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Organic syntheses vol 22 - Smith L.I.

Smith L.I., Adkins H. Organic syntheses vol 22 - John Willey, 1942. - 60 p.
Download (direct link): organicsynthesesvol221942.pdf
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2. Nbtes
1. The dilution is conveniently carried out by dividing the mixture among seven 3-gal. earthenware crocks.
2. The filtration can be performed by siphoning the mixture from the crocks through an 18.5-cm. Buchner funnel fitted to a 12-1. flask attached to a suction pump.
3. A fourth extraction with 500 cc. of chloroform gives only an additional 4 g. of product.
4. Dioxane is an excellent solvent for cleaning the flasks and crocks used in this first step.
5. This product is pure enough for most purposes. Pure white needles, melting at 117-118, may be obtained by repeating the crystallization from the chloroform-petroleum ether mixture. The recovery is about 89-90 per cent.
3. Methods of Preparation
The action of alcoholic potassium cyanide on m-dinitroben-zene was first studied by Lobry de Bruyn.1 The present method . is a modification of the procedure described by Mauthner.2
1 Lobry de Bruyn, Rec. trav. chim. 2, 205 (1883).
2 Mauthner, J. prakt. Chem. (2) 121, 259 (1929).
2,3- YLANTHRAQUIN ONE
37
2,3-DIMETHYLANTHRAQUINONE (Anthraquinone, 2,3-dimethyl-)

+

o2
ale.

II
^Av/

Submitted by . F. H. Allen and Alan Bell.
Checked by R. L. Shriner and John C. Robinson, Jr.
1. Procedure
A solution of 80 g. (0.5 mole) of 1,4-naphthoquinone (Org. Syn. Coll. Vol. 1, 1st Ed. (1932), p. 375; 2nd Ed. (1941)-,'p. 383) and 80 g. (1 mole) of 2,3-dimethylbutadiene-l,3 (p. 39) in 300 cc. of alcohol is refluxed for five hours, using a 1-1. round-bottomed flask and an efficient reflux condenser. The solution is cooled and placed in a refrigerator for ten to twelve hours. The crystalline mass is then broken up with a spatula, and the addition product is filtered and washed with 50 cc. of cold alcohol. The product forms white feathery crystals melting at 147-149 (Note 1). The yield is 116 g. (96 per cent of the theoretical amount based on the 1,4-naphthoquinone).
For the dehydrogenation, 40 g. of the addition product is dissolved in 600 cc. of 5 per cent alcoholic potassium hydroxide solution (Note 2) in a 1-1. three-necked flask equipped with a reflux condenser and inlet tube. A current of air is bubbled through
38
ORGANIC SYNTHESES
the solution for twenty-four hours; considerable heat is generated, and the initial green color soon changes to yellow. The yellow quinone that has separated is then filtered with suction and is washed, first with 200 cc. of water, then with 100 cc. of alcohol, and finally with 50 cc. of ether. The yield of air-dried product (m.p. 209-210) is 36.5-37.5 g. (94-96 per cent of the theoretical amount) (Note 3). The over-all yield for both steps is 90 per cent (Note 4).
2. Notes
1. The addition product is usually pure enough for the next step. It may be purified by recrystallization from acetone, ethyl alcohol, or methyl alcohol, and then it melts sharply at 150. If the crude product is deeply colored, it should be recrystallized, using a decolorizing carbon.
2. This is prepared by dissolving 30 g. of potassium hydroxide in 570 g. of 95 per cent ethyl alcohol.
3. The melting points given in the literature vary from 183 1 to 208 2.
4. Essentially the same percentage yield has been obtained using three times the amounts given.
3. Methods of Preparation
2,3-Dimethylanthraquinone has been obtained by ring closure of the corresponding o-benzoylbenzoic acid;11 2| 3 by oxidation of the corresponding anthrone;4 from 2-chloro- and 2,3-dichloro-l,4-naphthoquinone and 2,3-dimethylbutadiene-l,3 by the action of sodium hydroxide; 5 and from 2-methyl-l,4-naphthoquinone and
2,3-dimethylbutadiene-l,3 with subsequent dehydrogenation by sulfur.6 The addition product obtained by this procedure, but using a large excess of hydrocarbon, has been described recently.7
1 Elbs and Emich, Ber. 20, 1361 (1887); J. prakt. Chem. (2) 41, 6 (1890).
Heller, Ber. 43, 2891 (1910).
3 Fairbourne, J. Chem. Soc. 119, 1573 (1921).
4Limpricht and Martens, Ann. 312, 103 (1900).
61. G. Farbenind. A-G., Ger. pat. 500,160 [Frdl. 17, 1143 (1932); C. A. 24, 4790
(1930)].
6 Fieser and Seligman, J. Am. Chem. Soc. 56, 2690 (1934).
7 Fieser and Webber, J. Am. Chem. Soc. 02, 1362 (1940).
2,3-DIMETHYLBUTADTENE-l,3
39
2,3-DIMETHYLBUTADIENE-l ,3 (1,3-Butadiene, 2,3-dimethyl-)
(A) Hydrobromic Acid Method
OH
I
CH3їCH3 C=CH2
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