Cyclopropane

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C₃H₆ · 42.08 g/mol

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Drawn from its SMILES with RDKit

DangerExtremely flammable gas

Names and identifiers

IUPAC name: cyclopropane
Synonyms: Trimethylene, ciclopropano, cyclopropanum
+ 35 more
Zyklopropan, Trimethylene (cyclic), RC 270, DTXSID4058786, 99TB643425, CHEBI:30365, RefChem:5724, DTXCID1047734, 200-847-8, Cyclopropan, MFCD00001268, Cyclopropane [INN], Cyclopropanum [INN-Latin], Ciclopropano [INN-Spanish], HSDB 812, Cyclopropane [USP:INN], EINECS 200-847-8, UN1027, Cyclopropnane, UNII-99TB643425, Cyclopropane [Anaesthetics, volatile], Cyclopropane, >=99%, Cyclopropane (USP/INN), CYCLOPROPANE [MI], SCHEMBL173, CYCLOPROPANE [HSDB], SCHEMBL1203, SCHEMBL4817, SCHEMBL6917, SCHEMBL6918, CYCLOPROPANE [MART.], CYCLOPROPANE [WHO-DD], SCHEMBL2233531, SCHEMBL6640730, SCHEMBL6640735
Molecular formula: C₃H₆
Empirical formula: CH₂
Molecular weight: 42.08 g/mol
Exact mass: 42.04695
CAS number: 75-19-4
PubChem CID: 6351
Canonical SMILES: C1CC1
Isomeric SMILES: C1CC1
InChI: InChI=1S/C3H6/c1-2-3-1/h1-3H2
InChIKey: LVZWSLJZHVFIQJ-UHFFFAOYSA-N
Molfile

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

Physical properties

TemperaturePressureDensity

Appearance: Cyclopropane is a colorless gas with a petroleum-like odor. It is shipped as a liquid at 4-6 atms. It is easily ignited. The vapors are heavier than air. Contact with the liquid may cause frostbite. It can asphyxiate by the displacement of air and has a narcotic effect in high concentration (formerly used as an anesthetic gas). Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket.[1]
2 values
From CAMEO Chemicals, the most authoritative source here.
Value As written Source
–shown Cyclopropane is a colorless gas with a petroleum-like odor. It is shipped as a liquid at 4-6 atms. It is easily ignited. The vapors are heavier than air. Contact with the liquid may cause frostbite. It can asphyxiate by the displacement of air and has a narcotic effect in high concentration (formerly used as an anesthetic gas). Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket. [1] CAMEO Chemicals
– COLORLESS GAS [2] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J., Sr (Ed.). Hawley's Condensed Chemical Dictionary. 12th ed. New York, NY: Van Nostrand Rheinhold Co., 1993, p. 341
Odor: Odorless[2]
3 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– Mild, sweet [2] Hazardous Substances Data Bank (HSDB)cites U.S. Coast Guard, Department of Transportation. CHRIS - Hazardous Chemical Data. Manual Two. Washington, DC: U.S. Government Printing Office, Oct., 1978.
–shown Odorless [2] Hazardous Substances Data Bank (HSDB)cites Gerhartz, W. (exec ed.). Ullmann's Encyclopedia of Industrial Chemistry. 5th ed.Vol A1: Deerfield Beach, FL: VCH Publishers, 1985 to Present., p. VA2 291
– Characteristic odor resembling that of solvent naphtha [2] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J., Sr (Ed.). Hawley's Condensed Chemical Dictionary. 12th ed. New York, NY: Van Nostrand Rheinhold Co., 1993, p. 341
Melting point: -126.6 °C[3]
2 values
2 of 2 sources agree on it (most common value).
Value As written Source
−127.4 °C -197.3 °F (USCG, 1999) [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
−126.6 °Cshown -126.6 °C [3] PAC Chemical Database, U.S. Department of Energy
Boiling point: -33.5 °C @760 [mmHg][3]
2 values
2 of 2 sources agree on it (most common value).
Value As written Source
−32.9 °C -27.2 °F at 760 mmHg (USCG, 1999) [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
−33.5 °Cshown -33.5 °C @760 [mm Hg] [3] PAC Chemical Database, U.S. Department of Energy
Density: 1.879 @ 0°C[3]
2 values
Sources disagree; from PAC Chemical Database, U.S. Department of Energy, the most authoritative.
Value As written Source
– 0.676 at -27.4 °F (USCG, 1999) - Less dense than water [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
–shown 1.879 @ 0°C [3] PAC Chemical Database, U.S. Department of Energy
Solubility in water: 3.81 × 10² mg/l water at 35 °C[2]
2 values
From Hazardous Substances Data Bank (HSDB), the most authoritative source here.
Value As written Source
– OSTWALD SOLUBILITY COEFFICIENT (37 °C) IN H2O: 0.20; IN BLOOD: 0.42 AND IN OIL: 11.9 [2] Hazardous Substances Data Bank (HSDB)cites LaDu, B.N., H.G. Mandel, and E.L. Way. Fundamentals of Drug Metabolism and Disposition. Baltimore: Williams and Wilkins, 1971., p. 107
–shown 3.81X10+2 mg/l water at 35 °C [2] Hazardous Substances Data Bank (HSDB)cites Yalkowsky SH, Dannenfelser RM; Aquasol Database of Aqueous Solubility. Version 5. College of Pharmacy, Univ of Ariz - Tucson, AZ. PC Version (1992)
log P: log Kow = 1.72[2]
Vapor pressure: 5410 [mmHg] @25 °C[3]
2 values
2 of 2 sources agree on it (most common value).
Value As written Source
5410 mmHg 5.41X10+3 mm Hg at 25 °C/ calculated from experimentally derived coefficients/ [2] Hazardous Substances Data Bank (HSDB)cites Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989.
5410 mmHgshown 5410 [mm Hg] @25 °C [3] PAC Chemical Database, U.S. Department of Energy
Autoignition temperature: 497 °C (928 °F)[2]
2 values
Sources disagree; from Hazardous Substances Data Bank (HSDB), the most authoritative.
Value As written Source
500 °C 932 °F (USCG, 1999) [1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
498 °Cshown 928 °F (497 °C) [2] Hazardous Substances Data Bank (HSDB)cites Hawley, G.G. The Condensed Chemical Dictionary. 10th ed. New York: Van Nostrand Reinhold Co., 1981., p. 301

