However, this diels alder reaction is reversible by cracking dicyclopentadiene using slow distillation and keeping the cyclopentadiene cold. Please let a resonable explanation pertaining to diels alder reactions. Safety data sheet crude dicyclopentadiene version 2. Dicyclopentadiene, abbreviated dcpd, is a chemical compound with formula c 10h12. The diels alder reaction requires that the diene be oriented in the scis conformation for the reaction to take place. In conventional terminology, this is a 1,4addition of a diene and a dienophile. May react exothermically with reducing agents to release hydrogen gas. The diels alder retro diels alder concept is a powerful synthetic strategy in stereo and enantioselective routes to functionalized cycloalkenes. Besides being solventfree, the described procedure allows for almost complete utilization of dicyclopentadiene and avoids handling of.
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. The conversion occurs in hours at room temperature, but the monomer can be stored for days at. Synthesis of cyclopentadiene derivatives by retrodielsalder. In the cracking of dicyclopentadiene, why is it necessary to distill the product very slowly. Pdf improving the efficiency of the dielsalder process by using.
The major use is in resins, particularly, unsaturated polyester resins. You should notice that both of them have three double bonds. Dicyclopentadiene is coproduced in large quantities in the steam cracking of naphtha and gas oils to ethylene. Reactive chemical hazards have been a significant concern in the chemical process industries.
Prediction of heat of formation for exodicyclopentadiene. This chemical inventory is oshas premier onestop shop for occupational chemical information. These are compounds containing a nonaromatic closed ring of carbon atoms in which at least 2 atoms are connected by a double bond. Synthesis of 5vinyl2norbornene based on the dielsalder. The objective of this experiment was to crack dicyclopentadiene into two molecules of cyclopentadiene and mix cyclopentadiene with maleic anhydride to synthesize cisnorbornene5,6endodicarboxylic anhydride. Dicyclopentadiene, abbreviated dcpd, is a chemical compound with formula c10h12. The compound is unusually acidic pk a 16 for a hydrocarbon, a fact explained by the high stability of the aromatic cyclopentadienyl anion, c 5 h 5 simple compounds of this anion such as the commercially available.
Jul 19, 2011 this week youll be creating a product via the dielsalder reaction. Thus, when cyclopentadiene is obtained by cracking of dicyclopentadiene, one can. I recently did a distillation of dicyclopentadiene bp 166 c to get cyclopentadiene bp 40 c. 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. This dimer can be restored by heating to give the monomer the compound is mainly used for the production of cyclopentene and its derivatives.
Immobilized cyclopentadiene in the diels alderretrodiels. The information on this web page is provided to help you to work safely, but it is intended to be an overview of hazards, not a replacement for a full material safety data sheet msds. Heating up the cp dimer with crack it back to the monomer. The mass of cyclopentadiene that was collected was 0. After setting the reaction on ice, we observed the dielsalder reaction, with the product being cisnorbornene5,6endodicarboxylic anhydride ill call it the product. Solventfree dielsalder reactions of in situ generated. In the dielsalder reaction of cyclopentadiene with butenedioic anhydride, what are the two possible stereochemistries of the adduct. It compiles information from several government agencies and organizations. The vapors are irritating to the eyes and respiratory system. In other words, in the cracking of dicyclopentadiene, why is it necessary to distill the product very slowly.
What diene and what dienophile could be used to prepare each of the following. 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. It is stable at ambient temperatures and under recommended storage conditions, but can decompose at elevated temperatures. Successively, a second retrodielsalder reaction path a occurred spontaneously affording pyridazine 5,5. Dicyclopentadiene is coproduced in large quantities in the steam cracking of naphtha and gas oils to et. A solventfree diels alder reaction was carried out by heating a mixture of dicyclopentadiene and a dienophile. In a dielsalder reaction with cyclopentadiene and maleic. Dielsalder reactions chemical and biomolecular engineering.
Flame dry a 25ml roundbottomed flask with a small stir bar. Cyclopentadiene and dicyclopentadiene cheung major. The setup as instructed by my supervisor consisted of a simple watercooled liebig condenser. The retro dielsalder reaction rda is the microscopic reverse of the dielsalder reactionthe formation of a diene and dienophile from a cyclohexene.
