SORBITAN MONOOLEATE

Sorbitan Monooleate is a nonionic fatty acid ester supplied commercially as a mixture of partial oleate esters, commonly in the form of an amber, viscous liquid.
Sorbitan Monooleate serves principally as an emulsifier and wetting agent in cosmetic, pharmaceutical, food, agricultural, and industrial formulations.
The low hydrophilic–lipophilic balance of Sorbitan Monooleate makes the material especially suited to water-in-oil emulsions and to blends with more hydrophilic emulsifiers. 

CAS Number: 1338-43-8
EC Number: 215-665-4
Molecular Formula: Variable (partial-ester mixture; the principal 1,4-sorbitan monooleate constituent is C24H44O6)
Molecular Weight: Variable (mixture; the principal 1,4-sorbitan monooleate constituent is 428.60 g/mol)

Synonyms: Sorbitan oleate, sorbitan monooleic acid ester, anhydrosorbitol monooleate, SMO, E 494, INS 494, 1,4-Anhydrosorbitol Monooleate, D-Glucitol 1,4-Anhydro-6-(9-Octadecenoate), 1,4-Anhydro-D-Glucitol 6-(9-Octadecenoate), [(2R)-2-[(2R,3R,4S)-3,4-Dihydroxyoxolan-2-yl]-2-hydroxyethyl] (Z)-Octadec-9-enoate, [(2R)-2-[(2R,3R,4S)-3,4-Dihydroxytetrahydrofuran-2-yl]-2-hydroxyethyl] (Z)-Octadec-9-enoate, Span 80, Span-80, Span® 80, S 80, S-80, Arlacel 80, Alkamuls SMO, Armotan MO, Dehymuls SMO, Lonzest SMO, Glycomul O, Sorbitan O, Crill 4, Sorbester P 17, Disponil 100, Montan 80, Montane 80, Montane 80 VGA, Newcol 80, Nonion OP 80R, Nissan Nonion OP 80R, Sorgen 40, Sorgen 40A, Radiasurf 7155, Rheodol AO 10, Rheodol SP-O 10, Nikkol SO-15, Ionet S-80, Atmer 05, Emasol 410, Rikemal O 250, O 250, S 270, S 271, S-MAX 80, Mannide Monooleate

APPLICATIONS

Emulsion formulation

Sorbitan Monooleate is particularly effective when water droplets must be dispersed within a continuous oil phase.
Formulators normally introduce Sorbitan Monooleate into the oil phase before combining the phases, allowing the emulsifier to reach newly formed droplet surfaces during mixing.
At those surfaces, Sorbitan Monooleate helps limit droplet coalescence and supports the structure of a water-in-oil emulsion.
The low hydrophilic–lipophilic balance of Sorbitan Monooleate favors an oil-continuous system.
As water is added under suitable mixing conditions, Sorbitan Monooleate positions its oleate-rich portion toward the oil while its hydroxyl-bearing portion interacts with the aqueous interface.

Droplet size and stability still depend on the oil, water content, mixing energy, and other ingredients accompanying Sorbitan Monooleate.
Sorbitan Monooleate can be paired with a more hydrophilic emulsifier when an oil-in-water emulsion is required.
Changing the proportion of Sorbitan Monooleate in that emulsifier blend changes the combined hydrophilic–lipophilic balance and can alter which phase remains continuous.
A formulation containing Sorbitan Monooleate therefore requires testing with the actual oil or wax blend rather than selection by hydrophilic–lipophilic balance alone. 
Concentrated emulsions present a further use for Sorbitan Monooleate because a large interfacial area develops as droplets are divided and packed closely together.
Sorbitan Monooleate must be available at the interface during emulsification, while sufficient mixing must distribute the aqueous phase through the oil.
Increasing Sorbitan Monooleate without adjusting phase ratio or processing conditions does not by itself establish a stable concentrated emulsion.

Personal care and cosmetics

Sorbitan Monooleate enters water-in-oil creams and lotions as an emulsifier in the continuous oily phase.
When the formula contains appropriate oils, waxes, and water, Sorbitan Monooleate helps keep the dispersed water distributed through the finished cream.
The final texture depends on Sorbitan Monooleate alongside the viscosity of the oil phase, the dispersed-phase volume, and the cooling process.
For products formulated around vegetable oils or other unsaturated lipid ingredients, Sorbitan Monooleate offers a low-HLB emulsifier compatible with an oil-rich design.

