Description
Sodium dodecyl sulfate is an anionic surfactant, and is a typical representative of sulphate-based surfactant. It is abbreviated as SDS, and also known as AS, K12, coco alcohol sulfate, sodium lauryl sulfate and foaming agent. The commercial products are usually white to light yellow crystalline powder. It is non-toxic, slightly soluble in alcohol, insoluble in chloroform and ether, soluble in water, and has good anionic and nonionic complex compatibility. It has good emulsibility, foamability, and foaming, infiltrating, decontaminating and dispersing properties. It is abundant in foams and quickly biodegradable, and has solubility next only to fatty alcohol polyoxyethylene ether sodium sulphate (abbreviated as AES). It is not sensitive to alkali and hard water, but its stability is inferior to general sulfonate under acidic conditions and is close to AES. It is not favorable to exceed 95 °C upon long-term heating, and its irritation is at the middle level among surfactants, with an irritation index of 3.3 for a 10% solution, which is higher than AES and lower than sodium dodecyl benzene sulfonate (abbreviated as LAS). Toxicity LD50 is 1300mg/kg. There is no evidence that this product is carcinogenic, but high doses may indeed irritate the skin. However, in general sanitary products the concentration is limited when used as a forming agent, and is in line with national standards. So there is no need to concern.
Sodium dodecyl sulfate is a major component of detergent. It is usually used in the DNA extraction process to separate DNA after protein denaturation. It is often misread as sodium dodecyl sulfonate. It is widely used as a foaming agent in toothpaste, soap, shower gel, shampoo, detergent and cosmetics. 95% of personal care products and household cleaning products contain sodium lauryl sulfate.
The above information is edited by the chemicalbook of Jin Yinxue.
Chemical Properties
Sodium lauryl sulfate consists of white or cream to pale yellow coloured crystals, flakes, or powder having a smooth feel, a soapy, bitter taste, and a faint odor of fatty substances. It is easily soluble in water.
Uses
Wetting agent, detergent, especially in the textile industry. Electrophoretic separation of proteins and lipids. Ingredient of toothpastes.
Uses
Sodium dodecyl sulfate is an emulsifier and whipping aid that has a solubility of 1 g in 10 ml of water. It functions as an emulsifier in egg whites. It is used as a whipping aid in marshmallows and angel food cake mix. It also functions to aid in dissolving fumaric acid.
Production Methods
Sodium lauryl sulfate is prepared by sulfation of lauryl alcohol,
followed by neutralization with sodium carbonate.
Definition
ChEBI: Sodium dodecyl sulfate is an organic sodium salt that is the sodium salt of dodecyl hydrogen sulfate. It has a role as a detergent and a protein denaturant. It contains a dodecyl sulfate.
Application
Sodium dodecyl sulfate(151-21-3) has excellent detergency, emulsification and foaming power, can be used as detergents and textile auxiliaries, and is also used as an anionic surfactant, toothpaste foaming agent, mine fire extinguishing agents, foaming agents for fire extinguishers, emulsion polymerization emulsifiers, emulsifying and dispersing agents for medical use, shampoo and other cosmetic products, wool detergent, detergent for silky class fine fabrics and flotation agent for metal beneficiation.
GB 2760-96 stipulates as processing aids for food industry. It used as foaming agents; emulsifying agents; and anionic surfactants. It is used for cakes, drinks, proteins, fruits, fruit juice, and edible oil, and so on.
It is used as surfactants, detergents, foaming agents, and wetting agents, and so on.
It is used as relatively low-level ion-pairing reagents, and is cheaper than sodium heptanesulfonate and sodium pentanesulfonate when less demanding.
It is used as raw material for modifying materials.
It is used as additives in capillary electrophoresis analysis and is generally used as molar solution.
It is also used in other analysis such as flow column analysis.
Preparation
Sodium dodecyl sulfate can be synthesized by reacting dodecyl alcohol with sulfur trioxide gas, followed by neutralization with sodium hydroxide. The preparation of SDS involves the following steps: The reaction takes place in a vertical reactor at 32 °C. Nitrogen gas is introduced through the gas vents at a flow rate of 85.9 L/min. Lauryl alcohol is added at a flow rate of 58 g/min at 82.7 kPa. Liquid sulfur trioxide is fed into the flash evaporator at 124.1 kPa, with a flow rate of 0.9072 kg/h and a flash temperature of 100 °C. The sulfated product is quickly cooled to 50 °C, aged for 10-20 min, then neutralized with a base in a neutralization kettle controlled at 50 °C. The pH is adjusted to 7-8.5, and the liquid product is spray dried to obtain a solid product.
General Description
White to pale yellow paste or liquid with a mild odor. Sinks and mixes with water.
Air & Water Reactions
Insoluble in water.
Reactivity Profile
DODECYL SULFATE is incompatible with strong oxidizers. Sodium dodecyl sulfate is also incompatible with cationic materials and with acids with pH below 2.5. Salts, basic, such as DODECYL SULFATE, are generally soluble in water. The resulting solutions contain moderate concentrations of hydroxide ions and have pH's greater than 7.0. They react as bases to neutralize acids. These neutralizations generate heat, but less or far less than is generated by neutralization of the bases in reactivity group 10 (Bases) and the neutralization of amines. They usually do not react as either oxidizing agents or reducing agents but such behavior is not impossible.
Health Hazard
Inhalation of dust causes sneezing and coughing. Ingestion of large amounts causes irritation of stomach. Dust irritates eyes and may cause burns on prolonged contact. Contact with skin causes some irritation; continued exposure to water solution causes drying out and cracking.
Fire Hazard
Flash point data for Sodium dodecyl sulfate are not available; however, Sodium dodecyl sulfate is probably combustible.
