Sodium Dodecyl Sulfate

[151-21-3]  · C12H25NaO4S  · Sodium Dodecyl Sulfate  · (MW 288.38)

(used in surfactant-based reaction media)

Alternate Names: SDS; sodium lauryl sulfate; SLS.

Physical Data: mp 204-207 °C.

Solubility: sol H2O; insol Et2O; critical micelle concentration (CMC) in H2O (25 °C) = 8.1 mM.1

Form Supplied in: colorless or white solid.

Analysis of Reagent Purity: commercially available sodium dodecyl sulfate generally contains 1-dodecanol,2 which yields a minimum at the CMC in plots of surface tension vs. concentration. The presence of 1-dodecanol can be detected by an HPLC method.3 Impurities can also include surfactant homologs and electrolytes,2 which yield low surface tension values above the CMC.

Preparative Methods: by sulfation of 1-dodecanol with Sulfur Trioxide, followed by neutralization of the resultant dodecylsulfuric acid with Sodium Hydroxide.4

Purification: recrystallization from H2O and EtOH.5

Handling, Storage, and Precautions: harmful if inhaled or swallowed and is irritating to the eyes and skin; should be stored under nitrogen.2b

General Considerations.

In H2O, SDS forms micelles above its CMC. Aqueous micellar solutions solubilize neutral organic compounds that would otherwise be insoluble in H2O alone. Synthetic applications of micellar SDS have generally involved its ability to solubilize simultaneously both H2O-insoluble organic substrates and H2O-soluble (inorganic) reagents, and thus to facilitate their reactions under homogeneous conditions. An organic compound with even modest polarity is normally solubilized within a micelle in a preferred time-averaged orientation with the polar portion near or at the micelle-H2O interface and the nonpolar portion directed into the micelle's hydrocarbon interior. In several of the examples given below, regioselectivity has resulted from these orientational effects. The features and principles of micellar catalysis have been reviewed,6 including coulombic attraction and repulsion of ionic reagents from charged micelle-H2O interfaces. SDS can also be used to form microemulsions, which are isotropic, optically transparent dispersions of oil (hydrocarbon) in water or water in oil. Microemulsions are formed from specific proportions of a surfactant, a cosurfactant (usually a low molecular weight alcohol), H2O, and a hydrocarbon. Compared to aqueous micellar solutions, microemulsions can solubilize greater amounts of H2O-insoluble organic compounds and thus offer greater reaction capacity.

Electrophilic Aromatic Substitution.

Micellar SDS has been used as a reaction medium for the chlorination and bromination of alkyl phenyl ethers4,5a,7 and phenol7b,8 by several halogenating agents (eq 1). Compared to reactions in H2O alone, the para:ortho product ratio increased for pentyl, nonyl, and dodecyl phenyl ether, and decreased for anisole. Enhanced ortho relative to para substitution was obtained with phenol. In each case the observed regioselectivity derived at least in part from alignment of the substrate at the micelle-H2O interface and resultant differential steric shielding of the para and ortho positions by the micelle superstructure.

Electrophilic Addition to Alkenes.

Hydroxy- and alkoxymercurations of alkenes have been performed in micellar SDS.9 Hydroxymercuration of (1) with Mercury(II) Acetate, followed by reduction with Sodium Borohydride, gave a greatly enhanced yield of (2) in micellar SDS (90%) relative to that obtained in THF-H2O (20-25%) (eq 2).9a Also, the reactions of (1) and the related limonene9a gave greater cyclic ether:diol product ratios in the SDS environment than in aq THF. Both the enhanced yields and ratios were attributed to anisotropic solubilization of the alkylmercurial intermediate in a relatively H2O-poor micellar microenvironment. The hydroxymercuration of an aromatic diene, p-diallylbenzene, did not display enhanced chemoselectivity (mono vs. diol formation) in micellar SDS relative to THF-H2O.9b This result suggests that the micellar solubilization sites of aromatic substrates and reaction intermediates are more H2O-rich than those of aliphatic systems.

Alkoxymercuration of 1-octene in micellar SDS by added primary alcohols gave 2-octyl alkyl ethers.9b Thus when a given alcohol cannot be employed as both the reactant and solvent in the alkoxymercuration of an alkene, the use of micellar SDS-alcohol could be an attractive option.

Oxidation and Reduction.

Hypochlorite oxidations of alcohols to aldehydes and acids and of primary amines to nitriles have been performed in micellar SDS.10,11 A microemulsion composed of SDS, 1-butanol, H2O, and cyclohexane has been used for the very rapid oxidation of ethyl 2-chloroethyl sulfide to the corresponding sulfone by hypochlorite.12 SDS has been used as a catalyst in the oxidations of 3,6-dimethoxydurene and xylenes by Cerium(IV) Ammonium Nitrate under two-phase conditions.13 Selective reductions of a,b-unsaturated aldehydes and ketones have been performed with NaBH4 in micellar SDS.14 Compared to reactions in EtOH and H2O, greater fractions of unsaturated alcohols were obtained, relative to saturated alcohols.

Cyclization.

