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The product may be recrystallized most conveniently by dissolving it as rapidly as possible (Note 3) in 500 cc. of dry toluene
2 Org. Syn., 21, 88.
3 Badger, J. Chem. Soc. 1941, 536.
4 Stephen, J. Chem. Soc. 127, 1874 (1925).
which has been preheated to 80-85°. As soon as the solid is completely dissolved (two to three minutes of stirring), the solution is filtered through a warm Buchner funnel and the filtrate is immediately cooled in an ice-water bath. The yield of very pale yellow glistening needles is 25 to 26 g. (86-89 per cent recovery); they melt at 156° with vigorous decomposition (Note 4).
1. In a parallel experiment in which 25 g. of sodium peroxide was used, the precipitate was not the peroxide but evidently consisted of sodium ^-nitroperbenzoate.
2. ^-Nitrobenzoic acid may be recovered by acidification of the filtrate.
3. Excessive heating during recrystallization leads to extensive decomposition of the peroxide.
4. By a procedure similar to that described for ^-nitrobenzoyl peroxide, the following peroxides have been prepared: æ-nitro-benzoyl peroxide (m.p. 136-137°) in 90 per cent yield; anisoyl peroxide (m.p. 126-127°) in 86-89 per cent yields; />-bromoben-zoyl peroxide (m.p. 144°) in 73 per cent yield; and 3,4,5-tribromo-benzoyl peroxide (m.p. 186°) in 40 per cent yield.1 The procedure is not satisfactory for preparation of acetylsalicylyl peroxide, which is more conveniently prepared by action of hydrogen peroxide upon an acetone solution of the acid chloride.
3. Methods of Preparation
^-Nitrobenzoyl peroxide,2 as well as m-nitrobenzoyl peroxide2 and anisoyl peroxide,3 have been prepared in about 50 per cent yields from the acid chlorides and an acetone solution of hydrogen peroxide, in the presence of a basic substance such as pyridine, sodium acetate, or sodium hydroxide. w-Nitrobenzoyl peroxide has also been prepared by nitration of benzoyl peroxide with cold
1 Price, Kell, and Krebs, J. Am. Chem. Soc. 64, 1104 (1942).
2 Vanino and Uhlfelder, Ber. 33, 1046 (1900).
3 Vanino and Uhlfelder, Ber. 37, 3624 (1904).
PENTAMETHYLENE BROMIDE 67
concentrated nitric acid,4 or with a cold 6 or hot2 mixture of nitric and sulfuric acids.
PENTAMETHYLENE BROMIDE fPentane, 1,6-dibromo-)
H2 Ñ / \
H2C CH2 H2S04
I I + 2HBr -²-Ë ÂÃÑÍ2ÑÍ2ÑÍ2ÑÍ2ÑÍ2ÂÃ + H20
Submitted by D. W. Andrus.
Checked by Nathan L. Drake and Charles M. Eaker.
A hydrobromic acid solution (Org. Syn. Coll. Vol. 1, 1941, 26) is prepared in a 500-cc. round-bottomed flask by passing sulfur dioxide into a mixture of 120 g. (37.7 cc., 0.75 mole) of bromine, 50 cc. of water, and 150 g. of crushed ice. This is equivalent to a mixture of 253 g. (1.5 moles) of 48 per cent hydrobromic acid and 74 g. of concentrated sulfuric acid. To the mixture 21.5 g. (0.25 mole) of tetrahydropyrane (p. 90) is added, a reflux condenser is attached to the flask, and the light brown homogeneous mixture is refluxed for three hours (Note 1).
The heavy lower layer is separated (Note 2), washed once with a saturated solution of sodium bicarbonate, once with water, and then dried over 4-5 g. of anhydrous calcium chloride. The crude product is decanted from the calcium chloride, and the drying agent is rinsed once or twice with a small quantity of ethyl bromide which is added to the main product. The mixture is distilled under reduced pressure, and the pentamethylene bromide,
* Brodie, J. Chem. Soc. 17, 271 (1864).
6 Vanino, Ber. 30, 2004 (1897); Gelissen and Hermans, Ber. 58, 285 (1925).
which weighs 46-47 g. (80-82 per cent of the theoretical amount), is collected at 104-106°/19 mm.
1. The submitter refluxed the mixture for ten hours, but the checkers obtained equally good yields in three hours.
2. The upper aqueous layer contains considerable unchanged hydrobromic acid. If this layer is distilled, about 150 g. (0.9 mole) of constant-boiling hydrobromic acid (b.p. 123-124°/748 mm.) may be recovered.
3. Methods of Preparation
The methods of preparing pentamethylene bromide are given in Org. Syn. Coll. Vol. 1, 1941, 428, where the preparation of the dihalide from benzoylpiperidine and phosphorus pentabromide is described in detail. The procedure given above is based upon the work of Paul.1
a-PHENYLETHYLAMINE (Benzylamine, a-methyl-)
ÑåÍáÑÎÑÍç + NH3 + H2 --a--^0fke’> C6H5CHCH3 + H20
Submitted by John C. Robinson, Jr., and H. R. Snyder.
Checked by Nathan L. Drake and Daniel Draper.