Related Experiment Video
Updated: Aug 29, 2026

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
Published on: July 27, 2018
Photochemically generated arylnitrenium ions: substituent effects on reactivity studied by laser flash photolysis
Andrew C Kung1, Dominic Chiapperino, Daniel E Falvey
1Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742-2021, USA.
Abstract:
Laser flash photolysis is used to examine reaction rates of four arylnitrenium ions: N-methyl-N-(4-chlorophenyl)-, -(4-biphenylyl)-, -(4-methylphenyl)-, and -(4-methoxyphenyl)nitrenium ion. These intermediates are generated from photolysis of appropriately substituted N-aminopyridinium ions. Kinetic analysis of trapping rates shows that the nitrenium ions react with weak nucleophiles in the order 4-Cl approximately 4-Me > 4-Ph > 4-OMe. Generally, amines react with the arylnitrenium ions at or near the diffusion-limited rate. Only in cases where the least reactive nitrenium ion (4-OMe) reacts with sterically hindered amines is any deviation from this generalization observed. The addition of a 2-acetyl substituent to these structures produces an interesting effect. In the case of the 4-Cl and 4-Ph analogs, the electron-withdrawing acetyl group decreases the rate of nucleophilic addition, yet with the 4-OMe and 4-Me compounds, the acetyl group increases the rate of addition. These results are discussed in terms of competing electronic and steric effects.
More Related Videos
Related Concept Videos
meta-Directing Deactivators: –NO2, –CN, –CHO, –⁠CO2R, –COR, –CO2H
Radical Reactivity: Nucleophilic Radicals
Radical Reactivity: Steric Effects
Along with electronic factors, steric factors also account...
Radical Reactivity: Concentration Effects
Radical Reactivity: Overview
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3
![[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)
