Purification of Crude Anthracene

Crude anthracene (about 40%) is mixed in a vessel fitted with a mechanical stirrer, with 1J times its weight of benzol or solvent naphtha (90% at 160°) this specification means that 90% by volume distils up to 160°. Sodium nitrite to one-tenth of the weight of crude anthracene taken is dissolved in 10 times its weight of water, and sufficient 10% sulphuric acid (7-2 gms. for each 1 gm. of 10% nitrite) to decompose this quantity of nitrite is added to the benzol—anthracene mixture and the temperature maintained at 25°. The nitrite solution is then run in at such a speed that no red fumes escape. When all the solution has been added the mixture is filtered at the pump. The filtrate consists of two layers, one of sodium sulphate solution and one of solvent naphtha, or benzol containing the impurities such as nitroso-carbazol. The purified anthracene on the filter is washed with benzol or solvent naphtha this latter on a large scale is used for the final treatment of a fresh lot of crude anthracene. The initial benzol or solvent naphtha, after separation from the aqueous solution, is recovered by distillation. The anthracene from this treatment will be about 80% pure. It may be purified to 95% by crystallising from heavy bases (pyridine, etc.), and is finally raised by sublimation and re-crystallisation from benzol to 98%. (For the estimation of purity, see p. 497.) (C. T., 23, 8, 21 D.R.P., 122852.) 

Reaction LVIIL (b) Redaction of Aromatic Ketones to the corresponding Hydrocarbons by treatment with Hydriodic Acid or with Sodium in Alcoholic Solution. (B., 7, 1624 31, 999.)—Two methods for the 

Method I.—10 gms. (1 mol.) of benzophenone, 12 gms. (nearly 2 mols.) of hydriodie acid (B.P. 127°) and 2 gms. (more than 1 atom) of red phosphorus are heated together in a sealed tube for 6 hours at 160° (see p. 41). The reaction mixture is extracted with ether and the extract washed with water several times. It is then filtered, dried over calcium chloride for 24 hours, the ether removed on a water bath and the residue distilled. 

Method II.—-10 gms. (1 mol.) of benzophenone are refluxed with 100 gms. (excess) of alcohol, and 10 gms. (excess) of sodium wire are gradually added through an addition tube (see p. 50) to the boiling liquid. When the solution of the sodium is complete, the liquid in the flask is cooled, saturated with carbon dioxide, poured into cold water and the whole extracted with benzene. The extract is dried for 24 hours over calcium chloride, the benzene removed on a water bath, and the residue distilled under reduced pressure, the fraction 174°—176° at 80 mms. being retained. 

Reaction LVm. (c) Redaction of the Carbonyl to the Methylene Group by means of Zinc Amalgam and Hydrochloric Acid (Clemmensen). (B., 46, 1837 47, 51 47, 681.) 

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