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09:22
In Vitro Aggregation Assays Using Hyperphosphorylated Tau Protein
Published on: January 2, 2015
Ion pair aggregates and reactions; experiment and theory
1Department of Chemistry, University of California, Berkeley, CA 94720-1460, USA. astreit@berkeley.edu
Journal of Molecular Modeling
|December 13, 2005
Summary
Lithium enolate aggregation was studied using UV-vis spectroscopy and proton-transfer equilibria. Alkylation reactions primarily involve monomers, even in aggregated solutions.
Area of Science:
- Organic Chemistry
- Physical Chemistry
Background:
- Lithium enolates are key intermediates in organic synthesis.
- Understanding their aggregation behavior is crucial for reaction control.
Purpose of the Study:
- To determine aggregation equilibrium constants for lithium enolates.
- To investigate the impact of aggregation on reactivity.
Main Methods:
- UV-vis spectroscopy to monitor spectral changes with concentration.
- Proton-transfer equilibria to assess aggregation effects.
- Ab initio computations (HF level) for theoretical modeling.
- Solvation modeling using coordination and continuum dielectric methods.
Main Results:
- Established methods for determining lithium enolate aggregation constants.
- Identified common aggregates (dimers, tetramers).
- Observed reduced aggregation with alpha-substitution.
- Demonstrated that S(N)2 alkylations favor monomers.
Conclusions:
- Aggregation state significantly influences lithium enolate reactivity.
- Monomeric species are the active nucleophiles in S(N)2 alkylations.
- Computational methods accurately predict aggregation behavior and reactivity.
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