It is very possible that cyclopentadiene can dimerize. The dielsalder reaction has high synthetic utility for making unsaturated 6membered rings kahn, 2011. Cyclopentadiene has a much lower boiling point than the original substance, so we were able to remove it and use for the reaction. This week youll be creating a product via the dielsalder reaction.
Besides being solventfree, the described procedure allows for almost complete utilization of dicyclopentadiene and avoids. Cyclopentadiene maleic anhydride cis norbornene 56 endo. Apr 17, 2014 reaction mechanism the scheme below depicts the concerted mechanism of the diels alder reaction of cyclopentadiene and maleic anhydride to form cisnorbornene5,6endodicarboxylic anhydride. Dicyclopentadiene is coproduced in large quantities in the steam cracking of naphtha and gas oils to ethylene. Furthermore, while retro dielsalder reactions are well known and have been extensively used in organic synthesis, 2 with numerous examples of an in situ generated diene being trapped by a more reactive dienophile, 3 other than a report of a solventfree reaction of dicyclopentadiene with ethylene under high temperarature and pressure in an. A detailed study of the general application of immobilized cyclopentadiene in the diels alderretrodiels alder synthetic strategy has not yet been undertaken. The cracked gas leaving the furnace section of a steam cracker. Experiment 2 organic chemistry ii pahlavancherif dielsalder reaction preparation of endonorbornene5. 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. This dimer can be restored by heating to give the monomer.
Thermal cracking of dielsalder adducts equistar chemicals, lp. The simplest dielsalder reaction is the reaction of 1,3butadiene and ethylene to yield cyclohexene figure 1. Immobilized cyclopentadiene in the diels alderretrodiels. The dimer endodcpd can be formed easily at room temperature although full conversion takes several days. In a dielsalder reaction with cyclopentadiene and maleic. Cyclopentadiene belongs to the class of organic compounds known as cycloalkenes. The dielsalder reaction that you will be performing between cyclopentadiene and maleic anhydride occurs rapidly at room temperature. The dielsalder reaction is categorized as a pericyclic reaction, which involves the overlap of spatial orbitals as well as the hybridization and delocalization of the molecules. Example of diels alder reaction with electrondonating groups edg and electronwithdrawing groups ewg. 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. Dicyclopentadiene, abbreviated dcpd, is a chemical compound with formula c 10h12. Subject to polymerization if subjected to heat for prolonged periods or if contaminated.
The reaction kinetics of cyclopentadiene dimerization. Sep 14, 2001 they react readily with dienophiles, compounds with ethylenic or acetylenic unsaturation, to give diels. This reaction can form new carboncarbon bonds and new stereocenters. Why would a dielsalder product be soluble in ethyl acetate. The melting point analysis shows that the product of the dielsalder reaction was somewhat impure, but the product of the hydrolysis of the dielsalder adduct was very pure. When a synthetic sequence calls for the formation of a ring of carbon atoms, this problem is compounded. Nov 20, 20 cyclopentadiene acts as the diene for the reaction. The major use is in resins, particularly, unsaturated polyester resins. Jun 11, 2011 the reaction of cyclopentadiene and ethylene, giving norbornene, has been analyzed by gamess. Solventfree dielsalder reactions of in situ generated. I remember adding some iron powder was supposed to speed up the retrodielsalder reaction, i guess by lowering the effective concentration of the monomer through complexion. Example of dielsalder reaction with electrondonating groups edg and electronwithdrawing groups ewg. At room temperature, this cyclic diene dimerizes over the course of hours to give dicyclopentadiene via a dielsalder reaction.
Dielsalder reactions chemical and biomolecular engineering. Alder mechanism, to dicyclopentadiene at ambient conditions. The dielsalder reaction solely refers to the above reaction, but by altering the diene and dienophile, the final product can be altered to something the chemist desires. A solventfree dielsalder reaction was carried out by heating a mixture of dicyclopentadiene and a dienophile. Please let a resonable explanation pertaining to diels alder reactions. Most predominantly, dcpd molecules are formed and the product is further purified by vacuum distillation.
Measure 20 ml of dicyclopentadiene into a 100 ml flask and arrange for fractional distillation. Cyclopentadiene maleic anhydride cisnorbornene5,6endodicarboxylic anhydride etoachexane endo exo figure 2. The diels alder reaction requires that the diene be oriented in the scis conformation for the reaction to take place. When pure cyclopentadiene is stored it also undergoes a diels alder cycloaddition reaction and forms. 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. Give the structure of the product for each diels alder reaction shown below. Because it start distilling at a temperature 4042 c and before reaching this temperature it cant be distilled. Experiment 2 organic chemistry ii pahlavancherif diels. Cyclopentadiene is an organic compound with the formula c 5 h 6. This dimer can be restored by heating to give the monomer the compound is mainly used for the production of cyclopentene and its derivatives. Cyclopentadiene, formed in situ, reacted with the dienophile in a. Cyclopentadiene and dicyclopentadiene researchgate. Norbornene from cyclopentadiene and ethylene dielsalder. 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.
