3°° PRACTICAL ORGANIC CHEMISTRY allowing the mixture to stand overnight. Then filter the ethereal solution, wash the residual potash with more ether and then distil off the ether from a small (75 ml.) flask with the usual precautions (Fig. 64, p. 16^). Then replace the water-condenser by an air-condenser and distil the quinoline. Collect the fraction of b.p. 234-237°. Yield, 18 g. Quinoline is a colourless liquid, having b.p. 236° and d , 1-095. It has an odour similar to, but fainter than," that of pyridine: unlike pyridine, it is almost insoluble in water. Quinaldine. C 10 H 9 N. (The Doebner-Miller Synthesis.) Quinaldine (or 2-methylquinoline) can be prepared by the Doebner-Miller Synthesis, which in some respects is closely similar to the Skraup Synthesis (p. 297) but has some significant differences. When a mixture of aniline, hydrochloric acid and acetaldehyde is heated (in the absence of an oxidising agent), a vigorous reaction occurs with the pro-duction of quinaldine. In these circumstances, the main reactions are un-
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