1-Methylcyclopentene
1. Basic Identification
Chemical Name: 1-Methylcyclopent-1-ene
Synonyms: 1-Methylcyclopentene, 1-Methyl-1-cyclopentene
EINECS No.: 214-422-5
MDL No.: MFCD00001366
Molecular Formula: \(\boldsymbol{C_6H_{10}}\)
Molecular Weight: 82.14
SMILES: CC1=CCCC1
UN Number: UN 1993
HS Code: 2902199090
Hazard Classification: Class 3 Highly Flammable Liquid, Packing Group II
Chemical Category: Substituted cyclic olefin, fine chemical intermediate, pharmaceutical synthesis building block
2. Physical & Chemical Properties
Appearance
Colorless transparent mobile liquid with typical aliphatic hydrocarbon odor, highly volatile under ambient temperature.
Physical Constants
| Parameter | Standard Value | Remarks |
| Melting Point | -142 ℃ | Remains liquid under normal storage |
| Boiling Point | 74–76 ℃ (760 mmHg) | Medium low boiling point, easy distillation recovery |
| Density (20 ℃) | 0.773–0.776 g/mL | Lighter than water, floats fully on water |
| Refractive Index \(n_{20/D}\) | 1.432–1.434 | Purity control index |
| Closed Cup Flash Point | -10 ℃ | Extremely flammable |
| Autoignition Temperature | 360 ℃ | Low ignition energy required |
| Explosion Limit in Air (V/V) | 1.3% ~ 10.5% | Wide flammable range, explosion risk in enclosed spaces |
| Vapor Pressure (20 ℃) | 12.5 kPa | Vapor heavier than air, accumulates in low-lying areas |
| Water Solubility | Practically insoluble in water | Complete phase separation with water |
| Organic Miscibility | Fully miscible with ethanol, acetone, ethyl acetate, toluene, alkanes, ethers |
|
Core Chemical Characteristics
- Reactive trisubstituted carbon-carbon double bond
High electron density on C=C enables electrophilic addition: bromination, hydrochlorination, hydration, epoxidation to produce methylcyclopentane substituted intermediates. - Catalytic hydrogenation
Reacts with H₂ under Ni/Pd catalyst to form methylcyclopentane, high-purity alicyclic solvent raw material. - Diels-Alder cycloaddition
Acts as dienophile for heterocyclic scaffold construction in drug and agrochemical synthesis. - Auto-oxidation tendency
Exposure to air & UV light generates trace peroxides over long storage; nitrogen-sealed storage with stabilizer is required. - Incompatible hazardous materials
Strong oxidants, chlorine, bromine, peroxide initiators, hot concentrated mineral acids, alkali metals.
3. Export Industrial Quality Specifications
Premium Synthetic Grade ≥99.0% (Mainstream Export)
| Test Item | Standard Spec | Test Method |
| 1-Methylcyclopentene Assay | ≥99.0 % | GC-FID Gas Chromatography |
| Methylcyclopentane Impurity | ≤0.30 % | GC |
| Oxygenated impurities (alcohol/ketone) | ≤0.10 % | GC |
| Moisture Content | ≤0.03 % | Karl Fischer Titration |
| Peroxide Value | ≤5 ppm | Iodometric titration |
| Color (APHA) | ≤10 | Platinum-Cobalt Colorimetry |
| Distillate 73–77 ℃ | ≥95 vol% | Atmospheric distillation test |
| Appearance | Colorless clear liquid without turbidity or peroxide sediment | Visual Inspection |
Ultra-High Purity Electronic Grade ≥99.9%
Ultra-low moisture, peroxide and metal ions, nitrogen sealed packaging for semiconductor thin-film deposition monomer.
4. Main Industrial Applications
4.1 Pharmaceutical & Fine Chemical Intermediates (Core High-Value Field)
- Precursor for 1-methylcyclopentanol, 1-bromo-1-methylcyclopentane, 1-chloro-1-methylcyclopentane — critical methylcyclopentyl building blocks for cardiovascular, diuretic and anti-inflammatory APIs.
- Raw material for methylcyclopentene oxide, chiral epoxy intermediate used for side-chain modification of small-molecule drugs to adjust lipophilicity and bioavailability.
- Diels-Alder reaction substrate for constructing complex nitrogen/oxygen heterocyclic skeletons in peptide and small-molecule drug R&D labs.
4.2 Polymer & Resin Industry
- Comonomer for cyclic olefin copolymer (COC/COP), improves product transparency, heat resistance and low water absorption for optical lenses, medical disposable plastic parts.
- Crosslinking auxiliary monomer for UV-curable resin, enhances coating hardness, scratch resistance and anti-yellowing performance.
