Cyclopentadiene

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  • Identifiers

    CAS number
    542-92-7

    Molecular formula
    C5H6

    SMILES
    C1C=CC=C1

    Safety labels

    Flammable
    Flammable

    Acute Toxic
    Acute Toxic

    Irritant
    Irritant

  • Odor profile

    Fragrance
    Sweet 37.7%
    Citrus 32.54%
    Gassy 28.8%
    Spicy 24.72%
    Warm 21.21%
    Pungent 20.76%
    Dry 19.17%
    Lemon 18.29%
    Metallic 18.06%
    Green 17.67%

     

    Flavor
    Ammoniacal 23.79%
    Shrimp 20.63%
    Animal 19.05%
    Alkaline 18.45%
    Tarry 18.24%
    Spice 18.18%
    Tar 17.99%
    Terpentine 17.42%
    Rotten 16.98%
    Nitrile 16.85%

     

    Odor impact est.
    Low

    Odor threshold

    • Odor Threshold Low: 1.8 [mmHg]. Odor threshold from AIHA
    • Low Threshold= 5.0 mg/cu m; High threshold= 5.0 mg/cu m.

  • Properties

    XLogP3-AA
    1.8

    pKa est.
    8.02 (weak base)

    Molecular weight
    66.1 g/mol

    Vapor pressure est.

    • hPa @ 20°C
    • hPa @ 25°C

    Evaporation rate
    Ultra fast

    Melting point expt.

    • -121 °F (NIOSH, 2024)
    • -95.54 °C
    • -85 °C
    • -121 °F

    Boiling point

    • 107 °F at 760 mmHg (NIOSH, 2024)
    • 41 °C
    • 41.5-42.0 °C
    • 107 °F

    Flash point

    • -13.4 ˚C est.
    • 77 °F (NIOSH, 2024)
    • 77 °F
    • 77 °F (OPEN CUP)
    • -20 °C
    • 77 °F (open cup)
    • (oc) 77 °F

    Solubility expt.

    • Insoluble (NIOSH, 2024)
    • In water, 1,800 mg/L at 25 °C
    • Miscible with carbon tetrachloride; soluble in carbon disulfide, aniline, acetic acid, liquid petrolatum
    • Soluble in acetone; miscible with ethanol, ethyl ether, benzene
    • Solubility in water: insoluble
    • Insoluble

  • Synonyms

    • Cyclopentadiene
    • 1,3-CYCLOPENTADIENE
    • cyclopenta-1,3-diene
    • 542-92-7
    • Pyropentylene
    • Pentole
    • R-Pentine
    • HSDB 2514
    • EINECS 208-835-4
    • UNII-5DFH9434HF
    • 5DFH9434HF
    • 26912-33-4
    • DTXSID0027191
    • CHEBI:30664
    • DTXCID007191
    • EC 208-835-4
    • cyclopentadien
    • cyclo pentadiene
    • cyclo-pentadiene
    • CYCLOPENTADIENE [MI]
    • ghl.PD_Mitscher_leg0.1205
    • CHEMBL3188826
    • 1,3-CYCLOPENTADIENE [HSDB]
    • Tox21_302134
    • AKOS025295445
    • AT31522
    • NCGC00255341-01
    • CAS-542-92-7
    • DB-013019
    • NS00006170
    • 1.3-cyclopentadiene pound Dimer form pound(c)
    • A818675
    • Q424390
    • Q2209035
    • InChI=1/C5H6/c1-2-4-5-3-1/h1-4H,5H
    • 208-835-4

