Omeprazole

Athanor · official

C₁₇H₁₉N₃O₃S · 345.4 g/mol

IUPAC name: 6-methoxy-2-[(4-methoxy-3,5-dimethyl-2-pyridinyl)methylsulfinyl]-1H-benzimidazole

Also called Prilosec, Losec, proton pump inhibitor

Drugs Rings

Open in Athanor

Drawn from its SMILES with RDKit

WarningHarmful if swallowed, in contact with skin or if inhaled · Harmful if swallowed · Harmful in contact with skin · Causes skin irritation · May cause an allergic skin reaction · Causes serious eye irritation · Harmful if inhaled · May cause respiratory irritation · Harmful to aquatic life with long lasting effects

Names and identifiers

IUPAC name: 6-methoxy-2-[(4-methoxy-3,5-dimethyl-2-pyridinyl)methylsulfinyl]-1H-benzimidazole
Synonyms: Prilosec, Losec, proton pump inhibitor
+ 37 more
Antra, Omepral, Audazol, Omeprazon, Sanamidol, Mopral, Omapren, Omeprol, Omizac, Parizac, Ramezol, Zefxon, Zoltum, Ultop, Ceprandal, Dizprazol, Emeproton, Epirazole, Gastrimut, Gastroloc, Inhibitron, Logastric, Omeprazol, Peptilcer, Regulacid, Secrepina, Ulcometion, Belmazol, Dudencer, Gibancer, Indurgan, Inhipump, Miracid, Omegast, Ompanyt, Paprazol, Pepticum
Molecular formula: C₁₇H₁₉N₃O₃S
Empirical formula: C₁₇H₁₉N₃O₃S
Molecular weight: 345.4 g/mol
Exact mass: 345.11471
CAS number: 73590-58-6
PubChem CID: 4594
Canonical SMILES: CC1=CN=C(C(=C1OC)C)CS(=O)C2=NC3=C(N2)C=C(C=C3)OC
Isomeric SMILES: CC1=CN=C(C(=C1OC)C)CS(=O)C2=NC3=C(N2)C=C(C=C3)OC
InChI: InChI=1S/C17H19N3O3S/c1-10-8-18-15(11(2)16(10)23-4)9-24(21)17-19-13-6-5-12(22-3)7-14(13)20-17/h5-8H,9H2,1-4H3,(H,19,20)
InChIKey: SUBDBMMJDZJVOS-UHFFFAOYSA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: White to off-white crystalline powder[1]
Solubility in water: In water, 82.3 mg/L at 25 °C (estimated)[1]
2 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– Freely soluble in ethanol and methanol, and slightly soluble in acetone and isopropanol and very slightly soluble in water. [1] Hazardous Substances Data Bank (HSDB)cites Physicians' Desk Reference. 57th ed. Montvale, NJ: Thomson PDR, p. 627 (2003)
–shown In water, 82.3 mg/L at 25 °C /Estimated/ [1] Hazardous Substances Data Bank (HSDB)cites US EPA; Estimation Program Interface (EPI) Suite. Ver.3.11. June 10, 2003. Available from, as of Jun 7, 2004: https://www.epa.gov/oppt/exposure/pubs/episuitedl.htm
log P: log Kow = 2.23[1]
pKa: pKa1 = 1.2[1]
2 values
Only one source reports it.
Value As written Source
–shown pKa1 = 1.2 [1] Hazardous Substances Data Bank (HSDB)cites Hilal SH et al; pp. 291-353 in Quantitative Treatments of Solute/Solvent Interactions: Theoretical and Computational Chemistry Vol. 1 NY, NY: Elsevier (1994). SPARC pKa/property server Available from, as of Jun 7, 2004: https://ibmlc2.chem.uga.edu/sparc/
– pKa2 = 7.4 /Estimated/ [1] Hazardous Substances Data Bank (HSDB)cites Hilal SH et al; pp. 291-353 in Quantitative Treatments of Solute/Solvent Interactions: Theoretical and Computational Chemistry Vol. 1 NY, NY: Elsevier (1994). SPARC pKa/property server Available from, as of Jun 7, 2004: https://ibmlc2.chem.uga.edu/sparc/
Vapor pressure: 9.2 × 10⁻¹³ mmHg at 25 °C (estimated)[1]