The oil phase carries Sorbitan Monooleate to the interface as water is incorporated.
Formulators assess Sorbitan Monooleate against changes in droplet size, viscosity, and appearance during storage.
Sorbitan Monooleate also wets pigments in colour cosmetics before the pigments are distributed through an oil-rich base.
By coating the pigment surface, Sorbitan Monooleate can assist the breakup of dry agglomerates during grinding or mixing.
A uniform pigment dispersion containing Sorbitan Monooleate supports more consistent colour, although pigment treatment and processing remain decisive.
In sun-care formulations, Sorbitan Monooleate can wet and disperse zinc oxide or titanium dioxide particles in an appropriate oil phase.
More even distribution of these mineral particles can help formulators manage settling and visible agglomerates.
The presence of Sorbitan Monooleate does not establish the sun-protection performance of a finished formulation, which depends on the complete composition and testing. 

Oil-in-water cosmetic emulsions may incorporate Sorbitan Monooleate as one part of a mixed emulsifier system.
In that role, Sorbitan Monooleate contributes an oil-affine component while a more hydrophilic partner provides the stronger affinity for the external water phase.
The ratio involving Sorbitan Monooleate is adjusted for the chosen emollients, consistency agents, and intended product texture.
Pharmaceutical formulations
Pharmaceutical-grade Sorbitan Monooleate serves as an excipient in selected topical emulsions and lipophilic bases.
For a water-in-oil topical preparation, Sorbitan Monooleate helps distribute an aqueous phase throughout the continuous ointment or cream base.
Suitability of Sorbitan Monooleate for a particular medicine depends on the specified excipient grade, drug compatibility, and finished-formulation requirements.

Sorbitan Monooleate can wet poorly dispersed solids before incorporation into a lipophilic pharmaceutical base.
Documented examples include the dispersion of zinc oxide and calamine, for which Sorbitan Monooleate helps the oil phase contact particle surfaces.
The resulting uniformity depends on particle size, mixing, and the concentration of Sorbitan Monooleate in the complete preparation.
Sorbitan Monooleate has also been described as a dispersant for penicillin in lipophilic bases.
In such a preparation, Sorbitan Monooleate functions as a formulation excipient rather than as the therapeutic ingredient.
Compatibility and stability of a drug preparation containing Sorbitan Monooleate require evaluation for the specific active ingredient and dosage form. 

Selected pharmaceutical emulsions combine Sorbitan Monooleate with a more hydrophilic surfactant.
By varying the blend, formulators can change the emulsifying balance while Sorbitan Monooleate continues to contribute affinity for the lipid phase.
A pharmaceutical-grade supply of Sorbitan Monooleate must be assessed against the relevant specifications; technical and pharmaceutical grades are not automatically interchangeable.

Food processing and food formulations

Food-grade Sorbitan Monooleate is identified as the additive E 494 or INS 494 and has an established emulsifier and stabilizer function.
Where a particular food use is permitted, Sorbitan Monooleate can contribute to the distribution of oil and water phases in a formulated system.
Food use of Sorbitan Monooleate depends on the applicable jurisdiction, permitted category, and compliance of the supplied grade with the required specifications.

The partial-ester composition of Sorbitan Monooleate matters in food processing because ester distribution influences emulsifying behaviour.
Specifications for food-grade Sorbitan Monooleate therefore include measures such as acid, saponification, and hydroxyl values.
Those measures characterize a qualifying food-additive material and should not be assumed for every industrial grade of Sorbitan Monooleate.
One specifically defined processing application places Sorbitan Monooleate in polymer dispersions used to clarify cane or beet sugar juice or liquor.
Within that dispersion, Sorbitan Monooleate acts as an emulsifier for the processing formulation.
The stated application of Sorbitan Monooleate concerns the defined clarification process and does not establish unrestricted use in other foods. 

Agricultural formulations

Sorbitan Monooleate is recommended as an emulsifier for mineral oils in agricultural formulation work.
When water must be dispersed in a suitable oil phase, Sorbitan Monooleate helps form the interfacial layer around aqueous droplets.
The behaviour of Sorbitan Monooleate changes with the selected oil, water content, and other surfactants in the concentrate. 

A more hydrophilic component can be combined with Sorbitan Monooleate to adjust the response when a concentrate is diluted or otherwise processed.
Formulators test Sorbitan Monooleate in the actual concentrate and dilution water because emulsion behaviour depends on the whole system.
As a nonionic surfactant, Sorbitan Monooleate provides an oil-affine emulsifying component without introducing an ionic head group.
That characteristic can be useful when a formulation designer is balancing Sorbitan Monooleate with other surfactants and dissolved ingredients.
Compatibility of Sorbitan Monooleate with a specific agricultural active ingredient must be demonstrated in the intended formulation.

