In a
6-l. wide-mouthed bottle, packed in a pail with a freezing mixture of ice and salt and fitted with a
mechanical stirrer, a
thermometer, and a
separatory funnel, are placed
305 g. (5 moles) of nitromethane (p. 401),
530 g. (5 moles) of benzaldehyde (Note
1), and
1000 cc. of methyl alcohol. A solution of
sodium hydroxide is prepared by dissolving 210 g. (5.25 moles) of sodium hydroxide in approximately an equal volume of water and cooling. It is then diluted to 500 cc. with ice and water, poured into the funnel, and added with stirring to the
nitromethane mixture at such a rate that the temperature is kept at 10–15° (Note
2) and (Note
3).
A bulky white precipitate forms rapidly during the addition of the alkali. The mixture gets so thick that stirring becomes difficult and it may be advisable to add
100 cc. more of methyl alcohol. After fifteen minutes' standing, the pasty mass is converted to a clear solution by the addition of 3–3.5 l. of ice water containing crushed ice (Note
4).
Hydrochloric acid (made by diluting 1000 cc. of concentrated hydrochloric acid with 1500 cc. of water) is placed in a
15-l. mixing jar and the reaction mixture run into this from the separatory funnel at such a rate that the stream just fails to break into drops (Note
5). A pale yellow crystalline mass separates almost immediately as the alkaline solution comes in contact with the acid. After the stirring is stopped, the solid settles to the bottom of the jar. The major part of the cloudy liquid layer is removed by decantation, and the residue filtered by suction and washed with water until free from chlorides. This product is freed from all but a negligible amount of water by melting in a
beaker immersed in hot water. Two layers are formed, and on cooling again the lower layer of
nitrostyrene freezes; the water may then be poured off. The crude
nitrostyrene is purified by dissolving in
420 cc. of hot ethyl alcohol (Note
6), filtering the solution into a warm
suction flask to remove solid impurities, and then cooling until crystallization is complete. The yield of crude product melting at
56–58° is
650–670 g. The yield of recrystallized
nitrostyrene melting sharply at
57–58° is
600–620 g. (
80–83 per cent of the theoretical amount). The whole procedure, including purification, can be done in a day.