Trimethyl phosphite

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  • Identifiers

    CAS number
    121-45-9

    Molecular formula
    C3H9O3P

    SMILES
    COP(OC)OC

    Safety labels

    Flammable
    Flammable

    Corrosive
    Corrosive

    Irritant
    Irritant

    Health Hazard
    Health

  • Odor profile

    Fragrance
    Ethereal 48.17%
    Odorless 36.34%
    Alcoholic 32.25%
    Fruity 31.88%
    Sweet 31.61%
    Fresh 27.86%
    Sharp 21.32%
    Solvent 20.49%
    Fermented 20.2%
    Pungent 19.52%

     

    Flavor
    Fruity 40.98%
    Green 35.86%
    Bitter 35.62%
    Sweet 34.73%
    Vegetable 31.26%
    Alcoholic 31.22%
    Fatty 28.85%
    Musty 27.53%
    Earthy 27.15%
    Ether 26.61%

     

    Odor impact est.
    High

    Odor threshold

    • Odor Threshold Low: 0.001 [mmHg]. Odor threshold from AIHA
    • Odor threshold (tested by means of a laboratory test panel) are on the order of 0.1 ppb.

  • Properties

    XLogP3-AA
    0.1

    pKa est.
    8.03 (weak base)

    Molecular weight
    124.08 g/mol

    Vapor pressure est.

    • hPa @ 20°C
    • hPa @ 25°C

    Evaporation rate
    Ultra fast

    Melting point expt.

    • -108 °F (USCG, 1999)
    • -78 °C
    • -108 °F

    Boiling point

    • 232 °F at 760 mmHg (USCG, 1999)
    • 110 °C
    • 111.5 °C
    • 232 °F

    Flash point

    • 33.91 ˚C est.
    • 82 °F (USCG, 1999)
    • 28 °C (82 °F) - closed cup
    • 130 °F (54 °C) (open cup)
    • 23 °C c.c.
    • 82 °F

    Solubility expt.

    • Reacts with water (NIOSH, 2024)
    • Reacts (hydrolyzes) with water
    • Very soluble in ethanol, ether
    • Soluble in hexane, benzene, acetone, carbon tetrachloride, and kerosene
    • Solubility in water: reaction
    • Reacts

  • Synonyms

    • TRIMETHYL PHOSPHITE
    • 121-45-9
    • Trimethylphosphite
    • Trimethoxyphosphine
    • Phosphorous acid, trimethyl ester
    • Methyl phosphite
    • Trimethylfosfit
    • Trimethoxyfosfin
    • HSDB 1007
    • NSC 6513
    • PHOSPHOROUS ACID TRIMETHYL ESTER
    • Trimethylphosphit
    • TMPhite
    • P(OMe)3
    • trimethoxyphosphane
    • Trimethyl ester of phosphorous acid
    • EINECS 204-471-5
    • UN2329
    • Methyl phosphite ((MeO)3P)
    • UNII-26Q0321ZDG
    • P(OCH3)3
    • DTXSID4026979
    • AI3-60394
    • 26Q0321ZDG
    • NSC-6513
    • MFCD00008350
    • PHOSPHOROUS ACID,TRIMETHYL ESTER
    • DTXCID106979
    • CHEBI:183313
    • EC 204-471-5
    • TRIMETHYL PHOSPHITE [HSDB]
    • UN 2329
    • Trimethylfosfit [Czech]
    • Trimethoxyfosfin [Czech]
    • Fosforyn trojmetylowy [Czech]
    • Fosforyn trojmetylowy
    • Trimethyl Ester Phosphorous Acid; NSC 6513; Trimethoxyphosphine;
    • trimethyl-phosphite
    • trimethoxy phosphine
    • TRIMETHYL ESTER
    • Trimethyl phosphite, 97%
    • Trimethyl phosphite (TMPi)
    • SCHEMBL58775
    • Trimethyl phosphite (ACGIH)
    • Trimethyl phosphite, >=97%
    • Trimethyl phosphite, >=99%
    • CHEMBL3186364
    • Phophorous acid, trimethyl ester
    • WLN: 1OPO1 & O1
    • NSC6513
    • WDA20107
    • Tox21_200440
    • AKOS000121918
    • NCGC00257994-01
    • BP-21379
    • CAS-121-45-9
    • NS00004609
    • T0488
    • Q153418
    • Trimethyl phosphite [UN2329] [Flammable liquid]
    • Trimethyl phosphite, >=99.999% trace metals basis
    • 204-471-5

