Org. Synth. 1928, 8, 36
DOI: 10.15227/orgsyn.008.0036
BENZYLACETOPHENONE
[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:
Appendix
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)
Benzylacetophenone,
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
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