Org. Synth. 1950, 30, 99
DOI: 10.15227/orgsyn.030.0099
o-TOLUALDEHYDE
Submitted by H. B. Hass and Myron L. Bender
1.
Checked by Arthur C. Cope and Malcolm Chamberlain.
1. Procedure
Eleven and one-half grams (0.5 g. atom) of sodium is dissolved in 500 ml. of absolute ethanol in a 1-l. round-bottomed flask. Forty-six grams (0.52 mole) of 2-nitropropane is added, then 92.5 g. (0.50 mole) of o-xylyl bromide (Note 1). The flask is attached to a reflux condenser connected to a drying tube and shaken at intervals for 4 hours. The reaction mixture, originally at room temperature, becomes warm spontaneously, and a white precipitate of sodium bromide forms (Note 2).
After a reaction period of 4 hours the sodium bromide is separated by filtration and the ethanol is removed by distillation on a steam bath. The residue of product and sodium bromide is dissolved in 100 ml. of ether and 150 ml. of water. The ether layer is washed with two 50-ml. portions of 10% sodium hydroxide solution to remove any acetoxime and excess 2-nitropropane and is then washed with 50 ml. of water. The ether layer is separated and is dried with 15 g. of anhydrous sodium sulfate, and the ether is removed by distillation on a steam bath.
The crude product is distilled from a Claisen flask under reduced pressure. The yield of o-tolualdehyde boiling at 68–72°/6 mm., n25D 1.5430, is 41–44 g. (68–73%) (Note 3).
2. Notes
1.
o-Xylyl bromide may be obtained from the Eastman Kodak Company or may be prepared by the light-catalyzed bromination of
o-xylene.
22.
The solution is originally supersaturated with the sodium salt of
2-nitropropane, and a precipitate of this salt may be mistaken for
sodium bromide.
3.
This is a general method for the preparation of substituted benzaldehydes. The following aldehydes have been prepared by the same general procedure.
3
|
|
Aldehyde
|
Yield, %
|
|
|
p-Bromobenzaldehyde
|
75
|
|
Benzaldehyde
|
73
|
|
p-Carbomethoxybenzaldehyde
|
72
|
|
p-Cyanobenzaldehyde
|
70
|
|
p-Trifluoromethylbenzaldehyde
|
77
|
|
3. Discussion
A procedure for the preparation of
o-tolualdehyde from
o-toluanilide by the Sonn-Müller method has been published in
Organic Syntheses.4 In addition to the alternative methods of preparation listed there,
o-tolualdehyde has been prepared from
o-xylyl bromide5 or
chloride6 and
hexamethylenetetramine; by the Stephen reduction of
o-tolunitrile;
7 by the reduction of the latter with
lithium triethoxyaluminohydride8 or
sodium triethoxyaluminohydride;
9 by the condensation of
crotonaldehyde with
barium or calcium oxide at 300°;
10 by the oxidation of
o-methylbenzyl alcohol with
N-chlorosuccinimide;
11 by the reaction of
ethyl orthoformate with
o-tolylmagnesium bromide;
12 by the reaction of the
o-tolylmagnesium chloride-tetrahydrofuran complex with
methyl formate;
13 and by the procedure of the present preparation.
3This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
barium or calcium oxide
o-tolylmagnesium chloride-tetrahydrofuran complex
ethanol (64-17-5)
ether (60-29-7)
sodium hydroxide (1310-73-2)
sodium bromide (7647-15-6)
sodium sulfate (7757-82-6)
benzaldehyde (100-52-7)
sodium (13966-32-0)
Ethyl orthoformate
N-chlorosuccinimide (128-09-6)
ACETOXIME
methyl formate (107-31-3)
hexamethylenetetramine (100-97-0)
o-Tolunitrile (529-19-1)
chloride
crotonaldehyde (123-73-9)
2-nitropropane (79-46-9)
sodium triethoxyaluminohydride
lithium triethoxyaluminohydride
o-Xylene (95-47-6)
p-Bromobenzaldehyde (1122-91-4)
p-cyanobenzaldehyde (105-07-7)
o-Tolualdehyde (529-20-4)
o-toluanilide
o-tolylmagnesium bromide
o-Methylbenzyl alcohol (89-95-2)
o-xylyl bromide (576-23-8)
p-Carbomethoxybenzaldehyde (1571-08-0)
p-Trifluoromethylbenzaldehyde (455-19-6)
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