Dioctyl sodium sulphosuccinate or Docusate sodium or Diethylhexyl Sodium Sulfosuccinate is a chemical compound, the sodium salt of docusate.

The name describes the structure of the molecule:

• Dioctyl refers to dioctyl alcohol, a fatty alcohol with a chain of 8 carbons, which forms the basis of the molecule.
• Sodium indicates the presence of sodium ions (Na+) in the compound.
• Sulfosuccinate indicates that a sulphonic acid group has been added to the molecule and that it is a succinic acid derivative.

The synthesis process takes place in different steps:

• Preparation of dioctyl alcohol. Dioctyl alcohol, a fatty alcohol with an 8-carbon chain, is derived from natural sources or synthesised from petrochemical precursors.
• Sulphonation. Dioptyl alcohol is reacted with sulphur trioxide (SO3) in a process called sulphonation. This involves the addition of a sulphonic acid group to the alcohol, forming dioctyl sulphosuccinic acid.
• Neutralisation. The dioctyl-sulphosuccinic acid is then neutralised with a base, such as sodium hydroxide (NaOH), to form the sodium salt, sodium docusate.

It occurs as a colourless to yellowish transparent liquid or white powder that is easily soluble in water. Incompatible with strong acids, strong bases, heavy metal salts and reducing agents. Easy to hydrolyse when it encounters alkalis at high temperature. Flammable.

What it is used for and where

Synthetic anionic detergent

Medical and pharmaceutical

• Docusate sodium is an effective remedy for constipation and in particular as a stool softener. although Psyllium has been shown to be more effective (1).
• It is used to treat ear wax plugs that can cause blocked and painful ears and hearing loss. Methods of removing earwax include the mechanical technique and the use of cerumenolytic agents such as sodium Docusate and sodium bicarbonate.
• It is administered after urogynecological surgery.
• Emulsifier in tablets and pharmaceutical preparations.

Cosmetics

Cleansing agent. Ingredient that cleanses skin without exploiting the surface-active properties that produce a lowering of the surface tension of the stratum corneum. 

Surfactant - Emulsifying agent. Emulsions are thermodynamically unstable and are used to soothe or soften the skin and emulsify, so they need a specific, stabilising ingredient. This ingredient forms a film, lowers the surface tension and makes two immiscible liquids miscible. A very important factor affecting the stability of the emulsion is the amount of the emulsifying agent. Emulsifiers have the property of reducing the oil/water or water/oil interfacial tension, improving the stability of the emulsion and also directly influencing the stability, sensory properties and surface tension of sunscreens by modulating the filmometric performance.

Surfactant - Hydrotrope (solubilizing agents).  It has the property of facilitating the miscibility of other compounds that are poorly soluble in water and does not form micelles in the solubilisation process, even with a chemical reaction of complexation or molecular aggregation. The two fundamental solubilisation factors are the hydrotropic-solute association mediated by the depression of water activity and ionic dissociation.

Surfactant - Cleansing agent. Cosmetic products used to cleanse the skin utilise the surface-active action that produces a lowering of the surface tension of the stratum corneum, facilitating the removal of dirt and impurities. 

Other uses

• Pesticide industry, emulsifier.
• Textile industry: surfactant, penetrating agent and wetting agent below 40°C for cotton, linen, viscose and their blended products.
• Leather industry: penetrating agent.
• Paint industry: levelling agent.
• Photographic material: emulsifier.

Docusate sodium studies

Typical commercial product characteristics Docusate sodium

Appearance	Transparent colourless to yellowish liquid
Boiling Point	82°C
pH	5.0~7.0
Melting Point	173-179°C
Flash Point	199ºC
Density	1.1
Purity	99%
Specific Weight	1.05-1.15 at 25°C
Expiration date	2 years
Specific Gravity	1.05-1.15 at 25°C
PSA	118.18000
LogP	4.89030
Water Solubility	1.5 g/100 mL at 25°C
Storage	2-8°C
Safety

• Molecular Formula C₂₀H₃₇NaO ·₇S
• Linear Formula  CH₃(CH₂)₃CH(C₂H₅)CH₂O₂CCH₂CH(SO₃Na)CO₂CH₂CH(C₂H₅)(CH₂)₃CH₃ 
• Molecular Weight   444.6 
• Exact Mass   444.215759
• CAS  577-11-7
• UNII    F05Q2T2JA0
• EC Number   209-406-4
• DSSTox Substance ID  DTXSID8022959
• IUPAC  sodium;1,4-bis(2-ethylhexoxy)-1,4-dioxobutane-2-sulfonate
• InChI=1S/C20H38O7S.Na/c1-5-9-11-16(7-3)14-26-19(21)13-18(28(23,24)25)20(22)27-15-17(8-4)12-10-6-2;/h16-18H,5-15H2,1-4H3,(H,23,24,25);/q;+1/p-1  
• InChl Key      APSBXTVYXVQYAB-UHFFFAOYSA-M
• SMILES   CCCCC(CC)COC(=O)CC(C(=O)OCC(CC)CCCC)S(=O)(=O)[O-].[Na+]
• MDL number  MFCD00012455
• PubChem Substance ID    24859403
• ChEBI  4674
• RXCUI      71722
• RTECS   WN0525000
• NCI   C29000

Synonyms

• DOSS
• AOT
• Aerosol OT
• Rapisol B 90
• Bis(2-ethylhexyl) sulfosuccinate sodium salt
• Dioctyl sodium sulphosuccinate
• Docusate sodium
• Constonate
• Dioctyl sodium sulfosuccinate
• Doxol
• Dioctyl sulfosuccinate sodium salt

References_______________________________________________________________________

(1) McRorie JW, Daggy BP, Morel JG, Diersing PS, Miner PB, Robinson M. Psyllium is superior to docusate sodium for treatment of chronic constipation. Aliment Pharmacol Ther. 1998 May;12(5):491-7. doi: 10.1046/j.1365-2036.1998.00336.x.