Value	As written	Source
–	Freely soluble in ethanol and methanol, and slightly soluble in acetone and isopropanol and very slightly soluble in water.	[1] Hazardous Substances Data Bank (HSDB)cites Physicians' Desk Reference. 57th ed. Montvale, NJ: Thomson PDR, p. 627 (2003)
–shown	In water, 82.3 mg/L at 25 °C /Estimated/	[1] Hazardous Substances Data Bank (HSDB)cites US EPA; Estimation Program Interface (EPI) Suite. Ver.3.11. June 10, 2003. Available from, as of Jun 7, 2004: https://www.epa.gov/oppt/exposure/pubs/episuitedl.htm

Value	As written	Source
–shown	pKa1 = 1.2	[1] Hazardous Substances Data Bank (HSDB)cites Hilal SH et al; pp. 291-353 in Quantitative Treatments of Solute/Solvent Interactions: Theoretical and Computational Chemistry Vol. 1 NY, NY: Elsevier (1994). SPARC pKa/property server Available from, as of Jun 7, 2004: https://ibmlc2.chem.uga.edu/sparc/
–	pKa2 = 7.4 /Estimated/	[1] Hazardous Substances Data Bank (HSDB)cites Hilal SH et al; pp. 291-353 in Quantitative Treatments of Solute/Solvent Interactions: Theoretical and Computational Chemistry Vol. 1 NY, NY: Elsevier (1994). SPARC pKa/property server Available from, as of Jun 7, 2004: https://ibmlc2.chem.uga.edu/sparc/

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: 24
Rings: 3
Aromatic rings: 3
Fraction sp³ carbons (Fsp3): 0.29
H-bond donors: 1
H-bond acceptors: 5 computed here · PubChem 6
Rotatable bonds: 5
TPSA (Å²): 77.1 computed here · PubChem 96.3
Formal charge: 0
XLogP3: 2.2 PubChem
Complexity: 453 PubChem
Stereocenters: 0 defined, 1 undefinedCIP: S12: undefined
Double-bond geometry: None specified
Point group: C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

C59.11%
H5.54%
N12.17%
O13.90%
S9.28%

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: 2.9 Crippen (Wildman and Crippen 1999)
log S (water solubility): -3.94 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 3.06 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 345.42
log P ≤ 5 (Crippen): 2.9
H-bond donors ≤ 5: 1
H-bond acceptors ≤ 10: 5

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: 224 company reports to ECHA. Source [2].

Harmful or irritant

H302+H312+H332Harmful if swallowed, in contact with skin or if inhaled (12.5% of reports)
H302Harmful if swallowed (38.8% of reports)
H312Harmful in contact with skin (37.5% of reports)
H315Causes skin irritation (30.4% of reports)
H317May cause an allergic skin reaction (74.6% of reports)
H319Causes serious eye irritation (30.8% of reports)
H332Harmful if inhaled (37.9% of reports)
H335May cause respiratory irritation (30.4% of reports)
H412Harmful to aquatic life with long lasting effects (20.5% of reports)

Precautionary statements: P261, P264, P264+P265, P270, P271, P272, P273, P280, P301+P317, P302+P352, P304+P340, P305+P351+P338, P317, P319, P321, P330, P332+P317, P333+P317, P337+P317, P362+P364, P403+P233, P405, P501

View all classifications (2)

[2] European Chemicals Agency (ECHA) · 224 reports · WarningH302+H312+H332, H302, H312, H315, H317, H319, H332, H335, H412
[2] European Chemicals Agency (ECHA) · 38 reports · WarningH302

Safety data sheets on the supplier’s page: Quality Control Solutions (QCS Standards), Alfa Chemistry, Ambeed.

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]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
[2]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[3]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
[4]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[5]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
[6]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
[7]MassBank of North America (MoNA) · CC BY 4.0 · 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.