Org. Synth. 1946, 26, 90
DOI: 10.15227/orgsyn.026.0090
PYROGALLOL 1-MONOMETHYL ETHER
Submitted by Alexander R. Surrey
Checked by Lee Irvin Smith and Chien-Pen Lo.
1. Procedure
The apparatus consists of a 1-l. three-necked flask fitted with a gas inlet tube extending about 3 cm. into the flask and connected to the flask through a bubbler, a thermometer extending to the bottom, a mechanical stirrer, and a reflux condenser connected at the upper end with an exit tube leading to the hood. The reaction is carried out in an atmosphere of illuminating gas (Note 1).
In the flask are placed 60.8 g. (0.4 mole) of 2-hydroxy-3-methoxybenzaldehyde (Note 2) and 200 ml. of 2 N sodium hydroxide (0.4 mole). The mixture is stirred until almost all the solid has dissolved. The stirrer is replaced by a dropping funnel which contains 284 ml. (0.5 mole) of 6% hydrogen peroxide (Note 3). With occasional shaking, the hydrogen peroxide is added in portions of 20–25 ml. About 1 hour is required for the addition; the temperature is kept between 40° and 50°. After the addition of the first portion of hydrogen peroxide, the temperature rises to about 45° and a dark solution results. The temperature is allowed to fall to 40° before the next portion of the peroxide is added.
After all the hydrogen peroxide is added, the reaction mixture is allowed to cool to room temperature and is then saturated with sodium chloride, after which it is extracted four times with 100-ml. portions of ether. The combined extracts are dried over sodium sulfate. The ether is removed by distillation on a steam bath, and the residue is then distilled under reduced pressure. Pyrogallol monomethyl ether is collected at 136–138°/22 mm. The yield is 38–44.5 g. (68–80%) of a colorless to light yellow oil which solidifies on standing (Note 4).
2. Notes
1.
Nitrogen can be used in place of illuminating gas. The gas is introduced at the rate of about 3 bubbles per second.
2.
Practical
2-hydroxy-3-methoxybenzaldehyde (Eastman Kodak Company) was used in this preparation. Care should be taken when working with this material as its vapors are irritating and will cause sneezing.
3.
The
hydrogen peroxide solution was prepared by diluting
63 g. of a solution containing 27% hydrogen peroxide with water to 284 ml.4.
The procedure described is similar to that of Dakin
1 for the preparation of
catechol.
2 The reaction has been carried out using four times the quantities specified here; the yield was 81% (C. F. H. Allen, private communication).
3. Discussion
Pyrogallol monomethyl ether has been prepared by the methylation of
pyrogallol with
dimethyl sulfate3 or
methyl iodide;
4 by the decarboxylation of
2,3-dihydroxy-4-methoxybenzoic acid;
5 and by the methylation of
pyrogallol carbonate with
diazomethane and subsequent hydrolysis.
6 The method described is taken from the improved procedure of Baker and Savage
7 for the preparation of
pyrogallol monomethyl ether from
o-vanillin by oxidation with
hydrogen peroxide.
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
o-vanillin
ether (60-29-7)
sodium hydroxide (1310-73-2)
sodium chloride (7647-14-5)
sodium sulfate (7757-82-6)
nitrogen (7727-37-9)
dimethyl sulfate (77-78-1)
Catechol (120-80-9)
hydrogen peroxide (7722-84-1)
Methyl iodide (74-88-4)
Diazomethane (334-88-3)
pyrogallol (87-66-1)
pyrogallol monomethyl ether,
Pyrogallol 1-monomethyl ether (934-00-9)
2-hydroxy-3-methoxybenzaldehyde (148-53-8)
2,3-dihydroxy-4-methoxybenzoic acid (3934-81-4)
pyrogallol carbonate
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