Hydralazine Hydrochloride

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  • Identifiers

    CAS number
    304-20-1

    Molecular formula
    C8H9ClN4

    SMILES
    C1=CC=C2C(=C1)C=NN=C2NN.Cl

    Safety labels

    Acute Toxic
    Acute Toxic

    Irritant
    Irritant

    Health Hazard
    Health

  • Odor profile

    Fragrance
    Odorless 43.7%
    Meaty 36.84%
    Fishy 35.98%
    Cheesy 32.94%
    Burnt 31.99%
    Roasted 31.98%
    Cooked 31.42%
    Savory 27.0%
    Animal 26.55%
    Ripe 25.9%

     

    Flavor
    Bitter 65.33%
    Roasted 31.33%
    Odorless 27.83%
    Mild 25.11%
    Coffee 24.09%
    Very strong 23.11%
    Scallion 22.95%
    Indole 22.76%
    Cereal 22.29%
    Bread crust 21.91%

     

    Odor impact est.
    Low

  • Properties

    pKa est.
    4.61 (weak acid)

    Molecular weight
    196.64 g/mol

    Vapor pressure est.

    • hPa @ 20°C
    • hPa @ 25°C

    Evaporation rate
    Ultra slow

    Boiling point est.
    422°C

    Melting point expt.

    • Decomposes at 273 °C

    Flash point

    • 195.22 ˚C est.

    Solubility expt.

    • Very slightly soluble in ether and alcohol
    • In 95% ethanol, 0.2 g/100 ml
    • In water, 44.2 g/l @ 25 °C; 30.1 g/l @ 15 °C

  • Synonyms

    • HYDRALAZINE HYDROCHLORIDE
    • 304-20-1
    • HYDRALAZINE HCL
    • 1-Hydrazinophthalazine hydrochloride
    • Apresoline
    • 1-Hydrazinylphthalazine hydrochloride
    • Aiselazine
    • Dralzine
    • Hyperazin
    • Hyperex
    • Lopress
    • Hydralazine chloride
    • Slow-Apresolin
    • Apresine
    • Rolazine
    • Hydralazine monohydrochloride
    • Apresoline hydrochloride
    • Nor-press 25
    • 1-Hydrazinophthalazine monohydrochloride
    • 1(2H)-Phthalazinone, hydrazone, monohydrochloride
    • Hydralazine (hydrochloride)
    • CCRIS 334
    • phthalazin-1-ylhydrazine;hydrochloride
    • HSDB 434
    • 1(2H)-Phthalazinone, hydrazone, hydrochloride
    • Phthalazine, 1-hydrazinyl-, hydrochloride (1:1)
    • Praparat 5968
    • EINECS 206-151-0
    • NSC 89394
    • NSC-89394
    • UNII-FD171B778Y
    • DTXSID1044645
    • CHEBI:31672
    • Phthalazinone, hydrazone, monohydrochloride
    • FD171B778Y
    • Phthalazine, 1-hydrazino-, monohydrochloride
    • MC-1101
    • DTXCID9024645
    • NSC89394
    • Hydralazine hydrochloride [USP:JAN]
    • (Z)-1-Hydrazono-1,2-dihydrophthalazine hydrochloride
    • Phthalazinone hydrazone monohydrochloride
    • 1(2H)-Phthalazinone hydrazone hydrochloride
    • Apresoline-esidrix
    • 1044569-46-1
    • BIDIL COMPONENT HYDRALAZINE HYDROCHLORIDE
    • UNIPRES COMPONENT HYDRALAZINE HYDROCHLORIDE
    • DRALSERP COMPONENT HYDRALAZINE HYDROCHLORIDE
    • APRESAZIDE COMPONENT HYDRALAZINE HYDROCHLORIDE
    • CAM-AP-ES COMPONENT HYDRALAZINE HYDROCHLORIDE
    • HYDRA-ZIDE COMPONENT HYDRALAZINE HYDROCHLORIDE
    • HYDRAP-ES COMPONENT HYDRALAZINE HYDROCHLORIDE
    • SER-A-GEN COMPONENT HYDRALAZINE HYDROCHLORIDE
    • SER-AP-ES COMPONENT HYDRALAZINE HYDROCHLORIDE
    • Hydralazine-15N4Hydrochloride
    • APRESOLINE-ESIDRIX COMPONENT HYDRALAZINE HYDROCHLORIDE
    • SERPASIL-APRESOLINE COMPONENT HYDRALAZINE HYDROCHLORIDE
    • Hydrallazine hydrochloride
    • Hydralazine hydrochloride (USP:JAN)
    • HYDROSERPINE PLUS (R-H-H) COMPONENT HYDRALAZINE HYDROCHLORIDE
    • HYDRALAZINE HYDROCHLORIDE (MART.)
    • HYDRALAZINE HYDROCHLORIDE [MART.]
    • HYDRALAZINE HYDROCHLORIDE (USP-RS)
    • HYDRALAZINE HYDROCHLORIDE [USP-RS]
    • Hydralazine hydrochloride [JAN]
    • HYDRALAZINE HYDROCHLORIDE (USP IMPURITY)
    • HYDRALAZINE HYDROCHLORIDE [USP IMPURITY]
    • HYDRALAZINE HYDROCHLORIDE (USP MONOGRAPH)
    • HYDRALAZINE HYDROCHLORIDE [USP MONOGRAPH]
    • SR-01000075903
    • NCGC00015501-02
    • CAS-304-20-1
    • Apressinum
    • Apresoline (TN)
    • Prestwick_610
    • Hydralazinhydrochlorid
    • Hydralazini hydrochloridum
    • Hydrochloride, Hydralazine
    • 1-hydrazinophthalazine HCL
    • APRESSINUM [WHO-IP]
    • SCHEMBL36271
    • Phthalazine, monohydrochloride
    • SPECTRUM1500334
    • CHEMBL542541
    • Phthalazinone, monohydrochloride
    • HY-B0464R
    • BPI-103
    • PRA 027
    • HMS1568B19
    • HMS1920D17
    • Pharmakon1600-01500334
    • HY-B0464
    • WLN: T66 CNNJ BMZ & GH
    • 1(2H)-Phthalazinone, hydrochloride
    • Tox21_110163
    • Tox21_302496
    • Tox21_500593
    • CCG-40185
    • NSC757058
    • s2562
    • HYDRALAZINE HYDROCHLORIDE [MI]
    • AKOS008968535
    • AKOS025116605
    • AKOS028109609
    • Hydralazine hydrochloride (JP17/USP)
    • Tox21_110163_1
    • 1(2H)-Phthalazinone, monohydrochloride
    • CCG-266561
    • Hydralazine (hydrochloride) (Standard)
    • LP00593
    • NSC-757058
    • HYDRALAZINE HYDROCHLORIDE [HSDB]
    • HYDRALAZINE HYDROCHLORIDE [VANDF]
    • NCGC00015501-09
    • NCGC00093972-01
    • NCGC00093972-02
    • NCGC00093972-03
    • NCGC00093972-04
    • NCGC00256719-01
    • NCGC00261278-01
    • AC-18050
    • AC-37654
    • HYDRALAZINE HYDROCHLORIDE [WHO-DD]
    • HYDRALAZINE HYDROCHLORIDE [WHO-IP]
    • Phthalazin-1-ylhydrazine monohydrochloride
    • EU-0100593
    • H0409
    • NS00079253

