In a 2-l. bottle equipped with a mechanical stirrer are mixed 635 g. (800 cc., 11.0 moles) of u. s. p. acetone (Note 1) and (Note 2), 420 g. (400 cc., 4.0 moles) of freshly distilled benzaldehyde boiling at 178–180° (shaken with dilute sodium carbonate just before distillation), and 400 cc. of water. To this mixture, 100 cc. of 10 per cent aqueous sodium hydroxide is slowly added from a dropping funnel (Note 3), while the solution is stirred, and cooled by a water bath. The rate of addition of the alkali is so regulated that the temperature remains between 25–31°. This requires from one-half to one hour. The mixture is now stirred for two and one-quarter hours at room temperature (Note 4). At the end of this time dilute hydrochloric acid is added until the mixture is acid to litmus. The two layers which form are separated in a separatory funnel. The lower aqueous layer is extracted with 100 cc. of benzene, and the benzene solution added to the yellow oil which formed the upper layer in the first separation. This benzene solution is shaken with 100 cc. of water and separated.

The benzene is then removed by distilling from a steam bath, and the residue distilled under reduced pressure (Note 5), any water which condenses with the forerun being separated (Note 6). A special distilling flask with a fractionating side arm (p. 130) is best employed. The material which distils at 148–160° /25 mm., 133–143° /16 mm., or 120–130° /7 mm. weighs 430–470 g.; it solidifies to a crystalline mass on standing, and is pure enough for all practical purposes. On redistillation there is obtained 375–450 g. (65–78 per cent of the theoretical amount) of material boiling at 137–142° /16 mm. or 123–128° /8 mm., which solidifies on standing to crystals which melt at 40–42° (Note 7) and (Note 8).