Undecylenic Acid: Technical Specifications and Versatile Chemical Applications

1. Technical Overview

Undecylenic Acid, also known as 10-Undecenoic Acid ($C_{11}H_{20}O_2$), is a rare, unsaturated fatty acid produced through the vacuum pyrolysis (thermal cracking) of ricinoleic acid or castor oil methyl esters. It is characterized by a terminal double bond and an eleven-carbon chain. In the chemical industry, Undecylenic acid is a high-value “platform chemical” used as a starting material for a wide array of derivatives. It is globally recognized for its potent antifungal properties in medicine and as a critical precursor for the synthesis of Nylon 11, high-end fragrance esters, and specialized surfactants.

2. Chemical Structure & Composition

The molecular structure of Undecylenic acid is unique due to the position of its unsaturation.

• Terminal Double Bond: Unlike most natural fatty acids which have internal double bonds, Undecylenic acid has a double bond at the end of the chain ($CH_2=CH-$).

• Linear Chain: A saturated 11-carbon linear structure.

• Purity: Typically available in 97% to 99% purity.

The terminal double bond is highly reactive, allowing for precise chemical modifications such as polymerization, thiol-ene reactions, and oxidation.

3. Physical & Chemical Properties

• Appearance: Colorless to pale yellow liquid or a low-melting crystalline solid.

• Melting Point: ~24.5°C (often remains a supercooled liquid).

• Boiling Point: ~275°C at atmospheric pressure.

• Odor: Characteristic, persistent fatty/perspiration odor.

• Solubility: Insoluble in water; highly soluble in alcohol, ether, and chloroform.

• Refractive Index: 1.447 – 1.450 at 25°C.

4. Reaction Chemistry

The dual functionality (carboxyl group + terminal double bond) facilitates diverse reactions:

1. Antifungal Activity: The undecylenate ion disrupts fungal cell membranes, making it effective against Tinea species.

2. Hydrobromination: Reaction with hydrogen bromide followed by amination is the path to Nylon 11.

3. Esterification: Reacts with alcohols to produce Undecylenate esters (e.g., Methyl, Ethyl, or Zinc Undecylenate).

4. Ozonolysis: Can be cleaved to produce shorter-chain dicarboxylic acids.

5. When to Use vs. When NOT to Use

Use Undecylenic Acid when:

• Manufacturing antifungal ointments, powders, or medicated soaps.

• Synthesizing aroma chemicals such as Aldehyde C-11 or various “musk” fragrance notes.

• Producing bio-based polymers (Nylon 11) requiring high chemical resistance and dimensional stability.

Do NOT use Undecylenic Acid when:

• A completely odorless product is required (the natural odor is very strong and difficult to mask).

• The application requires a saturated fatty acid for high oxidative stability at extreme temperatures.

6. Compatibility Profile

Undecylenic acid is compatible with:

• Bases: Forms soluble sodium or potassium salts and insoluble metallic salts (like Zinc Undecylenate).

• Solvents: Acts as an excellent solvent for various therapeutic agents.

• Polymers: Compatible with various thermoplastic resins as a functionalizing additive.

7. Manufacturing Process (Product Focus)

Nova Industries produces high-purity Undecylenic acid via a controlled thermal process:

1. Pyrolysis: Castor oil methyl ester is subjected to rapid thermal cracking at temperatures between 450°C and 550°C under vacuum.

2. Fractional Distillation: The cracked mixture (containing Heptaldehyde and Methyl Undecylenate) is separated using high-efficiency distillation columns.

3. Hydrolysis: The Methyl Undecylenate fraction is hydrolyzed to yield the free acid.

4. Refining: A final vacuum distillation ensures the removal of heavy ends and color-causing impurities, achieving a purity of 99%+.

8. Technical Specifications Table

Parameter	Specification (High Purity)
Appearance	Pale Yellow to Colorless Liquid/Solid
Undecylenic Acid Content	98.0% Min
Acid Value (mg KOH/g)	300 – 305
Iodine Value (Wijs)	135 – 140
Melting Point	23°C – 25°C
Moisture Content	0.5% Max
Color (Gardner)	1.0 Max

9. Quality Grade Analysis

Nova Industries monitors the Acid Value and Purity via GC. A high acid value confirms the correct chain length and purity. For fragrance and pharma grades, we ensure that trace isomers and oxidation products are eliminated, as these can negatively impact the scent profile and therapeutic efficacy.

