Org. Synth. 1941, 21, 56
DOI: 10.15227/orgsyn.021.0056
2-HYDROXY-1,4-NAPHTHOQUINONE
[1,4-Naphthoquinone, 2-hydroxy-]
Submitted by L. F. Fieser and E. L. Martin.
Checked by Reynold C. Fuson and E. A. Cleveland.
1. Procedure
One liter of absolute methanol is cooled in a
3-l. round-bottomed flask to 0° in an
ice-salt bath, and
80 ml. of concentrated sulfuric acid is slowly added, with good shaking, the temperature being kept at 0°. The flask is removed from the freezing mixture, and
255 g. (1 mole) of ammonium 1,2-naphthoquinone-4-sulfonate (p. 633) is added and made into an even paste by thorough shaking. After standing for 30 minutes, during which time the temperature rises to 15–20°, the flask is heated gradually on the
steam bath with continuous shaking and rotating so that the solution reaches its boiling point in about 15 minutes. The solution becomes red,
sulfur dioxide is evolved, and
methoxynaphthoquinone begins to separate. The mixture is kept boiling very gently, with continued shaking, for 15 minutes, when the paste of separated material becomes very stiff.
Two hundred and fifty milliliters of methanol is added, and the heating and rotating continued for an additional 15–20 minutes. The reaction mixture is cooled to 20–25°, water and ice are added until the flask is nearly filled, and the
methoxynaphthoquinone is collected on a
15-cm. Büchner funnel and washed with cold water until the filtrate is nearly colorless; about 2–2.5 l. of water is required
(Note 1).
The moist material is washed into a solution of 30 g. of sodium hydroxide in 1.5 l. of water, and the mixture is heated rapidly nearly to the boiling point. In about 10 minutes all the ether is hydrolyzed and a deep red solution results (Note 2). The hot solution is filtered by suction from a trace of residue, transferred to a 2-l. beaker, and acidified while still hot by adding 130 ml. of 6 N hydrochloric acid slowly, and with good stirring. The yellow suspension of hydroxynaphthoquinone thus obtained is cooled to 0° and allowed to stand for 2 hours (Note 3). The hydroxynaphthoquinone is collected, washed with 2 l. of cold water, dried overnight at room temperature, and finally to constant weight at 60–80°. The yield is 101–112 g. (58–65% based on ammonium 1,2-naphthoquinone-4-sulfonate; 99%, based on methoxynaphthoquinone) (Note 4). The hydroxynaphthoquinone thus obtained is bright yellow, is granular, and melts, with decomposition, at about 188–189° (Note 5). It is of high quality and for ordinary uses requires no further purification (Note 6).
2. Notes
1.
The
methoxynaphthoquinone weighs
111–122 g. (
59–65%). It melts at
181–182° and can be further purified by crystallization from
ethanol. The pure substance forms pale yellow needles, m.p.
183.5°.
2.
Should the sodium salt separate during the heating or filtration, it is brought into solution by adding about 1 l. of water and heating.
3.
By allowing the precipitate to stand for the indicated period, the final product is granular, and the filtration is rapid.
4.
Numerous modifications have been tried without improving the yield. The loss is probably due to a partial reduction of the quinone sulfonate by the
sulfur dioxide liberated, but this was not prevented by adding
manganese dioxide to the reaction mixture and no pure product could be obtained from the mother liquor.
5.
The temperature of decomposition varies with the rate of heating and with the nature of the glass capillary.
6.
Crystallization from
ethanol containing a trace of
acetic acid gives glistening yellow needles, melting with decomposition at about
191–192°. The red samples of
hydroxynaphthoquinone often mentioned in the literature are not completely pure. Such material, or crude material of any kind, is best purified through either the sodium salt or the
methyl ether.
3. Discussion
Of the many reactions by which
hydroxynaphthoquinone has been obtained,
1,2 two have been developed into practical preparative methods, and both utilize the inexpensive
β-naphthol as the primary starting material. In the first method, this is converted into
β-naphthoquinone [Org. Syntheses Coll. Vol. 2, 430 (1943)], which reacts with
acetic anhydride-sulfuric acid to give
1,2,4-trihydroxynaphthalene triacetate, which is then hydrolyzed and oxidized to the desired product. The yield of the acetylation reaction is about
75%; that in the final step can be brought to
93% of the theoretical amount by hydrolyzing with ethanolic alkali in an atmosphere of
nitrogen and with a trace of
sodium hydrosulfite present, then diluting with water, acidifying, and adding
ferric chloride. The overall yield from
β-naphthol can thus be brought to
54%. The method is a good one, and it can be used to advantage for the preparation of many similar hydroxyquinones. With ordinary laboratory equipment, however, one is limited to 0.5 mole runs, and not more than about
50 g. of
hydroxynaphthoquinone can be prepared at a time.
The second method is that described above:
β-naphthol is converted through the nitroso derivative and
1-amino-2-naphthol-4-sulfonic acid into
naphthoquinone sulfonate, and this is subjected to acid hydrolysis. The sulfonate can be converted directly into
hydroxynaphthoquinone by the action of concentrated
sulfuric acid,
3,4 but the process is not so easily controlled as when the quinone is etherified as it is formed and the
ether subsequently hydrolyzed.
4 The overall yield from
β-naphthol is
46% of the theoretical amount, but all the reagents are inexpensive, and with ordinary apparatus,
150 g. of
hydroxynaphthoquinone can be made conveniently in one run (from
300 g. of β-naphthol).
The compound has also been prepared in good yield by air oxidation of
1,3-dihydroxynaphthalene,
5 which in turn was obtained from
ethyl γ-phenylacetoacetate.
6
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
ethanol (64-17-5)
sulfuric acid (7664-93-9)
hydrochloric acid (7647-01-0)
acetic acid (64-19-7)
methanol (67-56-1)
ether (60-29-7)
sodium hydroxide (1310-73-2)
sulfur dioxide (7446-09-5)
nitrogen (7727-37-9)
sodium hydrosulfite (7775-14-6)
β-naphthol (135-19-3)
methyl ether (115-10-6)
manganese dioxide (1313-13-9)
ferric chloride (7705-08-0)
1-AMINO-2-NAPHTHOL-4-SULFONIC ACID (116-63-2)
ethyl γ-phenylacetoacetate
β-naphthoquinone (524-42-5)
2-Hydroxy-1,4-naphthoquinone,
1,4-Naphthoquinone, 2-hydroxy-,
hydroxynaphthoquinone (83-72-7)
ammonium 1,2-naphthoquinone-4-sulfonate (53684-60-9)
methoxynaphthoquinone (2348-82-5)
acetic anhydride-sulfuric acid
1,2,4-trihydroxynaphthalene triacetate
naphthoquinone sulfonate
1,3-dihydroxynaphthalene (132-86-5)
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