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Uracil

Athanor · official

C4H4N2O2 · 112.09 g/mol

IUPAC name: 1H-pyrimidine-2,4-dione

Also called U, pyrimidine base, RNA base

Nucleic acid partsRingsRNA
Open in Athanor
The structure of Uracil
Drawn from its SMILES with RDKit
Harmful or irritantWarningCauses skin irritation · Causes serious eye irritation · May cause respiratory irritation

Names and identifiers

IUPAC name
1H-pyrimidine-2,4-dione
Synonyms
U, pyrimidine base, RNA base
+ 37 more

pyrimidine-2,4(1H,3H)-dione, 2,4(1H,3H)-Pyrimidinedione, Pyrod, Pirod, Hybar X, 2,4-Dioxopyrimidine, 2,4-Pyrimidinedione, 1H-Pyrimidine-2,4-dione, 1,2,3,4-tetrahydropyrimidine-2,4-dione, DTXSID4021424, 56HH86ZVCT, NSC-3970, SQ-6201, SQ-7726, SQ-8493, CHEBI:17568, BMS-205603-01, NSC3970, DTXCID101424, 2, 4-Dioxopyrimidine, RefChem:6338, 2-hydroxy-4-(1H)-pyrimidione, 2-hydroxy-4-(3H)-pyrimidione, 4-hydroxy-2-(1H)-pyrimidione, 200-621-9, 2,4-Dihydroxypyrimidine, pyrimidine-2,4-diol, 2,4-Pyrimidinediol, Uracil [USAN], RU 12709, MFCD00006016, 2-Hydroxy-4(3H)-pyrimidinone, NSC 3970, Ura, CCRIS 3077, 2-Hydroxy-4(1H)-pyrimidinone, SQ 6201

Molecular formula
C4H4N2O2
Empirical formula
C2H2NO
Molecular weight
112.09 g/mol
Exact mass
112.02728
CAS number
66-22-8
PubChem CID
1174
Canonical SMILES
C1=CNC(=O)NC1=O
Isomeric SMILES
C1=CNC(=O)NC1=O
InChI
InChI=1S/C4H4N2O2/c7-3-1-2-5-4(8)6-3/h1-2H,(H2,5,6,7,8)
InChIKey
ISAKRJDGNUQOIC-UHFFFAOYSA-N
Molfile

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

Calculated

Heavy atoms
8
Rings
1
Aromatic rings
1
Fraction sp³ carbons (Fsp3)
0
H-bond donors
2
H-bond acceptors
2
Rotatable bonds
0
TPSA (Ų)
65.7 computed here · PubChem 58.2
Formal charge
0
XLogP3
-1.1 PubChem
Complexity
161 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

  • C42.86%
  • H3.60%
  • N24.99%
  • O28.55%

Isotope pattern

100%112.0275.2%113.030114.032

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
-0.94 Crippen (Wildman and Crippen 1999)
log S (water solubility)
-0.5 ESOL (Delaney 2004), log mol/L
Synthetic accessibility
2.76 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

  • Molecular weight ≤ 500: 112.09
  • log P ≤ 5 (Crippen): -0.94
  • H-bond donors ≤ 5: 2
  • 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: 17 company reports to ECHA. Source [1].

  • Harmful or irritant
  • H315Causes skin irritation (11.8% of reports)
  • H319Causes serious eye irritation (11.8% of reports)
  • H335May cause respiratory irritation (11.8% of reports)

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

View all classifications (2)
  • [1] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 82.4% (14 of 17) of all reports.
  • [1] European Chemicals Agency (ECHA) · 17 reports · WarningH315, H319, H335

Safety data sheets on the supplier’s page: INTERBIOSCREEN, TargetMol, SynQuest Laboratories.

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]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
  4. [4]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
  5. [5]MassBank Europe · 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. ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
  9. ·Literature on PubChem

Data last updated 2026-10-14.