Octamethylcyclotetrasiloxane

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  • Identifiers

    CAS number
    556-67-2

    Molecular formula
    C8H24O4Si4

    SMILES
    C[Si]1(O[Si](O[Si](O[Si](O1)(C)C)(C)C)(C)C)C

    Safety labels

    Health Hazard
    Health

    Environmental Hazard
    Environmental

  • Odor profile

    Fragrance
    Odorless 64.86%
    Fruity 20.97%
    Green 18.79%
    Fresh 16.84%
    Ethereal 15.95%
    Alcoholic 15.58%
    Cooling 14.33%
    Earthy 13.86%
    Creamy 13.65%
    Meaty 13.62%

     

    Flavor
    Green 55.7%
    Earthy 50.4%
    Vegetable 39.74%
    Sulfurous 26.54%
    Sweet 25.16%
    Blackberry 24.66%
    Burnt 24.51%
    Potato 21.91%
    Herbal 21.62%
    Musty 20.9%

     

    Odor impact est.
    Low

  • Properties

    pKa est.
    7.79 (neutral)

    Molecular weight
    296.61 g/mol

    Melting point expt.

    • 17.5 °C

    Boiling point

    • 175 °C
    • BP: 74 °C at 20 mm Hg

    Flash point

    • 62.74 ˚C est.
    • 55 °C (131 °F) - closed cup
    • 56 °C

    Solubility expt.

    • In water, 0.056 mg/L at 23 °C
    • In synthetic seawater water, 0.033 mg/L at 25 °C
    • Soluble in carbon tetrachloride
    • Solubility in water: none

  • Synonyms

    • OCTAMETHYLCYCLOTETRASILOXANE
    • 556-67-2
    • Cyclotetrasiloxane, octamethyl-
    • 2,2,4,4,6,6,8,8-Octamethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane
    • Oktamethylcyklotetrasiloxan
    • OMCTS
    • Cyclic dimethylsiloxane tetramer
    • NUC silicone VS 7207
    • Union carbide 7207
    • Silicone SF 1173
    • Cyclomethicone 4
    • DTXSID7027205
    • KF 994
    • SF 1173
    • UC 7207
    • VS 7207
    • CZ227117JE
    • NSC-345674
    • DTXCID107205
    • CHEBI:25640
    • RefChem:167770
    • 209-136-7
    • Oktamethylzyklotetrasiloxan
    • MFCD00003269
    • Dimethylsiloxane Cyclic Tetramer
    • 2,2,4,4,6,6,8,8-octamethyl-1,3,5,7,2,4,6,8-tetroxatetrasilocane
    • s12400
    • C8H24O4Si4
    • CAS-556-67-2
    • CCRIS 1327
    • HSDB 6131
    • Oktamethylcyklotetrasiloxan [Czech]
    • EINECS 209-136-7
    • NSC 345674
    • BRN 1787074
    • UNII-CZ227117JE
    • Polysiloxane D4 CRS
    • Simethicone Impurity 3
    • bmse000765
    • EC 209-136-7
    • octamethyl-cyclotetrasiloxane
    • SCHEMBL18354
    • BIDD:ER0157
    • orb2945038
    • CHEMBL1869229
    • HMMGMWAXVFQUOA-UHFFFAOYSA-
    • OCTAMETHYCYCLOTETRASILOXANE
    • Octamethylcyclotetrasiloxane, 98%
    • CYCLOMETHICONE 4 [USP-RS]
    • Octamethylcyclotetrasiloxane (NIST)
    • Tox21_201398
    • Tox21_300547
    • CO9810
    • CYCLOTETRASILOXANE, OCTAMETHYL
    • MSK002144
    • NSC345674
    • AKOS008901191
    • MSK002144-100H
    • OCTAMETHYLCYCLOTETRASILOXANE [MI]
    • MSK002144-1000H
    • NCGC00164099-01
    • NCGC00164099-02
    • NCGC00164099-03
    • NCGC00254406-01
    • NCGC00258949-01
    • OCTAMETHYLCYCLOTETRASILOXANE [HSDB]
    • MSK002144-1000
    • CS-0213747
    • NS00043628
    • O0142
    • O9810
    • F83065
    • Octamethylcyclotetrasiloxane, analytical standard
    • Cyclotetrasiloxane, 2,2,4,4,6,6,8,8-octamethyl-
    • Q2013804
    • Octamethylcyclotetrasiloxane Solution in Hexane, 1000ug/mL
    • Octamethylcyclotetrasiloxane Solution in Hexane, 100ug/mL
    • Octamethylcyclotetrasiloxane Solution in Methanol, 1000?g/mL
    • 2,2,4,4,6,6,8,8-Octamethyl-1,3,5,7,2,4,6,8-tetraoxatetrasilocane #
    • Cyclomethicone 4, United States Pharmacopeia (USP) Reference Standard
    • D4 Cyclomethicone, Pharmaceutical Secondary Standard; Certified Reference Material
    • 25037-57-4
    • InChI=1/C8H24O4Si4/c1-13(2)9-14(3,4)11-16(7,8)12-15(5,6)10-13/h1-8H3
    • 556-67-2

