Castor oil
[CAS# 8001-79-4]

Identification

• Classification: API >> Digestive system medication >> Other digestive system medication
• Name: Castor oil
• Synonyms: Ricinolein
• Molecular Formula: C₅₇H₁₀₄O₉
• Molecular Weight: 933.43
• CAS Registry Number: 8001-79-4
• EC Number: 232-293-8
• FEMA: 2263
• SMILES: CCCCCC[C@@H](O)C/C=CCCCCCCCC(=O)OCC(COC(=O)CCCCCCC/C=CC[C@H](O)CCCCCC)OC(=O)CCCCCCC/C=CC[C@H](O)CCCCCC

Properties

• Density: 0.961 g/mL (25 °C) (Expl.)
• Melting point: -12 °C
• Boiling point: 313 °C (Expl.)
• Flash point: 229 °C
• Refraction index: 1.478 (Expl.)
• Alpha: +5°, c = 5 in ethanol (Expl.)
• Water solubility: <0.1 g/100 mL at 20 °C

Safety Data

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319

Discovery and Applications

Castor oil is a pale yellow, viscous vegetable oil obtained by pressing the seeds of the castor plant, Ricinus communis. Its use dates back thousands of years, with evidence of castor oil extraction and application found in ancient Egyptian artifacts and texts. The oil is primarily composed of triglycerides rich in ricinoleic acid, a unique hydroxy fatty acid that constitutes about 85-90% of its fatty acid content. This distinct chemical structure gives castor oil its characteristic properties, including high viscosity, lubricity, and solubility in alcohol.

Historically, castor oil was valued for its medicinal properties and was used as a laxative, purgative, and remedy for various ailments. Its effectiveness as a stimulant laxative was recognized by traditional medicine systems and later confirmed through pharmacological studies. The oil’s ability to promote intestinal motility is attributed to its ricinoleic acid content, which acts on the smooth muscles of the intestines.

In modern times, castor oil has found extensive applications across multiple industries. In the pharmaceutical field, it continues to be used as a laxative and as an excipient in topical formulations due to its emollient and skin-conditioning properties. Its compatibility with the skin and its moisturizing effect make it a common ingredient in creams, ointments, and cosmetics.

The unique chemical structure of castor oil also lends itself to industrial uses. It serves as a raw material for the production of bio-based polymers, lubricants, coatings, adhesives, and plasticizers. The hydroxyl groups in ricinoleic acid facilitate chemical modifications that produce derivatives such as sebacates, esters, and polyamides used in engineering plastics and synthetic resins.

In the cosmetics industry, castor oil is valued for its moisturizing, anti-inflammatory, and antimicrobial properties. It is commonly found in hair care products, lip balms, and skin lotions, where it enhances texture, hydration, and protection.

Castor oil is obtained by mechanical pressing or solvent extraction of castor seeds, followed by refining processes to remove impurities and toxins such as ricin, a potent protein toxin present in the seeds but not in the oil itself. Proper processing ensures that the oil is safe for pharmaceutical and cosmetic applications.

The versatility of castor oil, combined with its renewable origin and biodegradability, has led to increasing interest as a sustainable resource in green chemistry and environmentally friendly product formulations.

In summary, castor oil is a vegetable oil extracted from Ricinus communis seeds, historically used for medicinal purposes and now widely employed in pharmaceuticals, cosmetics, and industrial applications. Its high ricinoleic acid content provides unique chemical and physical properties that support its use as a laxative, emollient, and raw material for bio-based products. Its safety, effectiveness, and sustainability continue to underpin its importance in diverse fields.

References

2006. Castor oil: A vital industrial raw material. Bioresource Technology, 97(9).
DOI: 10.1016/j.biortech.2005.03.028

2012. Castor oil induces laxation and uterus contraction via ricinoleic acid activating prostaglandin EP3 receptors. Proceedings of the National Academy of Sciences of the United States of America, 109(23).
DOI: 10.1073/pnas.1201627109

2016. Castor Oil: Properties, Uses, and Optimization of Processing Parameters in Commercial Production. Lipid Insights, 9.
DOI: 10.4137/lpi.s40233