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Sodium dodecyl sulfate
Identifiers
CAS number 151-21-3 Yes check.svgY
ATC code A06AG11
SMILES
Properties
Molecular formula NaC12H25SO4
Molar mass 288.38 g mol−1
Density 1.01 g/cm³
Melting point

206 °C

 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Sodium lauryl sulfate (SLS), sodium laurilsulfate or sodium dodecyl sulfate (SDS or NaDS) (C12H25SO4Na) is an anionic surfactant used in many cleaning and hygiene products. The molecule has a tail of 12 carbon atoms, attached to a sulfate group, giving the molecule the amphiphilic properties required of a detergent.

Contents

Applications

SLS is a highly effective surfactant and is used in any task requiring the removal of oily stains and residues. As such the compound is found in high concentrations in industrial products including engine degreasers, floor cleaners, and car wash soaps. In household products, SLS is used in lower concentrations with toothpastes, shampoos, and shaving foams. It is an important component in bubble bath formulations for its thickening effect and its ability to create a lather.

It has recently found application as a surfactant in gas hydrate or methane hydrate formation reactions, increasing the rate of formation as much as 700 times.[1]

The product can also be used to aid in lysing cells during DNA extraction and for unraveling proteins in SDS-PAGE (see below).

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In medicine

In medicine, sodium laurilsulfate is used rectally as a laxative in enemas, and as an excipient on some dissolvable aspirins and other fiber therapy caplets.

SDS-PAGE

Sodium lauryl sulfate, in science referred to as sodium dodecyl sulfate (SDS), is commonly used in preparing proteins for electrophoresis in the SDS-PAGE technique.[2] This compound works by disrupting non-covalent bonds in the proteins, denaturing them, and causing the molecules to lose their native shape (conformation). Also, anions of SDS bind to the main peptide chain at a ratio of one SDS anion for every two amino acid residues.[citation needed] This effectively imparts a negative charge on the protein that is proportional to the mass of that protein (about 1.4 g SDS/g protein).

This new negative charge is significantly greater than the original charge of that protein. The electrostatic repulsion that is created by binding of SDS causes proteins to unfold into a rod-like shape thereby eliminating differences in shape as a factor for separation in the gel. Sodium lauryl sulfate is probably the most researched anionic surfactant compound. Like all detergent surfactants (including soaps), sodium lauryl sulfate removes oils from the skin, and can cause skin and eye irritation. The critical micelle concentration (CMC) in pure water at 25°C is 0.0082 M[3], and the aggregation number at this concentration is usually considered to be about 62[4]. The micelle ionization fraction (α) is around 0.3 (or 30%).[5]

Synthesis

SLS is synthesized by reacting lauryl alcohol with sulfuric acid to produce hydrogen lauryl sulfate which is then neutralized through the addition of sodium carbonate.[6] Lauryl alcohol is in turn usually derived from either coconut or palm kernel oil by hydrolysis, which liberates their fatty acids, followed by reduction of the acid group to an alcohol.

The actual structure of SLS: CnH2n+1SO4Na (n12)

Due to this synthesis method, SLS is actually not pure dodecyl sulfate but a mixture of alkyl sulfates with dodecyl sulfate as the main component.[7]

Health and safety

SLS has not been proven to be carcinogenic when either applied directly to skin or consumed.[8] SLS however is a strong surfactant and a number of health concerns have been raised in published reports.[9]

  • SLS may worsen skin problems in individuals with chronic skin hypersensitivity, with some people being affected more than others.[10][11][12]
  • SLS in toothpaste may cause aphthous ulcers, commonly referred to in some countries as canker sores.[13][14][15] Using SLS free toothpaste may reduce the sores.[16]
  • SLS has also been shown to irritate the skin of the face with prolonged and constant exposure (more than an hour) in young adults.[17] In animal studies SLS appears to cause skin and eye irritation.[9]

Research suggests that SLS could represent a potential effective microbicide, which can also inhibit and possibly prevent infection by various enveloped and non-enveloped viruses such as the Herpes simplex viruses, HIV, and the Semliki Forest Virus.[18][19]

