The photochemical reactions of 9-phenanthrenecarbonitrile with several secondary and primary amines and triethylamine have been investigated. Rate constants for fluorescence quenching by secondary and primary amines decrease with amine α-alkylation in spite of increased electron-donor ability of the more substituted amines. This trend is attributed to a steric effect on the equilibrium constant for reversible exciplex formation. The reactions of secondary and primary amines in nonpolar solvent result in selective N-H vs. α-C-H transfer from amine to arene, via a singlet exciplex. The ratio of α-C-H/N-H transfer increases with α-alkylation and increased solvent polarity and is larger for secondary vs. primary amines. The behavior of the intermediate free radical pairs is also dependent upon amine structure and solvent polarity.
ASJC Scopus subject areas
- Colloid and Surface Chemistry