Procedure for preparing cyclopentadiene from its dimer. The potential hazards from cyclopentadiene storage and use on kilogram scale are studied under adiabatic conditions. Diels alder reactions of cyclopentadiene brainmass. Experimental procedure cracking dicyclopentadiene to obtain cyclopentadiene as discussed in the introduction, cyclopentadiene must be obtained by cracking dicyclopentadiene. The objective of this experiment was to crack dicyclopentadiene into two molecules of cyclopentadiene and mix cyclopentadiene with maleic anhydride to synthesize. Catalytic enantioselective 1,4iodofunctionalizations of conjugated dienes.
The process of producing highpurity cyclopentadiene cpd has been investigated, including a gas phase thermal cracking process of dicyclopentadiene dcpd in the presence of h2 on a continuous. This and other undesirable side reactions are to be avoided if high yields of cyclopentadiene monomer are to be obtained. Pure cpd can be produced in situ by the thermal cracking of the dcpd at a. Its a colorless, waxy, flammable solid or liquid, with a camphorlike odor. However, it can stay unchanged for a long time in soil and in. But because of the way orbitals involved in the dielsalder reaction align, dielsalder products are always endo. I recently did a distillation of dicyclopentadiene bp 166 c to get cyclopentadiene bp 40 c. The osha analytical laboratory recently received a set of field samples that required analysis for dicyclopentadiene. And although it may seem tempting to believe that maleic anhydride can do that too, it is in an strans conformation, which isnt favorable in the dielsalder reaction, so i would only choose the cyclopentadiene dimerization as a plausible side product.
Preparation of cyclopentadiene from its dimer journal of. Cyclopentadiene production is usually not distinguished from dicyclopentadiene since they are interconverted. Howat discovered that an effective rate constant increases by 74% during the reaction at 40c. It plays a role in how your page is seen by search engine crawlers, and how it appears in serps. Can undergo exothermic polymierization reactions in the presence of various catalysts such as acids or initiators, if subjected to heat for prolonged periods, or if contaminated. Cdc niosh pocket guide to chemical hazards cyclopentadiene. Thus, when cyclopentadiene is obtained by cracking of dicyclopentadiene, one. A meta description is an html tag in the html code of your website, which allows you to customize a section of text that describes the page itself. Because of its reactivity, cpd is normally available only in the stable dimer form. The dimerization accounts for the partial or complete solidification of liquid cyclopentadiene in storage. Cracking of dicyclopentadiene before the beginning of lab the cyclopentadiene was prepared by a lab technician by cracking it. The reaction is strongly exothermic hazardous chemicals desk reference, p.
The flask containing dicyclopentadiene is now heated by means of an electric heating mantle or oil bath to approximately 160, or until cyclopentadiene distils smoothly at 3846 and a little dicyclopentadiene refluxes from the coldfinger friedrichs condenser. Us5321177a process for the vaporphase thermal cracking of. Its a good idea to keep it cold at this point since low temp slows the dimerization. Abstract the objective of this experiment was to crack dicyclopentadiene to create two molecules of cyclopentadiene, and then perform a dielsalder reaction by reacting the diene with maleic anhydride, the dienophile, to create cisnorbornene5,6endodicarboxylic anhydride. The spontaneous dimerization of cyclopentadiene at room temperature to. Ep0509445b1 ep92106424a ep92106424a ep0509445b1 ep 0509445 b1 ep0509445 b1 ep 0509445b1 ep 92106424 a ep92106424 a ep 92106424a ep 92106424 a ep92106424 a ep 92106424a ep 0509445 b1 ep0509445 b1 ep 0509445b1 authority ep european patent office prior art keywords dicyclopentadiene step cracking fraction weight prior art date 19910418 legal status the legal status is an assumption and is not. Cyclopentadiene and dicyclopentadiene researchgate. Cyclopentadiene can be prepared in situ from cracking of dicyclopentadiene.
Recently, as a process for manufacturing cyclopentadiene resinshaped articles, an attention has been given to reaction injection molding rim. Dicyclopentadiene dcpd 3a,4,7,7atetrahydo4,7methano1hindene c10h12 general dicyclopentadiene or dcpd is the dimer of cyclopentadiene cpd formed by a dielsalder addition reaction. To conduct rim, it is necessary to use high purity dicyclopentadiene dcpd as the raw material. It will react with a variety of dienes to afford the corresponding cyclohexene system. The influence of autocatalysis is only discussed at a constant temperature, near room temperature.
Cyclopentadiene is made by thermal cracking of its dimer, and on standing it slowly reverts to this species. Carbon oxides further information use water spray to cool unopened containers. In order to produce cyclopentadiene from its dimer, ener gy has to be provided so that the energy barrier to the cracking can be surpassed. Pure cpd can be produced in situ by the thermal cracking of the dcpd at a temperature near the normal boiling point of the dcpd. Dielsalder reaction of cyclopentadiene with maleic anhydride. Dicyclopentadiene, abbreviated dcpd, is a chemical compound with formula c 10 h 12. For the cracking reaction of dicyclopentadiene dcpd running as a firstorder reaction, e a 142. Dicyclopentadiene is coproduced in large quantities in the steam cracking of naphtha and gas oils to ethylene. The air samples had been collected with isopropyl alcohol impingers. Dicyclopentadiene, abbreviated dcpd, is a chemical compound with formula c10h12. Dcpd products from dow can best be characterized as highly reactive intermediates used for a wide range of resins, i.
It is very possible that cyclopentadiene can dimerize. When pure cyclopentadiene is stored it also undergoes a dielsalder cycloaddition reaction and forms dicyclopentadiene. Mar 02, 1999 increasing temperature increases the rate of the dicyclopentadiene cracking reaction. Cyclopentadiene dimerizes readily, via the dielsalder mechanism, to dcpd at. The major use is in resins, particularly, unsaturated polyester resins. The lower portion of the column which constitutes the cracking zone is.
