2- Naphthol dissolving metals

A 3-1. three-necked flask, equipped with a Dry Ice condenser (Note 1), a sealed Hershberg-type stirrer, and an inlet tube, is set up in a hood and charged with 108 g. (0.75 mole) of a-naphthol (Note 2). The stirrer is started, and to the rapidly stirred flask contents (Note 3) is added 11. of liquid ammonia as rapidly as possible (about 5 minutes). When the naphthol has gone into solution (about 10 minutes), 20.8 g. (3.0 g. atoms) of lithium metal (Note 4) is added in small pieces and at such a rate as to prevent the ammonia from refluxing too violently (Note 5). After the addition of the lithium has been completed (about 45 minutes), the solution is stirred for an additional 20 minutes and is then treated with 170 ml. (3.0 moles) of absolute ethanol which is added dropwise over a period of 30-45 minutes (Note 6). The condenser is removed, stirring is continued, and the ammonia is evaporated in a stream of air introduced through the inlet tube. The residue is dissolved in 1 1. of water, and, after the solution has been extracted with two 100-ml. portions of ether, it is carefully acidified with concentrated hydrochloric acid. The product formed is taken into ether with three 250-ml. extractions, and then the ether extract is washed with water and dried over anhydrous sodium sulfate. The ether is removed... 

Organic compounds such as l-nitroso-2-naphthol, thionalide, 2-mercapto-benzimidazole, and potassium thiocyanate have also been used as coprecipitation reagents. These compounds, except KSCN, are insoluble in water and form insoluble complex compounds with a number of metal ions. Precipitation reagents are first dissolved in small amounts of volatile, water insoluble... 

Uracil-5-azo-P-naphthol -3,6-disodium sulfonate R-salt), red needles with a metallic lustre, dissolves in water to give a red solution, dyes wool a deep orange-red. 

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