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THPC typically appears as a colorless to pale yellow viscous liquid or crystalline solid with a characteristic pungent odor.
It is highly hygroscopic and completely soluble in water, alcohols, and other polar solvents. Key parameters include melting point of 150-152°C (decomposes), density of 1.33 g/cm³ (80% solution), pH of 2-3 for aqueous solutions, and significant thermal decomposition beginning at 120°C.
The compound is strongly acidic due to the quaternary phosphonium cation and chloride counterion, with the phosphorus center existing in the +5 oxidation state.
CAS Number: 124-64-1
EC Number: 204-709-7
UN Number: 3261 (Corrosive liquid, basic, organic, n.o.s.)
Molecular Formula: C₄H₁₂ClO₄P or (HOCH₂)₄P⁺Cl⁻
Molecular Weight: 190.56 g/mol
Synonyms:
· THPC
· Phosphonium, tetrakis(hydroxymethyl)-, chloride
· Tetramethylolphosphonium chloride
· Tetrahydroxymethylphosphonium chloride
· Fire retardant THPC
Process Details:
· Reactants: Phosphine gas (highly toxic), formaldehyde (37% solution), hydrochloric acid
· Temperature: 60-80°C with careful temperature control
· Pressure: Atmospheric with phosphine gas introduction under controlled flow
· Safety: Extreme precautions due to phosphine toxicity and flammability
· Yield: 85-92% after purification
Alternative Production Methods:
1. From Phosphorus Trichloride: Sequential reaction with formaldehyde and reduction
2. Electrochemical Methods: Less common due to complexity
3. Continuous Flow Processes: For improved safety and consistency
Purification and Formulation:
Crude THPC undergoes:
1. Concentration: Vacuum evaporation to 70-80% active content
2. Decolorization: Activated carbon treatment
3. Stabilization: Addition of antioxidants (typically phosphites)
4. Adjustment: To specific concentration for different applications
Quality Specifications:
· Active Content: 70-80% for commercial grades
· Phosphine Residual: <1 ppm (critical safety parameter)
· Formaldehyde Content: <0.5% free formaldehyde
· pH (10% solution): 2.0-3.0
· Color (APHA): <100
· Iron Content: <5 ppm
· Water Content: 20-30% for standard grades
Global production capacity is estimated at 30,000-40,000 metric tons annually, dominated by specialty chemical producers including Italmatch Chemicals, Solvay, and several Chinese manufacturers. Pricing ranges from $3-5/kg for industrial grades to $8-12/kg for high-purity textile grades.
Chemical Reactivity and Functional Mechanisms
Flame Retardant Mechanism:
THPC functions through multiple synergistic mechanisms:
1. Char Formation: Promotes carbonaceous char via acid-catalyzed dehydration
2. Gas Phase Inhibition: Releases phosphorus oxides that scavenge free radicals
3. Thermal Protection: Endothermic decomposition absorbs heat
4. Melt Dripping Suppression: Increases viscosity of burning polymer
Chemical Transformations: THPC typically appears as a colorless to pale yellow viscous liquid or crystalline solid with a characteristic pungent odor. It is highly hygroscopic and completely soluble in water, alcohols, and other polar solvents. Key parameters include melting point of 150-152°C (decomposes), density of 1.33 g/cm³ (80% solution), pH of 2-3 for aqueous solutions, and significant thermal decomposition beginning at 120°C. The compound is strongly acidic due to the quaternary phosphonium cation and chloride counterion, with the phosphorus center existing in the +5 oxidation state.
CAS Number: 124-64-1
EC Number: 204-709-7
UN Number: 3261 (Corrosive liquid, basic, organic, n.o.s.)
