Org. Synth. 1958, 38, 26
DOI: 10.15227/orgsyn.038.0026
DIPHENYLACETALDEHYDE
[Acetaldehyde, diphenyl-]
Submitted by Donald J. Reif and Herbert O. House
1.
Checked by M. S. Newman and W. H. Powell.
1. Procedure
In a 1-l. separatory funnel is placed a solution of 39.2 g. (0.2 mole) of trans-stilbene oxide (Note 1) in 450 ml. of reagent benzene. To the solution is added 13.2 ml. (0.1 mole) of boron trifluoride etherate (Note 2). The solution is swirled, allowed to stand for 1 minute (Note 3), and then washed with two 300-ml. portions of water. The organic layer is separated, and the benzene is removed by distillation (Note 4). The residual crude aldehyde is purified by distillation under reduced pressure. The product, collected at 115–117°/0.6 mm., amounts to 29–32 g. (74–82%), nD25 1.5875–1.5877 (Note 5).
2. Notes
1.
The
trans-stilbene oxide (p.860) should be free of
trans-stilbene, since the
stilbene, if present, is not altered by the reaction conditions and will contaminate the final product.
2.
A
practical grade of boron trifluoride etherate, purchased from Eastman Kodak Company, was redistilled before use. The pure etherate boils at
126°.
3.
Longer reaction times result in a marked decrease in the yield of
diphenylacetaldehyde.
4.
The submitters found that distillation of the
benzene solution is necessary to obtain an anhydrous product. If the
benzene solution is dried over
magnesium sulfate and the
benzene removed under reduced pressure, the
diphenylacetaldehyde is contaminated with water.
5.
The product obtained by this procedure, when treated with
2,4-dinitrophenylhydrazine,
2 produced the
2,4-dinitrophenylhydrazone of
diphenylacetaldehyde, m.p.
146.8–147.8°, in
94% yield.
3. Discussion
Diphenylacetaldehyde has been prepared by the isomerization of
1,2-dihydroxy-1,2-diphenylethane either thermally
3 or in the presence of
sulfuric acid,
4,5,6 oxalic acid,
7 or
acetic anhydride.
8 The aldehyde has also been produced by the reaction of
2,2-dipheny1-2-hydroxyethyl ether with
sulfuric acid6,7 or
oxalic acid;
7,9 by the reaction of
hydrochloric acid with
2-amino-1,1-diphenylethanol;
10 by the reaction of hydrobromic
11 or hydrochloric
12 acid with
2-diethylamino-1,1-diphenylethanol; by the hydrolysis of
β,β-diphenylvinyl ethyl ether;
13 by the thermal rearrangement of
deoxybenzion;
14 by the hydrolysis and decarboxylation of the glycidic ester obtained from
ethyl chloroacetate and
benzophenone;
15 by passing a mixture of
diphenylacetic and formic acid over
thorium oxide on
pumice at 450°;
16 and by the hydrolysis of
diphenylacetaldehyde enol methyl ether (obtained from
benzophenone and
methoxymethylenetriphenylphosphorane).
17
Diphenylactaldehyde also has been prepared by the isomerization of
trans-stilbene oxide in the presence of
sodium bisulfite18 or
lithium diethylamide,
19 or by the isomerization of either
cis- or trans-stilbene oxide in the presence of
boron trifluride etherate.
2 The procedure chosen illustrates the ready isomerization of substituted
ethylene oxides to carbonyl compounds. The procedure is applicable to substituted epoxides in which one of the
carbon atoms of the
oxirane ring is bonded either to two other carbon atoms or to an aromatic nucleus or a
carbon-carbon double bond.
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
2,4-dinitrophenylhydrazone
2,2-dipheny1-2-hydroxyethyl ether
deoxybenzion
diphenylacetic and formic acid
pumice
diphenylacetaldehyde enol methyl ether
Diphenylactaldehyde
cis- or trans-stilbene oxide
sulfuric acid (7664-93-9)
hydrochloric acid (7647-01-0)
Benzene (71-43-2)
acetic anhydride (108-24-7)
Oxalic acid (144-62-7)
sodium bisulfite (7631-90-5)
thorium oxide
carbon (7782-42-5)
Benzophenone (119-61-9)
oxirane (75-21-8)
ethylene (9002-88-4)
Ethyl chloroacetate (105-39-5)
2,4-Dinitrophenylhydrazine (119-26-6)
magnesium sulfate (7487-88-9)
stilbene
Diphenylacetaldehyde,
Acetaldehyde, diphenyl- (947-91-1)
boron trifluoride etherate,
boron trifluride etherate (109-63-7)
1,2-dihydroxy-1,2-diphenylethane (52340-78-0)
2-amino-1,1-diphenylethanol
2-diethylamino-1,1-diphenylethanol
β,β-diphenylvinyl ethyl ether
methoxymethylenetriphenylphosphorane
lithium diethylamide
carbon-carbon
trans-Stilbene oxide (1439-07-2)
trans-Stilbene (103-30-0)
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