  • Applications

    Octamethylcyclotetrasiloxane (CAS 556-67-2) is widely used as a monomer feedstock for the production of polydimethylsiloxane (PDMS) and other siloxane polymers, underpinning silicone-based materials in polymers/plastics such as elastomers and silicone oils. It is also used as a processing solvent and carrier for silicone resins, coatings, and inks, aiding processing and controlling volatility of silicone-containing formulations. In perfumery and cosmetics/personal care, it functions as a volatile solvent and light carrier for fragrance ingredients and personal care formulations. In adhesives and sealants, it is used as a processing aid or intermediate in silicone-based formulations to improve mixing and handling. In electronics-related applications, such as silicone coatings and encapsulants, it serves as a low-viscosity siloxane component to optimize film formation and protective properties.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 182.6
    methanol 244.11
    isopropanol 118.08
    water 34.13
    ethyl acetate 181.63
    n-propanol 139.98
    acetone 268.77
    n-butanol 123.41
    acetonitrile 123.3
    DMF 459.95
    toluene 110.66
    isobutanol 85.32
    1,4-dioxane 304.06
    methyl acetate 163.99
    THF 698.9
    2-butanone 166.32
    n-pentanol 86.02
    sec-butanol 98.42
    n-hexane 38.65
    ethylene glycol 98.09
    NMP 539.5
    cyclohexane 72.78
    DMSO 448.41
    n-butyl acetate 122.15
    n-octanol 86.1
    chloroform 304.55
    n-propyl acetate 113.73
    acetic acid 216.78
    dichloromethane 288.73
    cyclohexanone 288.23
    propylene glycol 110.59
    isopropyl acetate 126.24
    DMAc 332.57
    2-ethoxyethanol 158.13
    isopentanol 76.34
    n-heptane 41.26
    ethyl formate 154.07
    1,2-dichloroethane 183.91
    n-hexanol 129.3
    2-methoxyethanol 336.93
    isobutyl acetate 76.56
    tetrachloromethane 80.61
    n-pentyl acetate 122.85
    transcutol 206.07
    n-heptanol 87.23
    ethylbenzene 51.9
    MIBK 104.25
    2-propoxyethanol 256.04
    tert-butanol 110.31
    MTBE 81.41
    2-butoxyethanol 139.26
    propionic acid 153.94
    o-xylene 71.24
    formic acid 155.88
    diethyl ether 167.47
    m-xylene 83.22
    p-xylene 58.91
    chlorobenzene 125.35
    dimethyl carbonate 149.89
    n-octane 22.01
    formamide 232.11
    cyclopentanone 459.54
    2-pentanone 173.72
    anisole 114.74
    cyclopentyl methyl ether 266.16
    gamma-butyrolactone 535.95
    1-methoxy-2-propanol 274.8
    pyridine 223.48
    3-pentanone 147.38
    furfural 407.03
    n-dodecane 17.15
    diethylene glycol 214.11
    diisopropyl ether 62.76
    tert-amyl alcohol 87.64
    acetylacetone 238.02
    n-hexadecane 19.07
    acetophenone 120.02
    methyl propionate 186.11
    isopentyl acetate 93.62
    trichloroethylene 265.05
    n-nonanol 81.28
    cyclohexanol 140.53
    benzyl alcohol 95.68
    2-ethylhexanol 74.91
    isooctanol 61.95
    dipropyl ether 120.9
    1,2-dichlorobenzene 119.23
    ethyl lactate 95.12
    propylene carbonate 284.19
    n-methylformamide 266.76