Pharmaceutical Applications
Sodium lauryl sulfate is an anionic surfactant employed in a wide
range of nonparenteral pharmaceutical formulations and cosmetics.
It is a detergent and wetting agent effective in both alkaline and
acidic conditions. In recent years it has found application in
analytical electrophoretic techniques: SDS (sodium dodecyl sulfate)
polyacrylamide gel electrophoresis is one of the more widely used
techniques for the analysis of proteins; and sodium lauryl sulfate
has been used to enhance the selectivity of micellar electrokinetic
chromatography (MEKC).
Biochem/physiol Actions
Sodium dodecyl sulphate?(SDS) helps to quickly disrupt the biological membranes. It is usually used as one of the major constituent of several reagents, that are used to purify nucleic acids. SDS can block the activity of RNase and deoxyribonuclease (DNase).
Contact allergens
This anionic detergent is widely used in cosmetics and industry. As a skin irritant agent, SLS can be used in several dermatological applications. It is also a good indicator of excited skin during patch testing.
Safety Profile
Poison by intravenous and intraperitoneal routes. Moderately toxic by ingestion. An experimental teratogen. A human skin irritant. An experimental eye and severe skin irritant. A mild allergen. Mutation data reported. When heated to decomposition it emits toxic fumes of SO, and Na2O. See also ESTERS and SULFATES.
Safety
Sodium lauryl sulfate is widely used in cosmetics and oral and
topical pharmaceutical formulations. It is a moderately toxic
material with acute toxic effects including irritation to the skin,
eyes, mucous membranes, upper respiratory tract, and stomach.
Repeated, prolonged exposure to dilute solutions may cause drying
and cracking of the skin; contact dermatitis may develop.(3)
Prolonged inhalation of sodium lauryl sulfate will damage the
lungs. Pulmonary sensitization is possible, resulting in hyperactive
airway dysfunction and pulmonary allergy. Animal studies have
shown intravenous administration to cause marked toxic effects to
the lung, kidney, and liver. Mutagenic testing in bacterial systems
has proved negative.
Adverse reactions to sodium lauryl sulfate in cosmetics and
pharmaceutical formulations mainly concern reports of irritation to
the skin or eyes following topical application.
Sodium lauryl sulfate should not be used in intravenous
preparations for humans. The probable human lethal oral dose is
0.5–5.0 g/kg body-weight.
LD50 (mouse, IP): 0.25 g/kg
LD50 (mouse, IV): 0.12 g/kg
LD50 (rat, oral): 1.29 g/kg
LD50 (rat, IP): 0.21 g/kg
LD50 (rat, IV): 0.12 g/kg
storage
Sodium lauryl sulfate is stable under normal storage conditions.
However, in solution, under extreme conditions, i.e. pH 2.5 or
below, it undergoes hydrolysis to lauryl alcohol and sodium
bisulfate.
The bulk material should be stored in a well-closed container
away from strong oxidizing agents in a cool, dry place.
Purification Methods
Purify this detergent by Soxhlet extraction with pet ether for 24hours, followed by dissolution in acetone/MeOH/H2O 90:5:5(v/v) and recrystallisation [Politi et al. J Phys Chem 89 2345 1985]. It has been purified by two recrystallisations from absolute EtOH, aqueous 95% EtOH, MeOH, isopropanol or a 1:1 mixture of EtOH/isopropanol to remove dodecanol, and dried under vacuum [Ramesh & Labes J Am Chem Soc 109 3228 1987]. SDS has also been purified by repeatedly foaming whereby a 0.15% aqueous solution is made to foam and the foam is discarded, then the H2O is removed in vacuo and the residue is diluted to the required concentrations [see Cockbain & McMullen Trans Faraday Soc 47 322 1951] or by liquid-liquid extraction [see Harrold J Colloid Sci 15 280 1960]. Dry it over silica gel. For DNA work it should be dissolved in excess MeOH passed through an activated charcoal column and evaporated until it crystallises out. It has also been purified by dissolving in hot 95% EtOH (14mL/g), filtering and cooling, then drying in a vacuum desiccator. Alternatively, it is crystallised from H2O, vacuum dried, washed with anhydrous Et2O and dried in vacuum again. These operations are repeated five times [Maritato J Phys Chem 89 1341 1985, Lennox and McClelland J Am Chem Soc 108 3771 1986, Dressik J Am Chem Soc 108 7567 1986]. [Beilstein 1 IV 1847.]
Properties and Applications
|
INDEX/GRADE
|
SPECIFICATION
|
|
Appearance
|
Needle form without hard lumps
|
|
Active matter
|
92% min
|
|
Petroleum eth soluble substances
|
1.5% max
|
|
Inorganic salts (NaCl+Na
2
SO
4
)
|
5.5% max
|
|
Water
|
5.0% max
|
|
pH value (1% aq. solution)
|
7.5-9.5
|
|
Whiteness (WG)
|
80 min
|
|
Heavy metal
|
20ppm max
|
|
As
|
3ppm max
|
Incompatibilities
Sodium lauryl sulfate reacts with cationic surfactants, causing loss
of activity even in concentrations too low to cause precipitation.
Unlike soaps, it is compatible with dilute acids and calcium and
magnesium ions.
Sodium lauryl sulfate is incompatible with salts of polyvalent
metal ions, such as aluminum, lead, tin or zinc, and precipitates with
potassium salts. Solutions of sodium lauryl sulfate (pH 9.5–10.0)
are mildly corrosive to mild steel, copper, brass, bronze, and
aluminum.
Regulatory Status
GRAS listed. Included in the FDA Inactive Ingredients Database
(dental preparations; oral capsules, suspensions, and tablets; topical
and vaginal preparations). Included in nonparenteral medicines
licensed in the UK. Included in the Canadian List of Acceptable
Non-medicinal Ingredients.