  • Applications

    Hydralazine Hydrochloride (CAS 304-20-1) is primarily used as an active pharmaceutical ingredient (API) in antihypertensive formulations. The hydrochloride salt improves water solubility and processability, supporting formulation development and manufacturing. It is also employed in medicinal chemistry and pharmaceutical research as a lead compound or reference material for hydrazine-containing analogs. In analytical settings, it serves as a reference standard or QC material for assay and impurity profiling in pharmaceutical analysis. Additionally, it is used in academic and industrial pharmacology studies to explore mechanism of action and structure-activity relationships of hydralazine-related compounds.

    gpt-5-nano

  • Solubility @25˚C

    Solvent Solubility (g/L)
    ethanol 3.9
    methanol 4.24
    isopropanol 2.7
    water 1.0
    ethyl acetate 1.98
    n-propanol 3.15
    acetone 5.43
    n-butanol 2.57
    acetonitrile 3.5
    DMF 34.53
    toluene 0.52
    isobutanol 2.34
    1,4-dioxane 7.66
    methyl acetate 2.29
    THF 11.69
    2-butanone 3.72
    n-pentanol 3.3
    sec-butanol 1.7
    n-hexane 0.09
    ethylene glycol 4.87
    NMP 27.85
    cyclohexane 0.09
    DMSO 71.97
    n-butyl acetate 3.67
    n-octanol 3.03
    chloroform 3.07
    n-propyl acetate 2.51
    acetic acid 6.98
    dichloromethane 6.34
    cyclohexanone 10.04
    propylene glycol 1.73
    isopropyl acetate 1.38
    DMAc 24.1
    2-ethoxyethanol 10.91
    isopentanol 2.54
    n-heptane 0.42
    ethyl formate 4.85
    1,2-dichloroethane 6.43
    n-hexanol 5.04
    2-methoxyethanol 16.41
    isobutyl acetate 1.66
    tetrachloromethane 0.93
    n-pentyl acetate 4.39
    transcutol 17.09
    n-heptanol 4.55
    ethylbenzene 0.81
    MIBK 2.45
    2-propoxyethanol 13.89
    tert-butanol 3.22
    MTBE 0.96
    2-butoxyethanol 11.12
    propionic acid 3.06
    o-xylene 0.92
    formic acid 9.46
    diethyl ether 0.95
    m-xylene 0.93
    p-xylene 1.34
    chlorobenzene 2.23
    dimethyl carbonate 2.63
    n-octane 0.24
    formamide 15.9
    cyclopentanone 13.81
    2-pentanone 2.95
    anisole 2.28
    cyclopentyl methyl ether 2.97
    gamma-butyrolactone 18.54
    1-methoxy-2-propanol 8.71
    pyridine 6.88
    3-pentanone 2.18
    furfural 23.97
    n-dodecane 0.23
    diethylene glycol 18.77
    diisopropyl ether 0.42
    tert-amyl alcohol 2.08
    acetylacetone 5.16
    n-hexadecane 0.26
    acetophenone 5.0
    methyl propionate 2.75
    isopentyl acetate 3.59
    trichloroethylene 10.48
    n-nonanol 3.15
    cyclohexanol 2.42
    benzyl alcohol 4.79
    2-ethylhexanol 3.28
    isooctanol 3.62
    dipropyl ether 2.49
    1,2-dichlorobenzene 3.7
    ethyl lactate 3.82
    propylene carbonate 7.6
    n-methylformamide 13.08
    2-pentanol 1.24
    n-pentane 0.08
    1-propoxy-2-propanol 8.51
