Purification of Naphthalene

Naphthalene (CAS NO. 91-20-3) is crystd one or more times from the following solvents: EtOH, MeOH, CCl4, benzene, glacial acetic acid, acetone or diethyl ether, followed by drying at 60°C in an Abderhalden drying apparatus. It is also purified by vacuum sublimation and by fractional crystn from its melt.
Other purification procedures include refluxing in EtOH over Raney Ni, and chromatography of a CCl4 soln on alumina with benzene as eluting solvent. Baly and Tuck purified naphthalene for spectroscopy by heating with conc H2SO4 and MnO2, followed by steam distn (repeating the process), and formation of the picrate which, after recrystallisation, was decomposed and the naphthalene was steam distd. It was then crystd from dilute EtOH. It can be dried over P2O5 under vacuum. It is also purified by sublimation and subsequent crystn from cyclohexane. Alternatively, it has been washed at 85O with 10% NaOH to remove phenols, with 50% NaOH to remove nitriles, with 10% H2SO4 to remove organic bases, and with 0.8g AlCl3 to remove thianaphthalenes and various alkyl derivatives. Then it was treated with 20% H2SO4, 15% Na2CO3 and finally distd.
Zone refining purified naphthalene from anthracene, 2,4-dinitrophenylhydrazine, methyl violet, benzoic acid, methyl red, chrysene, pentacene and indoline.