    2-pentanol 89.36
    n-pentane 45.64
    1-propoxy-2-propanol 172.73
    1-methoxy-2-propyl acetate 175.1
    2-(2-methoxypropoxy) propanol 114.25
    mesitylene 56.86
    ε-caprolactone 257.23
    p-cymene 48.2
    epichlorohydrin 344.32
    1,1,1-trichloroethane 153.75
    2-aminoethanol 138.2
    morpholine-4-carbaldehyde 426.3
    sulfolane 581.53
    2,2,4-trimethylpentane 15.94
    2-methyltetrahydrofuran 285.89
    n-hexyl acetate 146.53
    isooctane 14.14
    2-(2-butoxyethoxy)ethanol 148.9
    sec-butyl acetate 82.72
    tert-butyl acetate 123.82
    decalin 28.7
    glycerin 194.8
    diglyme 224.25
    acrylic acid 158.89
    isopropyl myristate 76.75
    n-butyric acid 177.85
    acetyl acetate 156.85
    di(2-ethylhexyl) phthalate 74.6
    ethyl propionate 123.68
    nitromethane 351.46
    1,2-diethoxyethane 114.47
    benzonitrile 102.58
    trioctyl phosphate 66.39
    1-bromopropane 122.98
    gamma-valerolactone 494.62
    n-decanol 63.57
    triethyl phosphate 73.49
    4-methyl-2-pentanol 53.27
    propionitrile 101.17
    vinylene carbonate 253.69
    1,1,2-trichlorotrifluoroethane 267.09
    DMS 137.09
    cumene 40.81
    2-octanol 67.23
    2-hexanone 107.41
    octyl acetate 97.17
    limonene 67.84
    1,2-dimethoxyethane 226.51
    ethyl orthosilicate 68.13
    tributyl phosphate 68.83
    diacetone alcohol 136.88
    N,N-dimethylaniline 94.88
    acrylonitrile 125.06
    aniline 132.3
    1,3-propanediol 160.02
    bromobenzene 123.52
    dibromomethane 200.14
    1,1,2,2-tetrachloroethane 233.3
    2-methyl-cyclohexyl acetate 108.4
    tetrabutyl urea 100.54
    diisobutyl methanol 47.48
    2-phenylethanol 127.77
    styrene 62.73
    dioctyl adipate 99.14
    dimethyl sulfate 231.54
    ethyl butyrate 113.43
    methyl lactate 163.3
    butyl lactate 110.3
    diethyl carbonate 80.47
    propanediol butyl ether 127.54
    triethyl orthoformate 89.18
    p-tert-butyltoluene 52.91
    methyl 4-tert-butylbenzoate 147.22
    morpholine 325.37
    tert-butylamine 79.57
    n-dodecanol 51.12
    dimethoxymethane 364.55
    ethylene carbonate 211.43
    cyrene 170.54
    2-ethoxyethyl acetate 153.97
    2-ethylhexyl acetate 86.44
    1,2,4-trichlorobenzene 142.7
    4-methylpyridine 190.86
    dibutyl ether 76.96
    2,6-dimethyl-4-heptanol 47.48
    DEF 197.26
    dimethyl isosorbide 240.83
    tetrachloroethylene 161.63
    eugenol 156.08
    triacetin 143.17
    span 80 134.17
    1,4-butanediol 69.91
    1,1-dichloroethane 144.12
    2-methyl-1-pentanol 58.98
    methyl formate 232.72
    2-methyl-1-butanol 77.16
    n-decane 27.34
    butyronitrile 103.93
    3,7-dimethyl-1-octanol 63.61
    1-chlorooctane 65.98
    1-chlorotetradecane 35.25
    n-nonane 26.3
    undecane 20.69
    tert-butylcyclohexane 24.66
    cyclooctane 36.94
    cyclopentanol 197.16
    tetrahydropyran 265.95
    tert-amyl methyl ether 86.2
    2,5,8-trioxanonane 176.96
    1-hexene 66.31
    2-isopropoxyethanol 103.03
    2,2,2-trifluoroethanol 120.0
    methyl butyrate 132.25

    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