Petroleum ether is composed of a mixture of larger alkanes more than six carbonswhereas hexane is only composed of six-carbon alkanes. The crystals were a pale yellow Diels alder reaction lab report, with an irregular, powdery shape. As such, the Diels—Alder reaction is governed by orbital symmetry considerations: This particular Diels-Alder reaction exploits an interesting phenomenon.
Chlorosulfonyl isocyanate can be utilized as a dienophile to prepare the Vince lactam. Since the observed melting point is lower than the expected melting point, the melting point may appear lower due to the presence of impurities. Despite the fact that the vast majority of Diels—Alder reactions exhibit stereospecific, syn addition of the two components, a diradical intermediate has been postulated  and supported with computational evidence on the grounds that the observed stereospecificity does not rule out a two-step addition involving an intermediate that collapses to product faster than it can rotate to allow for inversion of stereochemistry.
For the second week of experimentation, the percent yields observed were For instance, in uncommon combinations involving X groups on both diene and dienophile, a 1,3-substitution pattern may be favored, an outcome not accounted for by a simplistic resonance structure argument.
Mechanism[ edit ] The reaction is an example of a concerted pericyclic reaction. Since the petroleum ether is composed of larger alkanes, there are more intermolecular forces than are present in hexane; this consequence means that the environment of petroleum ether is slightly more soluble for polar molecules.
The complexed dienophile becomes more electrophilic and more reactive toward the diene, increasing the reaction rate and often improving the regio- and stereoselectivity as well. This preference is known as the Alder rule. Experiment Written by Vijay In this experiment, cyclopentadiene and maleic anhydride were reacted in solution to produce a single organic product in crystal form.
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.
The change from Sample A to Sample B thus increased the yield by reducing solubility of crystalline product. Conclusions Write a brief paragraph that summarizes your results.
E- and Z-dienophiles, for example, give rise to the adducts with corresponding anti- and syn-stereochemistry: Nonetheless, the yield of product is still low due to the following: Endo is favored over exo due to the reaction being under kinetic control; kinetic control indicates that the lower activation energy is favored.
Lewis acid catalysis also enables Diels—Alder reactions to proceed at low temperatures, i. Resonance structures of anthracene. In general, with respect to the energetically most well-matched HOMO-LUMO pair, maximizing the interaction energy by forming bonds between centers with the largest frontier orbital coefficients allows the prediction of the major regioisomer that will result from a given diene-dienophile combination.
For normal demand Diels—Alder scenarios, with electron-withdrawing substituents such as carbonyls attached to the dienophile, the endo transition state is typically preferred, despite often being more sterically congested. Spectra of starting materials are available on the Vista site.
Cyclopentadiene is a good diene for the Diels-Alder reaction because of its substitution and its locked s-cis conformation. The non-polar product should experience greater solubility in petroleum ether than in hexane due to the greater Van der Waals forces in the petroleum ether. The Diels-Alder adduct, 9,Dihydro-9,ethanoanthracene,dicarboxylic anhydride, was successfully synthesized from anthracene and maleic anhydride.
This issue may be no more than practicing the technique of transferring product and finding the most efficient way of doing so.
Changing the nonpolar solvent petroleum ether to hexane caused the largest effect on yield based off the Wiki data. The maximization of orbital interaction correctly predicts the product in all cases for which experimental data is available.
If the reaction were thermodynamically controlled, the overall more stable product, the exo product, would be the major product. 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.
Sample A was purified by vacuum filtration but otherwise prepared under the same procedure as the sample from Week 1. Since the reactants are in their ground state, the reaction is initiated thermally and does not require activation by light.
Such a scenario is termed an inverse electron demand Diels—Alder reaction. Examining the canonical mesomeric forms above, it is easy to verify that these results are in accord with expectations based on consideration of electron density and polarization.
This makes for an ideal recrystallization solvent. The purified crystals that were collected from the recrystallization were a faint off-white color, with a regular, shiny plate-like shape. You should also analyze any NMR spectra that you have from the reaction if applicable.
The end product cannot not be made in a single DA step because equivalent dienophile is either unreactive or inaccessible.
Sample B was purified by vacuum filtration, but also included an additional 0. Due to cyclopentadiene being substituted, the diene can draw on the electron density of the methylene in between the diene.
The dienophile undergoes Diels—Alder reaction with a diene introducing such a functionality onto the product molecule. The crude material was recrystallized from boiling xylene.Instructions for Writing Laboratory Reports Organic II Lab, CHEM L Diels-Alder reaction of Cyclohexadiene and Maleic Anhydride 2, 3.
Name, Lab Time, and Date[Self explanatory] A.M. Brilliant, MondayJanuary DEMO LAB REPORT Author: sarah l. SYNT The Diels-Alder ReaCtion of Anthracene with Maleic Anhydride (diene (diene (Eq.1) adduct (Eq.
2) adduct reactants and the symmetry of. Diels-Alder Reaction of Cyclopentadiene with Maleic Anhydride Johnson, Chad Philip; T/Th Lab, am Submitted February 09 th, Introduction Inthe chemists Otto Paul Hermann Diels, from Germany, and Kurt Alder, originally born in.
Diels-Alder Reaction 98 Standard Synthesis Lab Report Format 99 Standard Synthesis Laboratory Report Format: The following layout is standard for a “synthesis.
Diels-Alder Reaction: Experiment Written by Vijay In this experiment, cyclopentadiene and maleic anhydride were reacted in solution to produce. Lab #4 May 26, Diels Alder Reaction Introduction: Diels Alder Reaction is the reaction of a diene with a species capable of reacting with the diene, the dienophile.
A diene is a hydrocarbon that contains two carbon double bonds, while a dienophile is an electron-deficient alkene.Download