Potassium dodecyl sulfate

FIG. 2 Solubility of potassium dodecyl sulfate and sodium alcohol sulfates vs. temperature [68]. 

The surfactant counterion is important in MECC because it affects the Kraft point, that is, the temperature above which the solubility of the surfactant increases sharply as a result of micelle formation SDS has a lower Kraft point than potassium dodecyl sulfate and will therefore reach its CMC at a lower temperature. In MECC, many separation problems can be solved with standard MECC buffers and operating conditions Table 5.4 provides a list of standard operating conditions.19... 

A few practical notes should be emphasized regarding SDS electrophoresis. Potassium salts should be avoided and sodium salts used in their places because potassium dodecyl sulfate is quite insoluble. In addition, even sodium dodecyl sulfate is insoluble below about 10°C. Although not specifically cited above, disc gel electrophoresis may also be used in the presence of SDS. These techniques, described by Studier (11) and Ames (12), are of great advantage when the sample volume is in excess of 10 to 20 /Ltliters per gel. A widely used buffer system for SDS acrylamide gel electrophoresis is that developed by Laemmli (41). 

Organized media have also been used to influence the regiochemical outcome in the reactions. Photoaddition of 3-n-butylcyclopentenone with various terminal alkenes has shown a pronounced preference for the alignment of the enone and the alkenes with their polar groups toward the surface of the micelle. This effect is most pronounced in the case of 1-acetoxy-I-heptene, which gives exclusively the head-to-tail adduct in cyclohexane solvent but a 2.3 1 mixture in favor of the head-to-head isomer in the presence of potassium dodecyl sulfate (equation 13). 

In MEKC, an ionic surfactant is used as a pseudo-stationary phase, and the Krafft point is also an important temperature. At a temperatures lower than the Krafft point, C f does not exceed the CMC, due to reduced solubility and, therefore, no micelle is formed. At the Krafft point, C f reaches the CMC and then the formation of the micelle is begun. The Krafft point of SDS is 16°C in a pure water, whereas it is 31°C for potassium dodecyl sulfate in pure water. Thus, a potassium salt is not an adequate buffer component for the SDS-MEKC system. 

Potassium dodecyl sulfate is difficult to dissolve and SDS precipitates below 10° C. 

Potassium dodecyl sulfate. See Potassium lauryl sulfate... 

Potassium lauryl sulfate CAS 4706-78-9 EINECS/ELINCS 225-190-4 Synonyms Potassium dodecyl sulfate Sulfuric acid, monododecyl ester, potassium salt Definition Potassium salt of lauryl sulfate Empirical C12H26O4S K Formula CH3(CH2)ioCH20S03K Properties M.w. 304.49 anionic Toxicology TSCA listed Uses Surfactant, emulsifier in cosmetics detergent foaming agent in food-pkg. adhesives in paper/paperboard in contact with aq./fatty foods in cellophane for food pkg. food-contact textiles... 

The pH of the micellar mobile phase is usually buffered using the phosphoric or citric acid-base systems. Potassium ion caimot be used with SDS, as potassium dodecyl sulfate precipitates from aqueous solutions due to its high Krafft point (see Chapter 2). The column should be equilibrated by purging with the mobile phase until the pH before and after the column is identical. Only one peak is observed in the chromatograms of weak acids and bases because prototropic equilibria are much faster than the solute-micelle or solute-stationary phase dynamics. 

The surfactant concentration range in the mobile phase is usually relatively narrow. The lowest c( centration should be well above the CMC. Usual values are 0.05 M for SDS and 0.04 M for CTAB. Concentrations exceeding 0.20 M are not convenient due to the high viscosity of the mobile phase and degradation of the efficiencies. Most separations are performed in a buffered medium, phosphoric, and citric acid systems being the most appropriate. It should be taken into account that potassium salts are not compatible with SDS (which is used in more than 60% of the work involving MLC), since potassium dodecyl sulfate may precipitate from aqueous solution at room temperature. 

Trade Names POLYSTEP A-15-30K Potassium dodecyl sulfate. See Potassium lauryl sulfate Potassium ethylenediaminetetrakis (methylene phosphonate)... 

Synonyms Potassium dodecyl sulfate Sulfuric acid, monododecyl ester, potassium salt... 

The polymerization reaction is conducted at the desired temperature with a slow stirring regime for a certain period. A typical recipe for the emulsion polymerization of styrene is exemplified in Table 1 [40]. As seen here, potassium persulfate and sodium dodecyl sulfate were used as the initiator and the stabilizer, respectively. This recipe provides uniform polystyrene particles 0.22 /Lim in size. 

