Sulfamethoxazole
Athanor · official
C10H11N3O3S · 253.28 g/mol
IUPAC name: 4-amino-N-(5-methyl-1,2-oxazol-3-yl)benzenesulfonamide
Also called SMX, Bactrim, sulfonamide
WarningCauses skin irritation · May cause an allergic skin reaction · Causes serious eye irritation · May cause respiratory irritation · Very toxic to aquatic life · Very toxic to aquatic life with long lasting effectsNames and identifiers
- IUPAC name
- 4-amino-N-(5-methyl-1,2-oxazol-3-yl)benzenesulfonamide
- Synonyms
- SMX, Bactrim, sulfonamide
+ 38 more
Gantanol, Sulphamethoxazole, Sulfisomezole, Sulfamethoxazol, 4-Amino-N-(5-methyl-3-isoxazolyl)benzenesulfonamide, Radonil, Sinomin, 4-amino-N-(5-methylisoxazol-3-yl)benzenesulfonamide, Sulfamethylisoxazole, Sulfamethalazole, Azo-gantanol, Urobak, Sulfamethoxizole, Gantanol-DS, Ro 4-2130, Sulfametoxazol, Gamazole, 3-Sulfanilamido-5-methylisoxazole, Sulfamethoxazolum, 4-amino-N-(5-methyl-1,2-oxazol-3-yl)benzenesulfonamide, Benzenesulfonamide, 4-amino-N-(5-methyl-3-isoxazolyl)-, 5-Methyl-3-sulfanilamidoisoxazole, MS 53, 3-(p-Aminophenylsulfonamido)-5-methylisoxazole, DTXSID8026064, 3-(para-Aminophenylsulphonamido)-5-methylisoxazole, STX-608, Sulfanilamide, N1-(5-methyl-3-isoxazolyl)-, Ro-4-2130, 4-amino-N-(5-methyl-1,2-oxazol-3-yl)benzene-1-sulfonamide, Sulfanilamide, N'-(5-methyl-3-isoxazolyl)-, NSC-147832, CHEBI:9332, JE42381TNV, NSC147832, Sulfanilamide, N(1)-(5-methyl-3-isoxazolyl)-, DTXCID006064, sulfametoxazolo
- Molecular formula
- C10H11N3O3S
- Empirical formula
- C10H11N3O3S
- Molecular weight
- 253.28 g/mol
- Exact mass
- 253.05211
- CAS number
- 723-46-6
- PubChem CID
- 5329
- Canonical SMILES
- CC1=CC(=NO1)NS(=O)(=O)C2=CC=C(C=C2)N
- Isomeric SMILES
- CC1=CC(=NO1)NS(=O)(=O)C2=CC=C(C=C2)N
- InChI
- InChI=1S/C10H11N3O3S/c1-7-6-10(12-16-7)13-17(14,15)9-4-2-8(11)3-5-9/h2-6H,11H2,1H3,(H,12,13)
- InChIKey
- JLKIGFTWXXRPMT-UHFFFAOYSA-N
- Molfile
Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.