10. Impact of Impurities

• Saturated Fatty Acids: Lower the iodine value and can reduce the efficiency of subsequent chemical modifications.

• Peroxides: Indicate oxidation, which darkens the product and intensifies the odor.

11. Industry-Wise Application 1: Pharmaceuticals

Undecylenic acid is a time-tested antifungal agent. It is the active ingredient in many over-the-counter (OTC) treatments for athlete’s foot (Tinea pedis), ringworm, and diaper rash. It is often used in combination with its salt, Zinc Undecylenate.

12. Industry-Wise Application 2: Fragrance & Flavors

Used as a precursor for Aldehyde C-11 Undecylenic, which provides a characteristic “clean-linen” and citrus-floral note in high-end perfumes and soaps. It is also used in the synthesis of specialized flavor compounds.

13. Industry-Wise Application 3: Polymers (Nylon 11)

As the primary monomer source for Nylon 11, it provides a unique polymer that is 100% bio-based. Nylon 11 is used in automotive fuel lines, offshore oil and gas pipes, and sports equipment due to its exceptional impact resistance and low moisture absorption.

14. Industry-Wise Application 4: Metalworking Fluids

Undecylenic acid salts are utilized as specialized surfactants and corrosion inhibitors that offer superior wetting properties compared to standard long-chain fatty acids.

15. Formulation Guide

• Pharma: In topical formulations, typical concentrations range from 2% to 10%. It should be blended with emollients to minimize potential skin irritation.

• Esterification: Use an inert gas (nitrogen) during reaction to prevent the terminal double bond from oxidizing or polymerizing.

16. Sustainability Data

Undecylenic Acid is a 100% bio-based product. It is a cornerstone of “Green Chemistry,” providing a sustainable path to high-performance materials (like Nylon 11) that were historically reliant on petroleum.

17. Packaging & Logistics (Technical)

• Standard: 190kg/200kg HDPE or Epoxy-lined MS Drums.

• Bulk: 1000kg IBC Tanks.

• Logistics: Corrosive to some metals; HDPE is the preferred packaging. As it melts at ~24°C, it may arrive as a solid or liquid depending on the climate.

18. Storage Science

Must be stored in a cool, shaded area. It is sensitive to air and light. Drums should be nitrogen-blanketed once opened. Because it can solidify in cool weather, gentle warming (not exceeding 40°C) is required to liquefy the material for pumping.

19. Troubleshooting Guide

• Problem: Darkening or thickening of the liquid. Solution: This indicates polymerization or oxidation. Ensure storage temperatures are low and containers are air-tight.

• Problem: Off-odor in fragrance synthesis. Solution: Verify the purity via GC; trace impurities from the cracking process can interfere with delicate scent notes.

20. Regulatory Compliance

Our Undecylenic Acid is REACH Compliant, meets the requirements of the USP/BP (where specified), and is listed on major global chemical inventories.

21. Safety (SDS Summary)

• Handling: Corrosive to eyes and a skin irritant. Wear protective gloves and goggles.

• Fire: Flash point >140°C. Use CO2, dry chemical, or foam.

• Environment: Biodegradable; however, do not dispose of directly into the environment.

22. Sample Validation Process

Verify the Iodine Value and Acid Value. For pharmaceutical grade, an antifungal potency assay or a specific GC purity check for isomers is recommended.

23. Commercial Efficiency

Direct sourcing from Nova Industries ensures a product with consistent terminal unsaturation. This predictability is vital for manufacturers of Nylon 11 and complex esters, where batch-to-batch variation can lead to significant yield losses.

24. Technical FAQs

1. Is Undecylenic Acid same as Undecanoic Acid? No, Undecylenic acid is unsaturated (contains a double bond), whereas Undecanoic acid is fully saturated.

2. Why does it have a strong smell? The odor is inherent to its molecular structure and is a characteristic trait of the acid.

3. Is it 100% bio-based? Yes, it is derived exclusively from castor oil.

25. Contact CTA

For technical data sheets (TDS), safety protocols, or bulk export inquiries, please contact our technical team at: export@novaind.in