Curcumin (C21H20O6): structure, properties and hazards

Names and identifiers

IUPAC name: (1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-diene-3,5-dione
Synonyms: turmeric, diferuloylmethane, E100
+ 38 more
Diferuloylmethane, Natural yellow 3, Kacha haldi, Curcumin I, Curcuma, Haldar, Indian saffron, Gelbwurz, Yellow Ginger, (1E,6E)-1,7-Bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-diene-3,5-dione, Souchet, Haidr, Halad, Halud, Terra Merita, C.I. Natural Yellow 3, Safran d'Inde, Yo-Kin, Yellow puccoon, Diferaloylmethane, CI Natural Yellow 3, C.I. 75300, Jianghuangsu, Kurkumin, NanoCurc, Zlut prirodni 3, E 100, Lipocurc, Kurkum, CI 75300, DTXSID8031077, Curcumin e100, NSC32982, NSC-32982, CHEBI:3962, 1,5-Di(vanillyliden)acetylaceton, 1,5-Divanillyliden-2,4-pentandion, NSC-687842
Molecular formula: C₂₁H₂₀O₆
Empirical formula: C₂₁H₂₀O₆
Molecular weight: 368.4 g/mol
Exact mass: 368.12599
CAS number: 458-37-7
PubChem CID: 969516
Canonical SMILES: COC1=C(C=CC(=C1)C=CC(=O)CC(=O)C=CC2=CC(=C(C=C2)O)OC)O
Isomeric SMILES: COC1=C(C=CC(=C1)/C=C/C(=O)CC(=O)/C=C/C2=CC(=C(C=C2)O)OC)O
InChI: InChI=1S/C21H20O6/c1-26-20-11-14(5-9-18(20)24)3-7-16(22)13-17(23)8-4-15-6-10-19(25)21(12-15)27-2/h3-12,24-25H,13H2,1-2H3/b7-3+,8-4+
InChIKey: VFLDPWHFBUODDF-FCXRPNKRSA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: Orange-yellow needles[2]
3 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– Curcumin appears as orange-yellow needles. (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 Orange-yellow needles [2] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 352
– Orange yellow prisms, rhombic prisms from methanol [2] Hazardous Substances Data Bank (HSDB)cites Lide, D.R., G.W.A. Milne (eds.). Handbook of Data on Organic Compounds. Volume I. 3rd ed. CRC Press, Inc. Boca Raton ,FL. 1994., p. V3: 2933
Melting point: 180 to 183 °C (356 to 361 °F, NTP 1992)[1]
Density: 0.9348 at 15 °C (59 °F) (NTP, 1992) - Less dense than water[1]
Solubility in water: Very soluble in ethanol, acetic acid[2]
2 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– Slightly soluble (hot) (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 Very soluble in ethanol, acetic acid [2] Hazardous Substances Data Bank (HSDB)cites Lide, D.R., G.W.A. Milne (eds.). Handbook of Data on Organic Compounds. Volume I. 3rd ed. CRC Press, Inc. Boca Raton ,FL. 1994., p. V3: 2933
Refractive index: INDEX OF REFRACTION: 1.5118 @ 20 °C/D[2]

Value	As written	Source
–	Curcumin appears as orange-yellow needles. (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	Orange-yellow needles	[2] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr.; Hawley's Condensed Chemical Dictionary 15th Edition. John Wiley & Sons, Inc. New York, NY 2007., p. 352
–	Orange yellow prisms, rhombic prisms from methanol	[2] Hazardous Substances Data Bank (HSDB)cites Lide, D.R., G.W.A. Milne (eds.). Handbook of Data on Organic Compounds. Volume I. 3rd ed. CRC Press, Inc. Boca Raton ,FL. 1994., p. V3: 2933

Value	As written	Source
–	Slightly soluble (hot) (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	Very soluble in ethanol, acetic acid	[2] Hazardous Substances Data Bank (HSDB)cites Lide, D.R., G.W.A. Milne (eds.). Handbook of Data on Organic Compounds. Volume I. 3rd ed. CRC Press, Inc. Boca Raton ,FL. 1994., p. V3: 2933

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: 27
Rings: 2
Aromatic rings: 2
Fraction sp³ carbons (Fsp3): 0.14
H-bond donors: 2
H-bond acceptors: 6
Rotatable bonds: 8
TPSA (Å²): 93.1
Formal charge: 0
XLogP3: 3.2 PubChem
Complexity: 507 PubChem
Stereocenters: None
Double-bond geometry: C6=C7: E · C13=C14: E
Point group: C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

C68.47%
H5.47%
O26.06%

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: 3.37 Crippen (Wildman and Crippen 1999)
log S (water solubility): -4.05 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 2.43 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 368.39
log P ≤ 5 (Crippen): 3.37
H-bond donors ≤ 5: 2
H-bond acceptors ≤ 10: 6

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: 163 company reports to ECHA. Source [3].

Harmful or irritant

H315Causes skin irritation (92% of reports)
H319Causes serious eye irritation (92.6% of reports)
H335May cause respiratory irritation (91.4% 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

View all classifications (3)

[3] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for 7.4% (12 of 163) of reports.
[3] European Chemicals Agency (ECHA) · 163 reports · WarningH315, H319, H335
[3] European Chemicals Agency (ECHA) · WarningH315, H319

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

Keep container tightly closed in a dry and well-ventilated place. Recommended storage temperature: -20 °C Keep in a dry place.[2]

Safety data sheets on the supplier’s page: AA BLOCKS, Fluorochem, Sigma-Aldrich.

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]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]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[5]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
[6]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[7]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
[8]MassBank Europe · Linked only · via PubChem · retrieved 2026-10-14
[9]EU Food Improvement Agents · 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.

Similar structures

Vanillin 60%

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