Preparation and Properties of 7-Formyl-8-hydroxy-5-quinolinesulfonic Acid

8-Hydroxy-5-quinolinesulfonic acid (I), on condensation with formaldehyde in aqueous ammonia, produced 8-hydroxy-7-hydroxymethyl-5-quinolinesulfonic acid (IV), which, on oxidation with manganese (IV) oxide, gave 7-formyl-8-hydroxy-5-quinolinesulfonic acid (V). On treatment with boiling 6 M hydrochloric acid, V produced bis[α-hydroxy-(8-hydroxy-5-sulfo-7-quinolyl)methyl] ether (VIII).