Sodium Octyl Sulfate
Synonyms
Sodium n-Octyl Sulfate;
SOS;
Sulfuric acid, monooctyl ester, sodium salt;
Octyl sulfate, sodium salt;
Category
Anionic Surfactant
> Sulfate
>> Chain Alcohol Sulfate
>>> Alkanol Sulfate
>>>> Linear Alkanol Sulfate
Chemical Numbering System
CAS: 142-31-4
EINECS: 205-535-5
Molecular Formula & Molecular Weight
Molecular Formula: C8H17NaO4S; C8H18O4S.Na
Molecular Weight: 232.27
Structure
Properties
Appearance (1), solid; (2), liquid.
Odor faint characteristic odor.
Solubility soluble in water.
Physical - chemical properties
|
Melting point, °C |
181 - 183[1] |
|
CMC, 20°C, mmol/L |
130 / 134[1] |
|
HLB |
42 |
Stability stable in alkali, weak acid and hard water; unstable in strong acid, hydrolyzed, reduced to alcohol.
Risk Solid form: flammable material; irritation, moderate irritation to skin, eye, respiratory. Harmful products of combustion are CO, CO2 and so on. Contact with strong oxidants, can cause to burn.
GHS label: 
Liquid form: irritation, moderate irritation to skin, eye.
GHS label:
Animal Toxicity
Table 1 Animal toxicity values
|
mouse intraperitoneal LD50 |
396mg/kg[2] |
|
rat oral LD50 |
3200mg/kg[2] |
Ecology may be hazardous to environment. Water body should be given special attention.
Biodegradability biodegradable.
Characteristics excellent wetting, permeating, cleansing, emulsifying, hydrotropic, dispersing, solubilizing abilities. Resistant to hard water. Low foaming. Resistant to ozone. Easy to rinse.
Note (1), Avoid using in children cleaning products, such as shower gels, shampoo, skin care products.
Synthesis
Currently, sulfated reaction through continuous reactor (such as: falling film reactor) is the most widely used method for preparing sulfates.
Generally, octyl alcohol and sulfur trioxide react through reactor, then sodium hydroxide neutralizes, finally obtain product.
US patent 8,921,588 (Process for preparing sulfates and/or sulfonates in a micro-reaction system) presents a synthetic process. Conditions: mole ratio of sulfur trioxide and alcohols or other raw materials: 1:1; temperature: 30-60°C; reactor: falling film reactor.
US patent 6,455,488 (Process of making alkyl sulfate granulates) describes the preparation of a particulate alkyl sulfate, but does not involve the synthesis process.
US patent US 6,331,645 (Process for preparing powdery alkyl sulfates) describes the preparation of a powdery alkyl sulfate, but does not involve the synthesis process.
Quality Standards & Test Methods
1, Physical and chemical indexes
|
Item |
Physical and chemical indexes |
|
Liquid |
|
|
Actives, %, ≥ |
32.0 - 34.0 |
|
Solid content (1h, 120°C), ≥ |
34.0 - 37.0 |
|
Soluble materials in petroleum ether, %, ≤ |
1.0 |
|
Sodium chloride, %, ≤ |
0.5 |
|
Sodium sulfate, %, ≤ |
1.7 |
|
Sodium bicarbonate, %, ≤ |
0.25 - 0.45 |
|
pH (25°C, 10% solution) |
9.5-10.5 |
|
Color, Gardner, ≤ |
4 |
Test Methods
(1), Actives
GB/T 5173 Surface active agents and detergents -- Determination of anionic-active matter by direct two-phase titration procedure
ISO 2271 Surface active agents -- Detergents -- Determination of anionic-active matter by manual or mechanical direct two-phase titration procedure
(2), Solid content
In the drying oven, 120°C, 1h, weigh and calculate.
(3), Soluble materials in petroleum ether
GB/T 11989 Anionic surface active agents -- Determination of soluble matter content in light petroleum
ISO 894 Surface active agents -- Technical sodium primary alkylsulphates -- Methods of analysis
(4), Sodium chloride
GB/T 15963 Sodium lauryl sulfate
ISO 894 Surface active agents -- Technical sodium primary alkylsulphates -- Methods of analysis
(5), Sodium sulfate
GB/T 15963 Sodium lauryl sulfate
ISO 894 Surface active agents -- Technical sodium primary alkylsulphates -- Methods of analysis
(6), Sodium bicarbonate
Chinese Pharmacopoeia 2015 Edition Sodium bicarbonate
(7), pH
GB/T 6368 Surface active agents -- Determination of pH of aqueous solution - Potentiometric method
ISO 4316 Surface active agents -- Determination of pH of aqueous solutions -- Potentiometric method
(8), Color (Gardner)
GB/T 22295 Standard test method for color of transparent liquids (Gardner Color Scale)
ISO 4630 Clear liquids -- Estimation of colour by the Gardner colour scale
2, Hazardous substances indexes
|
Item |
Hazardous substances indexes |
|
|
Solid |
Liquid |
|
|
Heavy metals (as Pb), mg/kg, ≤ |
20 |
20 |
|
As, mg/kg, ≤ |
3 |
3 |
Test Methods
(1), Heavy metals (as Pb)
Safety and Technical Standards for Cosmetics (2015 Edition)
GB/T 30799 The test method of food detergents -- Determination of heavy metals
(2), As
Safety and Technical Standards for Cosmetics (2015 Edition)
GB/T 30797 The test method of food detergents -- Determination of total arsenic
3, Further explanation
(a), On physical and chemical indexes: firstly, shall be indicated carbon atom distribution; secondly, shall be indicated average molecular weight.
Major Uses
1, Typical applications
Use as wetting agent, permeating agent widely.
Use as hydrotrope.
2, Household detergents
Main ingredient or auxiliary ingredient for cleansing agent in dishwashing detergent, laundry detergent and other household products.
Particularly suitable for using as dishwasher cleaning agent.
3, Industrial cleaning agents
Main ingredient or auxiliary ingredient for cleansing agent in car cleaning products, metal cleaning products and other industrial cleaning products.
4, Emulsion polymerization
Emulsifier, particle size controlling agent in emulsion polymerization. Such as polyacrylamide emulsion, polycarbonate emulsion, polyurethane emulsion and so on.
5, Textile
Use as mercerizing agent.
6, Pets
Main ingredient or auxiliary ingredient for cleansing agent in shampoos and other pet products.
7, Fire extinguishing agent
Use as foaming agent.
Manufacturers
References
[1]: OECD. Category of Alkyl sulfates, Alkane Sulfonates and α-Olefin Sulfonates. SIDS Initial Assessment Report for SIAM 25. 2007.
[2]: ChemIDplus. Sodium Octyl Sulfate, 142-31-4
Update: 20131018(1); 20160809(2);