The endo product is usually favored by kinetic control due to secondary orbital interactions. Regardless of which situation pertains, the HOMO and LUMO of the components are in phase and a bonding interaction results as can be seen in the diagram below.
You can tackle problem Weigh both reagents in small beakers as the reagent has an unfortunate tendency to stick to the weighing boats. Below are some examples using this strategy.
Anthracenebeing less aromatic and therefore more reactive for Diels—Alder syntheses in its central ring can form a 9,10 adduct with maleic anhydride at 80 degrees Celsius and even with acetylenea weak dienophile, at degrees.
Petroleum ether is composed of a mixture of larger alkanes more than six carbonswhereas hexane is only composed of six-carbon alkanes.
The end product cannot not be made in a single DA step because equivalent dienophile is either unreactive or inaccessible. Below are some examples. Obviously, you also need a procedure. Let the maleic anhydride dissolve in the EtOAc, by heating if necessary.
The crystals were a pale yellow color, with an irregular, powdery shape. You will probably let it dry in your drawer for a week before you take a melting point and weigh your product for a percent yield.
Vacuum filtration appeared to lower yield because a purer product of lesser mass is prepared. The reaction has gone to completion because the melting point of the observed product is well above the melting points of the reactants and solvents involved; if the reaction had not gone to completion, the melting process would have begun much earlier due to maleic anhydride melting.
We will write a custom essay sample on Diels Alder Lab Report or any similar topic specifically for you Do Not Waste HIRE WRITER Crystal formation occurred almost immediately after removing the round-bottomed flask from the heating mantle, with even more crystals forming during the time the flask was in the ice bath.
Changing the nonpolar solvent petroleum ether to hexane caused the largest effect on yield based off the Wiki data. The crude material was recrystallized from boiling xylene. Reaction Development and Mechanistic Studies K. Since all three rings of anthracene can not simultaneously have benzenoid character Figure 1the electrons in the pi system of the central ring react more like those of a standard diene.
The s-cis conformation has both of the double bonds pointing on the same side of the carbon-carbon single bond that connects them. Nucleophilic acyl substitutions are discussed in Sections With its broad scope and simplicity of operation, the Diels-Alder is the most powerful synthetic method for unsaturated six-membered rings.
There are two main bicyclo ring systems that you typically have to deal with, and these are the ones that come from the diene being in a five-membered ring system and the diene being in a six-membered ring system.
This alternative constitutes a powerful synthesis of six-membered ring heterocycles. If the reaction were thermodynamically controlled, the overall more stable product, the exo product, would be the major product. Experiment Written by Vijay In this experiment, cyclopentadiene and maleic anhydride were reacted in solution to produce a single organic product in crystal form.
Once you know the mass of the diene you have, then calculate the mass of maleic anhydride needed and use that amount. The Diels-Alder reaction is discussed in section Also, being in a ring, the cyclopentadiene is locked into the s-cis conformation that facilitates the Diels-Alder Reaction.
Due to this fact, any unreacted starting materials would remain soluble throughout the recrystallization process. Since the observed melting point is lower than the expected melting point, the melting point may appear lower due to the presence of impurities.
Numbering Carbons The easiest way to predict Diels-Alder products is to number the six carbons that make up the cyclohexene ring. The Diels-Alder reaction is a member of a larger class of pericyclic reactions. These are reactions For your report: Calculate your percent yield.
Discuss the results of your percent yield, your melting point and IR spectrum. Predict the 1 H-NMR spectrum for the product. Cyclopentadiene is a good diene for the Diels-Alder reaction because of its substitution and its locked s-cis conformation.
Due to cyclopentadiene being substituted, the diene can draw on the electron density of the methylene in between the diene. Diels-Alder reaction entails the preparation of the six-membered carbocyclic rings, which are conjugated diene with an alkene.
The reaction of the product takes place in the single step to produce carbon-carbon bonds with the four stereocenters. Diels Alder Lab Report. or any similar topic specifically for you. Do Not Waste This particular Diels-Alder reaction exploits an interesting phenomenon.
Although aromatic compounds do not normally participate in Diels-Alder reactions, the central ring in anthracene is reactive as a diene. Since all three rings of anthracene can not. Lab 1 Report - Diels-Alder Reaction. the Diels Alder Reaction. Diels Alder Reaction. ACS Review 10 Conjugation in Alkadienes and Allylic Systems_unlocked.
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