. Practical methods of organic chemistry . SERIES 265 at 310-3200 for about 5 minutes, the fusion becomes liquid, andthe reaction is complete. The melted mass is then poured on astrong copper plate the edges of which have been turned up and ofsufficient size so that the bottom is coveredby a thin layer of the mass. The portionsof dark sodium naphtholate may be easilydistinguished from the brighter causticsoda. After cooling, the solid mass isbroken up and dissolved in water. Thenaphthol is precipitated at the boilingtemperature with concentrated hydro-chloric acid (under the hood), and afterco
. Practical methods of organic chemistry . SERIES 265 at 310-3200 for about 5 minutes, the fusion becomes liquid, andthe reaction is complete. The melted mass is then poured on astrong copper plate the edges of which have been turned up and ofsufficient size so that the bottom is coveredby a thin layer of the mass. The portionsof dark sodium naphtholate may be easilydistinguished from the brighter causticsoda. After cooling, the solid mass isbroken up and dissolved in water. Thenaphthol is precipitated at the boilingtemperature with concentrated hydro-chloric acid (under the hood), and aftercooling is extracted with ether. Theethereal solution is dried over anhydrousGlaubers salt, and then the ether isevaporated in an apparatus similar tothe one described on page 35 ; a frac-tionating flask with a very wide condens-ing tube is used. After the removal ofthe ether, the naphthol remaining back isdistilled over without the use of a condenser. Melting-point,1230. Boiling-point, 2860. Yield, half the weight of the sul-phonate FIG. 73. As above indicated, in a sodium hydroxide, or potassium hydroxidefusion of a sulphonic acid, besides the phenol, the alkali sulphite isformed, : C10H-. S03Na + 2 NaOH = C10H7. ONa + Na2S03 + H,0 Sodium naphtholate The free phenol is, therefore, not directly obtained on fusion, butthe alkali salt of it, from which, after the solution of the fusion in water,the phenol is liberated on acidifying with hydrochloric acid. The reaction just effected is in practice carried out on the largestscale in iron kettles to which stirring apparatus is attached. /3-naph-thol as well as its numerous mono- and poly-sulphonic acid derivativesobtained by treatment with sulphuric acid find extensive application for 266 SPECIAL PART the manufacture of azo dyes. Further, from the /3-naphthol, /3-naph*thylamine is prepared by the action of ammonia under pressure : + NH3 = + H20, which also finds technical use for the manufacture of azo
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