Cyclopentadiene
cyclopentadiene
CAS: 542-92-7
Molecular Formula: C5H6
Cyclopentadiene - Names and Identifiers
| Name | cyclopentadiene |
| Synonyms | pentole r-pentine JACS-542-92-7 pyropentylene cyclopentadiene Cyclopentadiene 1,3-Cyclopentadiene 2,4-Cyclopentadiene cyclopenta-1,3-diene |
| CAS | 542-92-7 |
| EINECS | 208-835-4 |
| InChI | InChI=1/C5H6/c1-2-4-5-3-1/h1-4H,5H2 |
Cyclopentadiene - Physico-chemical Properties
| Molecular Formula | C5H6 |
| Molar Mass | 66.1 |
| Density | d40 0.8235; d410 0.8131; d420 0.8021; d425 0.7966; d430 0.7914 |
| Melting Point | -85°; mp 32.5° |
| Boling Point | bp760 41.5-42.0° |
| Water Solubility | 10.3 mM at 25 °C (shake flask-UV spectrophotometry, Streitwieser and Nebenzahl, 1976) |
| Solubility | Miscible with acetone, benzene, carbon tetrachloride, and ether. Soluble in acetic acid, aniline, andcarbon disulfide (Windholz et al., 1983). |
| Vapor Presure | 381 at 20.6 °C, 735 at 40.6 °C, 1,380 at 60.9 °C (Stoeck and Roscher, 1977) |
| Appearance | Colorless liquid |
| Exposure Limit | TLV-TWA 75 ppm (～202 mg/m3) (ACGIH,NIOSH, and OSHA); IDLH 2000 ppm(NIOSH). |
| pKa | 16(at 25℃) |
| Stability | Stable at room temperature. Incompatible with oxidizing agents, acids and a wide variety of other compounds. May form peroxides in storage. May undergo spontaneous polymerisation.Decomposes on heating |
| Refractive Index | nD16 1.44632 |
| Physical and Chemical Properties | This product is a colorless liquid, M.P.-97.2 ℃, B. P. 40 ℃,n20D 1.4446, relative density 0.805 (19/4 ℃), miscible with alcohol, ether, benzene and carbon tetrachloride, soluble in carbon disulfide, aniline, acetic acid and liquid paraffin, insoluble in water. The polymerization was carried out at room temperature to produce dicyclopentadiene. cyclopentadiene dimer, M.P. -1 ℃, B. P. 170 ℃,n20D 1.1510, relative density 0.986. Cyclopentadiene is typically present as a dimer. |
Cyclopentadiene - Risk and Safety
| UN IDs | 1993 |
| Hazard Class | 3.2 |
| Packing Group | III |
| Toxicity | LD50 of dimer orally in rats: 0.82 g/kg (Smyth) |
Cyclopentadiene - Nature
Open Data Verified Data
colorless liquid, flammable and highly volatile, similar to the smell of terpene. Melting Point -85 °c, boiling point 41.5 °c. The relative density is 0.8024 and the refractive index is 1. 4429. Spontaneous ignition point 640 °c (in air). Insoluble in water, soluble in ethanol, ether, benzene, acetone, carbon tetrachloride and other organic solvents. Because it contains two double bonds and an active methylene group, the nature is very active. It is also easy to polymerize into dicyclopentadiene at normal temperature, but it can still be converted into cyclopentadiene by heating (176.6 to 190 ° C.). The heat of evaporation of monomeric cyclopentadiene was 354 719 5J/mol.
Last Update：2025-06-10 22:55:16
Cyclopentadiene - Preparation Method
Open Data Verified Data
- cyclopentadiene is recovered from industrial by-products. (1) with coal tar crude benzene head fraction as raw material, after polymerization, distillation, separation to obtain dicyclopentadiene, and then in 350~370 deg C for thermal cracking. (2) the high temperature cracking of natural gas and petroleum hydrocarbons, under appropriate conditions, that is, the formation of cyclopentadiene.
- in the synthesis method, cyclopentene or cyclopentane is used as a raw material, activated alumina, chromium oxide and potassium oxide are used as catalysts, and the reaction temperature is 600 ° C., and the pressure of 2666-3333PA is dehydrogenated to produce cyclopentadiene. In addition, 1,4-pentadiene, 1,3-pentadiene can also be used as raw materials to prepare cyclopentadiene.
Last Update：2022-01-01 10:38:28
Cyclopentadiene - Application
Open Data Verified Data
mainly used in the manufacture of Diene pesticides, plastics, coatings, pharmaceuticals, spices, synthetic rubber, petroleum resins, high-energy fuels.
