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Cocoiminodipropionate is an amphoteric surfactant derived from natural coconut alkyl chains chemically modified on a trimethylenediamine backbone and converted to disodium salts.
Exhibiting pH-dependent zwitterionic behavior, this compound is widely used in personal care and industrial formulations for its mildness and foam-enhancing properties.
Despite its commercial significance, publicly accessible peer-reviewed research is limited.
This article compiles and expands on its chemical identity, synthesis routes, physicochemical properties, surfactant mechanism, applications, safety profile, environmental impact, and analytical techniques, aiming to provide a comprehensive scientific resource.
Synonyms:
Disodium dicarboxyethyl cocopropylenediamine,N‑Alkyl(C₈–C₂₂) trimethylenedi‑amines, acrylated, sodium salts, Disodium cocoiminodipropionate
Introduction
Surfactants are amphiphilic molecules that reduce surface tension between phases and have diverse applications ranging from detergents to cosmetics.
Among the classes of surfactants, amphoteric surfactants offer unique properties, exhibiting positive or negative charge depending on the pH environment.
Cocoiminodipropionate (CAS 97659‑50‑2) is a relatively specialized amphoteric surfactant, derived from coconut oil alkyl chains, used in mild cleansing formulations and industrial products.
The purpose of this article is to provide a detailed overview of cocoiminodipropionate’s chemical structure, manufacturing, physicochemical characteristics, functional applications, and safety considerations, filling gaps in the publicly available literature.
Chemical Identity
Chemical Name: Cocoiminodipropionate
CAS Number: 97659‑50‑2
Molecular Formula: Variable (dependent on alkyl chain length), generally represented as CₙH₂ₙ₊ₓNNa₂O₄ where n ranges 8–22 carbons in the alkyl chain.
Molecular Weight: Variable; typical range approximately 350–600 g/mol depending on alkyl chain length.
The compound contains a trimethylenediamine (1,3-propanediamine) backbone functionalized with two propionate groups (dicarboxyethyl) and one long hydrophobic alkyl chain from coconut oil fatty acids.
The sodium salt form is commonly supplied for enhanced water solubility.
Synthesis and Manufacturing
Raw Materials
Coconut fatty alkyl amines (C₈–C₂₂): Derived from coconut oil, containing a mixture of fatty chains.
Trimethylenediamine (1,3-propanediamine): Acts as the hydrophilic backbone.
Acrylic acid or acrylate salts: Used to introduce carboxyethyl groups via Michael addition.
Synthetic Route
Alkylation: The primary amines of trimethylenediamine are reacted with coconut fatty alkyl halides or fatty acid derivatives under nucleophilic substitution conditions to attach the hydrophobic tail.
Acrylation: The secondary amine groups of the alkylated intermediate undergo Michael addition with acrylic acid or sodium acrylate to introduce two carboxyethyl groups on either side of the nitrogen atoms.
Neutralization: The resulting diacid form is neutralized with sodium hydroxide or sodium carbonate to produce the disodium salt, improving water solubility and stability.
Purification: The final product is filtered and standardized to appropriate concentration for industrial use.
Process Considerations
Control of alkyl chain distribution is critical to product consistency.
pH control during acrylation and neutralization affects final amphoteric balance.
Removal of unreacted acrylic acid and residual impurities is necessary for safety.
Molecular Structure and Characterization
Structural Features
The molecule possesses a hydrophobic tail from natural fatty acid chains (predominantly C₁₂–C₁₈ from coconut oil).
The hydrophilic region is based on a 1,3-propanediamine backbone substituted with two propionate carboxylate groups.
As a zwitterion, it carries a positive charge at the protonated amine under acidic conditions and negative charges on carboxylate groups under alkaline conditions.
Spectroscopic Characterization
¹H NMR and ¹³C NMR: Provide confirmation of alkyl chain length and backbone substitution.
FTIR Spectroscopy: Shows characteristic peaks for amine (~3300 cm⁻¹), carboxylate (~1550–1650 cm⁻¹ asymmetric and ~1400 cm⁻¹ symmetric stretching), and alkyl C-H stretching (~2900 cm⁻¹).
Mass Spectrometry (ESI-MS): Useful for molecular weight determination and identification of chain-length distribution.
Physicochemical Properties
Property Value / Range Notes
Physical state Liquid (viscous, pale yellow to clear) Supplied as aqueous solution
Solubility in water Highly soluble Due to sodium salt form
pH Range 2 – 10 (typically 6–8 in formulations) Amphoteric behavior depending on pH
Surface Tension ~30–40 mN/m at 1% concentration Shows good surfactant properties
Critical Micelle Concentration (CMC) 0.01 – 0.05 wt% (approximate) Depends on alkyl chain length
Foam Stability Moderate to high Beneficial for shampoos and cleansers
Surfactant Mechanism & Behavior
Amphoteric Behavior
At low pH (acidic), the nitrogen is protonated (+ charge), balancing with carboxylate groups (- charge), resulting in zwitterionic form with net positive or neutral charge.
At high pH (alkaline), carboxylate groups are deprotonated, leading to an overall anionic surfactant behavior.
This pH-dependent charge influences solubility, foaming, and mildness.
Surfactant Actions
Surface tension reduction: The molecule adsorbs at interfaces, reducing water surface tension to enable cleaning and emulsification.
Foaming: Enhances foam formation and stability due to balanced hydrophobic and hydrophilic groups.
Mildness: Due to zwitterionic nature, causes less irritation compared to purely anionic surfactants.
Compatibility: Mixes well with anionic, nonionic, and cationic surfactants, making it versatile in complex formulations.
Applications and Formulation Use
Personal Care
Shampoos and Hair Care: Acts as foam booster and cleanser.
Body Washes and Facial Cleansers: Provides mild cleansing without stripping skin oils.
Baby Products: Mild surfactant suitable for sensitive skin formulations.
Industrial Use
Detergents and Cleaners: Stabilizer and dispersant in household and industrial cleaners.
Emulsifiers: In formulations requiring gentle emulsification.
Textile and Leather Processing: Used in wetting and cleaning processes.
SAFETY INFORMATION ABOUT COCOIMINODIPROPIONATE
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off conSAFETYtaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
