SULPHINIC ACIDS AS ANALYTICAL REAGENTS

The "specific" action of sulphinic acids with metal ions is not limited to compounds in which there is direct attachment of the —SO 2 H group to an aromatic ring. Since both aliphatic and aromatic sulphinic acids react similarly the assumption that an aromatic group is necessarily co-ordinated to the metal atom through its π system is not valid; the precipitated products are simple salts of the acids. Ferric iron yields at least two products with sulphinic acids. Ceric cerium is reduced in acid solution but an orange-yellow precipitate containing cerium is obtained from acetate-buffered solutions. Naphthalenesulphinic acid may be used to quantitatively precipitate [Formula: see text] [Formula: see text] [Formula: see text] [Formula: see text] [Formula: see text] [Formula: see text] [Formula: see text] [Formula: see text].[Formula: see text] [Formula: see text]