In the second step, the remaining components of the original c5 fraction. Cyclopentadiene has a rather strong and disagreeable odor and. Cyclopentadiene is an organic compound with the formula c5h6. Dicyclopentadiene, abbreviated dcpd, is a chemical compound with formula c 10h12. And 180 dc is a bit much, id just stay under the boiling point of the dimer. Kinetic and thermodynamic control in the dielsalder reaction. Dicyclopentadiene have two bonds, one in the cyclopentene ringcpbond and the other in the norbornene ringnbbond. When pure cyclopentadiene is stored it also undergoes a dielsalder cycloaddition reaction and forms dicyclopentadiene. In this article, we theoretically analyze the diels. Melting points were taken with meltemp ii apparatus and are uncorrected. Cyclopentadiene and dicyclopentadiene cheung major.
Due to cyclopentadiene being substituted, the diene can draw on the electron density of the methylene in between the diene. 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 diels alder reaction, so i would only choose the cyclopentadiene dimerization as a plausible side product. Dicyclopentadiene dcpd 3a,4,7,7atetrahydo4,7methano1hindene c10h12 general dicyclopentadiene or dcpd is the dimer of cyclopentadiene cpd formed by a diels alder addition reaction. The dimer endodcpd can be formed easily at room temperature although full conversion takes several days. I remember adding some iron powder was supposed to speed up the retro diels alder reaction, i guess by lowering the effective concentration of the monomer through complexion. Nov 20, 20 after learning about the reaction, i was able to complete a dielsalder reaction in organic lab. Monomer and dimer are close enough in boiling point that a sloppy job will deliver a lot of dimer to the collection pot, which is a real pain to remove from many diels alder product mixtures. Cyclopentadiene and dicyclopentadiene researchgate. At room temperature, this cyclic diene dimerizes over the course of hours to give dicyclopentadiene via a dielsalder reaction. A solventfree dielsalder reaction was carried out by heating a mixture of dicyclopentadiene and a dienophile. Chinese universities 2008,242, 17579 article id 10059040200802l7505 diels alder addition of dicyclopentadiene with cyclopentadiene in polar solvents zhang xiangwen, jiang qiang, xiong zhongqiang, zou jijun, wang li and mi zhentao key laboratory for green chemical technology of ministry of education, school of chemical engineering and technology, tianjin university.
Cyclopentadiene acts as the diene for the reaction. Dielsalder reaction of cyclopentadiene with maleic anhydride. Dicyclopentadiene is coproduced in large quantities in the steam cracking of naphtha and gas oils to et. Experiment 14 the dielsalder cycloaddition reaction pg. Cyclopentadiene, formed in situ, reacted with the dienophile in a. Cracking apparatus the dielsalder reaction of cyclopentadiene with maleic anhydride the dielsalder reaction that you will be performing between cyclopentadiene and maleic anhydride occurs rapidly at room temperature. It is very possible that cyclopentadiene can dimerize. Dicyclopentadiene is coproduced in large quantities in the steam cracking of.
Please let a resonable explanation pertaining to diels alder reactions. Preparation of cyclopentadiene from its dimer journal of. The setup as instructed by my supervisor consisted of a simple watercooled liebig condenser. Kinetics of the thermal decompositions of exo and endodicyclopentadiene. The performance of ab initio, density functional, casscf. It is indeed a transition state at a crossroads, connecting two quite different reactions, the diels alder cycloaddition and the 3,3 cope enantiomerisation of the dimer product. Jul 19, 2011 this week youll be creating a product via the dielsalder reaction. Subject to polymerization if subjected to heat for prolonged periods or if contaminated. Above 150 c, dicyclopentadiene undergoes a retrodielsalder reaction at.
Cyclopentadiene cpd and dicyclopentadiene dcpd, which occur as byproducts in the steam cracking process in ethylene plants, are the major ingredients in the production of hydrocarbon resins. This new compound must be separated before the desired compound can be used. This dimer can be restored by heating to give the monomer. Search results for dicyclopentadiene at sigmaaldrich. In a dielsalder reaction with cyclopentadiene and maleic. The transition state for this process is none other than the green point reached earlier. Dicyclopentadiene, abbreviated dcpd, is a chemical compound with formula c 10 h 12. Sigmaaldrich offers a number of dicyclopentadiene products. In the diels alder reaction of cyclopentadiene and maleicanhydride what are the two side reactions of cyclopenadiene and maleic anhydride not including the endo and exo major products.
Most predominantly, dcpd molecules are formed and the product is further purified by vacuum distillation. Cracking of dicyclopentadiene before the beginning of lab the cyclopentadiene was prepared by a lab technician by cracking it. 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. Dcpd products originate from high temperature cracking of petroleum fractions and are best characterized as highly reactive intermediates used for a. Dec 21, 2015 dicyclopentadiene, abbreviated dcpd, is a chemical compound with formula c10h12. Dicyclopentadiene is coproduced in large quantities in the steam cracking of naphtha and gas oils to ethylene. The comparison of the results obtained with the twolayered oniom approach using different partitions for the high and lowlevel layers with those obtained employing the b3lyp631gd method for the entire. Diels alder reactions of cyclopentadiene brainmass. At room temperature, it is a clear light yellow color liquid with an acrid odor. Onepot catalytic transformation of dicyclopentadiene to high. I recently did a distillation of dicyclopentadiene bp 166 c to get cyclopentadiene bp 40 c. Cyclopentadiene cpd and dicyclopentadiene dcpd are two important products obtained from oil cracking, which are interconvertable through a dielsalder reaction. We started with dicyclopentadiene which had to be cracked into cyclopentadiene. The vapors are irritating to the eyes and respiratory system.
