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Pyrazole

Athanor · official

C3H4N2 · 68.08 g/mol

IUPAC name: 1H-pyrazole

Also called 1,2-diazole

Rings
Open in Athanor
The structure of Pyrazole
Drawn from its SMILES with RDKit
CorrosiveAcute toxicityHarmful or irritantHealth hazardDangerHarmful if swallowed · Toxic in contact with skin · Causes skin irritation · Causes serious eye damage · Causes serious eye irritation · May cause respiratory irritation · Causes damage to organs through prolonged or repeated exposure · Harmful to aquatic life with long lasting effects

Names and identifiers

IUPAC name
1H-pyrazole
Synonyms
1,2-diazole, 1H-Pyrazole, Pyrazol
+ 35 more

1H-pyrazol, 3QD5KJZ7ZJ, DTXSID2059774, NSC45410, NSC-45410, CHEBI:17241, RefChem:6183, DTXCID4037873, CHEBI:14973, 206-017-1, MFCD00005234, diazole, Hpz, EINECS 206-017-1, UNII-3QD5KJZ7ZJ, NSC 45410, AI3-60151, 2-Pyrromonazole, Pyrazole-, 3-pyrazole, Pyrazole, 98%, PYRAZOLE [MI], WLN: T5MNJ, EC 206-017-1, SCHEMBL1384, SCHEMBL1676, SCHEMBL1677, SCHEMBL2227, SCHEMBL18605, CHEMBL15967, SCHEMBL121648, SCHEMBL347149, SCHEMBL451169, SCHEMBL451354, SCHEMBL451899

Molecular formula
C3H4N2
Empirical formula
C3H4N2
Molecular weight
68.08 g/mol
Exact mass
68.03745
CAS number
288-13-1
PubChem CID
1048
Canonical SMILES
C1=CNN=C1
Isomeric SMILES
C1=CNN=C1
InChI
InChI=1S/C3H4N2/c1-2-4-5-3-1/h1-3H,(H,4,5)
InChIKey
WTKZEGDFNFYCGP-UHFFFAOYSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Physical properties

Appearance
Liquid[1]

Each value as its source reports it, with the source's number after it (listed under References). Where several sources report a property, the row shows the value most of them agree on, the rule the app uses; open the values to see every one.

Calculated

Heavy atoms
5
Rings
1
Aromatic rings
1
Fraction sp³ carbons (Fsp3)
0
H-bond donors
1
H-bond acceptors
1
Rotatable bonds
0
TPSA (Ų)
28.7
Formal charge
0
XLogP3
0.3 PubChem
Complexity
28 PubChem
Stereocenters
None
Double-bond geometry
None specified
Point group
Cs of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

  • C52.93%
  • H5.92%
  • N41.15%

Isotope pattern

100%68.0374.0%69.040

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P
0.41 Crippen (Wildman and Crippen 1999)
log S (water solubility)
-1.26 ESOL (Delaney 2004), log mol/L
Synthetic accessibility
3.74 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

  • Molecular weight ≤ 500: 68.08
  • log P ≤ 5 (Crippen): 0.41
  • H-bond donors ≤ 5: 1
  • H-bond acceptors ≤ 10: 1

Passes all four rules.

¹³C NMR shifts, predicted

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

Danger

Most widely reported: 265 company reports to ECHA. Source [2].

  • Corrosive
  • Acute toxicity
  • Harmful or irritant
  • Health hazard
  • H302Harmful if swallowed (98.9% of reports)
  • H311Toxic in contact with skin (80% of reports)
  • H315Causes skin irritation (99.6% of reports)
  • H318Causes serious eye damage (80% of reports)
  • H319Causes serious eye irritation (19.2% of reports)
  • H335May cause respiratory irritation (19.2% of reports)
  • H372Causes damage to organs through prolonged or repeated exposure (80% of reports)
  • H412Harmful to aquatic life with long lasting effects (80.4% of reports)

Precautionary statements: P260, P261, P262, P264, P264+P265, P270, P271, P273, P280, P301+P317, P302+P352, P304+P340, P305+P351+P338, P305+P354+P338, P316, P317, P319, P321, P330, P332+P317, P337+P317, P361+P364, P362+P364, P403+P233, P405, P501

View all classifications (2)
  • [2] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 0.4% (1 of 265) of reports.
  • [2] European Chemicals Agency (ECHA) · 265 reports · DangerH302, H311, H315, H318, H319, H335, H372, H412

Safety data sheets on the supplier’s page: Alfa Chemistry, CATO Research Chemicals Inc., BenchChem.

Always read the supplier’s safety data sheet before working with it.

Spectra

Experimental spectra held by these sources; each link opens the source's own record.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

  1. [1]EPA Chemical Data Reporting (CDR) · Public domain (US EPA) · via PubChem · retrieved 2026-10-14
  2. [2]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
  3. [3]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
  4. [4]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
  5. [5]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
  6. [6]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
  7. [7]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
  8. [8]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
  9. ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
  10. ·Literature on PubChem

Data last updated 2026-10-14.