Trimethoprim
An aminopyrimidine antibiotic whose structure consists of pyrimidine 2,4-diamine and 1,2,3-trimethoxybenzene moieties linked by a methylene bridge. — ChEBI
Safety documents & references
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Identity & molecular properties
Source-linked values| CAS number | 738-70-5 | ChEBI ↗ |
| Molecular formula | C14H18N4O3 | ChEBI ↗ |
| Molar mass | 290.323 g/mol | ChEBI ↗ |
| Monoisotopic mass | 290.13789 Da | ChEBI ↗ |
| Formal charge | 0 | ChEBI ↗ |
| ChEBI identifier | CHEBI:45924 | ChEBI ↗ |
Cross-source molecular data
PubChem| Molar mass | 290.32 g/mol | PubChem ↗ |
| Exact mass | 290.13789045 Da | PubChem ↗ |
| Computed XLogP | 0.9 | PubChem ↗ |
| Topological polar surface area (Ų) | 106 | PubChem ↗ |
| H-bond donors | 2 | PubChem ↗ |
| H-bond acceptors | 7 | PubChem ↗ |
| Rotatable bonds | 5 | PubChem ↗ |
PubChem computed values are shown separately from the ChEBI record. An exact InChIKey match was used to connect the records. Molecular descriptors do not describe a supplied product’s purity, particle size or performance.
Names & structural identifiers
Copy any identifiertrimethoprim5-(3,4,5-trimethoxybenzyl)pyrimidine-2,4-diamineIEDVJHCEMCRBQM-UHFFFAOYSA-NCOc1cc(Cc2cnc(N)nc2N)cc(OC)c1OCInChI=1S/C14H18N4O3/c1-19-10-5-8(6-11(20-2)12(10)21-3)4-9-7-17-14(16)18-13(9)15/h5-7H,4H2,1-3H3,(H4,15,16,17,18)Names & synonyms
Names are supplied by ChEBI. Trade names and related synonyms may describe a broader product context.
Classification & relationships
ChEBI ontologyRoles recorded in ChEBI
Database role annotations describe reported biological or chemical roles; they are not product approvals or recommendations for use.
Safety classification · Japan
NITE / Japanese government2,4-Diamino-5-(3,4,5-trimethoxybenzyl)pyrimidine [Trimethoprim] · H29-A-016
| Endpoint | Reported classification |
|---|---|
| Acute toxicity （Oral） | Category 3 |
| Reproductive toxicity | Category 1A, Additional category: Effects on or via lactation |
| Specific target organ toxicity - Repeated exposure | Category 2 (skin, hematopoietic system) |
| Hazardous to the aquatic environment （Acute） | Category 2 |
| Hazardous to the aquatic environment （Long-term） | Category 2 |
Selected source-reported endpoints. Other endpoints, rationales and conditions remain in the original classification. Missing or unlisted information does not mean non-hazardous. This is not a global classification or transport decision.
Read the original NITE classificationMass ↔ amount of substance
Calculated from sourced massUses 290.323 g/mol from ChEBI. Assumes the substance described by this record; no purity or concentration correction is applied.
Elemental composition
Theoretical mass fractionsCNOHCalculated theoretical mass fractions from the reported formula and PubChem periodic-table atomic masses. These are not assay or purity results.
Research & patent references
Selected source associationsSources & record history
Checked 27 Sep 2026Release 255, 9 September 2026. ChEBI three-star (manually annotated) source entry. View original record ↗ · CC BY 4.0
PubCAS formats source data, connects references and computes explicitly labelled conversions. CAS cross-references are supplied by ChEBI; they do not constitute CAS verification or endorsement.