The vapors are irritating to the eyes and respiratory system. Cracking of dicyclopentadiene chemistry stack exchange. Cyclopentadiene from its polymer patents class 585354. Cyclopentadiene from its polymer patents and patent. 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. And 180 dc is a bit much, id just stay under the boiling point of the dimer. Dcpd products originate from high temperature cracking of petroleum fractions and are best characterized as highly reactive intermediates used for a. Answer to this is the post lab questions for the diels alder cycloaddition reaction please answer all the questions.
Diels alder reaction mechanism, stereochemistry, endo. The simplest diels alder reaction is between 1,3butadiene and ethylene. In the cracking of dicyclopentadiene, why is it necessary to distill the product very slowly. Diels alder reactions work best when the dienophile contains one or more electron withdrawing groups as shown in figure 2. When i read your heading i said to myself its a reverse diels alder but retro diels alder is even better. In conventional terminology, this is a 1,4addition of a diene and a dienophile. Ethyl acetate is a very useful solvent because it can solubilize relatively polar molecules and is still immiscible with water it is actually one of the most polar solvents that is still immiscible with water. The kinetics for direct and reverse dielsalder reactions has been. Why would a dielsalder product be soluble in ethyl. What was the purpose of adding paraffin to the reaction flask when cracking dicyclopentadiene. Unlike the conventional method depending on retro dielsalder reaction of dicyclopentadiene to generate indirectly cyclopentadiene, the method of the present invention favors generation of cyclopentadiene and metal cyclopentadienide as well by adding dicyclopentadiene directly when the reaction temperature reaches to the boiling point of a.
Diels alder reaction with electron withdrawing group on the dienophile. This invention is applicable to the thermal cracking. Besides being solventfree, the described procedure allows for almost complete utilization of dicyclopentadiene and avoids handling of. After learning about the reaction, i was able to complete a dielsalder reaction in organic lab. 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. Dicyclopentadiene is coproduced in large quantities in the steam cracking of. Dicyclopentadiene appears as a liquid with an acrid odor. This is the post lab questions for the diels alder. After which the monomer is reacted with maleic anhydride in a process called diels alder cycloaddition reaction jorgensen 3580. A method for thermally cracking at least one diels alder adduct, said adduct having been originally formed from at least one conjugated diene compound and at least one unsaturated compound having at least one of a carbonyl group and a methylene group, said method comprising providing a feedstock containing said at least one adduct, subjecting said feedstock to controlled cavitation. The purpose of this experiment was to demonstrate the formation of sixmembered rings by cycloaddition, also known as a diels alder reaction. Cyclopentadiene acts as the diene for the reaction. This invention relates to thermal cracking of dielsalder adducts to form a thermally cracked cracked product that contains at least the original compounds from which the adducts were formed, and recovering at least one of the thus formed original compounds from the cracked product. 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.
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. In this process, the dielsalder reaction is the key step to produce a suitable hdf precursor. 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. The reaction product has been claimed to be solely endodcpd.
However, this dielsalder reaction is reversible by cracking dicyclopentadiene using slow distillation and keeping the cyclopentadiene cold. Dielsalder reaction of cyclopentadiene with maleic anhydride johnson, chad philip. Liquidphase cracking of dicyclopentadiene by reactive. Heat the dimer with an electric flask heating mantle until it refluxes briskly at such a rate that the monomeric diene begins to distill in about 5 min and soon reaches a steady boiling point in the range 4042 oc. Dicyclopentadiene, abbreviated dcpd, is a chemical compound with formula c10h12. Diels alder reaction of cyclopentadiene with maleic anhydride johnson, chad philip. Cyclopentadiene is one of the dienes frequently used in dielsalder reactions. The reaction kinetics of cyclopentadiene dimerization using. 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. It will dissolve in water and evaporates quickly from water and soil surfaces. What kind of reaction does the cracking of dicyclopentadiene represent.
A similar dielsalder system that is more easily studied is the dimerization of 1,3cyclopentadiene shown below. Thermal cracking of dielsalder adducts powers donald h. Dielsalder reaction of cyclopentadiene with maleic anhydride. These are compounds containing a nonaromatic closed ring of carbon atoms in which at least 2 atoms are connected by a double bond. Dicyclopentadiene is coproduced in large quantities in the steam cracking of naphtha and gas oils to et. Cyclopentadiene cpd and dicyclopentadiene dcpd, which occur as byproducts in the steam cracking process in ethylene plants, are the major ingredients in the. The dimer endodcpd can be formed easily at room temperature although full conversion takes several days 1. Cyclopentadiene is an organic compound with the formula c5h6. Paraffin oil has a boiling point greater than 370 degreec. If the polymerization takes place inside a container, the container may violently rupture.
