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NHOH NOH NOH
The acetophenoneoxime may be isolated by evaporating the mother liquors almost to dryness, adding water repeatedly to remove the alcohol, and then treating the oily residue with 1JV sodium carbonate solution.
1 I’okiut, Her. :w, 2.V20 (l'M)S); Aim. IWlt, 1Ä) (1<M2). See also Fischer, Scheibler, anil (noli, Her. lit, 2024 (²'ËÎ).
4. The melting point varies considerably with the rate and duration of heating. Values ranging from 215° to 231° have been reported in the literature. The product obtained appears to be perfectly stable and shows no tendency to assume the pink coloration reported by Posner.1
3. Methods of Preparation
The procedure described is that given by Posner,1 with some modifications and additions. The amino acid has also been prepared by boiling the oxime hydrate of /3-hydroxylaminohydro-cinnamohydroxamic acid with water;2 and by decarboxylation of /3-amino-/3-phenylethane- a, ct-dicarboxylic acid.3
2C6H5N02 + 4Zn + 8NaOH -»
C6H5N=NC6H5 + 4Na2Zn02 + 4H20
Submitted by H. E. Bigelow and D. B. Robinson.
Checked by W. E. Bachmann and W. S. Struve.
A 5-1. three-necked round-bottomed flask, fitted with a mer-cury-sealed stirrer and a reflux condenser, is placed on a steam cone. In the flask are placed 250 g. (208 cc., 2 moles) of nitrobenzene, 2.5 1. of methanol, and a solution of 325 g. (8.1 moles) of sodium hydroxide (Note 1) in 750 cc. of distilled water. To the mixture is added 265 g. (4.1 moles) of zinc dust (Note 2), the stirrer is started, and the mixture is refluxed for ten hours (Note 3). The mixture is filtered while hot, and the precipitate of sodium zincate is washed on the filter with a little warm
2 Posner, Ber. 40, 227 (1904).
3 Rodionow and Malewinskaja, Ber. 59', 2956 (1926); Rodionow, J. Am. Cliem. Soc. 51, 851 (1929); Evans and Johnson, ibid. 52, 5001 (19.50); Johnson and I.ivak, ibid. 58, 301 (1936).
methanol. All the methanol is distilled from the filtrate, the residue is chilled, and the crystalline azobenzene is filtered.
In order to remove zinc salts from the crude azobenzene, the latter is added to 500 cc. of 2 per cent hydrochloric acid, the mixture is warmed to about 70° in order to melt the azobenzene and is stirred rapidly for about five minutes. Stirring is continued while the mixture is chilled to solidify the azobenzene. The product is filtered, washed well with water, and recrystallized from a mixture of 720 cc. of 95 per cent alcohol and 60 cc. of water. The yield of azobenzene melting at 66-67.5° is 156-160 g. (84-86 per cent of the theoretical amount).
1. This amount assumes 100 per cent purity. The checkers used 342 g. of 95 per cent sodium hydroxide.
2. This amount assumes 100 per cent purity. The checkers used 288 g. of 92 per cent zinc dust.
3. At the end of this time, the reddish mixture should be free from the odor of nitrobenzene. If it is not, refluxing is continued for two to three hours longer.
3. Methods of Preparation
Azobenzene has been prepared in many different ways. The present method of preparation is a modification of the one used by Alexejew.1
1 Alexejew, Z. Chem: 4, 497 (1868).
o-C ARBO XYPHEN YLACETONITRILE (o-Toluic Acid, a-cyano-)
CH2CN ^ /CH2CN
Submitted by Charles C.Price and Richard G. Rogers.
Checked by W. E. Bachmann and Richard D. Morin.
A mixture of 100 g. of phthalide (Note 1) and 100 g. of powdered potassium cyanide is placed in a 2-1. round-bottomed flask fitted with a stirrer and a thermometer. The stirred mixture is heated to 180-190° (internal temperature) for four to five hours in an oil bath (Note 2). One liter of water is added to the cooled mass, and the mixture is stirred until the solid salts are dissolved (Note 3). Any insoluble material which separates is removed by filtration (Note 4). Under a hood, 6 N hydrochloric acid (20-60 cc.) is added to the dark aqueous solution until it becomes turbid (Note 5). The solution is carefully neutralized with sodium bicarbonate (Note 6), a few grams of Norite is added, and the mixture is stirred for several minutes and filtered. The nearly colorless filtrate is acidified with 40-50 cc. of concentrated hydrochloric acid and, after cooling in an ice bath, is filtered with suction. The yield is 80-100 g. (67-83 per cent of the theoretical amount) of white crystals which melt at 113-115° (Note 7).
1. The submitters used phthalide obtained from E. I. du Pont de Nemours and Company, Wilmington, Delaware. The checkers prepared it according to Org. Syn. 16, 71.