Reductions sodium dodecyl sulfate

Vinodgopal et al. prepared Pt/Ru bimetallic nanoparticles by sonochemical reduction of Pt(II) and Ru(III) in aqueous solutions. TEM images indicated that sequential reduction of the Pt(II) followed by the Ru(III) produced Pt-core/Ru-shell bimetallic nanoparticles. In the presence of sodium dodecyl sulfate (SDS), as a stabilizer, the nanoparticles had diameters between 5 and 10 nm. When PVP was used as the stabilizer, the rate of reduction is much faster, giving ultrasmall bimetallic nanoparticles of ca. 5nm diameter [141]. 

Clostridium sticklandii also expresses a proline reductase that can reduc-tively cleave proline to 8-aminovalerate (Seto and Stadtman 1976). PR was first purified by Seto and Stadtman (1976) by following the decomposition of proUne in the presence of dithiothreitol or NADH. They found PR to have a denatured mass of approximately 30kDa (sodium dodecyl sulfate-polyacrylomide gel electrophoresis SDS-PAGE) and a native size of approximately 300 kDa. The addition of selenite to the growth medium of C sticklandii did increase the specific activity of PR in extracts by threefold however, no selenium was detected in the purified enzyme. It should be noted that this purified enzyme had lost the ability to couple reduction of proline to NADH and thus probably was missing one or more components of the complete enzyme complex. 

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. 

FORMATION. Aqueous solutions of highly surface-active substances spontaneously tend to reduce interfacial energy of solute-solvent interactions by forming micelles. The critical micelle concentration (or, c.m.c.) is the threshold surfactant concentration, above which micelle formation (also known as micellization) is highly favorable. For sodium dodecyl sulfate, the c.m.c. is 5.6 mM at 0.01 M NaCl or about 3.1 mM at 0.03 M NaCl. The lower c.m.c. observed at higher salt concentration results from a reduction in repulsive forces among the ionic head groups on the surface of micelles made up of ionic surfactants. As would be expected for any entropy-driven process, micelle formation is less favorable as the temperature is lowered. 

The third structure shown in Figure 18 is sodium dodecyl sulfate (SDS), often used by research workers for solubilizing proteins. It is a sulfate ester of the C12 alcohol dodecanol. Commercially, this alcohol is produced by reduction of coconut oil, and the resultant mixture is called lauryl alcohol (from lauric acid, the predominant fatty acid in coconut oU). The alcohol portion of sodium lauryl sulfate is a mixture of chain lengths, the approximate composition being 8% Cg, 7% Cjo, 48% C12, 20% Ci4, 10% C16, and small amounts of longer chains. In bakeries the most common use of sodium lauryl sulfate is as a whipping aid. The compound is added to liquid egg whites at a maximum concentration of 0.0125%, or to egg white solids at a level of 0.1 %. It promotes the unfolding of egg albumin at the air-water interface and the stabilization of the foam. 

A comprehensive study on the sonochemical synthesis of colloidal solutions of noble metals was conducted by Grieser and coworkers [32-34]. The 515 kHz ultrasound-initiated reduction of AuCl4 to Au (0) was examined as a function of the concentration of various surface-active solutes [32]. The amount of AuCU reduced in the presence of ethanol, 1-propanol, and 1-butanol was found to be dependent on the surface excess of the alcohol at the gas/solution interface, i.e., the relative concentration of the alcohol at the gas/solution interface compared to the bulk solution concentration. The efficiency of reduction of AuCl4 in the presence of the surfactants sodium dodecyl sulfate or octaethylene glycol monodecyl ether was found to be related to the monomer concentration of the surfactant in solution. 

Water has been used to accelerate reductions, as in photochemical reduction of the ketone 28 (Figure 4.16) [51], Surfactants have also been shown to aid reactions in water, when sodium dodecyl sulfate was added, the ee rose from 61% to 94% in the preparation of 29 (Figure 4.16) [52]. 

Many surfactants are made from petroleum with hazardous reagents. Sulfur trioxide was used with the carcinogen benzene to make the alkylbenzenesulfonates described earlier. The carcinogen ethylene oxide is used to make many nonionic surfactants from phenols and long-chain alcohols. A common surfactant, sodium dodecyl sulfate, is made from an alcohol derived from coconut oil by reduction followed by treatment with sulfur trioxide. Long-chain tertiary amines derived from natural fats and oils are quat-ernized with methyl chloride. Perhaps this can be done with... 

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