Cephalexin
Athanor · official
C16H17N3O4S · 347.4 g/mol
IUPAC name: 7-[(2-amino-2-phenylacetyl)amino]-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid
Also called Keflex, cefalexin, cephalosporin
Names and identifiers
- IUPAC name
- 7-[(2-amino-2-phenylacetyl)amino]-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid
- Synonyms
- Keflex, cefalexin, cephalosporin
+ 33 more
DTXSID20274382, 7-(2-Amino(phenyl)acetamido)-3-methyl-8-oxo-5-thia-1-azabicyclo(4.2.0)oct-2-ene-2-carboxylic acid, 7-[2-Amino(phenyl)acetamido]-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, RefChem:1074313, DTXCID90225861, 7-(2-Amino-2-phenylacetamido)-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, 7-{[amino(phenyl)acetyl]amino}-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, ZAIPMKNFIOOWCQ-UHFFFAOYSA-N, 7-[(2-amino-2-phenylacetyl)amino]-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, CHEMBL287590, orb1226091, SCHEMBL10713860, DTXSID80860169, HMS3393A04, HMS5087B18, BBL013211, MFCD01166700, STK803646, AKOS005611612, NCGC00015241-02, NCGC00015241-03, NCGC00094945-01, NCGC00094945-02, 7-(D-.alpha.-Amino-.alpha.-phenylacetamido)-3-methyl-3-cephem-4-carboxylic acid monohydrate, NS00000471, 7-(D-alpha-amino-phenylacetamido)-3-methyl-3-cepheme-4-carboxylic acid, (6R,7R)-7-[(R)-2-Amino-2-phenylacetamido]-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]-oct-2-ene-2-carboxylic acid monohydrate, [6R-[6.alpha.,7.beta.(R*)]]-7-[(Aminophenylacetyl)amino]-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, 5-Thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, 7-[(aminophenylacetyl)amino]-3-methyl-8-oxo-, monohydrate [6R-[6.alpha.,7.beta.(R*)]]-, 7-([Amino(phenyl)acetyl]amino)-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid #, 7-(aminophenylacetyl)amino-3-methyl-8-oxo-5-thia-1-azabicyclo(4,2,0)oct-2-ene-2-carboxylic acid, 7-[(2-amino-2-phenyl-acetyl)amino]-3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid, 7a(2aAminoa2aphenylacetamido)a3amethyla8aoxoa5a thiaa1aazabicyclo[4.2.0]octa2aenea2acarboxylic acid
- Molecular formula
- C16H17N3O4S
- Empirical formula
- C16H17N3O4S
- Molecular weight
- 347.4 g/mol
- Exact mass
- 347.09398
- CAS number
- 15686-71-2
- PubChem CID
- 2666
- Canonical SMILES
- CC1=C(N2C(C(C2=O)NC(=O)C(C3=CC=CC=C3)N)SC1)C(=O)O
- Isomeric SMILES
- CC1=C(N2C(C(C2=O)NC(=O)C(C3=CC=CC=C3)N)SC1)C(=O)O
- InChI
- InChI=1S/C16H17N3O4S/c1-8-7-24-15-11(14(21)19(15)12(8)16(22)23)18-13(20)10(17)9-5-3-2-4-6-9/h2-6,10-11,15H,7,17H2,1H3,(H,18,20)(H,22,23)
- InChIKey
- ZAIPMKNFIOOWCQ-UHFFFAOYSA-N
- Molfile
Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.
Calculated
- Heavy atoms
- 24
- Rings
- 3
- Aromatic rings
- 1
- Fraction sp³ carbons (Fsp3)
- 0.31
- H-bond donors
- 3
- H-bond acceptors
- 5 computed here · PubChem 6
- Rotatable bonds
- 4
- TPSA (Ų)
- 112.7 computed here · PubChem 138
- Formal charge
- 0
- XLogP3
- 0.6 PubChem
- Complexity
- 600 PubChem
- Stereocenters
- 0 defined, 3 undefinedCIP: C10: undefined · C14: undefined · C22: 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
- C55.32%
- H4.93%
- N12.10%
- O18.42%
- S9.23%
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
- 0.44 Crippen (Wildman and Crippen 1999)
- log S (water solubility)
- -2.2 ESOL (Delaney 2004), log mol/L
- Synthetic accessibility
- 3.36 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)
Drug-likeness: Lipinski’s rule of five
- Molecular weight ≤ 500: 347.4
- log P ≤ 5 (Crippen): 0.44
- H-bond donors ≤ 5: 3
- 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
No GHS hazard classification was found in the sources.
Safety data sheets on the supplier’s page: Chem-Space.com Database, Molport, Vitas-M Laboratory.
Always read the supplier’s safety data sheet before working with it.
Spectra
- 13C NMRSpectraBase
- GC-MSNIST Mass Spectrometry Data Center
- LC-MSMassBank Europe (Q Exactive Orbitrap Thermo Scientific · LC-ESI-QFT · POSITIVE) · MassBank Europe (Q Exactive Orbitrap Thermo Scientific · LC-ESI-QFT · POSITIVE) · MassBank Europe (Q Exactive Orbitrap Thermo Scientific · LC-ESI-QFT · POSITIVE) · MassBank Europe (Q Exactive Orbitrap Thermo Scientific · LC-ESI-QFT · POSITIVE) · MassBank Europe (Q Exactive Orbitrap Thermo Scientific · LC-ESI-QFT · POSITIVE) · MassBank Europe (Q Exactive Orbitrap Thermo Scientific · LC-ESI-QFT · POSITIVE)
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]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
- [2]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
- [3]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
- [4]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.