Potassium laurate

Fig. 28.—Polymerization of isoprene in emulsion at 50°C using 0.3 g of K2S2O8 per 100 g. of monomer, and with the amounts of soap (potassium laurate) indicated in weight percent and in molality m. (Harkins. )...

Hayduk, W. and Laudie, H. "Vinyl chloride gas compressibility and solubility in water and aqueous potassium laurate solutions, J. Chem. Eng. Data, 19(3) 253-257, 1974a. 

Fig. 4-3 Plot of percent conversion versus time for emulsion polymerizations of styrene with different concentrations of potassium laurate at 60° C. The moles of emulsifier per polymerization charge (containing 180 g H2O, 100 g styrene, 0.5 g K2S2O8) are 0.0035 (plot 1), 0.007 (plot 2), and 0.014 (plot 3). After Williams and Bobalek [1966] (by permission of Wiley-Interscience, New York).

Potassium laurate [10124-65-9] M 338.4. Recrystd three times from EtOH [Neto and Helene JPC 91 1466 1987]. 

The composition data obtained for the series of mixed fatty acid-potassium soap systems, prepared by both the ethanol and petroleum ether routes, lend strong support to the formation of 1 to 1 acid-soap complexes. It is of interest to inquire into the phase relationships in these two-component systems. A phase diagram presented by McBain and Field (15) for the lauric acid-potassium laurate system shows that compound formation takes place between the two components at the 1 to 1 molar ratio, but the compound undergoes melting with decomposition at 91.3 °C. [A similar type of phase behavior has been reported by us for the sodium alkyl sulfate-alkyl alcohol (9) and sodium alkyl sulfonate-alkyl alcohol (12) systems, but in these cases the stoichiometry is 2 to 1]. 

Figure 1 shows the results obtained by Francois and Skoulios (27) on the conductivity of various liquid crystalline phases in the binary systems water-sodium lauryl sulfate and water-potassium laurate at 50 °C. As might be expected, the water-continuous normal hexagonal phase has the highest conductivity among the liquid crystals while the lamellar phase with its bimolecular leaflets of surfactant has the lowest conductivity. Francois (28) has presented data on the conductivity of the hexagonal phases of other soaps. She has also discussed the mechanism of ion transport in the hexagonal phase and its similarity to ion transport in aqueous solutions of rodlike polyelectrolytes. 

Figure 1. Electrical conductivity of liquid crystalline phases in water-sodium lauryl sulfate (Curve 1) and water-potassium laurate (Curve II) systems (27).

With spin echo NMR techniques, Charvolin and Rigny (40) found a diffusion coefficient of about 2 X 10"6 cm2/sec for potassium laurate in the cubic liquid crystalline phase it forms with water. 

A spectrum of perdeuterated potassium laurate in oriented soap-water multilayers (5) is presented in Figure 2. The measured quadrupolar coupling constants are much smaller than those of a static C-D bond, which are about 167 kHz (6) the residual quadrupolar splittings... 

Discussion. We can now propose a coarse description of the paraffinic medium in a lamellar lyotropic mesophase (potassium laurate-water). Fast translational diffusion, with D 10"6 at 90 °C, occurs while the chain conformation changes. The characteristic times of the chain deformations are distributed up to 3.10"6 sec at 90 °C. Presence of the soap-water interface and of neighboring molecules limits the number of conformations accessible to the chains. These findings confirm the concept of the paraffinic medium as an anisotropic liquid. One must also compare the frequencies of the slowest deformation mode (106 Hz) and of the local diffusive jump (109 Hz). When one molecule wants to slip by the side of another, the way has to be free. If the swinging motions of the molecules, or their slowest deformation modes, were uncorrelated, the molecules would have to wait about 10"6 sec between two diffusive jumps. The rapid diffusion could then be understood if the slow motions were collective motions in the lamellae. In this respect, the slow motions could depend on the macroscopic structure (lamellar or cylindrical, for example)... 

