Flash photolysis of 2,4,6‐trinitrotoluene solutions (TNT) indicates a photochemically induced isomerization leading to the aci‐quinoid isomer
with an absorption maximum at 460 nm in nonpolar solvents, or the conjugate base
of the aci‐quinoid isomer with absorption maxima at 500, 540, and 630 nm in polar solvents. Both species, the quinoid isomer and the conjugate base, have transient existence and their identification was based on detailed spectroscopic and kinetic studies presented here. The magnitude of the negative charge on the transient conjugate base was determined with salt effect experiments and found to be equal to unity.