On the Amazing Reactivity of the Ranelate Ion: New Applications of an Old Antiosporotic Drug

Ranelate ion, the major component of an old antiosporotic drug, exhibits a unusual chemical structure encompassing a thiophene ring with two carboxylic groups, a cyanonitrile substituent, and a nitrile diacetate group; it undergoes decarboxylation at the thiophene carbon-5 position in acidic solutions, yielding a photoreactive (H5Ran) species which converts into a remarkably stable blue dithiophene dye in the presence of UV light and air.