    1-methoxy-2-propyl acetate 5.42
    2-(2-methoxypropoxy) propanol 7.79
    mesitylene 0.84
    ε-caprolactone 8.49
    p-cymene 2.0
    epichlorohydrin 19.07
    1,1,1-trichloroethane 2.3
    2-aminoethanol 5.07
    morpholine-4-carbaldehyde 26.26
    sulfolane 38.51
    2,2,4-trimethylpentane 0.09
    2-methyltetrahydrofuran 4.9
    n-hexyl acetate 4.34
    isooctane 0.1
    2-(2-butoxyethoxy)ethanol 11.49
    sec-butyl acetate 1.3
    tert-butyl acetate 1.95
    decalin 0.17
    glycerin 7.32
    diglyme 23.73
    acrylic acid 4.47
    isopropyl myristate 2.02
    n-butyric acid 4.21
    acetyl acetate 1.7
    di(2-ethylhexyl) phthalate 3.87
    ethyl propionate 2.17
    nitromethane 13.86
    1,2-diethoxyethane 5.3
    benzonitrile 5.97
    trioctyl phosphate 3.18
    1-bromopropane 1.38
    gamma-valerolactone 24.35
    n-decanol 2.5
    triethyl phosphate 3.04
    4-methyl-2-pentanol 1.17
    propionitrile 2.85
    vinylene carbonate 8.07
    1,1,2-trichlorotrifluoroethane 20.38
    DMS 3.61
    cumene 1.08
    2-octanol 2.47
    2-hexanone 3.48
    octyl acetate 2.82
    limonene 2.27
    1,2-dimethoxyethane 16.0
    ethyl orthosilicate 2.69
    tributyl phosphate 3.08
    diacetone alcohol 6.09
    N,N-dimethylaniline 3.0
    acrylonitrile 5.88
    aniline 2.2
    1,3-propanediol 7.22
    bromobenzene 1.7
    dibromomethane 2.96
    1,1,2,2-tetrachloroethane 7.6
    2-methyl-cyclohexyl acetate 4.0
    tetrabutyl urea 5.9
    diisobutyl methanol 2.04
    2-phenylethanol 6.48
    styrene 0.7
    dioctyl adipate 3.58
    dimethyl sulfate 9.45
    ethyl butyrate 3.15
    methyl lactate 4.59
    butyl lactate 5.3
    diethyl carbonate 2.42
    propanediol butyl ether 7.27
    triethyl orthoformate 2.97
    p-tert-butyltoluene 1.79
    methyl 4-tert-butylbenzoate 7.95
    morpholine 8.84
    tert-butylamine 1.39
    n-dodecanol 1.94
    dimethoxymethane 10.91
    ethylene carbonate 5.97
    cyrene 12.6
    2-ethoxyethyl acetate 5.99
    2-ethylhexyl acetate 2.69
    1,2,4-trichlorobenzene 4.38
    4-methylpyridine 5.12
    dibutyl ether 2.03
    2,6-dimethyl-4-heptanol 2.04
    DEF 6.5
    dimethyl isosorbide 14.84
    tetrachloroethylene 6.51
    eugenol 9.6
    triacetin 5.14
    span 80 6.7
    1,4-butanediol 4.73
    1,1-dichloroethane 1.96
    2-methyl-1-pentanol 2.81
    methyl formate 10.41
    2-methyl-1-butanol 2.11
    n-decane 0.32
    butyronitrile 2.87
    3,7-dimethyl-1-octanol 2.49
    1-chlorooctane 1.47
    1-chlorotetradecane 0.72
    n-nonane 0.27
    undecane 0.27
    tert-butylcyclohexane 0.19
    cyclooctane 0.06
    cyclopentanol 3.78
    tetrahydropyran 2.93
    tert-amyl methyl ether 0.99
    2,5,8-trioxanonane 16.1
    1-hexene 0.42
    2-isopropoxyethanol 6.18
    2,2,2-trifluoroethanol 5.95
    methyl butyrate 3.59

    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