Chemical identification and physical properties exposure limits sampling information. Msds forms can be downloaded from the web sites of many chemical suppliers. Cyclopentadiene is a useful diene in dielsalder reactions as well as a precursor to metallocenes in organometallic chemistry. 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. Cdc niosh pocket guide to chemical hazards dicyclopentadiene. At the boiling point of dicyclopentadiene, equilibration with the. Define the terms diene and dienophile as they apply to the dielsalder reaction. Undergoes a spontaneous dimerization at room temperature to give dicyclopentadiene c10h12, cas no. Cyclopentadiene acts as the diene for the reaction. Alder mechanism, to dicyclopentadiene at ambient conditions. Cyclopentadiene project gutenberg selfpublishing ebooks. Dicyclopentadiene appears as a liquid with an acrid odor.
In the dielsalder reaction of cyclopentadiene and maleicanhydride what are the two side reactions of cyclopenadiene and maleic anhydride not including the endo and exo major products. Experiment 2 organic chemistry ii pahlavancherif diels. Synthesis of cyclopentadiene derivatives by retrodiels. Insights into the dielsalder reactions between cyclopentadiene. 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 dielsalder product mixtures.
Pdf the industrial application of the dielsalder reaction for the atomefficient synthesis of heterocyclic compounds constitutes an important. If the polymerization takes place inside a container, the container may violently rupture. This colorless liquid has a strong and unpleasant odor. To prepare substituted cyclopentadiene derivatives, we examined the reaction of norbornadiene derivatives 8al with a tetrazine 4 or 4. Cyclopentadiene is an organic compound with the formula c5h6.
Bearing in mind the usual caveat about the hazards of generalization. Solventfree diels alder reactions were carried out by heating a mixture of a volatile diene, such as 1,3butadiene, isoprene, or 2,3dimethyl1,3butadiene, and a dienophile, such as methyl vinyl. Above 150 c, dicyclopentadiene undergoes a retrodielsalder reaction at. Diels alder reactions work best when the dienophile contains one or more electron withdrawing groups as shown in figure 2. A similar dielsalder system that is more easily studied is the dimerization of 1,3cyclopentadiene shown below. When pure cyclopentadiene is stored it also undergoes a dielsalder cycloaddition reaction and forms. The reaction is strongly exothermic hazardous chemicals desk reference, p. Alder reactions of arynes with functionalized acyclic dienes have been reported for the synthesis of useful cissubstituted dihydronaphthalene building blocks. Cracking of dicyclopentadiene chemistry stack exchange. The dielsalder reaction will be carried out on half the reaction scale given in the text book. Which of the two products would you predict to be the most stable. Cdc niosh pocket guide to chemical hazards cyclopentadiene. Zhi cai, benxian shen, weilian liu, zhong xin and hao ling.
It is very possible that cyclopentadiene can dimerize. The dielsalder reaction is one of the most important methods for formation of sixmembered rings. 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 readily undergoes other dielsalder reactions with dienophiles such as 1,4benzoquinone. This is a perfect example of how a complex substance can be produced based on the simple dielsalder mechanism. Theoretical and experimental characterization of dicyclopentadiene. Dicyclopentadiene is coproduced in large quantities in the steam cracking of. The simplest dielsalder reaction is the reaction of 1,3butadiene and ethylene to yield cyclohexene figure 1. If your institution is not listed, please contact your librarian.
What kind of reaction does the cracking of dicyclopentadiene represent. Explain why it is the least stable adduct that is formed preferentially in this reaction. Diels alder reactions of cyclopentadiene brainmass. The dielsalder reaction is useful for the synthesis of. Dicyclopentadiene, abbreviated dcpd, is a chemical compound with formula c 10 h 12. Cyclopentadiene and dicyclopentadiene, which occur as byproducts in the steam cracking process in ethylene plants, are the major ingredients in the production of hydrocarbon resins, unsaturated polyester resins, elastomers, pesticides, flame retardants and a host of specialty chemicals. Chinese universities 2008,242, 17579 article id 10059040200802l7505 dielsalder 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. Most predominantly, dcpd molecules are formed and the product is further purified by vacuum distillation. 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. This reaction has a great synthetic importance and was discovered by two german chemists, otto diels and kurt alder, who received the 1950 nobel prize. Intrinsic kinetics on thermal dimerization of steam cracking c5 fraction. A solventfree dielsalder reaction was carried out by heating a mixture of dicyclopentadiene and a dienophile.