Value	As written	Source
–shown	Cyclopropane is a colorless gas with a petroleum-like odor. It is shipped as a liquid at 4-6 atms. It is easily ignited. The vapors are heavier than air. Contact with the liquid may cause frostbite. It can asphyxiate by the displacement of air and has a narcotic effect in high concentration (formerly used as an anesthetic gas). Under prolonged exposure to fire or intense heat the containers may rupture violently and rocket.	[1] CAMEO Chemicals
–	COLORLESS GAS	[2] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J., Sr (Ed.). Hawley's Condensed Chemical Dictionary. 12th ed. New York, NY: Van Nostrand Rheinhold Co., 1993, p. 341

Value	As written	Source
–	Mild, sweet	[2] Hazardous Substances Data Bank (HSDB)cites U.S. Coast Guard, Department of Transportation. CHRIS - Hazardous Chemical Data. Manual Two. Washington, DC: U.S. Government Printing Office, Oct., 1978.
–shown	Odorless	[2] Hazardous Substances Data Bank (HSDB)cites Gerhartz, W. (exec ed.). Ullmann's Encyclopedia of Industrial Chemistry. 5th ed.Vol A1: Deerfield Beach, FL: VCH Publishers, 1985 to Present., p. VA2 291
–	Characteristic odor resembling that of solvent naphtha	[2] Hazardous Substances Data Bank (HSDB)cites Lewis, R.J., Sr (Ed.). Hawley's Condensed Chemical Dictionary. 12th ed. New York, NY: Van Nostrand Rheinhold Co., 1993, p. 341

Value	As written	Source
−127.4 °C	-197.3 °F (USCG, 1999)	[1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
−126.6 °Cshown	-126.6 °C	[3] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
−32.9 °C	-27.2 °F at 760 mmHg (USCG, 1999)	[1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
−33.5 °Cshown	-33.5 °C @760 [mm Hg]	[3] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
–	0.676 at -27.4 °F (USCG, 1999) - Less dense than water	[1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
–shown	1.879 @ 0°C	[3] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
–	OSTWALD SOLUBILITY COEFFICIENT (37 °C) IN H2O: 0.20; IN BLOOD: 0.42 AND IN OIL: 11.9	[2] Hazardous Substances Data Bank (HSDB)cites LaDu, B.N., H.G. Mandel, and E.L. Way. Fundamentals of Drug Metabolism and Disposition. Baltimore: Williams and Wilkins, 1971., p. 107
–shown	3.81X10+2 mg/l water at 35 °C	[2] Hazardous Substances Data Bank (HSDB)cites Yalkowsky SH, Dannenfelser RM; Aquasol Database of Aqueous Solubility. Version 5. College of Pharmacy, Univ of Ariz - Tucson, AZ. PC Version (1992)

