Sodium lauryl sulfate

Chembox new
Name = Sodium dodecyl sulfate
ImageFile = SDS-2D-skeletal.png ImageSize = 300
ImageFile1 = SDS-sheet-3D-balls.png ImageSize1 = 300
IUPACName = Sodium dodecyl sulfate
OtherNames = Sodium monododecyl sulfate; Sodium lauryl sulfate; Sodium monolauryl sulfate; Sodium dodecanesulfate; dodecyl alcohol, hydrogen sulfate, sodium salt; n-dodecyl sulfate sodium; Sulfuric acid monododecyl ester sodium salt;
Section1 = Chembox Identifiers
CASNo = 151-21-3
SMILES = CCCCCCCCCCCCOS(=O)( [O-] )=O. [Na+]
Section2 = Chembox Properties
Formula = NaC₁₂H₂₅SO_{4
MolarMass = 288.38 g mol⁻¹
Density = 1.01 g/cm³
MeltingPt = 206 °C
BoilingPt =}

Sodium lauryl sulfate (SLS) or sodium dodecyl sulfate (SDS or NaDS) (C₁₂H₂₅SO₄Na) is an anionic surfactant that is used in industrial products including engine degreasers, floor cleaners, and car wash soaps; as well as in household products such as toothpastes, shampoos, shaving foams, some dissolvable aspirins, fiber therapy caplets, and bubble baths for its thickening effect and its ability to create a lather. The molecule has a tail of 12 carbon atoms, attached to a sulfate group, giving the molecule the amphiphilic properties required of a detergent.

Preparation

Sodium lauryl sulfate is prepared by esterification of sulfuric acid with dodecanol (lauryl alcohol, C₁₂H₂₅OH), followed by neutralization with sodium carbonate. [cite web | publisher = Chemicalland21 | url = http://chemicalland21.com/specialtychem/perchem/SODIUM%20LAURYL%20SULFATE.htm | title = Sodium Lauryl Sulfate] It is used in both industrially produced and home-made cosmetics.

Applications

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, and the aggregation number at this concentration is usually considered to be about 50. The micelle ionization fraction (α) is around 0.3 (or 30%).cite journal | author = Barney L. Bales, Luis Messina, Arwen Vidal, Miroslav Peric, and Otaciro Rangel Nascimento | title = Precision Relative Aggregation Number Determinations of SDS Micelles Using a Spin Probe. A Model of Micelle Surface Hydration | journal = J. Phys. Chem. B | year = 1998 | volume = 102 | issue = 50 | pages = 10347–10358 | doi = 10.1021/jp983364a]

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.Kazuyoshi Watanabe, Shuntaro Imai and Yasuhiko H. Mori. Surfactant effects on hydrate formation in an unstirred gas/liquid system: An experimental study using HFC-32 and sodium dodecyl sulfate. Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522. "Japan.Chemical Engineering Science." Volume 60, Issue 17, September 2005, Pages 4846-4857. [http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFK-4G7X9W5-6&_user=10&_coverDate=09%2F30%2F2005&_alid=442706800&_rdoc=1&_fmt=summary&_orig=browse&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=a323a5a6de479105ae8ddd8dd87162f3 Abstract] ]

DS-PAGE

Sodium lauryl sulfate is commonly used in preparing proteins for electrophoresis in the SDS-PAGE technique. [The acronym expands to "sodium dodecyl sulfate-polyacrylamide gel electrophoresis.] 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 SLS bind to the main peptide chain at a ratio of one SLS anion for every two amino acid residues. This effectively imparts a negative charge on the protein that is proportional to the mass of that protein (about 1.4 g SLS/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 SLS causes proteins to unfold into a rod-like shape thereby eliminating differences in shape as a factor for separation in the gel.

Reactions

SLS can be converted by ethoxylation to sodium laureth sulfate (sodium lauryl ether sulfate; SLES), which is less harsh on the skin, probably because it is not as much of a protein denaturant as is the unethoxylated substance.Fact|date=May 2008

afety

When handling SLS in its solid form use extreme caution; the compound easily particalizes into the air. If inhaled, it can cause a serious choking hazard.