See also

References

  1. ^ Watanabe K, Imai S, Mori YH (September 2005). "Surfactant effects on hydrate formation in an unstirred gas/liquid system: An experimental study using HFC-32 and sodium dodecyl sulfate.". Chemical Engineering Science 60 (17): 4846–4857. doi:10.1016/j.ces.2005.03.043. 
  2. ^ The acronym expands to "sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
  3. ^ P. Mukerjee and K. J. Mysels, "Critical Micelle Concentration of Aqueous Surfactant Systems", NSRDS-NBS 36, US. Government Printing Office, Washington,.D.C., 197 1.
  4. ^ N.J. Turro. A. Yekta, J. Am. Chem. Soc., 1978, 100, 5951
  5. ^ Barney L. Bales, Luis Messina, Arwen Vidal, Miroslav Peric, and Otaciro Rangel Nascimento (1998). "Precision Relative Aggregation Number Determinations of SDS Micelles Using a Spin Probe. A Model of Micelle Surface Hydration". J. Phys. Chem. B 102 (50): 10347–10358. doi:10.1021/jp983364a. 
  6. ^ SODIUM LAURYL SULFATE, Chemical Land21, http://chemicalland21.com/specialtychem/perchem/SODIUM%20LAURYL%20SULFATE.htm 
  7. ^ European Pharmacopoeia: Sodium laurilsulfate
  8. ^ CIR publication. Final Report on the Safety Assessment of Sodium Lauryl Sulfate and Ammonium Lauryl Sulfate. Journal of the American College of Toxicology. 1983 Vol. 2 (No. 7) pages 127-181.
  9. ^ a b NICNAS
  10. ^ Agner T (1991). "Susceptibility of atopic dermatitis patients to irritant dermatitis caused by sodium lauryl sulphate". Acta Derm. Venereol. 71 (4): 296–300. PMID 1681644. 
  11. ^ Nassif A, Chan SC, Storrs FJ, Hanifin JM (November 1994). "Abnormal skin irritancy in atopic dermatitis and in atopy without dermatitis". Arch Dermatol 130 (11): 1402–7. doi:10.1001/archderm.130.11.1402. PMID 7979441. 
  12. ^ Löffler H, Effendy I (May 1999). "Skin susceptibility of atopic individuals". Contact Derm. 40 (5): 239–42. doi:10.1111/j.1600-0536.1999.tb06056.x. PMID 10344477. 
  13. ^ Herlofson B, Barkvoll P (1994). "Sodium lauryl sulfate and recurrent aphthous ulcers. A preliminary study." (PDF). Acta Odontol Scand 52 (5): 257–9. doi:10.3109/00016359409029036. PMID 7825393. http://www.healthychoices.ukhq.co.uk/Articles/SLS-Ulcers.pdf. 
  14. ^ Chahine L, Sempson N, Wagoner C (December 1997). "The effect of sodium lauryl sulfate on recurrent aphthous ulcers: a clinical study". Compend Contin Educ Dent 18 (12): 1238–40. PMID 9656847. 
  15. ^ Herlofson BB, Barkvoll P (June 1996). "The effect of two toothpaste detergents on the frequency of recurrent aphthous ulcers". Acta Odontol. Scand. 54 (3): 150–3. doi:10.3109/00016359609003515. PMID 8811135. 
  16. ^ Healy C, Paterson M, Joyston-Bechal S, Williams D, Thornhill M (1999). "The effect of a sodium lauryl sulfate-free dentifrice on patients with recurrent oral ulceration.". Oral Dis 5 (1): 39–43. doi:10.1111/j.1365-2133.2005.06490.x. PMID 10218040. 
  17. ^ Marrakchi S, Maibach HI (2006). "Sodium lauryl sulfate-induced irritation in the human face: regional and age-related differences". Skin Pharmacol Physiol 19 (3): 177–80. doi:10.1159/000093112. PMID 16679819. 
  18. ^ Piret J, Désormeaux A, Bergeron MG. (2002). "Sodium lauryl sulfate, a microbicide effective against enveloped and nonenveloped viruses.". Curr Drug Targets 3 (1): 17–30. PMID 11899262. 
  19. ^ Piret J, Lamontagne J, Bestman-Smith J, Roy S, Gourde P, Désormeaux A, Omar RF, Juhász J, Bergeron MG. (2000). "In vitro and in vivo evaluations of sodium lauryl sulfate and dextran sulfate as microbicides against herpes simplex and human immunodeficiency viruses.". J Clin Microbiol 38 (1): 110–9. PMID 10618073. 

External links


Template:Not to be confused with

File:Sodium alkyl sulfates
Sodium laurilsulfate
Systematic (IUPAC) name
Sodium alkyl sulfates
Identifiers
CAS number  ?
ATC code A06AG11
PubChem  ?
Chemical data
Formula CnH2n+1SO4Na (n≈12)
Mol. mass ≈288.4 g/mol
Pharmacokinetic data
Bioavailability  ?
Metabolism  ?
Half life  ?
Excretion  ?
Therapeutic considerations
Pregnancy cat.

?

Legal status
Routes Rectal

Sodium laurilsulfate is a substance used as a laxative in enemas.

Chemically, it is a mixture of sodium alkyl sulfates. The main component is sodium lauryl sulfate, the sodium salt of dodecyl sulfuric acid.[1]

References


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