Ricinoleic Acid (RA): Technical Specifications and Chemical Versatility in Industrial Synthesis

1. Technical Overview

Ricinoleic acid (RA), chemically known as 12-hydroxy-9-octadecenoic acid (¹$C_{18}H_{34}O_3$), is a unique unsaturated fatty acid that constitutes approximately 90% of the fatty acid profile of castor oil.² Unlike common fatty acids such as stearic or oleic acid, Ricinoleic acid contains a secondary hydroxyl group on the 12th carbon atom.³ This trifunctional nature—possessing a carboxyl group, a double bond, and a hydroxyl group—makes it an exceptionally reactive intermediate.⁴ In industrial R&D, RA is the primary feedstock for producing high-value derivatives including sebacic acid, heptaldehyde, and various surfactants, offering a bio-based solution for complex chemical synthesis.

2. Chemical Structure & Composition

The molecular structure of Ricinoleic acid is defined by its 18-carbon chain with the following functional points:

• Carboxyl Group (C1): Allows for esterification and soap formation.⁵

• Double Bond (C9): Provides a site for hydrogenation, halogenation, or oxidation.⁶

• Hydroxyl Group (C12): Enables the formation of estolides, polyurethanes, and ethoxylated derivatives.

The high concentration of this single fatty acid in the castor triglyceride ensures that the purified Ricinoleic acid provided by Nova Industries maintains a consistent molecular weight and reactivity profile.

3. Physical & Chemical Properties

Ricinoleic acid is a pale yellow to amber viscous liquid at room temperature.

• Viscosity: Higher than most fatty acids due to hydrogen bonding between hydroxyl groups.

• Density: ~0.940 g/cm³ at 25°C.⁷

• Solubility: Soluble in most organic solvents including ethanol, acetone, and ether; insoluble in water.⁸

• Optical Activity: It is dextrorotatory, a property used to verify its botanical origin and purity.⁹

4. Reaction Chemistry

The chemical utility of RA is vast due to its reactive sites:

1. Pyrolysis: High-temperature cleavage yields Sebacic Acid (for Nylon 6,10) and Heptaldehyde.

2. Sulfonation: Reaction with sulfuric acid produces Turkey Red Oil (Sulfonated Castor Oil).¹⁰

3. Esterification: Reacts with alcohols to produce Ricinoleate esters used as plasticizers and emollients.¹¹

4. Ethoxylation: Produces non-ionic surfactants used as emulsifiers in crop protection and textiles.

5. When to Use vs. When NOT to Use

Use Ricinoleic Acid when:

• Synthesizing specialized surfactants requiring a high degree of biodegradability.

• Formulating transparent soaps or textile finishing agents.¹²

• Producing high-performance lubricants that require a polar fatty acid to improve metal adhesion.

Do NOT use Ricinoleic Acid when:

• A saturated, non-reactive wax is required (use 12-HSA instead).

• The application involves high-heat exposure in an open-air system where oxidative stability is the primary concern (saturated acids are preferred here).

6. Compatibility Profile

RA is highly compatible with:

• Polymers: Acts as a secondary plasticizer for nitrocellulose and various elastomers.¹³

• Solvents: Excellent solubility in oxygenated solvents.

• Synergy: Works effectively when blended with other fatty acids to adjust the titer (solidification point) of industrial soaps.

7. Manufacturing Process (Product Focus)

Nova Industries utilizes a controlled hydrolysis process to produce RA:

1. Saponification: Refined castor oil is reacted with an alkali to break the triglyceride bond.¹⁴

2. Acidification: The resulting soap is treated with a mineral acid to liberate the free Ricinoleic acid.

3. Glycerin Separation: The aqueous glycerin phase is removed, leaving the concentrated fatty acid.

4. Washing & Vacuum Drying: The acid is washed to remove trace minerals and dried under a high vacuum to achieve a moisture content below 0.5%.

8. Technical Specifications Table

Parameter	Specification (Ricinoleic Acid)
Appearance	Yellow to Brownish Yellow Viscous Liquid
Ricinoleic Acid Content	89% Min
Acid Value (mg KOH/g)	175 – 185
Iodine Value (Wijs)	82 – 92
Saponification Value	180 – 190
Hydroxyl Value	150 – 165
Moisture & Volatiles	0.5% Max
Color (Gardner)	5.0 Max

9. Quality Grade Analysis

Nova Industries focuses on the “Degree of Splitting.” Inferior RA often contains residual monoglycerides or diglycerides, which interfere with subsequent chemical reactions. Our RA ensures an acid value that closely matches the theoretical maximum, indicating high conversion and purity.