- Feedstock for high-purity methylcyclopentane solvent via catalytic hydrogenation.
4.3 Agrochemical & Dye Intermediates
- Addition reaction raw material for methylcyclopentyl herbicides and fungicides, boosts crop absorption and pesticide stability.
- Synthetic precursor for cyclopentyl fluorescent dyes and leather colorants.
4.4 Electronic & New Material Industry
- UHP grade as carbon source gas for semiconductor packaging thin-film CVD deposition.
- Low-temperature extraction solvent for high-purity rare metal separation processes.
5. Toxicology, Health Hazards & First Aid
Toxicity Profile
- Acute Oral LD50 (Rat) >2000 mg/kg (Category 4, harmful if swallowed)
- Inhalation hazard: High-concentration vapor causes strong narcotic effect, dizziness, nausea, loss of consciousness; long-term inhalation impairs liver function.
- Dermal hazard: Powerful skin degreaser; prolonged contact leads to dry, cracked skin and mild allergic rash.
- Eye hazard: Severe conjunctival irritation and corneal edema upon direct splashing.
- Environmental hazard: Harmful to aquatic organisms with long-term toxic risks.
Exposure Symptoms
- Inhalation of vapor: Throat irritation, headache, fatigue, lethargy; extreme concentration leads to unconsciousness.
- Skin contact: Dry tight skin, erythema, itching and chapping after continuous exposure.
- Eye splash: Sharp stinging pain, conjunctival swelling and temporary blurred vision.
- Oral ingestion: Abdominal distension, nausea, mild liver metabolic burden.
Complete First-Aid Procedures
- Inhalation: Move victim to fresh upwind air; supply oxygen for breathing difficulty, send to hospital for liver function monitoring.
- Skin Contact: Immediately remove contaminated clothing; continuously rinse affected skin with plenty of running cold water for ≥15 minutes.
- Eye Contact: Force open eyelids, flush eyes with abundant clean cold water for more than 15 minutes, mandatory ophthalmic follow-up.
- Oral Intake: DO NOT induce vomiting; drink large amounts of clean water/milk for dilution and seek emergency medical care.
6. Storage, Handling & Incompatibility Rules
Mandatory Storage Conditions
- Warehouse classification: Special Class 3 highly flammable liquid explosion-proof warehouse, isolated from oxidants, halogens, food and feed materials.
- Temperature control: Storage temperature ≤20 ℃, full light shielding away from sunlight and heat pipes to suppress peroxide generation.
- Sealing requirement: Steel drums sealed with PTFE gaskets, filled with nitrogen to isolate air; warehouse equipped with flammable vapor leakage alarm.
- Static control: All transfer pipelines and pallets must be static grounded; only non-sparking copper tools permitted for loading/unloading.
- Shelf life: 12 months under original sealed packaging; discard if peroxide value exceeds standard after opening.
Strictly Separated Incompatible Materials
Strong oxidants, chlorine/bromine, peroxide initiators, hot concentrated mineral acids, alkali metal powders, edible raw materials.
Safe Operation Specifications
- Operators wear nitrile anti-solvent gloves, impact chemical goggles, anti-static overalls and activated carbon organic vapor respirator.
- All feeding, transfer and sampling operations must be carried out in negative-pressure fume hood; smoking, open flames and static sparks prohibited within 15-meter radius.
- Small leakage: Absorb with dry inert sand, collect waste into sealed hazardous waste metal barrels, block sewers to avoid water pollution.
- Large leakage: Build sand retaining dikes to contain liquid, force ventilation to disperse flammable vapor, prevent infiltration into soil and water bodies.
7. Export Packaging & Global Transportation Regulations
Standard Export Packaging Modes
- Industrial bulk grade: 200L carbon steel sealed drum with PTFE anti-corrosion gaskets, nitrogen filled
- Medium batch goods: 25L plastic-lined iron drum
- Lab small reagent package: 1L / 5L brown light-proof pressure-resistant glass bottle with outer anti-leak carton
- Large bulk ocean shipment: 20ft stainless steel insulated ISO tank container with temperature monitoring
UN Transport Compliance Rules
UN 1993, Class 3 Highly Flammable Liquid, Packing Group II
- Road transport: Vehicles fitted with exhaust flame arrestors, dual dry powder & CO₂ fire extinguishers, full static grounding strips and ventilated cargo hold.
- Ocean shipment: Comply with IMDG flammable liquid dangerous goods regulations; affix flammable hazard labels on all drums, stacking height ≤2 layers.
- Loading ban: Mixed loading with oxidants, halogens, alkaline chemicals, edible goods and metal powders in one container is strictly forbidden.
