Limonene (C10H16): structure, properties and hazards

Names and identifiers

IUPAC name: (4R)-1-methyl-4-prop-1-en-2-ylcyclohexene
Synonyms: citrus oil, d-limonene, carvene
+ 39 more
D-Limonene, (+)-Limonene, (R)-(+)-Limonene, (D)-Limonene, (+)-(4R)-Limonene, (4R)-Limonene, (R)-4-Isopropenyl-1-methyl-1-cyclohexene, D-(+)-Limonene, (+)-Dipentene, Limonene, (+)-, Citrene, Refchole, (+)-R-Limonene, D-Limonen, Glidesafe, Glidsafe, Kautschiin, Carvene, (+)-p-Mentha-1,8-diene, d-p-Mentha-1,8-diene, FEMA No. 2633, Biogenic SE 374, (+)-alpha-Limonene, (+)-4-Isopropenyl-1-methylcyclohexene, d-Limoneno, (4R)-4-isopropenyl-1-methylcyclohexene, (R)-(+)-p-Mentha-1,8-diene, (+)-(R)-Limonene, (4R)-(+)-Limonene, (R)-1-Methyl-4-(1-methylethenyl)cyclohexene, Dipentene no. 122, (4R)-1-methyl-4-prop-1-en-2-ylcyclohexene, DTXSID1020778, Orange x, NCI-C55572, GFD7C86Q1W, 4betaH-p-mentha-1,8-diene, p-Mentha-1,8-diene, (R)-(+)-, (4R)-1-methyl-4-(1-methylethenyl)cyclohexene
Molecular formula: C₁₀H₁₆
Empirical formula: C₅H₈
Molecular weight: 136.23 g/mol
Exact mass: 136.12520
CAS number: 5989-27-5
PubChem CID: 440917
Canonical SMILES: CC1=CCC(CC1)C(=C)C
Isomeric SMILES: CC1=CC[C@@H](CC1)C(=C)C
InChI: InChI=1S/C10H16/c1-8(2)10-6-4-9(3)5-7-10/h4,10H,1,5-7H2,2-3H3/t10-/m0/s1
InChIKey: XMGQYMWWDOXHJM-JTQLQIEISA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: Colorless liquid or oil[4]
4 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– D-limonene is a clear colorless mobile liquid with a pleasant lemon-like odor. (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.
– Other Solid; CBI; Liquid; Dry Powder; Liquid; Other Solid [2] EPA Chemical Data Reporting (CDR)
– COLOURLESS LIQUID WITH CHARACTERISTIC ODOUR. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
–shown Colorless liquid or oil [4] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 12th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2012., p. V4: 2741
Odor: Citrus odor[4]
Melting point: -74.35 °C[5]
3 values
2 of 3 sources agree on it (most common value).
Value As written Source
−96.9 °C -142.4 °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.
−74 °C -74 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
−74.3 °Cshown -74.35 °C [5] PAC Chemical Database, U.S. Department of Energy
Boiling point: 178 °C[3]
3 values
2 of 3 sources agree on it (most common value).
Value As written Source
176 to 176 °C 348 to 349 °F at 760 mmHg (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.
178 °Cshown 178 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)
178 °C 178 °C @760 [mm Hg] [5] PAC Chemical Database, U.S. Department of Energy
Density: 0.8411 at 20 °C (68 °F) (NTP, 1992) - Less dense than water[1]
3 values
3 of 3 sources agree on it (most common value).
Value As written Source
–shown 0.8411 at 68 °F (NTP, 1992) - Less dense than water [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.
– Relative density (water = 1): 0.84 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
– 0.84 @ 20°C [5] PAC Chemical Database, U.S. Department of Energy
Solubility in water: Solubility in water at 25 °C: very poor[3]
4 values
From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.
Value As written Source
– less than 1 mg/mL at 67.1 °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.
– In water, 13.8 mg/L at 25 °C [4] Hazardous Substances Data Bank (HSDB)cites Massaldi HA, King CJ; J Chem Eng Data 18: 393-7 (1973)
– Miscible with fixed oils; slightly soluble in glycerin; insoluble in propylene glycol [4] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 12th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2012., p. V4: 2741
–shown Solubility in water at 25 °C: very poor [3] ILO-WHO International Chemical Safety Cards (ICSCs)
log P: log Kow = 4.57[4]
2 values
Sources disagree; from Hazardous Substances Data Bank (HSDB), the most authoritative.
Value As written Source
–shown log Kow = 4.57 [4] Hazardous Substances Data Bank (HSDB)cites Li J, Perdue EM; Physicochemical properties of selected monoterpenes. Preprints of papers presented at the 209th ACS National Meeting Anaheim, CA April 2-7, 35(1): 134-7 (1995)
– 4.2 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
Vapor pressure: 1.98 [mmHg] @25 °C[5]
5 values
Sources disagree; from PAC Chemical Database, U.S. Department of Energy, the most authoritative.
Value As written Source
1 mmHg 1 mmHg at 57 °F [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.
5 mmHg 5 mmHg at 104.7 °F [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.
10 mmHg 10 mmHg at 128.8 °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.
1.4 mmHg Vapor pressure, kPa at 20 °C: 0.19 [3] ILO-WHO International Chemical Safety Cards (ICSCs)
1.98 mmHgshown 1.98 [mm Hg] @25 °C [5] PAC Chemical Database, U.S. Department of Energy
Flash point: 48 °C (119 °F, NTP 1992)[1]
3 values
3 of 3 sources agree on it (most common value).
Value As written Source
48 °Cshown 119 °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.
48 °C 48 °C (closed cup) [4] Hazardous Substances Data Bank (HSDB)cites IPCS, CEC; International Chemical Safety Card on d-Limonene. (April 2005). Available from, as of February 3, 2006: https://www.inchem.org/documents/icsc/icsc/eics0918.htm
48 °C 48 °C c.c. [3] ILO-WHO International Chemical Safety Cards (ICSCs)
Autoignition temperature: 237 °C[3]
2 values
2 of 2 sources agree on it (most common value).
Value As written Source
237 °C 237 °C [4] Hazardous Substances Data Bank (HSDB)cites IPCS, CEC; International Chemical Safety Card on d-Limonene. (April 2005). Available from, as of February 3, 2006: https://www.inchem.org/documents/icsc/icsc/eics0918.htm
237 °Cshown 237 °C [3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
–	D-limonene is a clear colorless mobile liquid with a pleasant lemon-like odor. (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.
–	Other Solid; CBI; Liquid; Dry Powder; Liquid; Other Solid	[2] EPA Chemical Data Reporting (CDR)
–	COLOURLESS LIQUID WITH CHARACTERISTIC ODOUR.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–shown	Colorless liquid or oil	[4] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 12th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2012., p. V4: 2741

