How Do Aromatic Nitro Compounds React with Nucleophiles? Theoretical Description Using Aromaticity, Nucleophilicity
Kacper Błaziak1,2, Witold Danikiewicz3, Mieczysław Mąkosza3
1Faculty of Chemistry, University of Warsaw, 01-224 Warsaw, Poland.
Molecules (Basel, Switzerland)
|October 23, 2020
Summary
Nucleophilic aromatic substitution reactions (SNAr-H and SNAr-X) are controlled by nucleophile addition to the nitroaromatic ring. This addition step is rate-limiting, dictating the overall reaction
Area of Science:
- Organic Chemistry
- Reaction Mechanisms
- Computational Chemistry
Background:
- Nucleophilic aromatic substitution (SNAr) is a fundamental reaction in organic chemistry.
- Understanding the rate-limiting steps is crucial for reaction optimization.
- Nitroaromatic compounds are common substrates in SNAr reactions.
Purpose of the Study:
- To provide a comprehensive description of nucleophile addition to nitroaromatic rings.
- To elucidate the factors controlling the rate and direction of SNAr-H and SNAr-X reactions.
- To identify the rate-limiting step in these reactions under specific conditions.
Main Methods:
- Theoretical calculations including aromaticity (HOMA), electrophilicity, and nucleophilicity indices.
- Experimental validation of theoretical findings.
- Kinetic isotope effect modeling.
Main Results:
- Nucleophile addition to the nitroaromatic ring is the rate-limiting step for both SNAr-X and SNAr-H reactions.
- This is especially true when the subsequent transformation of the intermediate adduct is rapid.
- Theoretical parameters accurately describe the reaction mechanism.
Conclusions:
- The addition of a nucleophile is the key determinant of the overall reaction rate in SNAr processes.
- Understanding these factors allows for better control over reaction outcomes.
- This study provides valuable insights for designing and optimizing SNAr reactions.
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