Stearamidopropyl Dimethylamine is a cationic compound derived from stearic acid, a natural fatty acid, primarily used in hair care products as a conditioning and antistatic agent. Due to its ability to neutralize negative charges on the hair and improve detangling, it is widely used in conditioners and smoothing treatments. Additionally, as a naturally derived ingredient, it is often included in eco-friendly formulations.

Chemical Composition and Structure

Stearamidopropyl Dimethylamine is produced by reacting stearic acid with dimethylamine and an alkyl chain, forming a cationic amine with high affinity for keratin in the hair. Its molecular structure allows it to adhere to damaged areas of the hair shaft, improving texture and elasticity, reducing frizz, and making the hair easier to comb.

The name describes the structure of the molecule:

• Stearamidopropyl is a group derived from stearic acid, a long-chain fatty acid with 18 carbon atoms, modified by the addition of an amide group -CONH₂ and a propyl group -CH₂CH_3.
• Dimethylamine refers to an amine group -NH2 modified by the addition of two methyl groups -CH3.

Production Process

The compound is produced through an amidation process, where stearic acid is converted into an amide by reacting with dimethylamine, and then further modified to create a cationic conditioning agent. This process makes Stearamidopropyl Dimethylamine highly functional for improving hair structure and appearance. 

• Preparation of Components: The main ingredients for producing Stearamidopropyl Dimethylamine include stearic acid, dimethylaminopropylamine, and appropriate reagents for the reaction.

• Synthesis of the Amide: Stearic acid is mixed with dimethylaminopropylamine in a chemical reactor. During this process, stearic acid reacts with dimethylaminopropylamine to form the amide, generating Stearamidopropyl Dimethylamine. This step occurs in the presence of heat and, sometimes, in the presence of a catalyst to accelerate the reaction.

• Purification: The resulting product is purified to remove any impurities and chemical residues. This may include filtration and distillation processes to achieve a high-quality product.

• Quality Control and Packaging: Finally, Stearamidopropyl Dimethylamine undergoes quality control checks to verify its purity and functional properties. After analysis, it is packaged for distribution and use in cosmetic and hair care products.

Applications

• Hair Care: Used in conditioners, masks, and leave-in treatments to detangle hair, reduce frizz, and enhance softness and shine. It also helps maintain color retention in chemically treated hair.

• Emulsifying Agent: Also used as an emulsifier in formulations to stabilize oil and water mixtures, improving the texture and application of the product on hair.

• Smoothing Treatments: Found in smoothing treatments to make hair more manageable, smooth, and sleek without weighing it down.

Cosmetics

Stearamidopropyl Dimethylamine is used in cosmetics as a cationic surfactant usually in percentages lower than 5%.

Antistatic agent. Static electricity build-up has a direct influence on products and causes electrostatic adsorption. The antistatic ingredient reduces static build-up and surface resistivity on the surface of the skin and hair.

Added to shampoos instead of silicone compounds, it slides the hair adhering to their surface.

Commercial applications

Hair Conditioning Agent. Stearamidopropyl Dimethylamine is used in conditioners and hair treatments to detangle and condition the hair, making it soft and manageable.

Emulsifier in Cosmetic Products. It is used in creams and lotions to help mix water and oils, creating a uniform texture.

Antistatic Agent. Used in hair products to reduce static electricity, making the hair more manageable.

Silicone Substitute. It can be used as an alternative to silicones in hair products to improve shine and softness without weighing hair down.

Thickening Agent. It is used to increase the viscosity of cosmetic products.

Safety

The Cosmetic Ingredient Review Panel (Panel) examined the safety of fatty acid amidopropyl dimethylamines, which act primarily as antistatic agents in cosmetic products. Relevant animal and human data examined for these indicate that they are potential skin sensitisers that may be due in part to the sensitising impurity, 3,3-dimethylaminopropylamine. The Panel concluded that fatty acid amidopropyl dimethylamines are safe as cosmetic ingredients when formulated in a non-sensitising manner, which can be based on a quantitative risk assessment  (1).

Health and Safety Considerations

Safety in Use
Stearamidopropyl Dimethylamine is considered safe for use in cosmetic and hair care products. It is well tolerated and does not cause skin or eye irritation at commonly used concentrations. It is widely used in hair products with no known negative effects.

Allergic Reactions
Allergic reactions to this ingredient are extremely rare. However, as with any cosmetic ingredient, individuals with extremely sensitive skin should exercise caution and perform a patch test before use if needed.

Toxicity and Carcinogenicity
It is deemed safe by major regulatory authorities for use in cosmetic and personal care products.

Environmental Considerations
Stearamidopropyl Dimethylamine is biodegradable, but its production may involve resources derived from non-renewable sources such as petroleum. However, as it is a derivative of natural stearic acid, it can be a more eco-friendly choice compared to other synthetic conditioning agents.

Regulatory Status
Stearamidopropyl Dimethylamine is approved for use in cosmetics by major regulatory authorities, including the European Union and the Food and Drug Administration (FDA) in the United States.

Chemical safety

• Molecular Formula   C₂₃H₄₈N₂O
• Molecular Weight   368.65
• CAS   67799-04-6

• UNII   9070YRE8OF    P1IO9HNJ3V
• EC number  267-101-1 
• Nikkaji     J425.569K

Synonyms:

Lexamine ; N-[3-(Dimethylamino)propyl]stearamide; Stearamidopropyl dimethylamine; Octadecanamide; Stearamidopropyldimethylamine

References_____________________________________________________________________

 (1) Burnett, C. L., Boyer, I., Bergfeld, W. F., Belsito, D. V., Hill, R. A., Klaassen, C. D., ... & Heldreth, B. (2019). Safety assessment of fatty acid amidopropyl dimethylamines as used in cosmetics. International journal of toxicology, 38(1_suppl), 39S-69S.