Physical properties
- Appearance
- Almost white[2]
4 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source – Crystals or white powder. (NTP, 1992) [1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina. –shown Almost white [2] Hazardous Substances Data Bank (HSDB)cites Thomson Health Care Inc.; Physicians' Desk Reference 62 ed., Montvale, NJ 2008, p. 1752 – WHITE TO OFF-WHITE CRYSTALLINE POWDER [2] Hazardous Substances Data Bank (HSDB)cites Osol, A. and J.E. Hoover, et al. (eds.). Remington's Pharmaceutical Sciences. 15th ed. Easton, Pennsylvania: Mack Publishing Co., 1975., p. 1110 – Colorless crystalline powder [2] Hazardous Substances Data Bank (HSDB)cites Actor P et al; Ullmann's Encyclopedia of Industrial Chemistry. 7th ed. (2008). NY, NY: John Wiley & Sons; Chemotherapeutics. Online Posting Date: June 15, 2000. - Odor
- Odorless[2]
2 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source –shown Odorless [2] Hazardous Substances Data Bank (HSDB)cites Thomson Health Care Inc.; Physicians' Desk Reference 62 ed., Montvale, NJ 2008, p. 1752 – PRACTICALLY ODORLESS [2] Hazardous Substances Data Bank (HSDB)cites Osol, A. and J.E. Hoover, et al. (eds.). Remington's Pharmaceutical Sciences. 15th ed. Easton, Pennsylvania: Mack Publishing Co., 1975., p. 1110 - Melting point
- 167 °C (333 °F, NTP 1992)[1]
- Solubility in water
- In water, 610 mg/L at 37 °C[2]
4 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source – less than 1 mg/mL at 68 °F (NTP, 1992) [1] CAMEO Chemicalscites National Toxicology Program, Institute of Environmental Health Sciences, National Institutes of Health (NTP). 1992. National Toxicology Program Chemical Repository Database. Research Triangle Park, North Carolina. – PRACTICALLY INSOL IN WATER, ETHER & CHLOROFORM; 1 G IN 50 ML ALCOHOL & ABOUT 4 ML ACETONE; DISSOLVES IN HCL HYDROGEN CHLORIDE OR SODIUM HYDROXIDE SOLN THROUGH SALT FORMATION [2] Hazardous Substances Data Bank (HSDB)cites Osol, A. and J.E. Hoover, et al. (eds.). Remington's Pharmaceutical Sciences. 15th ed. Easton, Pennsylvania: Mack Publishing Co., 1975., p. 1110 –shown In water, 610 mg/L at 37 °C [2] Hazardous Substances Data Bank (HSDB)cites Yalkowsky, S.H., He, Yan., Handbook of Aqueous Solubility Data: An Extensive Compilation of Aqueous Solubility Data for Organic Compounds Extracted from the AQUASOL dATAbASE. CRC Press LLC, Boca Raton, FL. 2003., p. 658 – The solubility interactions of trimethoprim and sulfamethoxazole in binary solvents were studied using hexane (n-hexane)-ethyl acetate, ethyl acetate-methyl alcohol (methanol), and methyl alcohol-water as the solve mixtures. When solubilities were obtained for individual components, trimethoprim exhibited solvation in ethyl acetate-methyl alcohol mixtures, while sulfamethoxazole showed weaker solute-solvent interactions in the solvent series. At its peak, the solubility of sulfamethoxazole was about 8 times higher than that of trimethoprim when the drugs were combined. Sulfamethoxazole lowered [2] Hazardous Substances Data Bank (HSDB)cites Subrahmanyam CV et al; Indian Drugs 33: 195-1995 (May 1996) - log P
- log Kow = 0.89[2]
- pKa
- pKa1 = 1.6[2]
2 values
Only one source reports it.
Value As written Source –shown pKa1 = 1.6 [2] Hazardous Substances Data Bank (HSDB)cites PMID:15298203 Boreen AL et al; Environ Sci Technol 38: 3933-40 (2004) – pKa2 = 5.7 [2] Hazardous Substances Data Bank (HSDB)cites PMID:15298203 Boreen AL et al; Environ Sci Technol 38: 3933-40 (2004)
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
- 17
- Rings
- 2
- Aromatic rings
- 2
- Fraction sp³ carbons (Fsp3)
- 0.1
- H-bond donors
- 2
- H-bond acceptors
- 5 computed here · PubChem 6
- Rotatable bonds
- 3
- TPSA (Ų)
- 98.2 computed here · PubChem 107
- Formal charge
- 0
- XLogP3
- 0.9 PubChem
- Complexity
- 346 PubChem
- Stereocenters
- None
- 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
- C47.42%
- H4.38%
- N16.59%
- O18.95%
- S12.66%
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
- 1.37 Crippen (Wildman and Crippen 1999)
- log S (water solubility)
- -2.55 ESOL (Delaney 2004), log mol/L
- Synthetic accessibility
- 2.05 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)
Drug-likeness: Lipinski’s rule of five
- Molecular weight ≤ 500: 253.28
- log P ≤ 5 (Crippen): 1.37
- H-bond donors ≤ 5: 2
- 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: 165 company reports to ECHA. Source [3].
