Trimethyl phosphite

Trimethyl phosphite Basic information
Product Name:Trimethyl phosphite
Synonyms:PHOSPHOROUS ACID TRIMETHYL ESTER;TRIMETHYL PHOSPHONATE;TRIMETHYL PHOSPHITE;fosforyntrojmetylowy;Methyl phosphite ((MeO)3P);P(OCH3)3;TRIMETHYLPHOSPHIT S;Trimethyl phosphite solution
CAS:121-45-9
MF:C3H9O3P
MW:124.08
EINECS:204-471-5
Product Categories:organophosphorus compound;Building Blocks;Chemical Synthesis;Organic Building Blocks;Organic Phosphates/Phosphites;Phosphorus Compounds
Mol File:121-45-9.mol
Trimethyl phosphite Structure
Trimethyl phosphite Chemical Properties
Melting point −78 °C(lit.)
Boiling point 111-112 °C(lit.)
density 1.052 g/mL at 25 °C(lit.)
vapor density 4.3 (vs air)
vapor pressure 17 mm Hg ( 20 °C)
refractive index n20/D 1.408(lit.)
Fp 82 °F
storage temp. 2-8°C
solubility Chloroform, DMSO (Sparingly)
form Liquid
color Colorless
Specific Gravity1.052
explosive limit5.2-61.2%(V)
Water Solubility Hydrolyzes with water.
Sensitive Air & Moisture Sensitive
Hydrolytic Sensitivity4: no reaction with water under neutral conditions
BRN 956570
Exposure limitsTLV-TWA 10 mg/m3 (2 ppm) (ACGIH).
Stability:Moisture Sensitive
CAS DataBase Reference121-45-9(CAS DataBase Reference)
NIST Chemistry ReferencePhosphorous acid, trimethyl ester(121-45-9)
EPA Substance Registry SystemTrimethyl phosphite (121-45-9)
Safety Information
Hazard Codes Xn,T,F,Xi
Risk Statements 10-22-36/37/38-41-37/38-65-48/23/24/25-11-46-45-67-66-36
Safety Statements 26-39-62-45-16-53
RIDADR UN 2329 3/PG 3
WGK Germany 1
RTECS TH1400000
10-13-21
Autoignition Temperature250 °C
TSCA Yes
HS Code 2920 23 00
HazardClass 3
PackingGroup III
Hazardous Substances Data121-45-9(Hazardous Substances Data)
ToxicityLD50 orally in Rabbit: 1600 mg/kg LD50 dermal Rabbit 2600 mg/kg
MSDS Information
ProviderLanguage
Phosphorous acid trimethyl ester English
SigmaAldrich English
ALFA English
Trimethyl phosphite Usage And Synthesis
Chemical PropertiesTrimethyl phosphite is a colorless liquid. Distinctive pungent, pyridine-like odor. The Odor Threshold is 0.0001 ppm.
UsesTrimethyl phosphite has been used primarily as an intermediate in the manufacture of pesticides and the synthesis of organophosphate insecticides. It is also used as a fire retardants in the production of textiles, as an intermediate in the production of flame-retardant polymers for polyurethane foams, and as a catalyst.
Production MethodsProduced via a reaction between phosphorus trichloride and methanol in the presence of a tertiary amine catalyst such as diethylaniline.
DefinitionChEBI: Trimethyl phosphite is an organophosphorus compound that is phosphane in which the three hydrogens are replaced by methoxy groups. It is an alkylating agent used primarily in the synthesis of organophosphate compounds. It has a role as an alkylating agent.
ReactionsThe reaction of trimethyl phosphite and dimethyl acetylenedicarboxylate in the presence of dimedone as the proton source/nucleophile leads to 2-(dimethoxy-phosphoryl)-3-(2-hydroxy-4,4-dimethyl-6-oxo-cyclohex-1-enyl)-succinic acid dimethyl ester in 91 % yields.
It reacts with a catalytic amount of methyl iodide in the Arbuzov reaction to give dimethyl methylphosphonate:
P(OCH3)3 → CH3P(O)(OCH3)2
It is susceptible to oxidation to trimethyl phosphate.
General DescriptionTrimethyl phosphite appears as a clear colorless liquid with a strong foul odor. Flash point 99°F. Denser than water and insoluble in water. Vapors heavier than air. It is used in making pesticides, flame retardants and organophosphorous additives.
Air & Water ReactionsHighly flammable. Insoluble in water and denser than water. Slowly reacts with water to form phosphoric acid and corresponding organic alcohol. Trimethyl phosphite hydrolyzes in water to form dimethyl phosphite and methanol. The hydrolysis rate of trimethyl phosphite is expected to be similar to the hydrolysis rate of triethyl phosphite(SRC).
Reactivity ProfileAs soon as Trimethyl phosphite contacted a small amount of magnesium perchlorate in a flask, there was a flash and an explosion that shattered the flask (Allison 1968).
Health HazardTrimethyl phosphite is a skin, eye, and mucous membrane irritant with low subacute inhalation toxicity. Its irritating action on rabbits’ skin was moderate to severe. The pure liquid instilled into the eyes can cause severe irritation and swelling, which can last for a few days. Chronic exposure to 300–600 ppm concentration in air produced lung inflammation and cataracts in mice. There was no acute inhalation toxicity observed in test animals. The oral and dermal toxicities were low.
LD50 value, oral (rats): 1600 mg/kg
Teratogenic effects showing gross abnormalities were observed in newborn rats when pregnant rats were dosed with high concentrations of trimethyl phosphite.
The odor threshold for this compound was determined to be 0.0001 ppm (ACGIH 1986). The odor is irritating and pungent at high concentrations..


