A Publication
of Reliable Methods
for the Preparation
of Organic Compounds
Annual Volume
Org. Synth. 1928, 8, 36
DOI: 10.15227/orgsyn.008.0036
[Propiophenone, β-phenyl-]
Submitted by Roger Adams, J. W. Kern, and R. L. Shriner.
Checked by Henry Gilman and S. A. Harris.
1. Procedure
A solution of 20.8 g. (0.1 mole) of benzalacetophenone (p. 78) (Note 1) in 150 cc. of c.p. ethyl acetate (Note 2) is placed in the reaction bottle of the catalytic reduction apparatus (p. 61), and 0.2 g. of platinum oxide catalyst (p. 463) is added. The apparatus is evacuated, then filled with hydrogen, and the mixture shaken with hydrogen until 0.1 mole has been absorbed. The time required is usually about fifteen to twenty-five minutes (Note 3). The platinum is filtered off and the solvent removed from the filtrate by distillation. The benzylacetophenone is recrystallized from about 25 cc. of alcohol and melts at 72–73°. The yield is 17–20 g. (81–95 per cent of the theoretical amount).
2. Notes
1. The benzalacetophenone should be freshly recrystallized from alcohol just before using and should melt at 57°.
2. Owing to the comparatively slight solubility of benzalacetophenone in alcohol, ethyl acetate is used as a solvent during the reduction.
3. If 0.1 g. of catalyst is used the reduction requires about three hours; an increase in catalyst to 0.5 g. causes the reduction to take place in three or four minutes. The exact time depends to a considerable extent on the grade of benzalacetophenone used and it is not certain that the purest will necessarily be reduced in the shortest time.
3. Discussion
Benzylacetophenone can be prepared by the reduction of benzalacetophenone with zinc and acetic acid1 and catalytically with palladium and hydrogen;2 by the oxidation of the corresponding carbinol with chromic acid;3 and by the hydrolysis of ethyl benzylbenzoylacetate.4
This preparation is referenced from:

References and Notes
  1. Schneidewind, Ber. 21, 1325 (1888); Harries and Hübner, Ann. 296, 327 (1897).
  2. Straus and Grindel, Ann. 439, 294 (1924).
  3. Bauer, Compt. rend. 154, 1094 (1912).
  4. Perkin and Stenhouse, J. Chem. Soc. 59, 1007 (1891).

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

alcohol (64-17-5)

acetic acid (64-19-7)

ethyl acetate (141-78-6)

hydrogen (1333-74-0)

platinum oxide

Benzalacetophenone (94-41-7)

Propiophenone, β-phenyl- (1083-30-3)

platinum (7440-06-4)

zinc (7440-66-6)

palladium (7440-05-3)

chromic acid (7738-94-5)

ethyl benzylbenzoylacetate