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Description
Trimethyl Phosphate (TMP) is a colorless, transparent organophosphorus compound widely used as a solvent, reaction intermediate, methylating agent, flame-retardant additive, electrolyte component, and specialty chemical in the pharmaceutical, agrochemical, electronics, polymer, and chemical manufacturing industries. It is the trimethyl ester of phosphoric acid and possesses excellent solvent power, low viscosity, good thermal stability, and high chemical purity.
TMP is particularly valued for its ability to dissolve a wide range of organic and inorganic substances while maintaining excellent compatibility with numerous chemical systems. In organic synthesis, it functions as a methylation reagent and reaction medium, whereas in lithium-ion battery technology it serves as a flame-retardant electrolyte additive that enhances battery safety without significantly compromising electrochemical performance. It is also employed in the manufacture of pesticides, pharmaceutical intermediates, specialty resins, and advanced polymer materials.
Due to its relatively high polarity, low volatility compared with many organic solvents, and excellent solvency characteristics, Trimethyl Phosphate has become an important specialty solvent in modern industrial chemistry.
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CAS Number
CAS Number: 512-56-1
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Synonyms
• Trimethyl Phosphate
• TMP
• Phosphoric Acid Trimethyl Ester
• Trimethyl Orthophosphate
• Trimethyl Phosphoric Ester
• Methyl Phosphate
• Trimethyl Ester of Phosphoric Acid
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Physical Properties
Trimethyl Phosphate is supplied as a clear, colorless liquid with a faint characteristic odor. It possesses relatively low viscosity, excellent fluidity, and high purity suitable for industrial and electronic applications.
Typical characteristics include:
• Appearance: Clear, colorless liquid
• Physical state: Liquid
• Odor: Slight characteristic odor
• Molecular formula: C₃H₉O₄P
• Molecular weight: 140.07 g/mol
• Density: Approximately 1.20–1.23 g/cm³
• Boiling point: Approximately 197°C
• Melting point: Approximately −46°C
• Flash point: Approximately 107°C
• Viscosity: Low
• Water solubility: Completely miscible
Its low freezing point allows use under a wide range of operating temperatures.
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Chemical Properties
Trimethyl Phosphate is a neutral phosphate ester containing one phosphorus atom bonded to three methoxy groups. It exhibits excellent chemical stability under normal storage conditions while remaining sufficiently reactive for use in numerous synthetic reactions.
Important chemical characteristics include:
• High polarity
• Excellent solvent properties
• Good thermal stability
• Low viscosity
• Hydrolyzes slowly in strong acidic or alkaline conditions
• Excellent compatibility with polar organic compounds
• Low electrical conductivity
• Good flame-retardant characteristics
TMP may slowly hydrolyze to methanol and phosphoric acid under strongly acidic or alkaline conditions.
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Manufacturing Process
Commercial Trimethyl Phosphate is generally produced through esterification or transesterification reactions involving phosphorus oxychloride or phosphoric acid derivatives with methanol.
Typical manufacturing stages include:
• Preparation of phosphorus intermediate
• Controlled esterification with methanol
• Neutralization
• Removal of reaction by-products
• Vacuum distillation
• Purification
• Filtration
• Quality control analysis
• Packaging
High-purity electronic grades undergo additional purification to remove trace impurities.
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Mechanism of Action
Trimethyl Phosphate functions according to the application in which it is used.
As a solvent, it dissolves polar compounds through dipole interactions, facilitating homogeneous reaction mixtures.
In flame-retardant formulations, phosphorus-containing species promote char formation and reduce flammability during combustion.
Within lithium-ion batteries, TMP acts as a flame-retardant electrolyte additive by suppressing ignition while maintaining ionic conductivity and electrochemical stability.
In organic synthesis, it participates as a methylating or phosphorylating reagent under appropriate reaction conditions.
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Applications
Trimethyl Phosphate has numerous industrial applications.
Chemical Industry
• Organic synthesis
• Reaction solvent
• Methylation reactions
• Chemical intermediate
• Laboratory reagent
Pharmaceutical Industry
• Pharmaceutical intermediates
• API synthesis
• Specialty solvent
Electronics Industry
• Lithium-ion battery electrolytes
• Electronic chemicals
• High-purity solvents
Polymer Industry
• Flame-retardant additives
• Specialty resins
• Polymer processing
Agrochemical Industry
• Pesticide intermediates
• Herbicide synthesis
• Specialty agricultural chemicals
