Dicyclopentadiene cracking

Aliphatic C-5—C-6. Aliphatic feedstreams are typically composed of C-5 and C-6 paraffins, olefins, and diolefins, the main reactive components being piperylenes cis-[1574-41 -0] and /n j -l,3-pentadiene [2004-70-8f). Other main compounds iaclude substituted C-5 and C-6 olefins such as cyclopentene [142-29-OJ, 2-methyl-2-butene [513-35-9] and 2-methyl-2-pentene [625-27-4J. Isoprene and cyclopentadiene maybe present ia small to moderate quaatities (2—10%). Most steam cracking operatioas are desigaed to remove and purify isoprene from the C-5—C-6 fraction for applications ia mbbers and thermoplastic elastomers. Cyclopentadiene is typically dimerized to dicyclopentadiene (DCPD) and removed from C-5 olefin—diolefin feedstreams duriag fractionation (19). 

Cycloaliphatic Diene CPD—DCPD. Cycloatiphatic diene-based hydrocarbon resias are typically produced from the thermal or catalytic polymerization of cyclopeatadieae (CPD) and dicyclopentadiene (DCPD). Upon controlled heating, CPD may be dimerized to DCPD or cracked back to the monomer. The heat of cracking for DCPD is 24.6 kJ / mol (5.88 kcal/mol). In steam cracking processes, CPD is removed from C-5 and... 

Gyclopentadiene/Dicyclopentadiene-Based Petroleum Resins. 1,3-Cyclopentadiene (CPD) is just one of the numerous compounds produced by the steam cracking of petroleum distillates. Due to the fact that DCPD is polymerized relatively easily under thermal conditions without added catalyst, resins produced from cycloaHphatic dienes have become a significant focus of the hydrocarbon resin industry. 

The purity of a dicyclopentadiene stream may be expressed in terms of DCPD itself or in terms of available CPD monomer. Both analyses are deterrnined by gas chromatography (gc). The first analysis is capillary gc on a nonpolar column. The data from the analysis can be used to calculate the available CPD, assuming that all the DCPD and CPD codimers crack completely. In the second analysis the sample is charged to the gc equipment under temperature conditions (injection port 400°C) that cause essentially complete reaction of the dimers to monomers. 

Elastomers. Ethylene—propylene terpolymer (diene monomer) elastomers (EPDM) use a variety of third monomers during polymerization (see Elastomers, ethyiene-propylene-diene rubber). Ethyhdenenorbomene (ENB) is the most important of these monomers and requires dicyclopentadiene as a precursor. ENB is synthesized in a two step preparation, ie, a Diels-Alder reaction of CPD (via cracking of DCPD) with butadiene to yield 5-vinylbicyclo[2.2.1]-hept-2-ene [3048-64-4] (7) where the external double bond is then isomerized catalyticaHy toward the ring yielding 5-ethyhdenebicyclo[2.2.1]-hept-2-ene [16219-75-3] (ENB) (8) (60). 

Cyclopentadiene was prepared by cracking dicyclopentadiene of 95% purity purchased from Aldrich Chemical Company, Inc. 

ENB is normally prepared in a two-step process (Scheme 9.5). The first step involves in situ cracking of dicyclopentadiene to cyclopentadiene, and... 

Several different companies have greened various steps of the process. In VNB production by-products come from competing Diels-Alder reactions and polymerization, largely of cyclopentadiene. The reaction is usually carried out in a continuous tube reactor, but this results in fouling, due to polymerization, at the front end, where the dicyclopentadiene is cracked to cyclopentadiene at temperatures over 175 °C. Whilst fouling does not have a very significant effect on yield, over time it builds up. 

Dicyclopentadiene is the Diels-Alder reaction dimer of cyclopentadiene. It is the thermodynamically stable form of cyclopentadiene at room temperature, and is also a byproduct in the olefin cracking process. Industrially, it is isolated by distillation, and currently is readily available in North America. 

Commercial dicyclopentadiene (b.p. 170°) is placed in a flask and boiled to crack the dimer to the monomer. A 20-cm. glass-bead column permits taking relatively pure... 

Although a commodity chemical, dicyclopentadiene requires cracking at 250-... 

The cracking of dicyclopentadiene without dedicated equipment was pursued in the usual manner in the discovery setting without incident, and the team assumed that scale-up would be outsourced to a specialized facility. 

Dicyclopentadiene, obtained from the Aldrich Chemical Company, Inc. (or E. Merck, Darmstadt, FRG), was cracked just prior to use according to the procedure of Fieser and Williamson,2 to give the monomer, bp 40-42°C. 

Cyclopentadiene is a product of petroleum cracking. It dimerizes exothermically in a Diels-Alder reaction to dicyclopentadiene, which is a convenient form for storage and transport. Dicyclopentadiene plus cyclopentadiene demand in the United States amounted to 270 million lb in 1998. 

Ethylene and propylene are produced primarily by the cracking of naphtha. They also are available from the fractionation of natural gas. Ethylidene norbornene is produced by reacting butadiene with cyclopentadiene. 1,4 Hexadiene is produced from butadiene and ethylene. Dicyclopentadiene is obtained as a by-product from the cracking of heavy feedstocks to produce ethylene. 

During the last years ROMP has been developed to generate self-healing polymers. In these polymers droplets of dicyclopentadiene and of Grubbs-catalyst are incorporated. When the polymer cracks the droplets burst open, the catalyst comes into contact with the monomer and the plastic ideally heals itself [111]. This methodology is still far from application but it does indicate the power of ROMP. 

Cyclopentadiene is obtained by the thermal cracking of dicyclopentadiene (3a,4,7,7a-tetrahydro-4,7-methanoindene). Dicyclopentadiene is slowly distilled through a short fractionating column, collecting only that which refluxes below 44°. (Cyclopentadiene boils at 42.5°, dicyclopentadiene at 170°.) This cyclopentadiene must be used within 2 or 3 hours or stored at —78° until use, because slow dimerization occurs at room temperature. 

Solutions of NaC5H5 in tetrahydrofuran are available commercially. Alternatively, NaC5H5 can be prepared in the laboratory by cracking of dicyclopentadiene, followed by reduction ... 

In the cracking of dicyclopentadiene, why is it necessary to distill the product very slowly ... 

Components produced in lowyield that have high value. Dicyclopentadiene can be recovered from the products of steam naphtha cracking. Acetophenone is recovered as a byproduct of phenol manufacture, although it can also be made by oxidation of ethylbenzene or fermentation of cinnamic acid. 

Dicyclopentadiene (DCPD) is usually recovered as a high value product from the byproduct pyrolysis gasoline stream that is generated in steam cracking furnaces (see Ethylene and Propylene by Steam Cracking ). U.S. 6,258,989 (to Phillips Petroleum) gives a typical pyrolysis gasoline composition and describes a suitable... 

Cracking of dicyclopentadiene (Diels-Alder dimer of cyclopentadiene). This is an example of a retro Diels-Alder reaction. 

Diels-Alder reactions can sometimes reverse themselves through Retro-Diels-Alder reactions. For example, dicyclopentadiene can be cracked to form 1,3-cyclopentadiene by thermal dissociation. Retro reactions occur under situations where the fragments are stable by themselves. 

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