Molecular Formula: C₄H₁₂ClO₄P or (HOCH₂)₄P⁺Cl⁻
Molecular Weight: 190.56 g/mol
Synonyms:
THPC
Phosphonium, tetrakis(hydroxymethyl)-, chloride
Tetramethylolphosphonium chloride
Tetrahydroxymethylphosphonium chloride
Fire retardant THPC
Process Details:
Reactants: Phosphine gas (highly toxic), formaldehyde (37% solution), hydrochloric acid
Temperature: 60-80°C with careful temperature control
Pressure: Atmospheric with phosphine gas introduction under controlled flow
Safety: Extreme precautions due to phosphine toxicity and flammability
Yield: 85-92% after purification
Alternative Production Methods:
From Phosphorus Trichloride: Sequential reaction with formaldehyde and reduction
Electrochemical Methods: Less common due to complexity
Continuous Flow Processes: For improved safety and consistency
Purification and Formulation:
Crude THPC undergoes:
Concentration: Vacuum evaporation to 70-80% active content
Decolorization: Activated carbon treatment
Stabilization: Addition of antioxidants (typically phosphites)
Adjustment: To specific concentration for different applications
Quality Specifications:
Active Content: 70-80% for commercial grades
Phosphine Residual: <1 ppm (critical safety parameter)
Formaldehyde Content: <0.5% free formaldehyde
pH (10% solution): 2.0-3.0
Color (APHA): <100
Iron Content: <5 ppm
Water Content: 20-30% for standard grades
Global production capacity is estimated at 30,000-40,000 metric tons annually, dominated by specialty chemical producers including Italmatch Chemicals, Solvay, and several Chinese manufacturers. Pricing ranges from $3-5/kg for industrial grades to $8-12/kg for high-purity textile grades.
Chemical Reactivity and Functional Mechanisms
Flame Retardant Mechanism:
THPC functions through multiple synergistic mechanisms:
Char Formation: Promotes carbonaceous char via acid-catalyzed dehydration
Gas Phase Inhibition: Releases phosphorus oxides that scavenge free radicals
Thermal Protection: Endothermic decomposition absorbs heat
Melt Dripping Suppression: Increases viscosity of burning polymer
Chemical Transformations:
Condensation Reactions: With amines to form P-N bonds (Proban® process)
Oxidation: To tetrakis(hydroxymethyl)phosphonium oxide (THPO)
Reduction: To various phosphorus compounds
Complex Formation: With metal ions for synergistic effects
Comprehensive Application Spectrum
Textile Flame Retardancy (70% of consumption):
Cotton and Cotton Blends: Through Proban® and similar processes (15-30% add-on)
Technical Textiles: For military, industrial, and transportation applications
Case Example: In children's sleepwear, THPC-treated cotton achieves Class 1 flammability (US CPSC standard) with 50+ launderings durability.
Polymer Modification (15%):
Polyurethane Foams: As reactive flame retardant (3-10%)
Epoxy Resins: For printed circuit boards and composites (5-15%)
Unsaturated Polyesters: For construction and transportation
Case Example: In flexible PU foam for furniture, THPC derivatives provide flame retardancy meeting California TB 117 requirements without compromising comfort properties.
Paper and Wood Products (10%):
Paper Treatments: For specialty papers and boards
Wood Composites: For improved fire performance
Case Example: In decorative laminates, THPC treatments enable Class B fire ratings (ASTM E84) while maintaining machinability.
Other Applications (5%):
Oil Field Chemicals: As clay stabilizer and corrosion inhibitor
Water Treatment: As biocide and scale inhibitor
Leather Processing: As tanning agent and flame retardant
Adhesives: For improved fire performance
1. Condensation Reactions: With amines to form P-N bonds (Proban® process)
2. Oxidation: To tetrakis(hydroxymethyl)phosphonium oxide (THPO)
3. Reduction: To various phosphorus compounds
4. Complex Formation: With metal ions for synergistic effects
Comprehensive Application Spectrum
Textile Flame Retardancy (70% of consumption):
· Cotton and Cotton Blends: Through Proban® and similar processes (15-30% add-on)
· Technical Textiles: For military, industrial, and transportation applications
· Case Example: In children's sleepwear, THPC-treated cotton achieves Class 1 flammability (US CPSC standard) with 50+ launderings durability.
Polymer Modification (15%):
· Polyurethane Foams: As reactive flame retardant (3-10%)
· Epoxy Resins: For printed circuit boards and composites (5-15%)
· Unsaturated Polyesters: For construction and transportation
· Case Example: In flexible PU foam for furniture, THPC derivatives provide flame retardancy meeting California TB 117 requirements without compromising comfort properties.
Paper and Wood Products (10%):
· Paper Treatments: For specialty papers and boards
· Wood Composites: For improved fire performance
· Case Example: In decorative laminates, THPC treatments enable Class B fire ratings (ASTM E84) while maintaining machinability.
Other Applications (5%):
· Oil Field Chemicals: As clay stabilizer and corrosion inhibitor
· Water Treatment: As biocide and scale inhibitor
· Leather Processing: As tanning agent and flame retardant
· Adhesives: For improved fire performance
SAFETY INFORMATION ABOUT TETRAKIS(HYDROXYMETHYL)PHOSPHONIUM CHLORIDE
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