However, this dielsalder reaction is reversible by cracking dicyclopentadiene using slow distillation and keeping the cyclopentadiene cold. First determine which one of the maleic anhydride or the cyclopentadiene was the limiting reagent. To aid in product isolation, the entire reaction will. It can be accomplished spontaneously with heat, or with acid or base mediation. It will dissolve in water and evaporates quickly from water and soil surfaces. Cyclopentadiene project gutenberg selfpublishing ebooks. Abstract the objective of this experiment was to crack dicyclopentadiene to create two molecules of cyclopentadiene, and then perform a diels alder reaction by reacting the diene with maleic anhydride, the dienophile, to create cisnorbornene5,6endodicarboxylic anhydride. Jul 21, 2008 the evidence from the qualitative testing performed in the laboratory confirms the formation of sixmembered rings by cycloaddition, also known as a diels alder reaction. In the first step, cyclopentadiene is dimerized to give dicyclopentadiene by heat soaking the entire c5 fraction, either at normal pressure and 30 100 deg c over 5 24 hr or at elevated pressure and 140 150 deg c. Procedure the apparatus for the cracking of dicyclopentadiene to cyclopentadiene will be set up in the hood and will be used to prepare all of the cyclopentadiene needed for the dielsalder reaction and for the preparation of ferrocene. In the cracking of dicyclopentadiene, why is it necessary to distill the product very slowly.
Resin some components coloring petroleum resin in thermalcracked higher fractions. Dielsalder reactions in the presence of a minimal amount of water. Cyclopentadiene is obtained by cracking of dicyclopentadiene 27. Cyclopentadiene, after cracking of dicyclopentadiene 2a at 420430k, was. The retro dielsalder reaction rda is the microscopic reverse of the dielsalder reactionthe formation of a diene and dienophile from a cyclohexene. Nov 18, 20 cyclopentadiene is a good diene for the diels alder reaction because of its substitution and its locked scis conformation. Usually it is obtained by cracking of dicyclopentadiene and is used immediately in a reaction.
Alder cycloaddition between cyclopentadiene and c60 for which experimental results on energy barriers and reaction energies are known. The dielsalder is unlike other organic reactions in that it doesnt involve any nucleophiles, leaving groups, or radicals, so there is no real mechanism to learn. In other words, in the cracking of dicyclopentadiene, why is it necessary to distill the product very slowly. Cyclopentadiene production is usually not distinguished from dicyclopentadiene since they are interconverted. Stripped to its most basic components, this reaction is represented by the addition of 1,3butadiene to ethene shown below. Dicyclopentadiene wikimili, the best wikipedia reader.
Dielsalder reactions chemical and biomolecular engineering. The apparatus for the cracking of dicyclopentadiene to cyclopentadiene will be set up. Dicyclopentadiene is coproduced with ethylene from the c5 fraction in the steam cracking of naphtha and gas oils. The melting point analysis shows that the product of the diels alder reaction was somewhat impure, but the product of the hydrolysis of the diels alder adduct was very pure.
Jan 25, 2012 what kind of reaction does the cracking of dicyclopentadiene represent. If the polymerization takes place inside a container, the container may violently rupture. The purchased dicyclopentadiene was cracked at 160 c to produce. Onepot catalytic transformation of dicyclopentadiene to high energy density fuel exotetrahydrotricyclopentadiene. In the cracking of dicyclopentadiene, why is it ne. The dielsalder is a stereospecific reaction, because the stereochemistry of the dienophile is maintained in the cyclohexene product. To obtain cyclopentadiene monomer, commercial dicyclopentadiene is cracked by heating to 180 c. Solventfree dielsalder reactions of in situ generated.
Apr 17, 2014 the diels alder reaction is categorized as a pericyclic reaction, which involves the overlap of spatial orbitals as well as the hybridization and delocalization of the molecules. This colorless liquid has a strong and unpleasant odor. At room temperature, it is a white crystalline solid with a camphorlike odor. Cyclopentadiene is an organic compound with the formula c 5 h 6. The diels alder step was studied by density functional theory dft methods. Dicyclopentadiene appears as a liquid with an acrid odor. Experiment 2 organic chemistry ii pahlavancherif diels. Dielsalder reaction of cyclopentadiene forms dicyclopentadiene dcpd, which. The c9c10 fraction formally contains all kinds of diels alder adducts because the various c5 diolefin molecules form dimers during the process steps of the ethylene manufacturing process. Volume, enthalpy and entropy of activation of the dielsalder. The reaction kinetics of cyclopentadiene dimerization using. Dicyclopentadiene, abbreviated dcpd, is a chemical compound with formula c10h12.
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