Abstract cyclopentadiene and dicyclopentadiene, which occur as byproducts in the steam cracking process in. When pure cyclopentadiene is stored it also undergoes a diels alder cycloaddition reaction and forms. The dicyclopentadiene will be cracked for you by your t. A solventfree dielsalder reaction was carried out by heating a mixture of. It is unstable under ordinary conditions and, at room temperature, dimerizes into dicyclopentadiene. Abstract the dielsalder da reaction is so familiar to organic. 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. We started with dicyclopentadiene which had to be cracked into cyclopentadiene. Osha occupational chemical database occupational safety.
Nov 20, 20 after learning about the reaction, i was able to complete a dielsalder reaction in organic lab. Liquidphase cracking of dicyclopentadiene by reactive distillation. Diels alder reaction with electron withdrawing group on the dienophile. The diels alderretrodiels alder concept is a powerful synthetic strategy in stereo and enantioselective routes to functionalized cycloalkenes. Consecutive retrodielsalder reactions played an important role in these synthetic pathways. At room temperature, this cyclic diene dimerizes over the course of hours to give dicyclopentadiene via a dielsalder reaction. 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.
Summary the oligomerization of cyclopentadiene cpd and its dimer, dicyclopentadiene dcpd, to tricyclopentadiene tcpd through dielsalder reaction at temperatures between 120 and 150c was. At room temperature, it is a clear light yellow color liquid with an acrid odor. Stripped to its most basic components, this reaction is represented by the addition of 1,3butadiene to ethene shown below. Cracking cp you should be aware that cyclopentadiene cp will spontaneously react with itself, so it can only be stored as the dimer. Preparation of cyclopentadiene from its dimer journal of.
Cracking of dicyclopentadiene before the beginning of lab the cyclopentadiene was prepared by a lab technician by cracking it. Dicyclopentadiene may react vigorously with oxidizing agents. 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. It is not available commercially as the monomer, due to the rapid formation of dicyclopentadiene. An uncontrolled cracking of dcpd reverse diels alder reaction with subsequent polymerization may lead to rapid buildup of temperature and.
Cyclopentadiene was obtained by cracking and distillation of. This dimer can be restored by heating to give the monomer. It can be accomplished spontaneously with heat, or with acid or base mediation. Cyclopentadiene, formed in situ, reacted with the dienophile in a. Natural and unnatural polycarbocycles and polyheterocycles. Liquidphase cracking of dicyclopentadiene by reactive. Subject to polymerization if subjected to heat for prolonged periods or if contaminated.
Cyclopentadiene belongs to the class of organic compounds known as cycloalkenes. 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. As most of the cyclopentadiene derivatives are not stable enough at reaction condition. However, this dielsalder reaction is reversible by cracking dicyclopentadiene using slow distillation and keeping the cyclopentadiene cold. 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. The simplest diels alder reaction is the reaction of 1,3butadiene and ethylene to yield cyclohexene figure 1. Cyclopentadiene is a colorless liquid with an irritating, terpenelike odor. Dielsalder reaction of cyclopentadiene with maleic anhydride.
In the cracking of dicyclopentadiene, why is it ne. The influence of temperature on the kinetic constants was determined by fitting the results to the arrhenius equation. Dicyclopentadiene wikimili, the best wikipedia reader. To aid in product isolation, the entire reaction will. Experiment 14 the dielsalder cycloaddition reaction pg. Cyclopentadiene, formed in situ, reacted with the dienophile in a thermodynamically controlled reaction.
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. The hydrogen atoms in cyclopentadiene undergo rapid 1,5sigmatropic shifts as indicated by 1 h nmr spectra recorded at various. In some cases, isomerized cyclopentadienes 14 were also observed beside to 12.
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