202 PRACTICAL ORGANIC CHEMISTRY Transfer the diazotised solution, to a 600 ml. beaker, add 150 ml. of benzene, and stir the mixture vigorously to obtain an intimate mixture of the two liquids. Then again maintain the temperature at about 5° (by ice-salt cooling because of the heat evolved) whilst 27 ml. of 20% aqueous sodium hydroxide solution are added from a dropping-funnel during 40-50 minutes. When the addition of the alkali is complete, remove the ice-water bath, and allow the stirred mixture to reach room temperature. Pour the mixture into a 500 ml. flask fitted with a steam-distillation head, and with a steam-inlet tube reaching almost to the bottom of the flask. First distil of! the benzene in steam. Then place the flask in an oil-bath heated to 165-170°, and continue the steam-distillation (2-3 hours). The p-bromobiphenyl passes over and forms orange crystals in the water-condenser: therefore run the water out of the condenser for a short while from time to time to melt the orange deposit and allow it to
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