The largest consumption of dicyclopentadiene is linked to the production of resins including unsaturated polyester resins, petroleum resins, terpolymers, polynorbornenes, and other cyclic olefin polymers. Preparation of cyclopentadiene from dicyclopentadiene. This invention provides an improved dicyclopentadiene cracking process which entails rapidly heating the dimer in a heat transfer fluid to the cracking temperature in the absence of the monomer and rapidly removing the cyclopentadiene monomer vapor from the heat transfer fluid prior to condensation to the liquid state. Dicyclopentadiene may react vigorously with oxidizing agents. As for the necessity for the slow cracking of cyclopentadiene, i believe its a compromise between obtaining pure cyclopentadiene efficient slow fractional distillation and throughput rate of collection of distilate. Jan 23, 2016 i saw in books that reaction between dicyclopentadiene and maleic acid result in dicyclopentadiene maleat ester. Also, when cooling a piece of equipment that contains the hot bottoms from the distillation or cracking of dicyclopentadiene, care should be taken to exclude air.
Kommerziell erhaltliches dicyclopentadien iupacname. In the still, cyclopentadiene is vaporized, while any dicyclopentadiene is retained in. The way i viewed the above diagram the receiving flask is on the left, hence the friedrichs condenser is used to rapidly condense the hot, cracked cyclopentadiene rapidly. Stripped to its most basic components, this reaction is represented by the addition of 1,3butadiene to ethene shown below. May react exothermically with reducing agents to release hydrogen gas. The cyclopentadiene cpd molecules, from which dcpd products are made, originate from high temperature cracking of petroleum fractions in an ethylene manufacturing process. Structure, properties, spectra, suppliers and links for. Us patent for process for the vaporphase thermal cracking. To obtain cyclopentadiene monomer, commercial dicyclopentadiene is cracked by heating to 180 c. Cyclopentadiene dimer chemical reference number cas. Search results for dicyclopentadiene at sigmaaldrich.
A reactive distillation process was developed for cracking dicyclopentadiene dcpd to produce cyclopentadiene cpd. Vaporphase thermal cracking of dcpd is usually used as a step of process for manufacturing high purity dcpd. In the autoclave reactor, reaction temperature, reaction time, diluent, and. Dicyclopentadiene is coproduced with ethylene from the c5 fraction in the steam cracking of naphtha and gas oils. Cyclopentadiene dimerizes readily, via the dielsalder mechanism, to dcpd at ambient conditions. Gas phase cracking of dicyclopentadiene to produce. The mechanism of the reaction begins with the diene assuming the.
Dcpd products originate from high temperature cracking of petroleum fractions and are best characterized as highly reactive intermediates used for a. In the second step, the remaining components of the original c5 fraction, which have boiling points of 28 50 c, are distilled overhead, and crude dicyclopentadiene bp 172. Experimental procedure part a cracking of dicyclopentadiene part b diels alder. Dielsalder reactions in the presence of a minimal amount of water. Cyclopentadiene dimer cracks slowly to give monomeric cyclopentadiene, but on standing, even at elevated temperatures, the monomer reverts to the dimer. Process for producing cyclopentadiene and its homologues. Dicyclopentadiene is coproduced in large quantities in the steam cracking of. A process of preparing cyclopentadiene from dicyclopentadiene, which comprises continuously passing dicyclopentadiene in vapor phase into a cracking zone at a pressure not above 500 mm. And they said this is and ene reaction but i couldnt understand how this reaction is subset of ene reaction and how ester group is made. This new compound must be separated before the desired compound can be used. In other words, in the cracking of dicyclopentadiene, why is it necessary to distill the product very slowly. Liquidphase cracking of dicyclopentadiene by reactive.
Aldrich 454338 page 3 of 7 hazardous combustion products hazardous decomposition products formed under fire conditions. Cyclopentadiene and dicyclopentadiene cheung major. Cracking tube 2 is a stainless tube with an internal diamer of 10 mm and a length of 1,000 mm, which is vertically installed and externally heated by heater 3 to an average cracking temperature of gree. Jul 19, 2011 with cyclopentadiene and cyclohexadiene its possible to get both endo and exosubstituents.
The cyclopentadiene undergoes dimerization at 25 o c to produce. They are obtained from coal tar about 1020 gtonne and by steam cracking of naphtha about 14 kgtonne. Dicyclopentadiene, abbreviated dcpd, is a chemical compound with formula c 10h12. Dicyclopentadiene cracking process boulder scientific company. Dicyclopentadiene contains bht as stabilizer synonym. It will dissolve in water and evaporates quickly from water and soil surfaces. Vaporphase thermal cracking of dcpd is usually used as a step of process for manufacturing high purity. The setup as instructed by my supervisor consisted of a simple watercooled liebig condenser. In a dielsalder reaction with cyclopentadiene and maleic. Us patent for process for the vaporphase thermal cracking of. Cyclopentadiene, a reagent commonly used in organic synthesis, is known to spontaneously dimerize exothermically and thus should be stored cold and used quickly. Solventfree dielsalder reactions of in situ generated. The experimental procedure of obtaining cyclopentadiene followed the work from magnusson and eastwood and coworkers. Dicyclopentadiene wisconsin department of health services.
As dicyclopentadiene enters the air, it breaks down quickly into simpler, lesstoxic chemicals. At its simplest, this dimerisation can be described as a. The reaction kinetics of cyclopentadiene dimerization using. At room temperature, it is a white crystalline solid with a camphorlike odor. Characterization of the proteins from vigna unguiculata seeds.
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