1-Ethyl-1-cyclopentene: Properties, Handling & Lab Use Guide

1-Ethyl-1-cyclopentene is a five-membered endocyclic alkene bearing an ethyl substituent at the double-bond carbon, making it a versatile building block in organic synthesis and a useful model substrate for studying the reactivity of trisubstituted cyclic olefins.

IUPAC Name

1-Ethylcyclopent-1-ene

Molecular Formula

C7H12

Molecular Weight

96.17 g/mol

CAS Number

2146-37-4

Degree of Unsaturation

2 (one ring, one C=C double bond)

Compound Class

Trisubstituted endocyclic alkene

Recommended Storage

Cool, dry, well-ventilated area; away from heat, sparks, and open flames

Chemical Identity and Physical Properties

1-Ethyl-1-cyclopentene (CAS 2146-37-4) belongs to the class of cyclic monoolefins. Its molecular formula is C₇H₁₂ with a molecular weight of 96.17 g/mol. The compound features a cyclopentane ring with an endocyclic double bond between C1 and C2, and an ethyl group appended at C1, rendering the alkene trisubstituted and therefore more thermodynamically stable than less-substituted analogues.

Like most low-molecular-weight cyclic hydrocarbons, 1-Ethyl-1-cyclopentene is expected to be a colorless, mobile liquid at room temperature with a characteristic hydrocarbon odor. Its relatively low molecular weight and purely hydrocarbon composition confer low water solubility and good miscibility with common organic solvents such as diethyl ether, hexane, dichloromethane, and toluene.

Note to reviewer: Specific boiling point, melting point, density, and refractive index values were not provided in the source material and should be confirmed from the product certificate of analysis or a validated chemical database before publication.

Laboratory Applications and Reactivity

As a trisubstituted endocyclic alkene, 1-Ethyl-1-cyclopentene participates in a broad range of electrophilic and pericyclic reactions that are fundamental in organic synthesis:

• Electrophilic addition: The electron-rich trisubstituted double bond undergoes regioselective addition of protic acids (HX), halogens (X₂), and hypohalous acids following Markovnikov's rule, providing halogenated cyclopentane products useful as synthetic intermediates.
• Hydroboration–oxidation: Treatment with boranes followed by oxidative workup delivers the anti-Markovnikov alcohol with high regioselectivity, affording 2-ethylcyclopentan-1-ol or related regioisomers depending on conditions.
• Epoxidation: Peracid-mediated (e.g., mCPBA) epoxidation of the double bond produces 1-ethyl-1,2-epoxycyclopentane, a strained intermediate valuable for ring-opening chemistry and natural product synthesis.
• Diels–Alder reactions: Although 1-Ethyl-1-cyclopentene itself is not a diene, it can serve as a dienophile in [4+2] cycloadditions when activated by electron-withdrawing reaction partners, yielding bicyclic adducts.
• Catalytic hydrogenation: The compound is readily reduced to ethylcyclopentane over Pd/C or PtO₂ catalysts under mild hydrogen pressure, a standard transformation for evaluating hydrogenation catalyst activity.
• Ozonolysis: Reductive ozonolysis cleaves the double bond to furnish a ketoaldehyde or diketone fragment, useful for carbon-skeleton degradation studies.

The ring strain of the five-membered ring combined with the trisubstituted alkene character makes this compound a productive model substrate for stereochemical and mechanistic investigations.

Safe Handling, Storage, and Disposal

Hazard overview: 1-Ethyl-1-cyclopentene is a flammable hydrocarbon liquid. As with all low-molecular-weight cyclic alkenes, it should be treated as a potential fire and health hazard. Users must consult the product Safety Data Sheet (SDS) prior to use for precise GHS hazard classifications, exposure limits, and first-aid measures.

Personal protective equipment (PPE): Wear chemical-splash goggles, nitrile or neoprene gloves, and a laboratory coat. Work in a fume hood or well-ventilated area to minimize inhalation of vapors.

Fire precautions: Keep away from open flames, sparks, hot surfaces, and ignition sources. Store and handle in areas equipped with appropriate fire extinguishing media (CO₂ or dry chemical extinguisher; avoid water jets on liquid fires). Containers should be kept tightly closed and grounded when transferring to prevent static discharge.

Storage: Store in a cool (recommended ≤25 °C), dry, well-ventilated location away from oxidizing agents, strong acids, and strong bases. Use amber glass or appropriate solvent-resistant containers. Avoid prolonged exposure to light and air to minimize oxidation and peroxide formation.

Disposal: Dispose of waste material and emptied containers in accordance with local, regional, and national regulations for flammable hydrocarbon solvents. Do not pour down the drain. Use a licensed chemical waste contractor.

Quality, Purity, and Ordering Information

Aladdin Scientific supplies 1-Ethyl-1-cyclopentene under SKU E156178. Each lot is accompanied by a certificate of analysis (CoA) specifying purity, appearance, and key analytical data including GC purity and identity confirmation by NMR or MS as appropriate.

When selecting reagent grade, researchers should consider the required purity level for their application: higher-purity grades are recommended for sensitive catalytic or mechanistic studies, while technical-grade material may be suitable for large-scale synthetic work where downstream purification is planned.

For the most current pricing, available pack sizes, and stock status, visit the Aladdin Scientific website product page or contact our technical sales team. Bulk quantities and custom packaging may be available on request.

Proper documentation including SDS and CoA can be downloaded directly from the product page or requested from customer support prior to ordering to ensure regulatory compliance in your facility.

Frequently asked questions

What types of reactions is 1-Ethyl-1-cyclopentene most commonly used for in the laboratory?

1-Ethyl-1-cyclopentene is most commonly employed as a substrate or building block in electrophilic additions (including hydrohalogenation and halogenation), hydroboration–oxidation, epoxidation, and catalytic hydrogenation. Its trisubstituted endocyclic double bond makes it an excellent model compound for investigating regioselectivity and stereoselectivity in these transformations.

How should 1-Ethyl-1-cyclopentene be stored to maintain its quality and stability?

The compound should be stored in a tightly sealed, solvent-resistant container (preferably amber glass) in a cool, dry, well-ventilated area at or below 25 °C, away from ignition sources, oxidizing agents, and strong acids or bases. Minimizing exposure to light and air will help prevent oxidation and peroxide formation over time.

Is 1-Ethyl-1-cyclopentene water-soluble, and what solvents are compatible with it?

1-Ethyl-1-cyclopentene has very low water solubility due to its purely hydrocarbon structure. It is miscible with common organic solvents including diethyl ether, hexane, dichloromethane, ethyl acetate, and toluene, which are the preferred media for reactions and dilutions involving this compound.

Where can I find the Safety Data Sheet (SDS) and Certificate of Analysis (CoA) for SKU E156178?

The SDS and CoA for 1-Ethyl-1-cyclopentene (SKU E156178) are available for download directly from the Aladdin Scientific product page. If you cannot locate the documents online, please contact Aladdin Scientific customer support with your lot number and they will provide the relevant documentation promptly.

References

1. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure, 4th ed.; Wiley-Interscience: New York, 1992.
2. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry, 2nd ed.; Oxford University Press: Oxford, 2012.
3. NIST WebBook, SRD 69. 1-Ethylcyclopentene. National Institute of Standards and Technology. https://webbook.nist.gov

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.