A Publication
of Reliable Methods
for the Preparation
of Organic Compounds
Annual Volume
Org. Synth. 1925, 5, 15
DOI: 10.15227/orgsyn.005.0015
[1-Penten-3-one, 4,4-dimethyl-1-phenyl-]
Submitted by G. A. Hill and G. M. Bramann.
Checked by C. S. Marvel and A. B. Adams.
1. Procedure
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°.
2. Notes
1. The time may be shortened to twenty-four hours without greatly reducing the yield.
3. Discussion
Benzalpinacolone can be prepared by the action of benzaldehyde on pinacolone in the presence of aqueous-alcoholic alkalies.1 The procedure described is a modification of the method by Vorländer and Kalkow.1

References and Notes
  1. Vorländer and Kalkow, Ber. 30, 2269 (1897); Hill, Spear and Lachowicz, J. Am. Chem. Soc. 45, 1559 (1923).

Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

alcohol (64-17-5)

calcium chloride (10043-52-4)

Benzene (71-43-2)

sodium hydroxide (1310-73-2)

sodium bisulfite (7631-90-5)

benzaldehyde (100-52-7)

1-Penten-3-one, 4,4-dimethyl-1-phenyl- (538-44-3)

Pinacolone (75-97-8)