- Harmful or irritant
- Environmental hazard
- H315Causes skin irritation (38.2% of reports)
- H317May cause an allergic skin reaction (38.8% of reports)
- H319Causes serious eye irritation (37.6% of reports)
- H335May cause respiratory irritation (37.6% of reports)
- H400Very toxic to aquatic life (22.4% of reports)
- H410Very toxic to aquatic life with long lasting effects (22.4% of reports)
Precautionary statements: P261, P264, P264+P265, P271, P272, P273, P280, P302+P352, P304+P340, P305+P351+P338, P319, P321, P332+P317, P333+P317, P337+P317, P362+P364, P391, P403+P233, P405, P501
View all classifications (3)
- [3] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 32.1% (53 of 165) of reports.
- [3] European Chemicals Agency (ECHA) · 165 reports · WarningH315, H317, H319, H335, H400, H410
- [3] European Chemicals Agency (ECHA) · WarningH315, H317, H319, H335, H341, H350
First aid
- Eyes: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. Immediately transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop. Skin: Immediately flood affected skin with water while removing and isolating all contaminated clothing.[1]
Storage
- Commercially available sulfamethoxazole tablets and oral suspension should be protected from light and stored at a temperature less than 40 °C, preferably between 15-30 °C; freezing of the oral suspension should be avoided.[2]
Safety data sheets on the supplier’s page: Shenghe Chemical, Enamine, Glixx Labs Inc.
Always read the supplier’s safety data sheet before working with it.
Spectra
- NMRNMRShiftDB
- 1H NMRSpectraBase (BRUKER AC-300)
- 13C NMRSpectraBase
- GC-MSHuman Metabolome Database (HMDB) (EI-B · positive) · MassBank of North America (MoNA) (HITACHI M-80 · EI-B · positive) · MassBank of North America (MoNA) (HITACHI M-80 · EI-B · positive) · NIST Mass Spectrometry Data Center · NIST Mass Spectrometry Data Center · SpectraBase
- MS-MSHuman Metabolome Database (HMDB) (Positive) · Human Metabolome Database (HMDB) (Positive) · Human Metabolome Database (HMDB) (Positive) · Human Metabolome Database (HMDB) (Positive) · Human Metabolome Database (HMDB) (Positive) · Human Metabolome Database (HMDB) (Positive)
- LC-MSMassBank Europe (QExactive Orbitrap HF-X (Thermo Scientific) · LC-ESI-QFT · POSITIVE) · MassBank Europe (QExactive Orbitrap HF-X (Thermo Scientific) · LC-ESI-QFT · NEGATIVE) · MassBank Europe (Exploris 480 Orbitrap (Thermo Scientific) · LC-ESI-QFT · POSITIVE) · MassBank Europe (Exploris 480 Orbitrap (Thermo Scientific) · LC-ESI-QFT · NEGATIVE) · MassBank Europe (Bruker maXis Impact · LC-ESI-QTOF · POSITIVE) · MassBank Europe (Bruker maXis Impact · LC-ESI-QTOF · POSITIVE)
- Other MSMassBank Europe (QExactive Orbitrap HF-X (Thermo Scientific) · LC-APCI-QFT · NEGATIVE) · MassBank Europe (QExactive Orbitrap HF-X (Thermo Scientific) · LC-APCI-QFT · POSITIVE) · MassBank Europe (HITACHI M-80 · EI-B · POSITIVE) · MassBank Europe (TripleTOF 5600+SCIEX · ESI-QTOF · POSITIVE) · MassBank Europe (TripleTOF 5600+SCIEX · ESI-QTOF · POSITIVE) · MassBank Europe (TripleTOF 5600+SCIEX · ESI-QTOF · POSITIVE)
- UVHazardous Substances Data Bank (HSDB)
- FTIRSpectraBase (KBr WAFER)
- ATR-IRSpectraBase (Bio-Rad FTS · ATR-Neat (DuraSamplIR II))
- RamanSpectraBase (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]CAMEO Chemicals · Public domain (NOAA) · via PubChem · retrieved 2026-10-14
- [2]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
- [3]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
- [4]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
- [5]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
- [6]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
- [7]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
- [8]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
- [9]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.