“…Instead they form a floating film on the top with the carboxyl group oriented toward water and the non-polar groups oriented toward the gaseous phase. The saturated FFA, on the other hand, are more water soluble in nature and the solubility of FFA in water increases with decreasing carbon number or chain length and increasing temperature; butyric acid is completely soluble in water and stearic acid is the least soluble in nature [24][25][26]. These soluble FFA can then enter the starch granules to form amylose-lipid complexes [27].…”