Last Update：2025-08-19 16:24:40
Cyclopentadiene - Safety
Open Data Verified Data
- vapor is narcotic, can inhibit the central nervous system, and can damage the liver and blood, causing similar effects of benzene poisoning. Often inhaled low concentrations of steam can produce Head Pain, Abdominal Pain, and jaundice, anemia and other symptoms. The workplace should be well ventilated and the operator should wear protective equipment. Mouse oral LD50 820mg/kg, the maximum allowable concentration in the air of the workplace 5.0 mg/m3. Patients with inhalation of vapors should be removed from the contaminated area in a timely manner, placed to rest and kept warm. Severe cases should be diagnosed and treated.
- This product is contained in glass bottles or metal barrels. The container should be placed to prevent breakage. Store in a cool and well-ventilated place to prevent heat and keep away from fire. Isolation from oxidizing agents.
Last Update：2022-01-01 10:38:28
Cyclopentadiene - Reference Information
| Henry's Law Constant | 5.1 at 25 °C (approximate - calculated from water solubility and vapor pressure) |
| EPA chemical information | Information provided by: ofmpub.epa.gov (external link) |
| overview | the process of preparing ethylene from high-temperature cracking of oil-based raw materials will produce C5 fraction and C9 fraction by-products. the yield and composition vary with the type of cracking raw materials, cracking depth and process conditions. Cyclopentadiene can be obtained after C5 fraction and C9 fraction are separated. The process of separating cyclopentadiene from cracking C5 and C9 is relatively simple, and the heating dimerization method is commonly used. Cyclopentadiene self-polymerates at room temperature to form dicyclopentadiene. Cyclopentadiene is obtained by heating dicyclopentadiene before use. Therefore, the commodity on the market is dicyclopentadiene. |
| use | cyclopentadiene is used in pesticides to synthesize the insecticide chlordane, endosulfan intermediate tetrachlorocyclopentane, and can also be used to produce the insecticide The intermediate of imidacloprid, in addition, it is mainly used in the resin industry, synthetic rubber, etc. Mainly used for petroleum resin and synthetic rubber. Ethylene propylene rubber was synthesized with cyclopentadiene as the third monomer. Cyclopentadiene is active in nature and has become more and more important as a raw material for organic synthesis industry. The main routes are as follows. 1. Application of cyclopentadiene polymerization reaction Cyclopentadiene can synthesize dicyclopentadiene, tricyclopentadiene, tetra or pentacyclopentadiene and other polymers, of which dicyclopentadiene is the most useful. It is the third monomer of a variety of synthetic rubber and ethylene propylene rubber (EpDM). Cyclopentadiene and dicyclopentadiene are thermally polymerized to produce petroleum resins, which are used for tackifiers, plasticizers, coatings, preservatives and inks. 2. Application of Cyclopentadiene Addition Reaction Cyclopentadiene Selective Hydrogenation to Cyclopentene is the main method for industrial production of cyclopentene. 3. Application of diene addition reaction Cyclopentadiene is extremely easy to undergo Diels-Alder diene addition reaction with olefins, usually forming bicyclo [2.2.1] heptene derivatives. Cyclopentadiene can be converted by diene addition to produce many useful derivatives. For example, cyclopentadiene and ethylene are added to form norbornene; react with butadiene to form 5-vinyl-2-norbornene (VNB), and then translocation to form 5-ethyl-2-norbornene (ENB); react with m-pentadiene to form 5-propenyl-2-norbornene (PNB); react with maleic anhydride to form bicyclo [2.2.1] hept-5-en-2, 3-dicarboxylic acid anhydride (norbornadiic anhydride). In addition, cyclopentadiene reacts with propylene, acrylonitrile, and isoprene to obtain 5-methyl-2-norbornene, 5-cyano-2-norbornene, and 5-Or 6-methyltetrahydroindene are all monomers of synthetic resins. 4. The use of halogenation reaction halogen and halohydric acid can be quickly added to the unsaturated double bond of cyclopentadiene to produce many derivatives, such as hexachlorocyclopentadiene has great industrial value and is a synthetic pesticide aldrin, dieldrin, chlordane, endosulfan, Dabanke, Caoxanjiang, mirommet, carbochlorin, heptachlor and other pesticide raw materials. 5. The role of condensation reaction The methylene group in cyclopentadiene is very active and can be condensed with various aldehydes, ketones, etc. to form a large number of derivatives. Dimethylmethylene formed by the reaction of acetone and cyclopentadiene can be copolymerized with butadiene to prepare rubber. 