Cyclopentanol or Cyclopentyl alcohol: Preparation and Properties

Cyclopentanol or cyclopentyl alcohol is a cyclic alcohol. It is also known as hydroxycyclopentane.

Physical and Chemical Properties

Chemical FormulaC<sub>5</sub>H<sub>10</sub>OH
Molecular WeightApproximately 86.13 g/mol
Physical StateLiquid at room temperature
AppearanceColorless to pale yellow liquid
OdorCharacteristic odor
Melting Point-47.9°C (-54.2°F)
Boiling Point140-143°C (284-289°F)
Density~0.943 g/cm<sup>3</sup> at 20°C (68°F)
SolubilitySoluble in water, ethanol, and ether
FlammabilityFlammable liquid
Vapor Pressure~2.2 mmHg at 20°C (68°F)
Flash Point46°C (115°F) (closed cup)
Autoignition Temperature~285°C (545°F)
Refractive Indexn<sub>D</sub> 1.441 (20°C)
Viscosity~2.9 cP at 20°C (68°F)
HazardsIrritating to eyes, skin, and respiratory tract; may cause headache, dizziness, and nausea; flammable; harmful if swallowed or inhaled.


Cyclopentanol, also known as cyclopentyl alcohol, can be prepared through various synthetic routes. One common method involves the acid-catalyzed hydration of cyclopentene, an alkene. Here’s a simplified outline of the preparation of cyclopentanol using this method:

Materials Needed:

  • Cyclopentene
  • Water (solvent)
  • Sulfuric acid (catalyst)


  • Preparation of Reaction Mixture: In a reaction flask equipped with a reflux condenser, add cyclopentene and water in the appropriate stoichiometric ratio. The reaction typically uses excess water to ensure complete hydration of the alkene.
  • Addition of Catalyst: Add a small amount of sulfuric acid as a catalyst to facilitate the acid-catalyzed hydration reaction. The sulfuric acid serves to protonate the alkene, activating it for nucleophilic attack by water.
  • Refluxing: Heat the reaction mixture under reflux conditions, maintaining it at an elevated temperature. Refluxing ensures continuous vaporization of water and allows the reaction to proceed to completion.
  • Isolation of Cyclopentanol: After the reaction is complete, cool the reaction mixture and separate the organic layer containing cyclopentanol from the aqueous layer. Cyclopentanol can then be isolated from the organic layer by techniques such as simple distillation or extraction.
  • Purification: The crude cyclopentanol obtained from the reaction may contain impurities and unreacted starting materials. Purify the cyclopentanol by distillation under reduced pressure to remove volatile impurities and obtain the desired product in a purified form.
  • Characterization: Characterize the purified cyclopentanol using analytical techniques such as gas chromatography, infrared spectroscopy, or nuclear magnetic resonance spectroscopy to confirm its identity and purity.