  • Applications

    Trimethyl phosphite is primarily used as an organophosphorus building block in chemical synthesis. It serves as a convenient precursor in Arbuzov-type reactions to form dialkyl phosphonates and related phosphorus-containing intermediates, which underpin later steps in the manufacture of specialty chemicals, agrochemicals, and pharmaceuticals. It is also employed as a stabilizer and scavenger in polymer processing, where it helps trap halogen acids and peroxides to improve the thermal stability of PVC and other plastics. In coatings and inks, trimethyl phosphite may be added to suppress oxidation and extend service life. As a versatile phosphite ester, it is common in formulation work and research to prepare phosphorus-containing esters and explore radical- or nucleophile-initiated transformations.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 979.08
    methanol 1586.23
    isopropanol 714.42
    water 315.0
    ethyl acetate 341.8
    n-propanol 733.52
    acetone 535.66
    n-butanol 662.74
    acetonitrile 677.61
    DMF 825.15
    toluene 143.08
    isobutanol 476.81
    1,4-dioxane 670.1
    methyl acetate 411.26
    THF 801.22
    2-butanone 400.65
    n-pentanol 404.79
    sec-butanol 632.44
    n-hexane 67.27
    ethylene glycol 505.72
    NMP 609.67
    cyclohexane 146.97
    DMSO 798.05
    n-butyl acetate 209.66
    n-octanol 193.7
    chloroform 1478.5
    n-propyl acetate 209.88
    acetic acid 1466.91
    dichloromethane 1133.32
    cyclohexanone 429.8
    propylene glycol 439.69
    isopropyl acetate 210.78
    DMAc 577.87
    2-ethoxyethanol 772.37
    isopentanol 425.61
    n-heptane 91.67
    ethyl formate 415.64
    1,2-dichloroethane 516.06
    n-hexanol 276.55
    2-methoxyethanol 1279.09
    isobutyl acetate 126.56
    tetrachloromethane 459.25
    n-pentyl acetate 204.97
    transcutol 596.47
    n-heptanol 227.2
    ethylbenzene 76.12
    MIBK 173.51
    2-propoxyethanol 491.35
    tert-butanol 761.12
    MTBE 445.06
    2-butoxyethanol 418.2
    propionic acid 539.17
    o-xylene 119.32
    formic acid 1503.05
    diethyl ether 526.05
    m-xylene 95.39
    p-xylene 103.72
    chlorobenzene 202.54
    dimethyl carbonate 152.1
    n-octane 44.51
    formamide 1461.54
    cyclopentanone 493.83
    2-pentanone 315.28
    anisole 182.95
    cyclopentyl methyl ether 375.91
    gamma-butyrolactone 557.71
    1-methoxy-2-propanol 710.19
    pyridine 460.26
    3-pentanone 249.1
    furfural 625.08
    n-dodecane 24.6
    diethylene glycol 465.05
    diisopropyl ether 147.95
    tert-amyl alcohol 616.93
    acetylacetone 266.44
    n-hexadecane 26.12
    acetophenone 179.89
    methyl propionate 276.34
    isopentyl acetate 178.09
    trichloroethylene 922.68
    n-nonanol 170.04
    cyclohexanol 493.64
    benzyl alcohol 226.01
    2-ethylhexanol 173.6
    isooctanol 178.79
    dipropyl ether 228.62
    1,2-dichlorobenzene 198.05
    ethyl lactate 153.19
    propylene carbonate 306.85
    n-methylformamide 807.25
    2-pentanol 423.89
    n-pentane 127.7
    1-propoxy-2-propanol 345.35
    1-methoxy-2-propyl acetate 186.04
    2-(2-methoxypropoxy) propanol 180.62
    mesitylene 74.83
    ε-caprolactone 386.92
    p-cymene 89.22
    epichlorohydrin 671.94
    1,1,1-trichloroethane 564.44
    2-aminoethanol 697.01
    morpholine-4-carbaldehyde 613.74
    sulfolane 558.37
    2,2,4-trimethylpentane 67.04
    2-methyltetrahydrofuran 608.9
    n-hexyl acetate 212.51
    isooctane 42.42
    2-(2-butoxyethoxy)ethanol 280.27
    sec-butyl acetate 140.58
    tert-butyl acetate 231.48
    decalin 45.78
    glycerin 655.37
    diglyme 613.03
    acrylic acid 558.85
    isopropyl myristate 82.63
    n-butyric acid 633.79
    acetyl acetate 235.62
    di(2-ethylhexyl) phthalate 81.4
    ethyl propionate 171.9
    nitromethane 1308.19
    1,2-diethoxyethane 270.65
    benzonitrile 249.61
    trioctyl phosphate 76.62
    1-bromopropane 353.0
    gamma-valerolactone 653.37
    n-decanol 114.86
    triethyl phosphate 106.65
    4-methyl-2-pentanol 197.79
    propionitrile 437.53
    vinylene carbonate 316.87
    1,1,2-trichlorotrifluoroethane 760.62
    DMS 112.51
    cumene 65.02
    2-octanol 167.83
    2-hexanone 213.85
    octyl acetate 109.84
    limonene 141.56
    1,2-dimethoxyethane 692.51
    ethyl orthosilicate 119.88
    tributyl phosphate 77.38
    diacetone alcohol 281.29
    N,N-dimethylaniline 159.6
    acrylonitrile 496.26
    aniline 270.17
    1,3-propanediol 876.75
    bromobenzene 177.41
    dibromomethane 753.2
    1,1,2,2-tetrachloroethane 810.7
    2-methyl-cyclohexyl acetate 138.73
    tetrabutyl urea 103.81
    diisobutyl methanol 129.22
    2-phenylethanol 195.42
    styrene 94.48
    dioctyl adipate 107.08
    dimethyl sulfate 209.8
    ethyl butyrate 185.39
    methyl lactate 211.58
    butyl lactate 163.73
    diethyl carbonate 127.57
    propanediol butyl ether 273.62
    triethyl orthoformate 159.62
    p-tert-butyltoluene 97.91
    methyl 4-tert-butylbenzoate 218.87
    morpholine 823.25
    tert-butylamine 521.82
    n-dodecanol 84.98
    dimethoxymethane 508.63
    ethylene carbonate 274.01
    cyrene 214.75
    2-ethoxyethyl acetate 226.62
    2-ethylhexyl acetate 143.79
    1,2,4-trichlorobenzene 232.72
    4-methylpyridine 394.41
    dibutyl ether 152.34
    2,6-dimethyl-4-heptanol 129.22
    DEF 412.36
    dimethyl isosorbide 255.68
    tetrachloroethylene 699.22
    eugenol 192.25
    triacetin 176.64
    span 80 181.71
    1,4-butanediol 389.26
    1,1-dichloroethane 549.69
    2-methyl-1-pentanol 286.11
    methyl formate 528.56
    2-methyl-1-butanol 445.31
    n-decane 46.22
    butyronitrile 478.99
    3,7-dimethyl-1-octanol 157.18
    1-chlorooctane 114.51
    1-chlorotetradecane 43.11
    n-nonane 48.07
    undecane 31.56
    tert-butylcyclohexane 47.45
    cyclooctane 60.64
    cyclopentanol 539.59
    tetrahydropyran 582.34
    tert-amyl methyl ether 364.88
    2,5,8-trioxanonane 327.64
    1-hexene 137.12
    2-isopropoxyethanol 415.93
    2,2,2-trifluoroethanol 778.35
    methyl butyrate 245.32

