Pyrazine
Athanor · official
C4H4N2 · 80.09 g/mol
Also called 1,4-diazine, paradiazine
DangerHighly Flammable liquid and vapor · Flammable solid · Causes skin irritation · Causes serious eye irritation · May cause respiratory irritationNames and identifiers
- IUPAC name
- pyrazine
- Synonyms
- 1,4-diazine, paradiazine, 1,4-Diazine
+ 37 more
p-Diazine, Paradiazine, Piazine, 1,4-Diazabenzene, pyrazin, 1,4-Diazin, DTXSID8049410, NSC-400221, FEMA NO. 4015, 2JKE371789, CHEMBL15797, CHEBI:30953, RefChem:1113271, 206-027-6, MFCD00006122, pyrazine phase IV, pyrazine phase III, Pyrazines, CCRIS 1331, EINECS 206-027-6, NSC 400221, 1,4-Diazabenzene; 1,4-Diazine; Paradiazine; Piazine; p-Diazine, UNII-2JKE371789, Piazine (obsol.), 1, 4-Diazabenzene, Glucosamine Impurity 4, Pyrazine, >=99%, PYRAZINE [FHFI], Glucosamine Impurity 4, PYRAZINE [MI], SCHEMBL1978, SCHEMBL5179, Pyrazine, >=99%, FG, Pyrazine, analytical standard, SCHEMBL138403, SCHEMBL214348, SCHEMBL347153
- Molecular formula
- C4H4N2
- Empirical formula
- C2H2N
- Molecular weight
- 80.09 g/mol
- Exact mass
- 80.03745
- CAS number
- 290-37-9
- PubChem CID
- 9261
- Canonical SMILES
- C1=CN=CC=N1
- Isomeric SMILES
- C1=CN=CC=N1
- InChI
- InChI=1S/C4H4N2/c1-2-6-4-3-5-1/h1-4H
- InChIKey
- KYQCOXFCLRTKLS-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
- -0.2 PubChem
- Complexity
- 26 PubChem
- Stereocenters
- None
- Double-bond geometry
- None specified
- Point group
- D2h 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
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
- 1.97 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
Danger
Most widely reported: 165 company reports to ECHA. Source [1].
- Flammable
- Harmful or irritant
- H225Highly Flammable liquid and vapor (47.9% of reports)
- H228Flammable solid (44.2% of reports)
- H315Causes skin irritation (99.4% of reports)
- H319Causes serious eye irritation (99.4% of reports)
- H335May cause respiratory irritation (98.8% of reports)
Precautionary statements: P210, P233, P240, P241, P242, P243, P261, P264, P264+P265, P271, P280, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P319, P321, P332+P317, P337+P317, P362+P364, P370+P378, P403+P233, P403+P235, P405, P501
Safety data sheets on the supplier’s page: VladaChem, BenchChem, RR Scientific.
Always read the supplier’s safety data sheet before working with it.
Spectra
- NMRNMRShiftDB
- 1H NMRSpectraBase (Varian A-60)
- 13C NMRSpectraBase
- 15N NMRSpectraBase
- GC-MSHuman Metabolome Database (HMDB) (EI-B · positive) · Human Metabolome Database (HMDB) (EI-B · positive) · Human Metabolome Database (HMDB) (EI-B · positive) · MassBank of North America (MoNA) (VARIAN MAT-44 · EI-B · positive) · MassBank of North America (MoNA) (HITACHI M-80B · EI-B · positive) · MassBank of North America (MoNA) (HITACHI M-80B · EI-B · positive)
- MS-MSHuman Metabolome Database (HMDB) (ESI-ITFT · positive) · Human Metabolome Database (HMDB) (ESI-ITFT · positive) · Human Metabolome Database (HMDB) (ESI-ITFT · positive) · Human Metabolome Database (HMDB) (ESI-ITFT · positive) · Human Metabolome Database (HMDB) (Positive) · Human Metabolome Database (HMDB) (Positive)
- Other MSMassBank Europe (VARIAN MAT-44 · EI-B · POSITIVE) · MassBank Europe (HITACHI M-80B · EI-B · POSITIVE)
- FTIRSpectraBase (CAPILLARY CELL: MELT)
- ATR-IRSpectraBase (Bruker Tensor 27 FT-IR · ATR-Neat (DuraSamplIR II))
- Vapor Phase IRSpectraBase (DIGILAB FTS-14 · Vapor Phase)
- RamanSpectraBase (Bruker MultiRAM Stand Alone FT-Raman Spectrometer · FT-Raman)
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]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
- [2]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
- [3]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
- [4]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
- [5]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
- [6]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
- [7]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
- ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
- ·Literature on PubChem
Data last updated 2026-10-14.