A number of health concerns about SLS have been raised in published reports.Agner T. Susceptibility of atopic dermatitis patients to irritant dermatitis caused by sodium lauryl sulphate. "Acta Derm Venereol." 1991;71(4):296-300. PMID 1681644] A. Nassif, S. C. Chan, F. J. Storrs and J. M. Hanifin. Abstract: Abnormal skin irritancy in atopic dermatitis and in atopy without dermatitis. "Arch Dermatol." November 1994;130(11):1402. [http://archderm.ama-assn.org/cgi/content/abstract/130/11/1402 Abstract] ] Marrakchi S, Maibach HI. Sodium lauryl sulfate-induced irritation in the human face: regional and age-related differences. "Skin Pharmacol Physiol." 2006;19(3):177-80. Epub 2006 May 4. PMID 16679819] These studies indicate that:

* SLS may cause a number of skin problems (for which the non-specific term is "dermatitis"), with some people being affected more than others.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.] Loffler H, Effendy I. Skin susceptibility of atopic individuals. Department of Dermatology, University of Marburg, Germany. "Contact Dermatitis." 1999 May;40(5):239-42. PMID 10344477]
* SLS in toothpaste may cause aphthous ulcers, commonly referred to in some countries as "canker sores". [cite journal | author = Herlofson B, Barkvoll P | title = Sodium lauryl sulfate and recurrent aphthous ulcers. A preliminary study. | journal = Acta Odontol Scand | volume = 52 | issue = 5 | pages = 257–9 | year = 1994 | pmid=7825393 | url=http://www.healthychoices.ukhq.co.uk/Articles/SLS-Ulcers.pdf | format=PDF | doi = 10.3109/00016359409029036 ] Chahine L, Sempson N, Wagoner C. The effect of sodium lauryl sulfate on recurrent aphthous ulcers: a clinical study. "Compend Contin Educ Dent." 1997 Dec;18(12):1238-40. PMID 9656847] Herlofson BB, Barkvoll P. The effect of two toothpaste detergents on the frequency of recurrent aphthous ulcers. "Acta Odontol Scand." 1996 Jun;54(3):150-3. PMID 8811135] However, some studies find no connection between SLS in toothpaste and mouth ulcers. [cite journal | author = Healy C, Paterson M, Joyston-Bechal S, Williams D, Thornhill M | title = The effect of a sodium lauryl sulfate-free dentifrice on patients with recurrent oral ulceration. | journal = Oral Dis | volume = 5 | issue = 1 | pages = 39–43 | year = 1999 | pmid=10218040 | doi = 10.1111/j.1365-2133.2005.06490.x]

ee also

* Ammonium lauryl sulfate

References

External links

* [http://tomsofmaine.custhelp.com/cgi-bin/tomsofmaine.cfg/php/enduser/std_adp.php?p_faqid=2&p_created=1158586355&p_sid=ed3QIp*i&p_accessibility=0&p_redirect=&p_lva=&p_sp=cF9zcmNoPSZwX3NvcnRfYnk9JnBfZ3JpZHNvcnQ9JnBfcm93X2NudD05Miw5MiZwX3Byb2RzPSZwX2NhdHM9JnBfcHY9JnBfY3Y9JnBfc2VhcmNoX3R5cGU9YW5zd2Vycy5zZWFyY2hfbmwmcF9wYWdlPTE*&p_li=&p_topview=1 Tom of Maine's FAQ: Is sodium lauryl sulfate (SLS) safe for use?]
* [http://www.snopes.com/inboxer/household/shampoo.asp Urban Legends Reference Pages: Shampoo Sham, snopes.com]
* [http://hpd.nlm.nih.gov/cgi-bin/household/brands?tbl=chem&id=98 Household Products Database of products containing sodium lauryl sulfate]