Organic Syntheses, CV 5, 49
Submitted by A. Rieche, H. Gross, and E. Höft
1.
Checked by G. N. Taylor and K. B. Wiberg.
1. Procedure
A solution of
72 g. (0.60 mole) of mesitylene in 375 ml. of dry methylene chloride is placed in a
1-l. three-necked flask equipped with a
reflux condenser, a
stirrer, and a
dropping funnel. The solution is cooled in an
ice bath, and
190 g. (110 ml., 1.0 mole) of titanium tetrachloride is added over a period of 3 minutes. While the solution is stirred and cooled,
57.5 g. (0.5 mole) of dichloromethyl methyl ether2 is added dropwise over a 25-minute period. The reaction begins (as indicated by evolution of
hydrogen chloride) when the first drop of chloro ether is added. After the addition is complete, the mixture is stirred for 5 minutes in the ice bath, for 30 minutes without cooling, and for 15 minutes at 35°.
The reaction mixture is poured into a
separatory funnel containing about 0.5 kg. of crushed ice and is shaken thoroughly. The organic layer is separated, and the aqueous solution is extracted with two
50-ml. portions of methylene chloride. The combined organic solution is washed three times with 75-ml. portions of water. A crystal of
hydroquinone is added to the
methylene chloride solution (Note
1) which is then dried over anhydrous
sodium sulfate. After evaporation of the solvent, the residue is distilled to give the crude product, b.p.
68–74° (0.9 mm.). After redistillation there is obtained
60–66 g. (
81–89%) of
mesitaldehyde; b.p.
113–115° (11 mm.),
n20D 1.5538.
2. Notes
3. Discussion
4. Merits of the Preparation
The preparation of
mesitaldehyde is an example of a generally applicable method for the preparation of aromatic aldehydes by treatment of aromatic compounds with
dichloromethyl methyl ether.
12 Aldehydes derived from polynuclear aromatic compounds,
12,13 phenols,
14 phenol ethers,
12 and hetero-aromatic compounds
12 are also obtained using this procedure. In addition, colchicine derivatives have been formylated
15 by means of
dichloromethyl methyl ether.
This preparation is referenced from:
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