SOLUTIONS OF ALKALI SOAPS AND WATER IN FATTY ACIDS .3. IR AND NMR INVESTIGATIONS

IR and NMR studies of the solutions L2 have yielded following information on the structure of the solutions in this region. Sodium caprylate dissolves in water-free caprylic acid to form an acid soap with the composition 1 NaC8 ·2 HC8 dissolved in the acid. The soap and acid are bound by strong hydrogen bonds. When water is added to this solution these bonds are dissolved and the water molecules bound; only at a water content of 40-50 per cent is this process completed. The destruction of the strong hydrogen bonds between soap and acid enable more fatty acid to be bound to the soap in the concentration range where there is enough acid - that is when the caprylic acid content is higher than 70 per cent; in this range there forms an acid soap with the composition 1 NaC8·3 HC8·x H2O. Spectroscopic measurements in the long, narrow salient of the region L2 show that in the solution when the water content exceeds 40-50 per cent free" water occurs. At the same concentration there begins a greatly increased interaction between the methylene groups of the hydrocarbon chains. The results are consistent with the view that the solution changes from being a hydrocarbon-continuous one to being a water-continuous one. © 1969 Dr. Dietrich Steinkopff Verlag."