    Scent© AI

1 4

IFRA standard 51

Recommendation
No restriction
Maximum acceptable concentrations in the finished product (%)
Category 1
Products applied to the lips
 No restriction Category 7A
Rinse-off products applied to the hair with some hand contact
 No restriction
Category 2
Products applied to the axillae
 No restriction Category 7B
Leave-on products applied to the hair with some hand contact
 No restriction
Category 3
Products applied to the face/body using fingertips
 No restriction Category 8
Products with significant anogenital exposure
 No restriction
Category 4
Products related to fine fragrance
 No restriction Category 9
Products with body and hand exposure, primarily rinse off
 No restriction
Category 5A
Body lotion products applied to the body using the hands (palms), primarily leave on
 No restriction Category 10A
Household care products with mostly hand contact
 No restriction
Category 5B
Face moisturizer products applied to the face using the hands (palms), primarily leave on
 No restriction Category 10B
Household care products with mostly hand contact, including aerosol/spray products (with potential leave-on skin contact)
 No restriction
Category 5C
Hand cream products applied to the hands using the hands (palms), primarily leave on
 No restriction Category 11A
Products with intended skin contact but minimal transfer of fragrance to skin from inert substrate without UV exposure
 No restriction
Category 5D
Baby Creams, baby Oils and baby talc
 No restriction Category 11B
Products with intended skin contact but minimal transfer of fragrance to skin from inert substrate with potential UV exposure
 No restriction
Category 6
Products with oral and lip exposure
 No restriction Category 12
Products not intended for direct skin contact, minimal or insignificant transfer to skin
 No restriction