Industrial fluids, pigments, and cleaning formulations

Sorbitan Monooleate functions as an emulsifier in selected lubricant formulations.
By occupying an oil–water interface, Sorbitan Monooleate can help maintain dispersed droplets where the fluid design calls for an emulsion.
Lubricity, corrosion behaviour, and service stability of a lubricant containing Sorbitan Monooleate are properties of the finished fluid, not of the emulsifier alone.
Pigment concentrates provide another industrial setting for the wetting action of Sorbitan Monooleate.
During dispersion, Sorbitan Monooleate helps a compatible liquid phase contact pigment particles that otherwise retain air or form persistent agglomerates.
The benefit of Sorbitan Monooleate is evaluated through dispersion quality and stability in the specific medium. chemical.kao.com
Sorbitan Monooleate can also act as a wetting component in a solvent-based cleaner or degreaser.

In a documented formulation example, Sorbitan Monooleate assists contact between the cleaning liquid and the treated surface.
Cleaning effectiveness with Sorbitan Monooleate depends on the solvents, soils, surface materials, and other ingredients selected for the formulation. 

Industrial water-in-oil systems may incorporate Sorbitan Monooleate when dispersed water must remain distributed within a hydrocarbon-rich phase.
Sorbitan Monooleate acts at the droplet interface rather than dissolving the two bulk liquids into one phase.
Temperature changes, contaminants, and prolonged storage can alter the stability of a system containing Sorbitan Monooleate.

Specialist and laboratory uses

Sorbitan Monooleate has an established role as an emulsifier in industrial emulsion explosives.
In that application, Sorbitan Monooleate contributes to the water-in-oil structure of a specially engineered emulsion.
The performance and safe manufacture of a formulation containing Sorbitan Monooleate depend on the entire controlled process, rather than on the emulsifier in isolation. 
Laboratories use Sorbitan Monooleate to prepare model water-in-oil emulsions for studies of interfacial behaviour.
Varying Sorbitan Monooleate concentration in a defined oil allows researchers to examine changes in droplet formation and interfacial properties.
These studies clarify the function of Sorbitan Monooleate in a controlled system without establishing identical behaviour in every commercial oil.
Multiple-emulsion research can employ Sorbitan Monooleate to stabilize the inner water-in-oil stage before a second emulsification step.

Sorbitan Monooleate remains associated with the inner droplet interface while another emulsifier may stabilize the outer oil-in-water interface.
The resulting water-in-oil-in-water system is an experimental formulation whose stability depends on both interfaces and the selected phases. PubMed
Sorbitan Monooleate has also been studied as a component of laboratory-prepared nonionic surfactant vesicles.
In that research setting, Sorbitan Monooleate contributes to self-assembled structures formed under specified preparation conditions.
Such studies describe experimental systems and do not establish a routine medical application for an unspecified grade of Sorbitan Monooleate. 

DESCRIPTION

Sorbitan Monooleate belongs to the sorbitan fatty acid ester family.
Commercial Sorbitan Monooleate is a mixture of partial esters formed from sorbitol-derived polyols and oleic acid.
The most abundant constituent of Sorbitan Monooleate is generally 1,4-sorbitan monooleate, alongside smaller amounts of other monoesters and higher esters. 

Esterification links the fatty acid portion of Sorbitan Monooleate to a sorbitol-derived polyol.
Because the commercial material contains more than one ester species, Sorbitan Monooleate has no single exact molecular formula for the whole mixture.
The formula C24H44O6 and molecular weight 428.60 g/mol describe a principal monoester constituent of Sorbitan Monooleate, rather than every molecule present.
The oleate portion gives Sorbitan Monooleate strong affinity for compatible oils.
Unesterified hydroxyl groups provide the more water-affine region of Sorbitan Monooleate and allow adsorption at an oil–water interface.
This unequal affinity for the two phases explains why Sorbitan Monooleate usually favours an oil-continuous emulsion.
Sorbitan Monooleate is nonionic and has a typical hydrophilic–lipophilic balance near 4.3.
A low balance value indicates that Sorbitan Monooleate is more oil-affine than surfactants selected to stabilize many water-continuous emulsions.
Blending Sorbitan Monooleate with a more hydrophilic emulsifier allows a formulator to adjust the behaviour of the combined system. chemical.kao.com
Sorbitan Monooleate commonly appears as an amber, viscous oily liquid with a slight characteristic odour.