10. Impact of Impurities

• Residual Glycerin: Can cause unwanted darkening and smoke generation during high-temperature esterification.

• High Moisture: Acts as a chain-stopper in polyurethane synthesis and promotes the hydrolysis of finished esters.

11. Industry-Wise Application 1: Surfactants & Detergents

RA is the base for many high-end surfactants. Its sodium and potassium soaps are highly soluble and possess unique bactericidal properties, making them ideal for specialized industrial cleaners and transparent bar soaps.

12. Industry-Wise Application 2: Textile & Leather

Used extensively in the production of Turkey Red Oil (Sulfonated Castor Oil), RA provides excellent wetting and leveling properties in dyeing processes.¹⁵ In leather treatment, it acts as a fat-liquoring agent to provide softness and flexibility.¹⁶

13. Industry-Wise Application 3: Plastics & Rubber

RA and its esters serve as internal lubricants and processing aids for rubber compounding.¹⁷ They help in the dispersion of fillers and improve the flow of the compound during molding.

14. Industry-Wise Application 4: Pharmaceuticals & Personal Care

In the pharma industry, RA is used as an intermediate for producing undecylenic acid (an antifungal agent). In cosmetics, it is utilized for its emollient properties and as a stabilizer for pigments in lipsticks.¹⁸

15. Formulation Guide

• Saponification: When making RA soaps, ensure accurate calculation of the SAP value to avoid excess free alkali.

• Storage in Process: If being pumped through a plant, keep the lines slightly warmed (30-35°C) to maintain consistent flow, as viscosity increases significantly at lower temperatures.

16. Sustainability Data

Ricinoleic Acid is 100% bio-based and renewable. It has a high bio-carbon content and is completely biodegradable, making it an excellent choice for companies aiming to meet “Green Chemistry” targets.

17. Packaging & Logistics (Technical)

• Standard: 190kg/200kg HDPE Drums.¹⁹

• Bulk: 1000kg IBC Tanks or ISO Tanks.

• Stability: RA is stable for transport but should be protected from extreme cold to prevent the deposition of saturated fractions.

18. Storage Science

RA is susceptible to atmospheric oxidation due to its double bond. It should be stored in tightly sealed containers. For bulk storage, 316-grade stainless steel tanks are required. Using mild steel can lead to iron contamination, which causes the acid to turn dark red or black.

19. Troubleshooting Guide

• Problem: Darkening of the product in the reactor. Solution: Check for iron contamination or ensure the reaction is carried out under an inert nitrogen blanket.

• Problem: Poor solubility in the surfactant phase. Solution: Verify the acid value; a low acid value indicates incomplete hydrolysis.

20. Regulatory Compliance

Our Ricinoleic Acid is REACH Compliant, ensuring it meets the safety and environmental requirements for the European market. It is also listed on major global chemical inventories (TSCA, DSL, AICS).²⁰

21. Safety (SDS Summary)

• Handling: Wear protective gloves and goggles. RA is a mild skin irritant.

• First Aid: Wash skin with soap and water; flush eyes with water if contact occurs.

• Environment: Avoid large-scale release into water bodies; although biodegradable, it creates a high oxygen demand.

22. Sample Validation Process

Procurement labs should validate the Acid Value and Hydroxyl Value. For surfactant manufacturers, a test of the solubility of its potassium soap in water is a reliable indicator of the fatty acid profile’s quality.

23. Commercial Efficiency

Sourcing manufacturer-direct RA from Nova Industries ensures that the “Chain of Purity” is maintained from the castor seed to the acid. This consistency reduces the need for batch-to-batch adjustments in the formulation, saving both time and raw material costs.

24. Technical FAQs

1. Can RA be used to make polyurethane? Yes, the C12 hydroxyl group allows it to react with isocyanates to form bio-based PU coatings.²¹

2. What is the difference between RA and Castor Oil? Castor oil is a triglyceride (a molecule of glycerin with three fatty acids), while RA is the free fatty acid itself. RA is much more reactive.

3. Is RA biodegradable? Yes, it is a naturally occurring fatty acid and is fully biodegradable under aerobic conditions.

25. Contact CTA

For detailed technical data sheets (TDS) or safety data sheets (SDS), please reach out to our technical team at: export@novaind.in