In a
1500-cc. bottle are placed
100 g. (1 mole) of pinacolone (p. 462),
120 g. (1.13 moles) of freshly distilled benzaldehyde,
380 cc. of 95 per cent alcohol, 130 cc. of water, and
100 cc. of 10 per cent sodium hydroxide solution. The bottle is stoppered tightly, placed on a
shaking machine, and agitated vigorously for about thirty-two hours (Note
1).
The reaction mixture is poured into a
separatory funnel and diluted with an equal volume of water. The
benzalpinacolone is separated by extracting three times with
300-cc. portions of benzene. The
benzene extracts are combined and washed, first with water until the alkali is entirely removed, then with a saturated solution of
sodium bisulfite, and finally two or three times with water. After drying over
calcium chloride, the
benzene is removed by distilling from a
steam bath, and the residue is distilled under reduced pressure. The yield of distilled
benzalpinacolone boiling at
143–146° /10 mm. is
165–175 g. (
88–93 per cent of the theoretical amount). This product is slightly yellow and melts at
41–42°. It is pure enough for most purposes. It may be recrystallized from
95 per cent alcohol and is then obtained in almost pure white crystals, melting at
43°.