Thiazoles silver® nitrate

In the complex of /ra r-2,2 -(l,4-but-2-enediyldithio)dithiazole (L) and silver nitrate, there is a symmetric center located at the midpoint of the l,4-but-2-enediyl group with the two thiazole rings antiparallel to each other <2005JST(752)40>. 

As discussed in Section 3.06.5.3.2, 2-phenylthiazole undergoes electrophilic substitution at the heteroaromatic ring. However, bromination in sulfuric acid in the presence of silver sulfate introduces bromine into the para-position of the benzene ring <85CS295>. This is caused by the protonation of the thiazole ring and the ensuing deactivation. A similar behavior is observed in the nitration of 2-phenylthiazole with nitric acid in sulfuric acid. Also in this case the electrophilic substitution is directed towards the para-position (the ratio of the o /m p-isomers being 3 8 89). 

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