338 PRACTICAL ORGANIC CHEMISTRY and hydroquinone, />-C 8 H 4 (OH) 2 , are soluble in water; the remainder are sparingly soluble or insoluble in water. All phenols are soluble in sodium hydroxide solution, in some cases (e.g., catechol, resorcinol, hydroquinone) with rapid darkening in colour. GENERAL REACTIONS.* 1. Do not liberate CO 2 from Na 2 CO 3 solutions (distinction from carboxylic acids, p. 347). 2. Give characteristic colorations with ferric chloride. 3. Give toluene-/>-sulphonyl derivatives. 4. Give benzoyl, p-nitrobenzoyl and 3,5-dinitrobenzoyl deriva-tives. 5. Give urethanes with phenylisocyanate. 6. Couple in alkaline solution with diazotised amines to give orange or red azo-dyes. 7. Form phthaleins. 8. Certain phenols give white bromo-derivatives with bromine water. 9. Certain phenols give the Liebermann Nitroso Reaction. 1. Sodium carbonate solution (cf. Section 5, p. 330). Note that phenols (except those containing acidic groups, e.g., nitrophenols) give no reaction with sodium carbonate solution. 2. Ferric chloride coloration.
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