Fire HazardSpecial Hazards of Combustion Products: Toxic fumes of PO x
Safety ProfileModerately toxic by ingestion and skin contact. An experimental teratogen. A severe skin and eye irritant. Flammable liquid when exposed to heat, flame, or oxidizers. To fight fire, use water, foam, fog, CO2. Violent explosive reaction on contact with magnesium perchlorate or trimethyl platinum(IV) azide tetramer. When heated to decomposition it emits toxic fumes of POx. An intermediate in the production of pesticides, fire retardants, and organic phosphorus additives. See also ESTERS.
Potential ExposureTrimethyl phosphite is a flame retardant, and used as an intermediate in the manufacture of a number of pesticides, and organophosphorus additives.
CarcinogenicityTrimethyl phosphite was genotoxic in mouse lymphoma assays but was not mutagenic in various bacterial assays.
ShippingUN2329 Trimethyl phosphite, Hazard Class: 3; Labels: 3-Flammable liquid.
Purification MethodsTreat the phosphite with Na (to remove water and any dialkyl phosphonate), then decant and distil it with protection against moisture. It has also been treated with sodium wire for 24hours, then distilled in an inert atmosphere onto activated molecular sieves [Connor et al. J Chem Soc, Dalton Trans 511 1986]. It can be fractionally distilled using a spinning band column at high reflux ratio. It is a colourless liquid which is slowly hydrolysed by H2O. [Gillis et al. J Am Chem Soc 80 2999 1958, NMR: Callis et al. J Am Chem Soc 79 2719 1957, Kosolapoff Organophosphorus Compounds, Wiley p 203 1950, Beilstein 1 IV 1256.]
IncompatibilitiesVaor May form explosive mixture with air. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Violent reaction with magnesium perchlorate. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. Reacts (hydrolyzes) with water. Incompatible with air, moisture.
Waste DisposalTrimethyl phosphite may be burned in a chemical incinerator equipped with an afterburner and scrubber.
Trimethyl borate Vinyltrimethoxysilane Orthophosphorus acid Triethyl phosphate DIPHENYL METHYL PHOSPHATE PARAOXON BENZYL DIETHYL PHOSPHITE Olibanum oil TRIMETHYL THIOPHOSPHATE Tris(2-chloroethyl) phosphate (Trifluoromethoxy)benzene Trimethyl phosphite BUTYL OLEATE Dimethyl succinate Triphenyl phosphate Phosphorus Dimethyl phosphite TRIS(2-CHLOROETHYL) PHOSPHITE

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