computational study of substitution effects in acetylenic diels-alder reactions emily sotelo mentor...
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Discovered by chemists Otto Diels and Kurt Alder in 1928-recognized with a Nobel Prize in Chemistry in 1950 The Diels-Alder ReactionTRANSCRIPT
Computational Study of Substitution Effects in Acetylenic Diels-Alder Reactions
Emily Sotelo Mentor Dr. Adam Moser
Overview
Background Research MotivationMethods: Quantum Chemistry Calculations Results Implications for future work
BackgroundResearch MotivationMethod Calculations Results Future Work
Discovered by chemists Otto Diels and Kurt Alder in 1928-recognized with a Nobel Prize in Chemistry in 1950
The Diels-Alder
Reaction
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Importance of the Diels-
Alder Reaction
2. High Stereochemical Control
1. Ring Formation
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Reaction Components
Energetically favorable due to formation of new σ bonds
Diene only reacts in s-cis conformation
Electron withdrawing groups activate the dienophile
Concerted mechanism Kinetic control
can dominate
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Reaction of Interest
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Reaction of Interest
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Literature Review
The Diels-Alder Reaction of Acetylene is slower than that of Ethylene
Higher activation energy due to distortion energy
Only performed in lab using catalysts & radicals
Adding activating groups to both ends of the triple bond increases the reactivity
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My Research
Seems to be this gap in the literature discussing the very basic components of this very important reaction of acetylene and butadiene
We have decided to study this computationally because you can examine lot reaction properties quickly
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Quantum Chemistry
Method Describes what approximation will be used to solve the equation
Basis Set Describes what math is available to solve this equation
Branch of computational chemistry which uses mathematical approximations to solve the Schrödinger equation
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Substituents
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Calculations
ΔH, ΔG, Δ‡H, and Δ‡GHOMO-LUMO Energies
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Single Substitution
EWG
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HOMO-LUMO
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Single Substitution
EDG
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Double Substitution
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Dihedral Scan
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Dihedral Scan
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Dihedral Scan
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Dihedral Scan
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Dihedral Scan
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Dihedral Scan
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Dihedral Scan
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Summary
Most effective substituent to lower activation barrier
Lowers LUMO energy
This barrier is lowered further by substituting both ends of the triple bond
Steric effects seem to be the dominating force when locking the conformation of the dienophile
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Next Steps
Continue to work with more substituents to see if these trends continue
Substitute both reactants to gain a better understanding of not only thermodynamics/kinetics but stereochemistry
Continue to work with the dihedral scanning
Use higher, more accurate levels of theory to
See if trends continue Closer to experimental data
Acknowledgments
Dr. Adam Moser Dr. Sean Mulcahy Science Hall faculty
Loras College Peers, Friends and Family
References
Cramer, C.J. (2002). Essentials of Computational Chemistry. Hoboken, NJ: Wiley.
Dai, M, Sarlah, D, Yu, M. Danishefsky, S, Jones, G, Houk, KN. 2006. Highly Selective Dielss-Alder Reactions of Directly Connected Enyne Dieneophiles. J Am Chem Soc 129, 645-657.
Froese, RDJ, Coxon, JM, West, SC, Morokuma, K. 1997. Theoreical Studies of DA reaction of Acetylenic Compounds. J. Org. Chem 63, 6991-6996.
Nicolaou KC, Snyder SA, Montagnon T, Vassilikogiannakis G (2002). The Diels-Alder Reaction in total synthesis. Angew Chem Int Ed 41: 1668-1698.
Rahm, A., Rheingold, A.L, Wulff, WD. 2000. Asymmetric Diels-Alder Reactions with Chiral Acetylenic Carbene Complexes as Dienophiles. Tetrahedrom 56, 4951-4965
Smith, J. (2011). Organic Chemistry 3rd Edition. New York, NY: McGraw-Hill.
EXTRA SLIDES
Δ‡G Thermodynamic vs. Kinetic Control
Reaction Profile & T-State Calculations
Quantum Chemistry
Method: Hartree Fock
Treats each electron separately
Assumes frozen nucleus
Basis Set:6-31G(d) Equations which describe
the shape of the orbital Slater and Gaussian The basis set is a split
valance meaning there are two types of electrons, core and valence electrons with the valence electrons participating in the reaction behavior of molecule.
Split valence basis sets uses this knowledge to treat these two types of electrons differently.
HOMO-LUMO
Changing Levels of Theory