Value	As written	Source
−96.9 °C	-142.4 °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.
−74 °C	-74 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
−74.3 °Cshown	-74.35 °C	[5] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
176 to 176 °C	348 to 349 °F at 760 mmHg (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.
178 °Cshown	178 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
178 °C	178 °C @760 [mm Hg]	[5] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
–shown	0.8411 at 68 °F (NTP, 1992) - Less dense than water	[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.
–	Relative density (water = 1): 0.84	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–	0.84 @ 20°C	[5] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
–	less than 1 mg/mL at 67.1 °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.
–	In water, 13.8 mg/L at 25 °C	[4] Hazardous Substances Data Bank (HSDB)cites Massaldi HA, King CJ; J Chem Eng Data 18: 393-7 (1973)
–	Miscible with fixed oils; slightly soluble in glycerin; insoluble in propylene glycol	[4] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J. Sr. (ed) Sax's Dangerous Properties of Industrial Materials. 12th Edition. Wiley-Interscience, Wiley & Sons, Inc. Hoboken, NJ. 2012., p. V4: 2741
–shown	Solubility in water at 25 °C: very poor	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
–shown	log Kow = 4.57	[4] Hazardous Substances Data Bank (HSDB)cites Li J, Perdue EM; Physicochemical properties of selected monoterpenes. Preprints of papers presented at the 209th ACS National Meeting Anaheim, CA April 2-7, 35(1): 134-7 (1995)
–	4.2	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
1 mmHg	1 mmHg at 57 °F	[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.
5 mmHg	5 mmHg at 104.7 °F	[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.
10 mmHg	10 mmHg at 128.8 °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.
1.4 mmHg	Vapor pressure, kPa at 20 °C: 0.19	[3] ILO-WHO International Chemical Safety Cards (ICSCs)
1.98 mmHgshown	1.98 [mm Hg] @25 °C	[5] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
48 °Cshown	119 °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.
48 °C	48 °C (closed cup)	[4] Hazardous Substances Data Bank (HSDB)cites IPCS, CEC; International Chemical Safety Card on d-Limonene. (April 2005). Available from, as of February 3, 2006: https://www.inchem.org/documents/icsc/icsc/eics0918.htm
48 °C	48 °C c.c.	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

