An Experimental Radical Electrophilicity Index.

Area of Science:

• Chemical kinetics
• Physical organic chemistry

Background:

• Electrophilicity is a key chemical property for understanding reactivity.
• Existing methods for quantifying electrophilicity often rely on computational approaches.

Purpose of the Study:

• To introduce and validate an experimental electrophilicity index (ϻ) for radical classification.
• To establish a reliable experimental method that complements computational predictions.

Main Methods:

• Determining the equilibrium constant for the reversible addition of a radical (R•) to an aromatic radicophile (histamine).
• Establishing the experimental electrophilicity (ϻ) scale based on these equilibrium constants.

Main Results:

• The experimental electrophilicity index (ϻ) successfully classifies radicals.
• The ϻ-scale shows excellent agreement with the computed global electrophilicity index (ω).

Conclusions:

• The experimental approach provides a robust method for measuring radical electrophilicity.
• This work validates the computational global electrophilicity index (ω) using experimental data.