RT REACTION
In a 2-l. three-necked round-bottomed flask fitted with a 40-in. reflux condenser, a mercury-sealed stirrer, and a dropping funnel are placed 100 g. (0.69 mole) of ?-naphthol and 300 g. of 95% ethanol. The stirrer is started, and a solution of 200 g. (5 moles) of sodium hydroxide in 415 g. of water is rapidly added. The resulting solution is heated to 70–80° on a steam bath, and the dropwise addition of chloroform is started. After the reaction begins, further heating is unnecessary. A total of 131 g. (1.1 moles) of chloroform is added at such a rate that gentle refluxing is maintained. Near the end of the addition the sodium salt of the phenolic aldehyde separates. Stirring is continued for 1 hour after all the chloroform has been added.The ethanol and excess chloroform are removed by distillation from a steam bath. Hydrochloric acid (sp. gr. 1.18) is added dropwise to the residue, with good stirring, until the contents of the flask are acid to Congo red paper. The dark oil that separates is mixed with a considerable amount of sodium chloride. Sufficient water to dissolve the salt is added, and the oil is separated and washed several times with hot water. By distillation of the oil under reduced pressure there is obtained 87.5–93.7 g. of a slightly colored distillate which boils at 163–166° at 8 mm. (Note 5) and which solidifies on cooling. Recrystallization of the solid from 75 ml. of ethanol yields 45.2–57.5 g. (38–48%) of pure 2-hydroxy-1-naphthaldehyde, melting at 79–80°.
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Topic: PIGMENT YELLOW 101 (Read 6799 times)