Retinoic acid

Athanor · official

C₂₀H₂₈O₂ · 300.4 g/mol

IUPAC name: (2E,4E,6E,8E)-3,7-dimethyl-9-(2,6,6-trimethylcyclohexen-1-yl)nona-2,4,6,8-tetraenoic acid

Also called tretinoin, Retin-A, all-trans retinoic acid, ATRA, vitamin A acid, vitamin A

Vitamins Drugs

Open in Athanor

Drawn from its SMILES with RDKit

DangerHarmful if swallowed · Causes skin irritation · Causes serious eye irritation · May cause respiratory irritation · May damage fertility or the unborn child · Very toxic to aquatic life · Very toxic to aquatic life with long lasting effects · Toxic to aquatic life with long lasting effects

Names and identifiers

IUPAC name: (2E,4E,6E,8E)-3,7-dimethyl-9-(2,6,6-trimethylcyclohexen-1-yl)nona-2,4,6,8-tetraenoic acid
Synonyms: tretinoin, Retin-A, all-trans retinoic acid
+ 39 more
ATRA, vitamin A acid, vitamin A, all-trans-Retinoic acid, Vitamin A acid, trans-Retinoic acid, Aberel, Eudyna, Dermairol, Renova, all-trans-Vitamin A acid, Cordes vas, Retin A, Tretin M, all-trans-Tretinoin, Retionic acid, all-trans-Vitamin A1 acid, beta-Ra, Retin-A Micro, Vitamin A1 acid, all-trans-, beta-Retinoic acid, Tretinoina, Atralin, all-(E)-Retinoic acid, All Trans Retinoic Acid, Vitamin A acid, all-trans-, NSC-122758, Retinoic acid, all-trans-, Betarretin, Tretinoinum, A-Acido (Argentina), all trans-Retinoic acid, Aberela [Norway], Avitoin [Norway], Acnavit [Denmark], Effederm [France], Kerlocal, Refissa, Oristar rna
Molecular formula: C₂₀H₂₈O₂
Empirical formula: C₁₀H₁₄O
Molecular weight: 300.4 g/mol
Exact mass: 300.20893
CAS number: 302-79-4
PubChem CID: 444795
Canonical SMILES: CC1=C(C(CCC1)(C)C)C=CC(=CC=CC(=CC(=O)O)C)C
Isomeric SMILES: CC1=C(C(CCC1)(C)C)/C=C/C(=C/C=C/C(=C/C(=O)O)/C)/C
InChI: InChI=1S/C20H28O2/c1-15(8-6-9-16(2)14-19(21)22)11-12-18-17(3)10-7-13-20(18,4)5/h6,8-9,11-12,14H,7,10,13H2,1-5H3,(H,21,22)/b9-6+,12-11+,15-8+,16-14+
InChIKey: SHGAZHPCJJPHSC-YCNIQYBTSA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: All-trans-retinoic acid is a yellow to light-orange crystalline powder. (NTP, 1992)[1]
Melting point: 179 to 182 °C (354 to 360 °F, NTP 1992)[1]
Solubility in water: ... Soluble in ether; slightly soluble in ... chloroform.[2]
2 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– less than 1 mg/mL at 77 °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.
–shown ... Soluble in ether; slightly soluble in ... chloroform. [2] Hazardous Substances Data Bank (HSDB)cites Reynolds, J.E.F., Prasad, A.B. (eds.) Martindale-The Extra Pharmacopoeia. 28th ed. London: The Pharmaceutical Press, 1982., p. 508
log P: log Kow = 6.30[2]

Value	As written	Source
–	less than 1 mg/mL at 77 °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.
–shown	... Soluble in ether; slightly soluble in ... chloroform.	[2] Hazardous Substances Data Bank (HSDB)cites Reynolds, J.E.F., Prasad, A.B. (eds.) Martindale-The Extra Pharmacopoeia. 28th ed. London: The Pharmaceutical Press, 1982., p. 508

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: 22
Rings: 1
Aromatic rings: 0
Fraction sp³ carbons (Fsp3): 0.45
H-bond donors: 1
H-bond acceptors: 1 computed here · PubChem 2
Rotatable bonds: 5
TPSA (Å²): 37.3
Formal charge: 0
XLogP3: 6.3 PubChem
Complexity: 567 PubChem
Stereocenters: None
Double-bond geometry: C10=C11: E · C12=C14: E · C15=C16: E · C17=C19: E
Point group: C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

C79.96%
H9.39%
O10.65%

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: 5.6 Crippen (Wildman and Crippen 1999)
log S (water solubility): -4.9 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 3.11 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 300.44
log P ≤ 5 (Crippen): 5.6
H-bond donors ≤ 5: 1
H-bond acceptors ≤ 10: 1

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

Danger

Most widely reported: 188 company reports to ECHA. Source [3].

Harmful or irritant
Health hazard
Environmental hazard

H302Harmful if swallowed (29.8% of reports)
H315Causes skin irritation (73.4% of reports)
H319Causes serious eye irritation (16.5% of reports)
H335May cause respiratory irritation (14.9% of reports)
H360May damage fertility or the unborn child (72.9% of reports)
H400Very toxic to aquatic life (59% of reports)
H410Very toxic to aquatic life with long lasting effects (58% of reports)
H411Toxic to aquatic life with long lasting effects (16% of reports)

Precautionary statements: P203, P261, P264, P264+P265, P270, P271, P273, P280, P301+P317, P302+P352, P304+P340, P305+P351+P338, P318, P319, P321, P330, P332+P317, P337+P317, P362+P364, P391, P403+P233, P405, P501

View all classifications (2)

[3] European Chemicals Agency (ECHA) · 188 reports · DangerH302, H315, H319, H335, H360, H400, H410, H411
[2] Hazardous Substances Data Bank (HSDB) · WarningH302, H401

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

Tretinoin Gel, USP: Store below 30 °C (86 dg F). Tretinoin Cream, USP: Store below 27 °C (80 °F).[2]
Capsules: Store at 20 deg to 25 °C (68 deg to 77 °F).[2]
Keep container tightly closed in a dry and well-ventilated place. Recommended storage temperature -20 °C. Storage class (TRGS 510): Non Combustible Solids.[2]

Safety data sheets on the supplier’s page: AKos Consulting & Solutions, ChemoSapiens, AA BLOCKS.

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]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.