6. Application of oxidation reaction In industry, maleic anhydride is prepared by gas phase catalytic oxidation of cyclopentadiene or a mixture containing cyclopentadiene. 7. Synthesis of isocyanate compounds cyclopentadiene and acrylonitrile addition to produce 2-cyanonorbornene, and then through carboxyl synthesis and other reactions to prepare diisocyanate compounds. They are all raw materials for polyurethane plastics. 8. Synthetic polyol compound dicyclopentadiene is synthesized by carboxyl group to obtain dialdehyde, and then hydrogenated to obtain diol. It can be used in polyurethane production, such as as plasticizer. Thermoplastic polyurethane can be produced by reacting with toluene diisocyanate and adipic acid. The polyol prepared by the addition reaction of hexachlorocyclopentadiene and diacetylcyclopentene reacts with 4,4 'diisocyanate diphenylmethane to form a polymer with excellent impact thermal stability. 9. Synthesis of sandalwood alcohol β-sandalwood alcohol can be prepared from cyclopentadiene. In addition, cyclopentadiene and bromocrotonic acid can also be used as raw materials to produce β-sandalwood alcohol through a series of reactions. Beta-sandalwood alcohol is one of the precious spices with elegant aroma and lasting fragrance. 10. Synthesis of high-energy hydrocarbon fuels with high specific gravity due to the high density of dicyclopentadiene and cyclopentadiene, which produces high calorific value during combustion, makes it an excellent high-energy fuel. |
| production method | industrial cyclopentadiene mainly comes from the pre-benzene fraction of crude benzene obtained from coal coking process and C5 fraction of by-product of hydrocarbon cracking to ethylene. In the cracked C5 fraction, cyclopentadiene contains about 10-15%, which is the main source of cyclopentadiene. The pre-benzene fraction obtained in light benzene refining contains about 30% cyclopentadiene. Taking advantage of the easily heated dimerization of cyclopentadiene, the mixed fraction is first heated at a temperature of 100-130 ℃ to make cyclopentadiene dicyclopentadiene, and crude dicopentadiene is obtained by distillation. High-purity cyclopentadiene is obtained by high-temperature depolymerization. The synthesis method has the following methods for preparing cyclopentadiene. (1) Using cyclopentene or cyclopentane as raw material, using active oxygen aluminum (84%), chromium oxide (14%), potassium oxide 2% as catalyst, dehydrogenation at 600 ℃, 2.7-3.3kPa. (2) Cyclopentadiene is produced by dehydrogenation and cyclization of 1,4-pentadiene;(3) Cyclopentadiene is produced by dehydrogenation and cyclization of 1,3-pentadiene. the preparation method is to separate the pre-benzene fraction of coal tar to obtain the pure cyclopentadiene dimer, and the cyclopentadiene monomer is obtained by high temperature cracking and fractionation. The cyclopentadiene dimer is added to the dimer cracking kettle heated by the heat transfer oil cycle. When the kettle temperature reaches 165 ℃, the dimer pyrolysis is obviously accelerated, and the dimer is fractionated by the packed tower directly connected with the pyrolysis kettle. Cyclopentadiene is evaporated from the top of the tower, the amount of cooling water is controlled, and the fraction with the top temperature of 39~43 ℃ is collected as the required product, and the yield of cyclopentadiene is about 58%. This process is batch medium temperature cracking. If it is changed to continuous pipeline high temperature cracking, the reaction yield can reach more than 90%. |
| category | flammable liquid |
| toxicity classification | highly toxic |
| acute toxicity | oral-rat LD50: 113 mg/kg; Oral-mouse LD50: 800 mg/kg |
| Explosive hazard characteristics | High temperature, open flame and air can explode |
| flammability hazard characteristics | flammable in case of open flame, high temperature and oxidant; Strong decomposition at high temperature; Stimulating smoke from combustion |
| storage and transportation characteristics | warehouse ventilation and low temperature drying; Store separately from oxidants and acids; It is not suitable to store for a long time to prevent polymerization |
| fire extinguishing agent | dry powder, dry sand, carbon dioxide, foam, 1211 fire extinguishing agent |
| occupational standard | TWA 200 mg/m3; STEL 300 mg/m3 |
| toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |
| immediate life-threatening and health concentration | 750 ppm |
Last Update：2024-04-09 02:00:05
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