Full Export Document Package
- Batch Certificate of Analysis (COA)
- GHS-compliant MSDS / SDS
- Technical Data Sheet (TDS)
- Marine Dangerous Goods Declaration
- REACH Compliance Registration Report
8. GHS Global Hazard Label Statements
Signal Word: Danger
Hazard Statements:
H225 Highly flammable liquid and vapor
H315 Causes skin irritation
H319 Causes serious eye irritation
H336 May cause drowsiness or dizziness
H412 Harmful to aquatic life with long lasting effects
Precautionary Statements:
P210 Keep away from heat, sparks, open flames, hot surfaces – No smoking
P261 Avoid breathing vapor/mist
P280 Wear protective gloves, eye protection
P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes
P403+P235 Store in a well-ventilated place. Keep cool, tightly sealed under inert gas and protected from light.
9. Fire Emergency Disposal Plan
Approved Fire Extinguishing Agents
- Primary: Dry chemical powder, carbon dioxide (CO₂)
- Auxiliary: Alcohol-resistant foam fire extinguishing agent
Forbidden Agents
Direct high-pressure water jet (liquid floats on water surface and spreads flammable vapor to expand fire risk)
Fire Site Operation Steps
- Evacuate all personnel to upwind safe zone, isolate fire area and cut all ignition sources.
- Continuously cool surrounding 1-methylcyclopentene drums with water mist to avoid thermal expansion rupture and volatile vapor leakage.
- Collect all fire residual waste liquid and solid as hazardous waste for centralized incineration; prohibit direct discharge into water systems.
10. Printable Export COA Template
CERTIFICATE OF ANALYSIS
Product Name: 1-Methylcyclopentene
CAS No.: 1126-78-9
Grade: Export Industrial Synthetic Grade
Batch No.: ____________
Net Weight: 200kg/drum
Manufacture Date: ____________
| Test Item | Standard Spec | Test Result | Test Method |
| 1-Methylcyclopentene Assay | ≥99.0 % |
| GC Gas Chromatography |
| Methylcyclopentane Impurity | ≤0.30 % |
| GC |
| Oxygenated Impurities | ≤0.10 % |
| GC |
| Moisture Content | ≤0.03 % |
| Karl Fischer Titration |
| Peroxide Value | ≤5 ppm |
| Iodometric Titration |
| Color (APHA) | ≤10 |
| Platinum-Cobalt Colorimetry |
| Appearance | Colorless clear liquid without sediment or turbidity | Visual Inspection |
|
Conclusion: This batch complies with export industrial standard of 1-Methylcyclopentene.
Inspector Signature: ____________
Issuance Date: ____________
11. E-commerce Listing Copy (Alibaba / Echemi Direct Use)
Product Title
1-Methylcyclopentene CAS 1126-78-9 99% Colorless Highly Flammable Substituted Cyclic Olefin Raw Material for Methylcyclopentanol Methylcyclopentyl Halide Pharmaceutical Intermediate COC Optical Resin Monomer
Short Description
1-Methylcyclopentene (C₆H₁₀, CAS 1126-78-9) ≥99% low-boiling flammable trisubstituted cyclic olefin liquid. Core precursor for methylcyclopentanol, methylcyclopentyl halide drug intermediates; also key monomer for cyclic olefin copolymer (COC) optical transparent resin. Full set of UN1993 Class 3 flammable dangerous goods export documents COA, MSDS and TDS available for global bulk drum shipment.
Full Description
1-Methylcyclopentene (CAS 1126-78-9) is a small-ring substituted unsaturated cycloalkene fine chemical, supplied as colorless volatile liquid with GC purity ≥99.0%. Its electron-rich trisubstituted C=C double bond supports versatile addition, hydrogenation, epoxidation and cycloaddition reactions, serving as a core building block in pharmaceutical, polymer and agrochemical synthesis.
Core downstream application sectors: starting material for manufacturing methylcyclopentyl series API intermediates (methylcyclopentanol, chloro/bromo-methylcyclopentane); monomer for high-transparency cyclic olefin copolymer (COC/COP) used in optical lenses, medical disposable plastic parts; epoxidation feedstock for methylcyclopentene oxide chiral synthetic blocks; precursor for methylcyclopentyl herbicide/fungicide intermediates and laboratory Diels-Alder reaction reagents. We supply standard industrial synthesis grade and ultra-high purity electronic special grade with ultra-low peroxide and metal impurities.
Packed in nitrogen-filled light-proof sealed carbon steel drums for full-container sea freight. Classified UN1993 Class 3 highly flammable liquid dangerous goods, we provide complete IMDG transport, customs clearance and REACH compliance certificates for stable long-term global supply to pharmaceutical factories, optical material manufacturers and fine chemical R&D labs.
