Title: Cyclopentane
CAS Registry Number: 287-92-3
Additional Names: Pentamethylene
Molecular Formula: C5H10
Molecular Weight: 70.13
Percent Composition: C 85.63%, H 14.37%
Literature References: Occurs in petroleum. Found in petr ether fractions. Prepd by cracking cyclohexane in the presence of alumina at high temps and pressure: Haensel, Ipatieff, Ind. Eng. Chem. 35, 632 (1943); by reduction of cyclopentadiene: David et al., Bull. Soc. Chim. Fr. [5] 11, 561 (1944). Toxicity data: Lazarew, Arch. Exp. Pathol. Pharmakol. 149, 116 (1930).
Properties: Mobile, flammable liq. mp -94.4°. bp 49.3°. d420 0.7460. nD20 1.4068. Insol in water. Miscible with other hydrocarbon solvents, alcohol, ether. LC (2 hr in air) in mice: 110 mg/l (Lazarew).
Melting point: mp -94.4°
Boiling point: bp 49.3°
Index of refraction: nD20 1.4068
Density: d420 0.7460
Toxicity data: LC (2 hr in air) in mice: 110 mg/l (Lazarew)
CAUTION: Potential symptoms of overexposure are irritation of eyes, skin, nose and throat; lightheadedness, dizziness, euphoria, incoordination, nausea, vomiting, stupor; dry, cracking skin. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 86.
Cyclopentanol Cyclopentanone Cyclopenthiazide Cyclopentobarbital Cyclopentolate

Skeletal formula Space-filling model
CAS number 287-92-3 YesY
PubChem 9253
ChemSpider 8896 YesY
EC number 206-016-6
ChEBI CHEBI:23492 YesY
RTECS number GY2390000
Jmol-3D images Image 1
Molecular formula C5H10
Molar mass 70.1 g/mol
Appearance clear, colorless liquid
Odor mild, sweet
Density 0.751 g/cm3
Melting point −93.9 °C; −137.0 °F; 179.2 K
Boiling point 49.2 °C; 120.6 °F; 322.3 K
Solubility soluble in ethanol, acetone, ether
Acidity (pKa) ~45
Refractive index (nD) 1.4065
Main hazards Flammable[1]
NFPA 704
NFPA 704.svg
Flash point −37.2 °C; −35.0 °F; 236.0 K
Autoignition temperature 361 °C; 682 °F; 634 K
Related compounds
Related compounds cyclopropane, cyclobutane, cyclohexane
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Cyclopentane is a highly flammable alicyclic hydrocarbon with chemical formula C5H10 and CAS number 287-92-3, consisting of a ring of five carbon atoms each bonded with two hydrogen atoms above and below the plane. It occurs as a colorless liquid with a petrol-like odor. Its melting point is −94 °C and its boiling point is 49 °C. Cyclopentane is in the class of cycloalkanes, being alkanes that have one or more rings of carbon atoms.

The typical structure of cyclopentane is the "envelope" conformation.

It is formed by cracking cyclohexane in the presence of alumina at a high temperature and pressure.