Value	As written	Source
237 °C	237 °C	[4] Hazardous Substances Data Bank (HSDB)cites IPCS, CEC; International Chemical Safety Card on d-Limonene. (April 2005). Available from, as of February 3, 2006: https://www.inchem.org/documents/icsc/icsc/eics0918.htm
237 °Cshown	237 °C	[3] ILO-WHO International Chemical Safety Cards (ICSCs)

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: 10
Rings: 1
Aromatic rings: 0
Fraction sp³ carbons (Fsp3): 0.6
H-bond donors: 0
H-bond acceptors: 0
Rotatable bonds: 1
TPSA (Å²): 0
Formal charge: 0
XLogP3: 3.4 PubChem
Complexity: 163 PubChem
Stereocenters: 1 definedCIP: C4: R
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

C88.16%
H11.84%

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: 3.31 Crippen (Wildman and Crippen 1999)
log S (water solubility): -2.7 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 3.16 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 136.24
log P ≤ 5 (Crippen): 3.31
H-bond donors ≤ 5: 0
H-bond acceptors ≤ 10: 0

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

Danger

Harmonized EU classification (CLP Annex VI). Source [6].

Flammable
Harmful or irritant
Health hazard
Environmental hazard

H226Flammable liquid and vapor
H304May be fatal if swallowed and enters airways
H315Causes skin irritation
H317May cause an allergic skin reaction
H400Very toxic to aquatic life
H412Harmful to aquatic life with long lasting effects

Precautionary statements: P210, P233, P240, P241, P242, P243, P261, P264, P272, P273, P280, P301+P316, P302+P352, P303+P361+P353, P321, P331, P332+P317, P333+P317, P362+P364, P370+P378, P391, P403+P235, P405, P501

View all classifications (2)

[6] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH226, H304, H315, H317, H400, H412
[7] European Chemicals Agency (ECHA) · 2,981 reports · DangerH304, H317, H400, H410, H412

Exposure limits

MAK (Maximale Arbeitsplatz Konzentration): 28 mg/m[3]

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]
Fresh air, rest.[3]
Remove contaminated clothes. Rinse and then wash skin with water and soap.[3]
First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.[3]

Storage

Fireproof. Separated from strong oxidants. Store in an area without drain or sewer access.[3]
Safe Storage of Pesticides. Always store pesticides in their original containers, complete with labels that list ingredients, directions for use, and first aid steps in case of accidental poisoning. Never store pesticides in cabinets with or near food, animal feed, or medical supplies. Do not store pesticides in places where flooding is possible or in places where they might spill or leak into wells, drains, ground water, or surface water.[4]

Incompatibilities

Reacts violently with a mixture of iodine pentafluoride and tetrafluoroethylene, causing fire and explosion hazard. Reacts with oxidants.[4]

Safety data sheets on the supplier’s page: LGC Standards, VladaChem, 10X CHEM.

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]EPA Chemical Data Reporting (CDR) · Public domain (US EPA) · via PubChem · retrieved 2026-10-14
[3]ILO-WHO International Chemical Safety Cards (ICSCs) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[4]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
[5]PAC Chemical Database, U.S. Department of Energy · Public domain (US DOE) · via PubChem · retrieved 2026-10-14
[6]Regulation (EC) No 1272/2008 of the European Parliament and of the Council · EU reuse policy, CC BY 4.0 · via PubChem · retrieved 2026-10-14
[7]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[8]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
[9]Human Metabolome Database (HMDB) · Linked only · via PubChem · retrieved 2026-10-14
[10]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[11]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[12]MassBank Europe · 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.