Salts of monovalent metals of alcohol and alcohol ether sulfates are soluble in water, with the solubility dependend on the cation and the chain length. Ammonium salts are more soluble than sodium salts and these are more soluble than potassium salts. On the other hand, sulfates with short hydrophobic chains are more soluble than those with longer chains but the short-chain molecules have a solubilizing effect on the more insoluble longer chain molecules [68], The solubility of sodium salts of different alcohol sulfates is shown in Fig. 2 and the solubility of sodium and potassium salts of dodecyl sulfate is compared. 

DVB (purity > 98 %) was polymerized using sodium dodecyl sulfate (SDS) as emulsifier in the presence of various initiators, such as potassium persulfate (PPS) [51,77-82], 2,2 -azobisisobutyronitrile (AIBN) [83] and also by thermal initiation [84]. 

In Figure 4, the values of log cmc are presented as a function of the logarithm of total concentration of counter ion, log[X]. The slopes of these plots are -0.67 for sodium dodecyl sulfate, -0.6 for potassium dodecanoate, and -0.9 for disodium dodecyl phosphate. 

In accordance with Equation 22, the values of log cmc + (Pll/-) log f+ are also plotted against log[X] in the same figure. Thelinear relations obtained now give slopes of -0.9 for sodium dodecyl sulfate and potassium dodecanoate, and -1.8 for disodium dodecyl phosphate, which are in fairly good agreement with the theoretical values of -1 and -2, respectively. The results obtained here suggest that the condensation of counter ions on the ionic micellar surface and the reduction of electrostatic energy play important roles in the ionic micelle formation. 

Water-soluble l,3-bis(di(hydroxyalkyl)phosphino)propane derivatives were thoroughly studied as components of Pd-catalysts for CO/ethene (or other a-olefins) copolymerization and for the terpolymerization of CO and ethene with various a-olefins in aqueous solution (Scheme 7.17) [59], The ligands with long hydroxyalkyl chains consistently gave catalysts with higher activity than sulfonated DPPP and this was even more expressed in copolymerization of CO with a-olefins other than ethene (e.g. propene or 1-hexene). Addition of anionic surfactants, such as dodecyl sulfate (potassium salt) resulted in about doubling the productivity of the CO/ethene copolymerization in a water/methanol (30/2) solvent (1.7 kg vs. 0.9 kg copolymer (g Pd)" h" under conditions of [59]) probably due to the concentration of the cationic Pd-catalyst at the interphase region or around the micelles which solubilize the reactants and products. Unfortunately under such conditions stable emulsions are formed which prevent the re-use... 

Later, similar experiments were made for cationic networks of polyfdiallyl-dimethylammonium bromide) in the presence of sodium dodecyl sulfate or potassium salts of carboxylic acids with different lengths of hydrocarbon groups [66-68]. 

The protein used was crystalline bovine serum albumin (BSA) obtained from Armour Laboratories. Sodium dodecyl sulfate (SDS) was synthesized from pure dodecyl alcohol and chlorosulfonic acid, recrystallized, and washed with ethyl ether. Sulfuric acid was reagent grade purchased from the J. T. Baker Chemical Co. and used directly. Reagent grade potassium hydroxide purchased from the Mallinkrodt Co. was purified by foaming a concentrated solution, removing the foam, and using the solution directly. 

Contents chromium potassium sulfate dodecahydrate, sodium dodecyl sulfate, dextran sulfate, formamide, phosphate salt, magnesium sulfate, pepsin, polyethylene glycol, and Triton. It has a low toxicity and is irritating to the eyes and skin. It is a colorless, nonviscous liquid. 

In the present experiments greatly enhanced rates of thermal emulsion polymerization were observed when potassium octadecanoate or sodium dodecyl sulfate (at 0.12 mol dm ) whereas sodium dodecyl benzene sulfonate and Triton1 X-100 (Rohm Haas, a non-ionic emulsifier octylphenoxypoly(ethyleneoxy)-ethanol) did not enhance the rate. The conversion after 12 hr at 60 °C with potassium octadecanoate was 69 % whereas with sodium dodecyl benzene sulphonate it was only 29 % (Fig. 2). 

It thus seems that sodium dodecyl sulfate, sodium tetrapropylene benzene sulfonate, and potassium octadecanoate do accelerate the thermal initiation reaction of styrene but that Triton X-100 and sodium dodecyl benzene sulfonate do not although the latter is effective in accelerating thermal initiation of alkyl methacrylates (3 ). ... 

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