Purification Methods
If reasonably pure, then fractionate it through an efficient column. Otherwise purify it via the bisulfite adduct. To a solution of NaHSO3 (32.5g, 0.31mol) in H2O (57mL) is added 95% EtOH (18mL) and set aside overnight. Any bisulfite-sulfate that separated is removed by filtration, and the filtrate is added to the tetralone (14.6g, 0.1mol) and shaken vigorously. The adduct separates in a few minutes as a white precipitate and is kept on ice for ~3.5hours with occasional shaking. The precipitate is collected, washed with 95% EtOH (13mL), then with Et2O (4 x 15mL, by stirring the suspension in the solvent, filtering and repeating the process). The colourless product is dried in air and stored in air tight containers in which it is stable for extended periods (yield is ~17g). This bisulfite (5g) is suspended in H2O (25mL), and Na2CO3.H2O (7.5g) is added (pH of solution is ~10). The mixture is then extracted with Et2O (5 x 10mL, i.e. until the aqueous phase does not test for tetralone — see below). Wash the combined extracts with 10% aqueous HCl (10mL), H2O (10mL, i.e. until the washings are neutral), dry (MgSO4), filter, evaporate and distil the residual oil using a Claisen flask under reduced pressure and in a N2 atmosphere. The pure tetralone is a colourless liquid b 70-71o/0.25mm (see also above). The yield is ~2g. Tetralone test: Dissolve a few drops of the tetralone solution (ethereal or aqueous) in 95% EtOH in a test tube and add 10 drops of 25% NaOH down the side of the tube. A deep blue colour develops at the interface with air. [Soffer et al. Org Synth Coll Vol IV 903 1963, Cornforth et al. J Chem Soc 689 1942, UV: Soffer et al. J Am Chem Soc 1556 1952.] The phenylhydrazone has m 108o [Crawley & Robinson J Chem Soc 2001 1938]. [Beilstein 7 H 370, 7 II 295, 7 III 1422, 7 IV 1018.]
