1-Ethyl-1-cyclopentene: Properties, Uses & FAQs

1-Ethyl-1-cyclopentene is a five-membered carbocyclic compound bearing an endocyclic trisubstituted double bond and an exocyclic ethyl substituent, making it a versatile building block in organic synthesis.

IUPAC Name

1-Ethylcyclopent-1-ene

Molecular Formula

C7H12

Molecular Weight

96.17 g/mol

Compound Class

Cyclic trisubstituted alkene (endocyclic)

Double Bond Character

Endocyclic, trisubstituted — relatively electron-rich and reactive toward electrophilic addition

Aladdin SKU

E156178

What Is 1-Ethyl-1-cyclopentene?

1-Ethyl-1-cyclopentene (CAS not confirmed in source material; see review flag) is a monocyclic olefin with the molecular formula C₇H₁₂ and a molecular weight of approximately 96.17 g/mol. The compound consists of a cyclopentane ring with a double bond between C1 and C2 (making it an endocyclic alkene) and an ethyl group attached to C1. This substitution pattern produces a trisubstituted alkene, which is more stable than mono- or disubstituted alkenes due to hyperconjugative and inductive stabilization from the alkyl substituents. The compound is a colourless, volatile liquid under standard laboratory conditions.

Physical and Chemical Properties

As a trisubstituted cyclic alkene, 1-Ethyl-1-cyclopentene exhibits characteristic olefinic reactivity. Key physicochemical attributes include:

• Molecular Formula: C₇H₁₂
• Molecular Weight: 96.17 g/mol
• Appearance: Colourless liquid (expected; verify with CoA)
• Solubility: Practically insoluble in water; miscible with common organic solvents such as diethyl ether, THF, dichloromethane, and hexane
• Stability: Stable under normal conditions; may undergo polymerization or oxidation on prolonged exposure to light, heat, or air

Specific values for boiling point, density, refractive index, and flash point are not confirmed in the current source material and should be verified against the product Certificate of Analysis (CoA) or a validated chemical database.

Reactivity and Synthetic Applications

The trisubstituted endocyclic double bond of 1-Ethyl-1-cyclopentene renders it reactive toward a broad range of classical alkene transformations:

• Electrophilic addition: Reacts with hydrogen halides (HX) following Markovnikov's rule, producing tertiary alkyl halide products. The cyclopentyl ring constrains regiochemistry and may influence stereoselectivity.
• Hydration: Acid-catalysed or oxymercuration–demercuration conditions provide Markovnikov alcohols; hydroboration–oxidation yields the anti-Markovnikov alcohol.
• Epoxidation: Peracids (e.g., mCPBA) convert the alkene to the corresponding cyclopentene oxide, a useful chiral building block precursor.
• Dihydroxylation: OsO₄-mediated or KMnO₄ conditions furnish cis-diols.
• Metathesis: May participate in ring-opening or cross-metathesis reactions with appropriate ruthenium catalysts, though the five-membered ring is less strained than cyclobutene and ring-opening selectivity should be confirmed experimentally.
• Diels–Alder: As a dienophile or diene component depending on electronic modification.

These reactivities make 1-Ethyl-1-cyclopentene a useful intermediate in the synthesis of substituted cyclopentanols, cyclopentanones, and spirocyclic frameworks.

Handling, Storage and Safety

As with most low-molecular-weight cyclic alkenes, appropriate precautions should be observed when working with 1-Ethyl-1-cyclopentene:

• Personal Protective Equipment: Use chemical-resistant gloves, safety goggles, and a lab coat. Work in a well-ventilated fume hood.
• Flammability: The compound is expected to be flammable given its hydrocarbon nature and low molecular weight. Confirm flash point from the Safety Data Sheet (SDS) before use.
• Storage: Store in a tightly sealed container away from heat, ignition sources, oxidising agents, and direct light. Refrigerated storage (2–8 °C) is generally recommended for volatile alkenes to minimise evaporative loss and degradation.
• Disposal: Dispose of in accordance with local regulations for flammable organic solvents. Do not pour down the drain.

Always consult the current Aladdin Scientific SDS for SKU E156178 for authoritative hazard information before handling.

Ordering and Specifications

1-Ethyl-1-cyclopentene is available from Aladdin Scientific under SKU E156178. When placing an order or evaluating the reagent, consider the following:

• Purity: Confirm the purity grade from the product page or Certificate of Analysis. For sensitive synthetic applications, higher-purity lots are recommended.
• Pack sizes: Available pack sizes are listed on the Aladdin Scientific product page. Contact customer service for bulk or custom quantities.
• Documentation: CoA, SDS, and NMR/GC data may be available upon request for quality verification purposes.
• Lead time: Check current stock status on the website or contact your regional Aladdin Scientific representative.

For technical enquiries about this product, please contact Aladdin Scientific technical support, referencing SKU E156178.

Frequently asked questions

What is the molecular formula and molecular weight of 1-Ethyl-1-cyclopentene?

1-Ethyl-1-cyclopentene has the molecular formula C7H12 and a molecular weight of approximately 96.17 g/mol. It is a seven-carbon monocyclic alkene with one degree of unsaturation from the endocyclic double bond and one from the ring.

Is 1-Ethyl-1-cyclopentene a trisubstituted alkene, and why does that matter?

Yes, 1-Ethyl-1-cyclopentene is a trisubstituted alkene: the double-bond carbons bear three alkyl substituents in total (two ring carbons and the exocyclic ethyl group). Trisubstituted alkenes are more stable and more reactive toward electrophilic addition than less-substituted analogues, and they often exhibit useful regioselectivity and stereoselectivity in reactions such as hydroboration, epoxidation, and hydration.

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

The compound should be stored in a tightly sealed container, away from heat sources, ignition sources, oxidising agents, and direct sunlight. Refrigerated conditions (2–8 °C) are generally recommended for volatile cyclic alkenes to minimise evaporation and slow potential oxidative degradation. Always confirm storage recommendations with the Aladdin Scientific SDS for SKU E156178.

What types of reactions can 1-Ethyl-1-cyclopentene undergo?

As a trisubstituted alkene, it readily undergoes electrophilic addition (e.g., hydrohalogenation following Markovnikov's rule), hydration (acid-catalysed or oxymercuration), hydroboration–oxidation (anti-Markovnikov), epoxidation with peracids, and dihydroxylation. It may also serve as a substrate in cross-metathesis or Diels–Alder reactions depending on the reaction conditions.

What is the Aladdin Scientific SKU for 1-Ethyl-1-cyclopentene?

1-Ethyl-1-cyclopentene is listed under SKU E156178 in the Aladdin Scientific catalogue. You can search this SKU directly on the Aladdin Scientific website or contact customer service for ordering assistance, bulk pricing, or documentation requests.

References

1. March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure. Wiley-Interscience. General reference for alkene reactivity and electrophilic addition.
2. Clayden, J.; Greeves, N.; Warren, S. Organic Chemistry. Oxford University Press. Reference for trisubstituted alkene stability and hydroboration selectivity.
3. Aladdin Scientific Product Page: 1-Ethyl-1-cyclopentene, SKU E156178. Aladdin Scientific.

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