Cyclopentadiene cpd and dicyclopentadiene dcpd are two important products obtained from oil cracking, which are interconvertable through a dielsalder reaction. Cracking apparatus the dielsalder reaction of cyclopentadiene with maleic anhydride. Dicyclopentadiene, abbreviated dcpd, is a chemical compound with formula c 10 h 12. The experiment aimed at the conducting of a retro diels alder reaction through the cracking of dicyclopentadiene dimer into the monomer units.
In the cracking of dicyclopentadiene, why is it ne. The mass of cyclopentadiene that was collected was 0. To aid in product isolation, the entire reaction will. To crack the dicyclopentadiene, we used fractional distillation, which involves boiling the. In a cycloaddition reaction, a 1,3diene reacts with an alkene, or dienophile, to produce a sixmembered ring. Above 150 c, dicyclopentadiene undergoes a retrodielsalder reaction at. Mar 26, 2017 the experiment aimed at the conducting of a retro diels alder reaction through the cracking of dicyclopentadiene dimer into the monomer units. Cyclopentadiene cpd, boiling at 42c, is an unsaturated, high reactive.
In other words, in the cracking of dicyclopentadiene, why is it necessary to distill the product very slowly. This reaction involves the conjugation of a diene with some dienophile. Give the structure of the product for each dielsalder reaction shown below. Cracking of dicyclopentadiene before the beginning of lab the cyclopentadiene was prepared by a lab technician by cracking it. Usually it is obtained by cracking of dicyclopentadiene and is used. Dicyclopentadiene should never be distilled to dryness since there is danger of explosion if peroxides are present. Cyclopentadiene is a colorless liquid with an irritating, terpenelike odor. 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. Dicyclopentadiene dcpd 3a,4,7,7atetrahydo4,7methano1hindene c10h12 general dicyclopentadiene or dcpd is the dimer of cyclopentadiene cpd formed by a dielsalder addition reaction.
Dicyclopentadiene wikimili, the best wikipedia reader. To crack the dicyclopentadiene, we used fractional distillation, which involves boiling the mixture to remove a certain compound by recondensing it. Unlike the conventional method depending on retro dielsalder reaction of dicyclopentadiene to generate indirectly cyclopentadiene, the method of the present invention favors generation of cyclopentadiene and metal cyclopentadienide as well by adding dicyclopentadiene directly when. 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 dimerizes readily, via the dielsalder mechanism, to dcpd at. Stripped to its most basic components, this reaction is represented by. Preparation of cyclopentadiene from its dimer journal of. At the boiling point of dicyclopentadiene, equilibration with the. Summary the oligomerization of cyclopentadiene cpd and its dimer, dicyclopentadiene dcpd, to tricyclopentadiene tcpd through dielsalder reaction at temperatures between 120 and 150c was. A method for thermally cracking dielsalder adducts and for altering organic streams. What was the purpose of adding paraffin to the reaction flask when. Cyclopentadiene is obtained by cracking of dicyclopentadiene 27 moffett, r.
Gas phase cracking of dicyclopentadiene to produce. The evidence from the qualitative testing performed in the laboratory confirms the formation of sixmembered rings by cycloaddition, also known as a dielsalder reaction. 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. The reaction of cyclopentadiene and ethylene, giving norbornene, has been analyzed by gamess. Kinetic and thermodynamic control in the dielsalder reaction.
At room temperature, it is a clear light yellow color liquid with an acrid odor. Dicyclopentadiene is coproduced with ethylene from the c5 fraction in the steam cracking of naphtha and gas oils. Diels alder reactions of cyclopentadiene brainmass. Alder adducts, with oxygen and halogen to give oxygenates and halide derivatives. Cyclopentadiene and dicyclopentadiene cheung major. Results and discussion when combining the reagents, a cloudy mixture was produced and problems arose in the attempt to completely dissolve the mixture. The simplest diels alder reaction is the reaction of 1,3butadiene and ethylene to yield cyclohexene figure 1. This invention relates to thermal cracking of diels alder adducts to form a thermally cracked cracked product that contains at least the original compounds from which the adducts were formed, and recovering at least one of the thus formed original compounds from the cracked product. Jul 19, 2011 this week youll be creating a product via the dielsalder reaction. The formation of new carboncarbon bonds is one of the most important aspects of synthetic organic chemistry. You should notice that both of them have three double bonds. Cyclopentadiene, formed in situ, reacted with the dienophile in a thermodynamically controlled reaction. 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.
This colorless liquid has a strong and unpleasant odor. A solventfree diels alder reaction was carried out by heating a mixture of dicyclopentadiene and a dienophile. Experiment 14 the dielsalder cycloaddition reaction pg. 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. This dimer can be restored by heating to give the monomer the compound is mainly used for the production of cyclopentene and its. 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. The diels alder reaction is one of the most important reactions in all of organic chemistry because of the applicability of it.
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