The measurement of the hydrolysis of solutions of sodium salts of fatty acids. I.

Abstract

Summary pH values of recrystallized samples of sodium acetate, NaAc.3H2O, measured with the Beckman pH meter at 25°C., using the “blue glass” electrode were near pH 8, rather than the calculated and true value for pure sodium acetate of 8.88. Titration curves were made beginning with decinormal solution of the slightly acid salt and adding sodium hydroxide; the pH at the inflection of these curves was near the correct value, 8.8. Sodium hydroxide titration curves in aqueous solution were made at 50°C. for myristic acid and lauric acid, decinormal at the equivalence point. The point of inflection came after the equivalence point, giving the values of hydrolysis alkalinity for these two soaps. Sodium hydroxide titrations in 80% alcohol at room temperature were made in the presence of phenolphthalein for Eastman myristic, Kahlbaum lauric, Lepkovsky myristic and the very pure Francis lauric acid. Concentrations at the equivalence point were about N/60. In every case the equivalence point, the point of inflection, and the color change coincided with the color change occurring near an apparent pH of 10.5 as indicated in alcohol. The solubility of Eastman lauric acid was measured in a number of non‐aqueous solvents at temperatures ranging from 23 to 26°C. Solubility was least in a sample of Braun‐Knecht‐Heimann medicinal mineral oil.