Value	As written	Source
5410 mmHg	5.41X10+3 mm Hg at 25 °C/ calculated from experimentally derived coefficients/	[2] Hazardous Substances Data Bank (HSDB)cites Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989.
5410 mmHgshown	5410 [mm Hg] @25 °C	[3] PAC Chemical Database, U.S. Department of Energy

Value	As written	Source
500 °C	932 °F (USCG, 1999)	[1] CAMEO Chemicalscites U.S. Coast Guard. 1999. Chemical Hazard Response Information System (CHRIS) - Hazardous Chemical Data. Commandant Instruction 16465.12C. Washington, D.C.: U.S. Government Printing Office.
498 °Cshown	928 °F (497 °C)	[2] Hazardous Substances Data Bank (HSDB)cites Hawley, G.G. The Condensed Chemical Dictionary. 10th ed. New York: Van Nostrand Reinhold Co., 1981., p. 301

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: 3
Rings: 1
Aromatic rings: 0
Fraction sp³ carbons (Fsp3): 1
H-bond donors: 0
H-bond acceptors: 0
Rotatable bonds: 0
TPSA (Å²): 0
Formal charge: 0
XLogP3: 1.6 PubChem
Complexity: 4 PubChem
Stereocenters: None
Double-bond geometry: None specified
Point group: D3h of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

C85.63%
H14.37%

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: 1.17 Crippen (Wildman and Crippen 1999)
log S (water solubility): -0.84 ESOL (Delaney 2004), log mol/L
Synthetic accessibility: 1.01 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

Molecular weight ≤ 500: 42.08
log P ≤ 5 (Crippen): 1.17
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 [4].

Flammable
Compressed gas

NFPA 704[2]

H220Extremely flammable gas

Precautionary statements: P203, P210, P222, P280, P377, P381, P403

View all classifications (2)

[4] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH220
[5] European Chemicals Agency (ECHA) · 154 reports · DangerH220, H280, H340, H350

First aid

Inhalation: Remove promptly to fresh air; if symptoms of asphyxia- tion persist, administer artificial respiration and oxygen; treat symptomatically thereafter. Skin: If frostbite has occurred, apply warm water; treat burn. (USCG, 1999)[1]
General First Aid: · Call 911 or emergency medical service. · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination. · Move victim to fresh air if it can be done safely. · Administer oxygen if breathing is difficult. · If victim is not breathing: -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance. -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped…[6]

Safety data sheets on the supplier’s page: RR Scientific, SynQuest Laboratories, CymitQuimica.

Always read the supplier’s safety data sheet before working with it.

Spectra

NMRNMRShiftDB
13C NMRSpectraBase
GC-MSMassBank of North America (MoNA) (JEOL JMS-DX-300 · EI-B · positive) · NIST Mass Spectrometry Data Center · NIST Mass Spectrometry Data Center · NIST Mass Spectrometry Data Center · SpectraBase
Other MSHazardous Substances Data Bank (HSDB) · MassBank Europe (JEOL JMS-DX-300 · EI-B · POSITIVE)
IRHazardous Substances Data Bank (HSDB)
Vapor Phase IRSpectraBase (Vapor Phase)
RamanSpectraBase

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]PAC Chemical Database, U.S. Department of Energy · Public domain (US DOE) · via PubChem · retrieved 2026-10-14
[4]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
[5]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
[6]Emergency Response Guidebook (ERG) · Public domain (US DOT) · via PubChem · retrieved 2026-10-14
[7]NMRShiftDB · Linked only · via PubChem · retrieved 2026-10-14
[8]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
[9]MassBank of North America (MoNA) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
[10]NIST Mass Spectrometry Data Center · Linked only · via PubChem · retrieved 2026-10-14
[11]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.