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Hexamine, also known as hexamethylenetetramine, is a heterocyclic organic compound with the formula C₆H₁₂N₄.
Hexamine is a crystalline solid with a pale yellow color, soluble in water and polar solvents.
Hexamine is widely used in medicine, industrial chemistry, and as a fuel in camping stoves.
Hexamine acts as a formaldehyde releaser and is a precursor to various chemical syntheses.
CAS Number: 100-97-0
Synonyms:
Hexamethylenetetramine,Methenamine,Urotropine,Hexamethylene tetraamine, Methenamin,C6H12N4,Hexamine (IUPAC)
Hexamine, also referred to as hexamethylenetetramine or methenamine, is a crystalline, white organic compound known for its symmetrical tetrahedral structure.
It is widely used in a variety of chemical industries due to its ability to act as a source of formaldehyde and its stability under ambient conditions.
This compound plays an essential role in pharmaceutical formulations, explosives manufacturing, and even in niche applications such as corrosion inhibitors and solid fuel tablets.
Its relevance spans both legacy industrial applications and modern materials science.
The compound is formed by a network of methylene (-CH2-) and nitrogen atoms, making up a cage-like structure that is highly stable.
It is a heterocyclic compound featuring nitrogen atoms at the vertices of a tetrahedron, joined by methylene bridges.
This unique configuration allows it to serve as a versatile ligand and reactant.
History and Discovery
Hexamine was first synthesized by Aleksandr Butlerov in 1859. Butlerov reacted formaldehyde with ammonia, resulting in the formation of a stable crystalline compound.
The simplicity of its synthesis and the robustness of the molecule led to rapid adoption in the chemical industry.
During World War I and II, hexamine gained strategic significance due to its role in the production of RDX, a high-energy explosive.
Synthesis Methods
The most common synthesis method involves the reaction of formaldehyde with ammonia in aqueous medium:
6 HCHO + 4 NH3 → C6H12N4 + 6 H2O
This reaction is exothermic and results in high yields under controlled conditions. Variants include:
Batch processing for pharmaceutical-grade material
Continuous flow synthesis for industrial-grade hexamine
Microwave-assisted synthesis for research applications
Analytical Characterization
IR Spectroscopy: Peaks around 1330 and 1430 cm⁻¹ correspond to C-N and N-H bending
1H NMR: Single sharp signal for methylene groups
Mass Spectrometry: Parent ion at m/z = 140
X-Ray Diffraction: Confirms cubic crystal lattice
TGA/DSC: Decomposition observed around 280 °C
Thermodynamic and Kinetic Properties
Standard Enthalpy of Formation: -113.9 kJ/mol
Gibbs Free Energy: -79.4 kJ/mol
Activation Energy: Moderate under acidic hydrolysis conditions
Reaction Rate: Accelerated in acidic medium due to protonation of nitrogen
Reactivity and Stability
Hexamine is stable under ambient conditions. It reacts in acidic environments to slowly hydrolyze, releasing formaldehyde and ammonium ions.
In presence of strong oxidizers, it undergoes nitration reactions forming powerful explosives.
Industrial Manufacturing Processes
Manufacturing involves:
Continuous Stirred Tank Reactors (CSTRs)
Control of pH and temperature to optimize yield
Crystallization and filtration to isolate pure product
Drying under vacuum to avoid decomposition
Quality Specifications and Standards
Purity: ≥99.5% (pharma-grade)
Moisture: <0.5%
Residue on Ignition: <0.05%
Compliance: USP, BP, Ph. Eur.
Heavy Metals: <10 ppm
Applications in Explosives
Hexamine serves as a precursor to RDX (cyclonite):
Nitration with nitric acid yields RDX
Used in military and mining operations
Component in plastic explosives and propellants
Use in Pharmaceuticals
Hexamine salts (e.g., methenamine hippurate) are used for:
Urinary tract antiseptics
Prevention of recurring infections
Releasing formaldehyde under acidic urinary conditions to exert antimicrobial effect
Role in Polymer and Resin Production
Acts as a hardening agent in phenol-formaldehyde resins
Enhances thermal and chemical resistance
Improves curing speed in molding compounds
Fuel Tablets and Emergency Combustion
Used in solid fuel stoves for military and camping
Compact and lightweight
Burns cleanly and produces minimal ash
High calorific value (~30 MJ/kg)
Laboratory Reagent and Synthesis Intermediate
Reagent in organic synthesis
Intermediate for heterocyclic compounds
Formaldehyde source in polymer reactions
Complexing agent in metal salt reactions
Water Treatment and Corrosion Inhibition
Inhibits metal corrosion by forming protective films
Utilized in closed-loop cooling systems
Compatible with steel and copper systems
Agriculture and Soil Treatment
Used in controlled-release urea formulations
Minimizes ammonia volatilization
Improves nitrogen use efficiency in crops
Biological Interactions and Biodegradability
Mildly toxic at high doses
Biodegradable under aerobic conditions
Hydrolyzed in acidic media
No significant bioaccumulation
SAFETY INFORMATION ABOUT HEXAMINE
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 contaminated 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
