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Computational study of epoxy-amine reactions.
Satoshi Okumoto1, Shinichi Yamabe
1Matsushita Electric Works, Ltd., 1048, Kadoma, Osaka 571-8686, Japan.
Journal of Computational Chemistry
|December 24, 2002
Summary
Amine clusters, particularly tetramers, facilitate ethylene oxide reactions via zwitterionic intermediates. Hydrogen bonding in mixed amine-alcohol reactants further stabilizes this favorable reaction pathway.
Area of Science:
- Computational chemistry
- Chemical kinetics
- Reaction mechanisms
Background:
- Ethylene oxide reactions with amines are crucial in chemical synthesis.
- Uncatalyzed reactions between single amine and oxide molecules exhibit high activation energy.
- Amine clustering is hypothesized to lower activation barriers.
Purpose of the Study:
- To investigate the reaction mechanism between ethylene oxide and methylamine clusters using computational methods.
- To determine the role of amine cluster size in reaction kinetics.
- To explore the influence of hydrogen bonding on the reaction pathway.
Main Methods:
- Density functional theory (DFT) calculations were employed.
- Various amine cluster sizes (dimer, trimer, tetramer, pentamer) were modeled.
- Reaction pathways involving zwitterionic intermediates were analyzed.
Main Results:
- An amine tetramer demonstrated a favorable reaction pathway with ethylene oxide.
- Zwitterionic intermediates and a proton relay mechanism were identified.
- A back-side S(N)2 nucleophilic attack was proposed.
- Mixed amine-alcohol reactants showed enhanced reactivity due to strong hydrogen bonding.
Conclusions:
- Amine cluster size significantly impacts the reaction rate and mechanism.
- The tetramer cluster provides an optimal configuration for ethylene oxide reaction.
- Hydrogen bonding plays a critical role in stabilizing transition states and facilitating the reaction.