General description
Hexamethylphosphoramide is made from the reaction of dimethylamine and phosphorus oxychloride. It has a molecular weight of 179.2, appearing as colorless or light yellow transparent liquid with slightly astringent taste. It has a relative density of 1.0253~1.0257 (20 ℃), refractive index of 1.4582~1.4589 (20 °C), the freezing point of 2~7 °C and the boiling point of 116~117 °C (1480Pa). It is soluble in polar and non-polar solvents. It is also miscible with the commonly used plasticizers such as dioctyl phthalate, dioctyl sebacate, and triphenyl phosphite in any proportion. It has a similar toxicity to phosphate. Avoid contact with skin. Its containers should be tightly sealed to prevent leakage and water absorption to be deteriorated Hexamethylphosphoramide is the light stabilizer of the PVC, enabling an excellent anti-aging properties of outdoor products with excellent weather resistance, therefore being known as highly-efficient weathering agent of PVC.
Addition of 2 to copies of this product to the PVC film can significantly improve both the weather resistance and cold resistance as well as reducing the processing temperature by 10 °C. This product can also be used as the excellent polar solvent of many kinds of polymer materials such as polyphenylene sulfide, polyurethane and polyamide for improving the resin quality, simplifying the process and reducing costs. Addition it into the ethylene-propylene rubber can improve the flexibility and oil resistance. It can also be used as a co-catalyst for the polymerization of propylene to improve the catalytic efficiency of the main catalyst.
Harmful effects and symptoms of poisoning
To animals: Hexamethylphosphoramide (HMPA) is known to have various kinds of toxic effects on experimental animals. HMPA-induced acute poisoning in rats is characterized with nephropathy, severe bronchiectasis and bronchial pneumonia. Application of HMPA repetitively to rabbit skin can lead to weight loss, changes in gastric function and apparent neurological disorders. Rats subjecting to oral administration of HMPA can exhibit testicular atrophy and semen deficiencies. Small chickens subjecting to oral administration of HMPA can also get highly inhibited growth in its testis. HMPA has been known to induce mutagenesis in Drosophila. However, the effects of HMPA on sex chromosomes in mice showed that the frequency of chromosome aberration induced by HMPA was not significant compared with the control group. Preliminary results of the toxicity study upon inhaling HMPA revealed that nasal tumors will appear in rats after 8 months after being exposed to 400 to 4000 ppb HMPA. In some diseased mice, cancer initiated from the epithelium connecting the nasal bone can fill the nasal cavity and penetrates into the brain. Rats exposed to 50 ppb HMPA didn’t develop nasal cancer compared with the control group.
To humans: the role of HMPA on human toxicity has not been reported.
Protective measures
The traditional measure is that the operator should wear protective clothing, wearing protective glasses and gloves, to avoid direct contact with the product with the production site should be well ventilated.
Chemical properties
It appears as colorless transparent flammable liquid with a medium ammonia flavor. It is soluble in water, polar and non-polar solvents.
Uses
1. It can be used as the efficient anti-corrosion agent of PVC and other kinds of chlorine-containing resin products and coatings.
2. The product is the weathering solvent of polyvinyl chloride and excellent polar solvent, having a significant effect on the low temperature resistance and aging resistance of the agricultural film; it is a multi-functional high-boiling polar solvent that is aprotic. It can be used as the solvents of polymer synthesis with special effect on the synthesis of polyphenylene sulfide and aromatic polyamide and so on. This product, as the co-catalyst of propylene polymerization catalyst, when supplied to the ethylene propylene rubber, can improve the missile and oil resistance of the latter one. Hexamethylphosphoramide can also be used as a gas chromatographic fixative, ultraviolet inhibitor, rocket fuel additives for lowering the freezing point and chemical sterilizers.
3. It is effective non-proton solvent; as fixative of gas chromatography (highest usage temperature: 35°C with methanol as the solvent); used for separation and analysis of hydrocarbons; for separation of alkanes, alkenes and alkynes; accelerator of stereo-specific reaction; Ultraviolet inhibitor of PVC.
Production method
It can be obtained through the reaction between dimethylamine and alkali chlorophosphorus. Put the dimethylamine and phosphorus oxychloride for reaction in triethylene glycol as the solvent; control the temperature at 40-60 °C; upon reaction, add ammonia as acid-binding agent with interaction with the generated hydrogen chloride to become ammonium chloride precipitation. After completion of the reaction, filtration was performed. Recycle the trichlorethylene from the filtration and then perform alkali treatment, and then conduct distillation, collecting the fraction of 113-118 °C (2.0kPa) fractions to derive Hexamethylphosphoramide (HMPA). Tsinghua Unisplendour Group Corporation has cooperated with the production plant to develop a new solvent-free process that can achieve a product purity of 99.2% or more. The industrial hexamethylphosphoramide appears as colorless or light yellow transparent liquid. Catalyst grade content ≥ 99.5%; first-class grade ≥ 99.0%; second-class products ≥ 98.0%. Fixed consumption amount of raw materials: dimethylamine 2410kg/t, phosphorus oxychloride: 1610kg/t, liquid ammonia 430kg/t.
Description
Hexamethylphosphoric triamide is a colorlessliquid with a spicy odor. Molecular weight = 179.24; .Specific gravity (H2O:1l)= 1.03; Boiling point= 232.8℃;FreezingMelting point = 6.1℃; Relative vapor density(air= 1)=6.18; V apor pressure = 0.03 mmHg at 20℃;Flash point= 104.4℃. Hazard Identification (basedonNFPA-704 M Rating System): Health 2, Flammability 1,Reactivity 0. Soluble in water.
