216 PRACTICAL ORGANIC CHEMISTRY should be carried out with pure hydrazobenzene. This com-pound, however, when kept in store undergoes atmospheric oxidation to azobenzene (p. 212), and such samples are therefore usually orange-red in colour due to contamination with azo-benzene If the hydrazobenzene is coloured in this way, it should be purified by the following process, which reduces any azobenzene back to hydrazobenzene. Add io g. of the crude hydrazobenzene to 80 ml. of ethanol contained in a flask fitted with a reflux water-condenser. Heat the mixture on a water-bath until the ethanol boils, and then add io g. of zinc dust and 30 ml. of 30% aqueous sodium hydroxide solution. Remove the flask from the water-bath and shake the contents vigorously from time to time. After about io minutes, replace the flask on the water-bath and boil the contents for 3-5 minutes. Filter the mixture at the pump, transfer the filtrate to a beaker and cool in ice-water with stirring. The hydrazobenzene separates as colourless crystals, which are filtered off at the pump
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This note was uploaded on 09/19/2011 for the course CHM 2211 taught by Professor Castalleano during the Fall '06 term at University of Florida.