Compendial descriptions of Sorbitan Monooleate also allow light cream to tan beads or flakes and a waxy solid, depending on the material supplied.
The liquid form covered here should therefore be checked against the appearance stated for a particular grade of Sorbitan Monooleate.
Sorbitan Monooleate does not dissolve in cold water.
Warm water can disperse Sorbitan Monooleate, although a dispersion must not be mistaken for a molecular solution.
Sorbitan Monooleate can dissolve in selected organic liquids under suitable temperature conditions, while solvent compatibility remains formulation-dependent. 

Commercial composition and quality specifications influence the properties of Sorbitan Monooleate.
Acid value reflects residual acidity, whereas saponification and hydroxyl values provide information about ester and hydroxyl content in Sorbitan Monooleate.
A food-grade specification for Sorbitan Monooleate defines ranges for these measures, but an unspecified industrial grade may have different limits.
The carbon–carbon double bond in the oleate portion is an important structural feature of Sorbitan Monooleate.
Normal storage stability does not remove the need to protect Sorbitan Monooleate from excessive heat and incompatible oxidizing agents.
Changes in odour, colour, or analytical values can be relevant when assessing the condition of stored Sorbitan Monooleate.
The ability of Sorbitan Monooleate to wet particles is distinct from the stability of an entire suspension.

Sorbitan Monooleate can help a compatible liquid spread across a pigment or mineral surface during mixing.
Particle size, loading, liquid-phase viscosity, and other stabilizers still govern whether a dispersion containing Sorbitan Monooleate remains uniform.
Food, cosmetic, pharmaceutical, and industrial supplies of Sorbitan Monooleate can share the same broad chemical identity.
Those supplies of Sorbitan Monooleate may differ in permitted impurities, analytical limits, and documentation for their intended use.
An application calling for a defined grade of Sorbitan Monooleate must be assessed against that grade’s requirements.

PROPERTIES

Chemical character: Nonionic mixture of partial sorbitol-derived oleate esters
Common appearance: Amber, viscous oily liquid
Odour: Slight characteristic odour
Hydrophilic–lipophilic balance: Approximately 4.3
Water behaviour: Insoluble in cold water; dispersible in warm water
Organic-solvent behaviour: Soluble in ethanol and selected organic solvents under suitable temperature conditions
Acid value: Not more than 8 mg KOH/g under the cited food-additive specification
Saponification value: 145–160 mg KOH/g under the cited food-additive specification
Hydroxyl value: 193–210 mg KOH/g under the cited food-additive specification
Water content: Not more than 2% under the cited food-additive specification 

FIRST AID

Inhalation:

Move a person exposed to Sorbitan Monooleate mist or vapour to fresh air.
Keep the person comfortable for breathing.
Obtain medical advice if symptoms develop or the person feels unwell.

Skin contact:

Remove clothing contaminated with Sorbitan Monooleate.
Rinse the affected skin thoroughly with water.
Obtain medical advice if irritation or a rash develops.

Eye contact:

Rinse eyes exposed to Sorbitan Monooleate with plenty of water.
Remove contact lenses if present and easy to remove, then continue rinsing.
Seek medical advice if eye irritation persists.

Ingestion:

Rinse the mouth after accidental ingestion of Sorbitan Monooleate.
Do not induce vomiting or give anything by mouth to an unconscious person.
Obtain medical advice following ingestion.

HANDLING AND STORAGE

Handling:

Avoid unnecessary contact with Sorbitan Monooleate during transfer and formulation.
Wear suitable protective gloves and eye protection when handling Sorbitan Monooleate.
Wash hands and exposed skin after handling and before eating or drinking.

Ventilation:

Provide adequate ventilation where Sorbitan Monooleate is poured, mixed, or heated.
Use local exhaust when a process can generate Sorbitan Monooleate mist or vapour.
Control splashing and aerosol formation during high-speed mixing.

Storage:

Keep Sorbitan Monooleate in a tightly closed container in a cool, shaded area.
Separate stored Sorbitan Monooleate from incompatible oxidizing agents.
Protect Sorbitan Monooleate from excessive heating and contamination during repeated use.

Spill and leak procedures:

Restrict access to a Sorbitan Monooleate spill because the oily liquid can make floors slippery.
Collect Sorbitan Monooleate with a suitable absorbent material and place the recovered material in an appropriate container.
Prevent Sorbitan Monooleate from entering drains and manage the collected waste according to local requirements.

Handling precautions:

Select transfer equipment and protective clothing for the amount of Sorbitan Monooleate being handled.
If Sorbitan Monooleate is heated, control the temperature and avoid inhaling any fumes generated by overheating.
Keep Sorbitan Monooleate containers closed between uses and clean contaminated work surfaces promptly.