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Castor Oil Ethoxylates

The standard RIMPRO series of Polyethoxylated castor oil is RIMPRO CO

Castor Oil Ethoxylates Empirical Formula

Polyoxyethylene castor oil derivatives are complex mixtures of various hydrophobic and hydrophilic components.

In RIMPRO-CO 35 castor oil the hydrophobic constituents comprise about 83% of the total mixture, the main component being glycerol polyethylene glycol ricinoleate. Other hydrophobic constituents include fatty acid esters of polyethylene glycol along with some unchanged castor oil. The hydrophilic part (17%) consists of polyethylene glycols and glycerol ethoxylates

In RIMPRO -CO-40, approximately 75% of the components of the mixture are hydrophobic. These comprise mainly fatty acid esters of glycerol polyethylene glycol and fatty acid esters of polyethylene glycol. The hydrophilic portion consists of polyethylene glycols and glycerol ethoxylates.

RIMPRO Appearance at
HLB Solid
Min %
CO-2.5 Clear viscous
Colorless liquid
147+5 48-58 2.14 99.5 0.2
CO-5.0 Pale Yellow
Viscous liquid
133+5 43-53 3.87 99.5 0.2
CO-10 Pale Yellow
Viscous liquid
111+5 35-45 6.49 99.5 0.2
CO-20 Pale Yellow
Viscous liquid
85+5 25-35 9.8 99.5 0.2
CO-30 Pale Yellow
Viscous liquid
68+5 19-29 11-.8 99.5 0.2
CO-35 Pale Yellow
Viscous liquid
60+5 17-27 12.54 99.5 0.2
CO-40 Pale Yellow
Viscous liquid
56+5 15-25 13.15 99.5 0.2
CO-60 Pale Yellow
to waxy solid
55+5 10-20 14.83 99.5 0.2
Stability and Storage Conditions

RIMPRO -CO-35 forms stable solutions in many organic solvents such as chloroform, ethanol and propan-2-ol; it also forms clear, stable, aqueous solutions.RIMPRO-CO-35 is miscible with other polyoxyethylene castor oil derivatives and on heating with fatty acids, fatty alcohols and some animal and vegetable oils. Solutions of RIMPRO -CO-40 in aqueous alcohols are also stable.

On heating an aqueous solution the solubility of RIMPRO -CO-35 is reduced and the solution becomes turbid. Aqueous solutions of polyoxyl castor oil heated for prolonged periods may separate into solid and liquid phases on cooling. However, the product can be restored to its original form by homogenization.

Aqueous solutions of RIMPRO -CO-35 are stable in the presence of low concentrations of electrolytes such as acids or salts, with the exception of mercuric chloride.

Aqueous solutions of RIMPRO -CO-35 can be sterilized by autoclaving for 20 minutes at 121 oC. In this process a product may acquire a deeper color although this has no significance for product stability. Aqueous solutions of polyoxyl castor oil can similarly be sterilized by autoclaving at 121 oC, but this may cause a slight decrease in the pH value.

Polyoxyethylene castor oil derivatives should be stored in a well-filled, airtight container, protected from light, in a cool, dry, place.


Polyoxyethylene castor oil derivatives are used in a variety of oral, topical and parenteral pharmaceutical formulations.

Acute and chronic toxicity tests in animals have shown polyoxyethylene castor oil derivatives to be essentially nontoxic and nonirritant materials. However, several serious anaphylactic reactions have been observed in humans and animals following parenteral, and more rarely, oral administration of formulations containing polyoxyethylene castor oil derivatives.

Handling Precautions

Observe normal precautions appropriate to the circumstances and quantity of material handled. Eye protection and gloves are recommended.

Applications in Pharmaceutical Formulation or Technology
Polyoxyethylene castor oil derivatives are nonionic surfactants used in oral, topical and parenteral pharmaceutical formulations. They are also used in cosmetics animal feeds and Textile.

RIMPRO -CO-35 is mainly used as an emulsifying and solubilizing agent, and is particularly suitable for the production of aqueous liquid preparations containing volatile oils, fat-soluble vitamins and other hydrophobic substances.

RIMPRO -CO-35 has also been used as a solvent in proprietary injections of diazepam, propanidid and alfaxalone with alfadolone acetate. RIMPRO -CO-35 is also used in the production of glycerin suppositories.

In veterinary practice, RIMPRO -CO-35 can be used to emulsify cod liver oil, and oils and fats incorporated into animal feeding stuffs.

In cosmetics, RIMPRO -CO-35 is mainly used as a solubilizing agent for perfume bases and volatile oils in vehicles containing 30-50% v/v alcohol (ethanol or propan-2-ol). In hand lotions it can be used to replace castor oil.

RIMPRO -CO-40 may be used in preference to RIMPRO -CO-35 in oral formulations since it is almost tasteless. In aqueous alcoholic or completely aqueous solutions, RIMPRO -CO-40 can be used to solubilize vitamins, essential oils and certain drugs. Other materials which can be solubilized are; alfadolone; alfaxalone; hexacholrophane; hexetidine; methotrimeprazine; miconazole; propanidid; and thiopentone.

In aerosol vehicles which include water, the addition of RIMPRO -CO-40 improves the solubility of the propellant in the aqueous phase. This enhancement applies both to dichlorodifluoromethane and to propane/butane mixtures.

Foam formation in aqueous ethanol solutions containing RIMPRO -CO-40 can be suppressed by the addition of small amounts of polypropylene glycol 2000.

RIMPRO -CO-40 is also used as an emulsifier of fatty acids and alcohols.
Emulsifier, Co-emulsifier, Dispersant, Solubilizer, Lubricant, Antistant, Emollient Wetting agent, Scouring agent, Deformer, Softener, Lubricant, Viscosity control Agent, Dying Assistant Dye Carrier, Leveling agent, Stabilizer, Penetrate.