Isomeric benzothiazoles having the nitro and methyl groups ortho to each other are converted into tautomeric aci-nitro derivatives on irradiation in heptane solution; in water, the corresponding more deeply colored anions are formed. The efficiency of photochromic transformations strongly depends on the position of the nitro and methyl groups in the benzene ring of the benothiazole molecule.
Isomeric benzothiazoles having the nitro and methyl groups ortho to each other are converted into tautomeric aci-nitro derivatives on irradiation in heptane solution; in water, the corresponding more deeply colored anions are formed. The efficiency of photochromic transformations strongly depends on the position of the nitro and methyl groups in the benzene ring of the benothiazole molecule.