  • Applications

    Cyclopentadiene (CAS 542-92-7) is a reactive diene building block used across industry: it serves as the key precursor for cyclopentadienyl ligands that form organometallic complexes, including metallocenes, which are employed as catalysts in polymerization and other fine-chemical syntheses; it is a feedstock for norbornene and other bicyclic monomers that underpin high‑performance polymers, coatings and adhesives; it is also used to prepare fulvenes and related heterocycles for specialty chemicals and exploratory pharmaceutical research; and it participates in Diels–Alder chemistry to generate adducts and intermediates used in large‑scale chemical manufacturing.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 567.01
    methanol 426.62
    isopropanol 468.95
    water 0.93
    ethyl acetate 425.14
    n-propanol 492.0
    acetone 583.74
    n-butanol 485.72
    acetonitrile 353.32
    DMF 480.21
    toluene 237.87
    isobutanol 345.82
    1,4-dioxane 693.25
    methyl acetate 372.51
    THF 1086.5
    2-butanone 477.77
    n-pentanol 346.89
    sec-butanol 432.35
    n-hexane 273.77
    ethylene glycol 176.83
    NMP 435.92
    cyclohexane 278.52
    DMSO 585.31
    n-butyl acetate 438.64
    n-octanol 228.43
    chloroform 633.59
    n-propyl acetate 245.08
    acetic acid 419.12
    dichloromethane 480.27
    cyclohexanone 462.78
    propylene glycol 303.75
    isopropyl acetate 243.77
    DMAc 417.97
    2-ethoxyethanol 366.81
    isopentanol 339.66
    n-heptane 340.12
    ethyl formate 159.71
    1,2-dichloroethane 337.01
    n-hexanol 614.87
    2-methoxyethanol 540.74
    isobutyl acetate 178.62
    tetrachloromethane 161.55
    n-pentyl acetate 163.11
    transcutol 1078.29
    n-heptanol 226.45
    ethylbenzene 121.21
    MIBK 240.28
    2-propoxyethanol 703.95
    tert-butanol 493.98
    MTBE 461.22
    2-butoxyethanol 329.5
    propionic acid 375.65
    o-xylene 144.3
    formic acid 91.98
    diethyl ether 663.6
    m-xylene 160.48
    p-xylene 131.12
    chlorobenzene 203.68
    dimethyl carbonate 144.97
    n-octane 82.62
    formamide 114.47
    cyclopentanone 580.5
    2-pentanone 433.36
    anisole 242.98
    cyclopentyl methyl ether 555.33
    gamma-butyrolactone 456.75
    1-methoxy-2-propanol 524.29
    pyridine 469.84
    3-pentanone 346.63
    furfural 326.99
    n-dodecane 56.75
    diethylene glycol 457.14
    diisopropyl ether 234.5
    tert-amyl alcohol 398.82
    acetylacetone 328.74
    n-hexadecane 60.06
    acetophenone 168.28
    methyl propionate 341.11
    isopentyl acetate 323.52
    trichloroethylene 493.74
    n-nonanol 201.59
    cyclohexanol 381.54
    benzyl alcohol 174.61
    2-ethylhexanol 403.71
    isooctanol 170.75
    dipropyl ether 633.72
    1,2-dichlorobenzene 146.24
    ethyl lactate 133.21
    propylene carbonate 257.82
    n-methylformamide 221.71
    2-pentanol 386.71
    n-pentane 265.71
    1-propoxy-2-propanol 644.41
    1-methoxy-2-propyl acetate 383.92
    2-(2-methoxypropoxy) propanol 319.73
    mesitylene 103.39
    ε-caprolactone 350.79
    p-cymene 135.85
    epichlorohydrin 462.77
    1,1,1-trichloroethane 354.45
    2-aminoethanol 303.53
    morpholine-4-carbaldehyde 485.06
    sulfolane 488.37
    2,2,4-trimethylpentane 97.12
    2-methyltetrahydrofuran 741.11
    n-hexyl acetate 257.62
    isooctane 86.83
    2-(2-butoxyethoxy)ethanol 428.83
    sec-butyl acetate 179.07
    tert-butyl acetate 251.51
    decalin 99.07
    glycerin 318.8
    diglyme 632.17
    acrylic acid 293.86
    isopropyl myristate 136.92
    n-butyric acid 428.99
    acetyl acetate 240.42
    di(2-ethylhexyl) phthalate 110.75
    ethyl propionate 233.73
    nitromethane 392.58
    1,2-diethoxyethane 459.81
    benzonitrile 172.16
    trioctyl phosphate 87.21
    1-bromopropane 384.68
    gamma-valerolactone 515.3
    n-decanol 161.78
    triethyl phosphate 114.0
    4-methyl-2-pentanol 204.24
    propionitrile 310.35
    vinylene carbonate 195.63
    1,1,2-trichlorotrifluoroethane 400.91
    DMS 184.63
    cumene 89.66
    2-octanol 138.84
    2-hexanone 308.26
    octyl acetate 169.21
    limonene 245.97
    1,2-dimethoxyethane 476.51
    ethyl orthosilicate 122.95
    tributyl phosphate 100.85
    diacetone alcohol 311.1
    N,N-dimethylaniline 169.17
    acrylonitrile 284.04
    aniline 270.6
    1,3-propanediol 323.4
    bromobenzene 217.38
    dibromomethane 424.12
    1,1,2,2-tetrachloroethane 429.57
    2-methyl-cyclohexyl acetate 204.3
    tetrabutyl urea 137.93
    diisobutyl methanol 218.07
    2-phenylethanol 230.96
    styrene 165.34
    dioctyl adipate 169.95
    dimethyl sulfate 170.91
    ethyl butyrate 301.94
    methyl lactate 194.76
    butyl lactate 149.27
    diethyl carbonate 164.23
    propanediol butyl ether 300.42
    triethyl orthoformate 212.33
    p-tert-butyltoluene 137.25
    methyl 4-tert-butylbenzoate 174.07
    morpholine 806.15
    tert-butylamine 394.4
    n-dodecanol 141.14
    dimethoxymethane 415.2
    ethylene carbonate 176.52
    cyrene 187.94
    2-ethoxyethyl acetate 220.64
    2-ethylhexyl acetate 280.27
    1,2,4-trichlorobenzene 183.91
    4-methylpyridine 344.22
    dibutyl ether 314.47
    2,6-dimethyl-4-heptanol 218.07
    DEF 367.36
    dimethyl isosorbide 345.61
    tetrachloroethylene 286.73
    eugenol 174.68
    triacetin 246.31
    span 80 313.85
    1,4-butanediol 167.93
    1,1-dichloroethane 396.5
    2-methyl-1-pentanol 273.93
    methyl formate 148.02
    2-methyl-1-butanol 343.91
    n-decane 88.03
    butyronitrile 307.16
    3,7-dimethyl-1-octanol 252.8
    1-chlorooctane 171.15
    1-chlorotetradecane 84.04
    n-nonane 100.07
    undecane 66.83
    tert-butylcyclohexane 97.49
    cyclooctane 126.56
    cyclopentanol 427.55
    tetrahydropyran 796.05
    tert-amyl methyl ether 359.7
    2,5,8-trioxanonane 469.41
    1-hexene 433.64
    2-isopropoxyethanol 306.55
    2,2,2-trifluoroethanol 118.62
    methyl butyrate 245.36

    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