The acid-catalyzed cyclization of (+)-citronellal (3) in H2O gives diols (4) and (5) (2:1 ratio) as the major products (eq 3).15a In micellar SDS, the product ratio increases to 5:1 and the rate of cyclization also increases.15a The product and rate effects in micellar SDS are consistent with orientational effects for reactive conformations of (3) at the micelle-H2O interface. Furthermore, the cyclization can be performed in micellar SDS with concentrations of (3) far above its solubility in H2O alone. Micellar SDS significantly altered the ratio of acyclic to cyclic alcohol products in the acid-catalyzed solvolysis of linalyl acetate.15b

In micellar SDS and vesicular dipalmitoylphosphatidylcholine (DPPC), the aggregate-H2O interfaces induce stereoselectivity in the radical cyclization of bromohydrin (6) (eq 4).16 In C6H6 and pH 10 buffer the (7):(8) ratios are 0.77 and 1.03, respectively, whereas in the pH 10 buffer with SDS and DPPC the (7):(8) ratios are 2.29 and 2.39, respectively. These results are consistent with differential stabilization at the aggregate-H2O interfaces of the diastereomeric transition states leading to (7) and (8).

Miscellaneous.

Diazonium ion (10), formed from amine (9) (eq 5), in the presence of H3PO2 gives (11) with, and (12) without, micellar SDS.17

There have been many other reports of reactions of organic substrates performed in micellar SDS under conditions that would not be synthetically useful.6 Generally, the focus of these studies has been kinetics and/or regio- and stereoselectivity. However, the clear potential exists for the application of their results to organic synthesis. The conditions under which SDS undergoes acid- and base-catalyzed hydrolyses (eq 6) are generally more severe than those used in reactions performed in micellar SDS;18 thus the hydrolysis of SDS can usually be neglected.

Synthetic Application of Other Surfactants.

In most cases, other anionic surfactants would be expected to offer results comparable to those obtained above with SDS. Cationic surfactants such as hexadecyltrimethylammonium bromide catalyze reactions involving anionic reagents.6 In general, the isolation of organic products from surfactant-based reaction media can be facilitated by the use of cleavable surfactants.19 A cleavable surfactant can be converted into nonsurfactant products after its use in a surfactant-based reaction solvent, thereby eliminating problems resulting from the presence of a surfactant during workup, such as the formation of persistent emulsions.


1. Mukerjee, P.; Mysels, K. J. Nat. Stand. Ref. Data Ser. 1971, NSRDS-NBS 36, 66.
2. (a) Vijayendran, B. R. J. Colloid Interface Sci. 1977, 60, 418. (b) Smith, A. J. Colloid Interface Sci. 1978, 66, 575.
3. Czichocki, G.; Vollhardt, D.; Much, H. J. Colloid Interface Sci. 1983, 95, 275.
4. Jaeger, D. A.; Robertson, R. E. JOC 1977, 42, 3298.
5. (a) Jaeger, D. A.; Wyatt, J. R.; Robertson, R. E. JOC 1985, 50, 1467. (b) Mukerjee, P.; Cardinal, J. R. J. Phys. Chem. 1978, 82, 1620.
6. (a) Fendler, J. H.; Fendler, E. J. Catalysis in Micellar and Macromolecular Systems; Academic: New York, 1975. (b) Fendler, J. H. Membrane Mimetic Chemistry; Wiley: New York, 1982.
7. (a) Jaeger, D. A.; Clennan, M. W.; Jamrozik, J. JACS 1990, 112, 1171. (b) Onyiriuka, S. O.; Suckling, C. J. JOC 1986, 51, 1900.
8. (a) Onyiriuka, S. O.; Suckling, C. J.; Wilson, A. A. JCS(P2) 1983, 1103. (b) Onyiriuka, S. O.; Suckling, C. J. CC 1982, 833. (c) Onyiriuka, S. O. Bioorg. Chem. 1986, 14, 97.
9. (a) Link, C. M.; Jansen, D. K.; Sukenik, C. N. JACS 1980, 102, 7798. (b) Sutter, J. K.; Sukenik, C. N. JOC 1982, 47, 4174. (c) Sutter, J. K.; Sukenik, C. N. JOC 1984, 49, 1295. (d) Livneh, M.; Sutter, J. K.; Sukenik, C. N. JOC 1987, 52, 5039.
10. Jursic, B. S 1988, 868.
11. Jursic, B. JCR(S) 1988, 168.
12. Menger, F. M.; Elrington, A. R. JACS 1990, 112, 8201.
13. Skrzewski, J.; Cichacz, E. BCJ 1984, 57, 271.
14. Jursic, B.; Sunko, D. E. JCR(S) 1988, 202.
15. (a) Clark, B. C., Jr.; Chamblee, T. S.; Iacobucci, G. A. JOC 1984, 49, 4557. (b) Clark, B. C., Jr.; Chamblee, T. S.; Iacobucci, G. A. JOC 1989, 54, 1032.
16. Wujek, D. G.; Porter, N. A. T 1985, 41, 3973.
17. Abe, M.; Suzuki, N.; Ogino, K. J. Colloid Interface Sci. 1983, 93, 285.
18. (a) Kurz, J. L. J. Phys. Chem. 1962, 66, 2239. (b) Garnett, C. J.; Lambie, A. J.; Beck, W. H.; Liler, M. JCS(F1) 1983, 79, 953.
19. Jaeger, D. A.; Jamrozik, J.; Golich, T. G.; Clennan, M. W.; Mohebalian, J. JACS 1989, 111, 3001, and references therein.

David A. Jaeger

University of Wyoming, Laramie, WY, USA



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