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Pyridazine

Athanor · official

C4H4N2 · 80.09 g/mol

Also called 1,2-diazine, orthodiazine

Rings
Open in Athanor
The structure of Pyridazine
Drawn from its SMILES with RDKit
Harmful or irritantWarningHarmful if swallowed · Causes skin irritation · Causes serious eye irritation · May cause respiratory irritation

Names and identifiers

IUPAC name
pyridazine
Synonyms
1,2-diazine, orthodiazine, Orthodiazine
+ 37 more

1,2-Diazine, o-Diazine, 1,2-Diazabenzene, 449GLA0653, NSC-90792, DTXSID7059777, CHEBI:30954, RefChem:177556, DTXCID7037892, 206-025-5, pyridazin, oizine, MFCD00006463, NSC 90792, Pyridazine, 98%, 1,2-Diazin, UNII-449GLA0653, P0616, EN300-85759, Q420238, BCP22434, PYRIDAZINE [MI], AM20090381, SCHEMBL2851, SCHEMBL5104, A819700, SCHEMBL20899, SCHEMBL64299, CHEMBL15719, SCHEMBL218022, SCHEMBL347256, SCHEMBL450070, orb3029461, SCHEMBL1395780, SCHEMBL6003246, SCHEMBL29471424, PDK0164

Molecular formula
C4H4N2
Empirical formula
C2H2N
Molecular weight
80.09 g/mol
Exact mass
80.03745
CAS number
289-80-5
PubChem CID
9259
Canonical SMILES
C1=CC=NN=C1
Isomeric SMILES
C1=CC=NN=C1
InChI
InChI=1S/C4H4N2/c1-2-4-6-5-3-1/h1-4H
InChIKey
PBMFSQRYOILNGV-UHFFFAOYSA-N
Molfile

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

Calculated

Heavy atoms
6
Rings
1
Aromatic rings
1
Fraction sp³ carbons (Fsp3)
0
H-bond donors
0
H-bond acceptors
2
Rotatable bonds
0
TPSA (Ų)
25.8
Formal charge
0
XLogP3
-0.7 PubChem
Complexity
30 PubChem
Stereocenters
None
Double-bond geometry
None specified
Point group
C2v of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

  • C59.99%
  • H5.03%
  • N34.98%

Isotope pattern

100%80.0375.1%81.04082.042

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
0.48 Crippen (Wildman and Crippen 1999)
log S (water solubility)
-1.38 ESOL (Delaney 2004), log mol/L
Synthetic accessibility
2.32 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

  • Molecular weight ≤ 500: 80.09
  • log P ≤ 5 (Crippen): 0.48
  • H-bond donors ≤ 5: 0
  • H-bond acceptors ≤ 10: 2

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

Warning

Most widely reported: 5 company reports to ECHA. Source [1].

  • Harmful or irritant
  • H302Harmful if swallowed (20% of reports)
  • H315Causes skin irritation
  • H319Causes serious eye irritation
  • H335May cause respiratory irritation

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

Safety data sheets on the supplier’s page: Mcule, J&H Chemical Co.,ltd, Hunan Huateng Pharmaceutical Co., Ltd..

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]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
  2. [2]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
  3. [3]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
  4. [4]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
  5. ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
  6. ·Literature on PubChem

Data last updated 2026-10-14.