250 THE PREPARATION OF UNSYMMETRICAL BIARYLS In a 1-1. three-necked flask are placed 50 g. of m-nitroaniline, 250 cc. of glacial acetic acid, and 125 cc. of acetic anhydride. The flask is warmed on a steam bath for about an hour with occasional swirling; the solid m-nitroaniline dissolves, and a light-yellow solution is obtained. The outlet tube from the drying tower is attached to a tube which passes through a stopper in one neck of the flask and extends below the surface of the solu-tion. The center neck is fitted with a stirrer passing through a glycerol seal, 6 * and the other neck holds a calcium chloride tube. The flask con-taining the hot solution is immersed in an ice bath, and the solution is stirred in order to precipitate the wwiitroacetanilide as a fine powder. When the mixture is at 5°, nitric acid is allowed to drip on the sodium nitrite in the generator at the rate of 1-2 drops per second. The com-pressed air is adjusted so that there is no nitric oxide (which turns into
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