Chemical Properties
Hexamethylphosphoric triamide is a colorless
liquid with a spicy odor.
Chemical Properties
colourless or light amber liquid with an aromatic spicy odour
Uses
Hexamethylphosphoramide is a dipolar co-solvent and an effective additive used in reactions like reduction of halides, deoxygenation of sulfones, halide olefin couplings and cleavage of carbon-sulfur bond.
Uses
Solvent for polymers; polymerization
catalyst; stabilizer against thermal degradation
in polystyrene; UV stabilizer in polyvinyl and
polyolefin resins
Uses
Aprotic solvent in organic synthesis. Solvent for polymers, gases; polymerization catalyst; thermal stabilizer in polystyrene; protective additive for polyvinyl and polyolefin resins against uv light degradation. De-icing additive for jet fuels. Chemosterilant for a number of insect pests; chemical mutagen.
Definition
ChEBI: Hexamethylphosphoric triamide is a phosphoramide. It has a role as a mutagen and an insect sterilant.
General Description
Clear colorless to light amber liquid with a spicy odor.
Air & Water Reactions
Water soluble.
Reactivity Profile
Hexamethylphosphoramide may react with strong oxidizing agents and strong acids . Susceptible to formation of highly toxic and flammable phosphine gas in the presence of strong reducing agents such as hydrides. Partial oxidation by oxidizing agents may result in the release of toxic phosphorus oxides.
Hazard
Possible carcinogen. Toxic by skin contact.
Combustible.
Health Hazard
The acute toxicity of hexamethylphosphoramide is low. HMPA can cause irritation
upon contact with the skin and eyes. Hexamethylphosphoramide has been found to
cause cancer in laboratory animals exposed by inhalation and meets the criteria for
classification as an OSHA "select carcinogen." Chronic exposure to HMPA can
cause damage to the lungs and kidneys. Reproductive effects in male animals treated
with hexamethylphosphoramide have been observed. HMPA should be regarded as a
substance with poor warning properties.
Fire Hazard
Combustible liquid. Its decomposition at high temperatures or in a fire can produce
phosphine, phosphorus oxides, and oxides of nitrogen, which are extremely toxic.
Carbon dioxide or dry chemical extinguishers should be used for HMPA fires.
Fire Hazard
Hexamethylphosphoramide is combustible.
Flammability and Explosibility
Combustible liquid. Its decomposition at high temperatures or in a fire can produce phosphine, phosphorus oxides, and oxides of nitrogen, which are extremely toxic. Carbon dioxide or dry chemical extinguishers should be used for HMPA fires.
Potential Exposure
Hexamethylphosphoric triamide is a
material possessing unique properties and is widely used as
a solvent in small quantities, in organic and organometallic
reactions in laboratories. This is the major source of occu pational exposure to HMPA in the United States. It is also
used as a processing solvent in the manufacture of aramid
fibers. HMPA has been evaluated for use as an ultraviolet
light absorber or inhibitor in polyvinylchloride formulations;
as an additive for antistatic effects; as a flame retardant; and
as a deicing additive for jet fuels. Hexamethylphosphoric
triamide has also been extensively investigated as an insect
chemosterilant.
First aid
If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek med-ical attention immediately. If this chemical contacts theskin, remove contaminated clothingand wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, includ-ing resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medi-cal attention. Give large quantities of water and inducevomiting. Do not make an unconscious person vomit.
Carcinogenicity
Hexamethylphosphoramide is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals.
storage
this compound should be handled only in a fume hood, using appropriate impermeable gloves and splash goggles to prevent skin and eye contact. Containers of this substance should be stored in secondary containers.
Shipping
UN3082 Environmentally hazardous substances,
liquid, n.o.s., Hazard class: 9; Labels: 9-Miscellaneous haz ardous material, Technical Name Required
Purification Methods
The industrial synthesis is usually by treatment of POCl3 with excess of dimethylamine in isopropyl ether. Impurities are water, dimethylamine and its hydrochloride. It is purified by refluxing over BaO or CaO at about 4mm pressure in an atmosphere of nitrogen for several hours, then distilled from sodium at the same pressure. The middle fraction (b ca 90o) is collected, refluxed over sodium under reduced pressure under nitrogen and distilled. It is kept in the dark under nitrogen, and stored in solid CO2. It can also be stored over 4A molecular sieves. Alternatively, it is distilled under vacuum from CaH2 at 60o and is crystallised twice in a cold room at 0o, seeding the liquid with crystals obtained by cooling in liquid nitrogen. After about two-thirds are frozen, the remaining liquid is drained off [Fujinaga et al. Pure Appl Chem 44 117 1975]. For tests of purity see Fujinaga et al. in Purification of Solvents, Coetzee Ed., Pergamon Press, Oxford, 1982. For efficiency of desiccants in drying HMPA see Burfield and Smithers [J Org Chem 43 3966 1978, Sammes et al. J Chem Soc, Faraday Trans 1 281 1986]. [Beilstein 4 IV 284.] CARCINOGEN.
Incompatibilities
Incompatible (possibly violent reaction;
fire and explosions) with oxidizers (chlorates, nitrates,peroxides, permanganates, perchlorates, chlorine, bromine,
fluorine, etc.). Keep away from alkaline materials, chemi cally active metals, strong acids, strong bases.
Waste Disposal
Excess hexamethylphosphoramide and waste material containing this substance should be placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines.