KC189JO[Pg.180]

The results for effects upon mechanical stability are summarised in Table II. That lithium laurate behaves similarly to, say, potassium laurate is perhaps surprising, in that it is known that a lithium salt is mor ffective in reducing the mechanical stability of natural rubber -ftian is the corresponding potassium salt (6.). The inference has been drawn that the counterion of the car-boxylate soap has a negligible effect upon the ability of the soap to enhance mechanical stability, relative to the effect of the anion, at least for those cations for which specific adsorption effects are absent. 

Pesticidal soaps are potassium salts of fatty acids. The most effective soaps are potassium salts of capric (C10), lauric (C12), myristic (C14), palmitic (C16), and stearic (C,8) acids (Ware and Whitacre, 2004). The chemical structure of potassium laurate is as follows ... 

Examples of pharmaceutical importance include potassium laurate, CH3(CH2)ioCOO K, and sodium lauryl sulphate, CH3(CH2)iiS04 Na" ". 

In the polymerization of styrene or the copolymerization of isoprene and styrene, a soap such as potassium laurate has been found to be a powerful catalyst. The reaction, starting from an emulsion of monomer drops, ends with polymer particles, and is characterized both by the gradual disappearance of the soap from the aqueous phase during the reaction, and by the fact that the polymer particles, much smaller than in an uncatalyzed reaction, increase in size as the yield of polymer is increased. 

Several other pyrolytic studies were performed on nylon 6. In one such study [4], the influence of several aliphatic carboxylates on nylon 6 thermal degradation was studied. The carboxylates that were evaluated include sodium butyrate, sodium caproate, sodium a-ethylcaproate, sodium caprylate, sodium laurate, potassium caproate, potassium laurate, and lithium caproate. Small amounts of these aliphatic carboxylates strongly increase the thermal decomposition rate even at 280° C. The effect of aliphatic carboxylates can be explained by the deprotonation of one of the amide groups of the polymer followed by the nucleophilic substitution of a neighboring carbonyl group, in a reaction as shown below ... 

Potassium laurate (potassium dodecanoate) [10124-65-9] M 338.4. Recrystallise it three times from EtOH [Neto Helene J Phys Chem 91 1466 1987]. [Beilstein 2 H 360,2 I 156,2 II 318, 2 HI 880, 2 IV 186.] See purification of sodium dodecanoate below. 

In an emulsion polymerization of isoprene with 0.10 M potassium laurate at 50°C the estimated time required for 100% conversion at steady rate is 30 h. The final latex has 40 g of polymer per 100 mL with particles of 450 A diameter. During stage II, the growing swollen polymer particles contain 20 g of monomer per 100 mL of swollen polymer. Assuming that there is no change in total volume on polymerization, estimate the polymerization rate constant from these data. Assume that the polymer has a density of 0.90 g/cm . 

The most effective additives for increasing the stability of the foam produced by surfactant solutions appear to be long-chain, often water-insoluble, polar compounds with straight-chain hydrocarbon groups of approximately the same length as the hydrophobic group of the surfactant. Examples are lauryl alcohol for use with sodium dodecyl sulfate, Af,/V-bis(hydroxyethyl) lauramide for use with dodecylbenzenesulfonate, lauric acid for use with potassium laurate, and N,N-dimethyldodecylamine oxide for use with dodecylbenzenesulfonate and other anionics. 

It may be mentioned that the stearate above i 5 normal is hardly a solution, 1 5N sodium stearate at 90° is a viscid gum On the other hand, 2 oN potassium laurate solution with a similarly shaped curve is a clear oily liquid The form of the curve is thus due to the constituents in the system and is not due to mechanical effects, eg gel formation, skins on the surface, or other changes of state The effect is also not due to hystensis, as is the case m the dehydration of certain gels, for it is independent of the age or method of preparation of the soap solution or whether water may have been previously added or taken away It will be pointed out later that the existence of the minimum m the boiling pomt nse is due to dehydration of the colloidal constituents, thereby releasing a quantity of solvent which effectively dilutes the solution and thus produces a diminished nse in the boiling point Were it not for this, the boiling point would nse steadily all the way with increase m concentration... 

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