Picosecond Transient Absorption Studies of Dinitrotoluenes in Solution

Article abstract of DOI:10.1021/j100286a018

Employing picosecond transient spectroscopy, we have studied the photochemistry of 2,6-, 2,4-, and 3,4-dinitrotoluenes in solution.With 266 nm excitation (ca. 1 mJ, 22 ps) similar broad transient absorptions in the 420-650-nm region are observed for each isomer.They are assigned to their lowest n?^* excited triplet states.For the 2,6 and the 2,4 compounds, the initial triplet absorptions evolve to yield spectra characteristic of the aci-quinoid species, which are formed following intramolecular hydrogen transfer from the methyl group to the ortho nitro group.Intramolecular hydrogen abstraction rates of 0.5E9 and 0.6E9 s^-1 are estimated for the 2,6 and 2,4 isomers, respectively.