Triiodothyronine (C15H12I3NO4): structure, properties and hazards

Names and identifiers

IUPAC name: (2S)-2-amino-3-[4-(4-hydroxy-3-iodophenoxy)-3,5-diiodophenyl]propanoic acid
Synonyms: T3, liothyronine, Cytomel
+ 38 more
thyroid hormone, 3,3',5-Triiodo-L-thyronine, Liothyronin, 3,5,3'-triiodothyronine, L-Liothyronine, Tresitope, triothyrone, O-(4-Hydroxy-3-iodophenyl)-3,5-diiodo-L-tyrosine, Liotironina, Triiodo-L-thyronine, L-triiodothyronine, 3,5,3'-Triiodo-L-thyronine, Liothyroninum, Lyothyronine, Cyronine, L-3,3',5-TriioDOThyronine, (2S)-2-amino-3-[4-(4-hydroxy-3-iodophenoxy)-3,5-diiodophenyl]propanoic acid, 3,3',5-Triiodothyronine, 3,5,3'TRIIODOTHYRONINE, Rathyronine, (s)-, L-3,5,3'-Triiodothyronine, DTXSID8023216, L-Tyrosine, O-(4-hydroxy-3-iodophenyl)-3,5-diiodo-, Thyronine, 3,3',5-triiodo-, L-, 06LU7C9H1V, 3,5,3'-triiodothyronine, l-, CHEBI:18258, 4-(4-Hydroxy-3-iodophenoxy)-3,5-diiodophenylalanine, NSC-80203, 4-(3-Iodo-4-hydroxyphenoxy)-3,5-diiodophenylalanine, 4-(4-hydroxy-3-iodophenoxy)-3,5-diiodo-L-phenylalanine, DTXCID403216, Alanine, 3-(4-(4-hydroxy-3-iodophenoxy)-3,5-diiodophenyl)-, L-, (2S)-2-AMINO-3-(4-(4-HYDROXY-3-IODOPHENOXY)-3,5-DIIODOPHENYL)PROPANOIC ACID, NSC80203, Therapeutic T3, (2S)-2-azaniumyl-3-(4-(4-hydroxy-3-iodophenoxy)-3,5-diiodophenyl)propanoate, RefChem:55511
Molecular formula: C₁₅H₁₂I₃NO₄
Empirical formula: C₁₅H₁₂I₃NO₄
Molecular weight: 650.97 g/mol
Exact mass: 650.79010
CAS number: 6893-02-3
PubChem CID: 5920
Canonical SMILES: C1=CC(=C(C=C1OC2=C(C=C(C=C2I)CC(C(=O)O)N)I)I)O
Isomeric SMILES: C1=CC(=C(C=C1OC2=C(C=C(C=C2I)C[C@@H](C(=O)O)N)I)I)O
InChI: InChI=1S/C15H12I3NO4/c16-9-6-8(1-2-13(9)20)23-14-10(17)3-7(4-11(14)18)5-12(19)15(21)22/h1-4,6,12,20H,5,19H2,(H,21,22)/t12-/m0/s1
InChIKey: AUYYCJSJGJYCDS-LBPRGKRZSA-N
Molfile

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

Physical properties

Solubility in water: In water, 3.958 mg/l at 37 °C.[1]
log P: log Kow = 0.93[1]

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: 23
Rings: 2
Aromatic rings: 2
Fraction sp³ carbons (Fsp3): 0.13
H-bond donors: 3
H-bond acceptors: 4 computed here · PubChem 5
Rotatable bonds: 5
TPSA (Å²): 92.8
Formal charge: 0
XLogP3: 1.7 PubChem
Complexity: 402 PubChem
Stereocenters: 1 definedCIP: C2: S
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

C27.68%
H1.86%
I58.48%
N2.15%
O9.83%

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: 3.95 Crippen (Wildman and Crippen 1999)
log S (water solubility): -6.42 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 3.13 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 650.98
log P ≤ 5 (Crippen): 3.95
H-bond donors ≤ 5: 3
H-bond acceptors ≤ 10: 4

Breaks 1 of the 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: 174 company reports to ECHA. Source [2].

Harmful or irritant

H315Causes skin irritation (98.9% of reports)
H319Causes serious eye irritation (98.9% of reports)
H335May cause respiratory irritation (98.3% 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

Storage

Commercially available liothyronine sodium tablets should be stored in tight containers at a temperature less than 40 °C, preferably between 15-30 °C. Commercially available liothyronine sodium injection should be stored at 2-8 °C. (liothyronine sodium)[1]

Safety data sheets on the supplier’s page: Achemtek, Aladdin Scientific, AbaChemScene.

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]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
[4]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
[5]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[6]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
[7]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
[8]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.

Similar structures

Tanimoto similarity on Morgan fingerprints (radius 2) with RDKit 2026.09, at least 45%.

Isomers in the library

Reverse triiodothyronine