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Org. Synth. 1930, 10, 4
DOI: 10.15227/orgsyn.010.0004
n-AMYLBENZENE
[Benzene, amyl-]
Submitted by Henry Gilman and J. Robinson.
Checked by C. S. Marvel and S. S. Rossander.
1. Procedure
One mole of benzylmagnesium chloride is prepared in a 2-l. three-necked, round-bottomed flask from 24.3 g. (1 gram atom) of magnesium turnings, 126.5 g. (115 cc., 1 mole) of benzyl chloride, and 500 cc. of anhydrous ether, according to the directions given in Org. Syn. Coll. Vol. I, 1941, 471.
The solution of benzylmagnesium chloride is cooled with running water, and 456 g. (2 moles) of n-butyl p-toluenesulfonate (Note 1) dissolved in about twice its volume of anhydrous ether is then added slowly with stirring through the separatory funnel at such a rate that the ether just boils. The time required for the addition is about two hours. A white solid soon forms and the mixture assumes the consistency of a thick cream. Stirring is continued, without cooling, for about two hours, and the mixture is hydrolyzed by pouring onto crushed ice to which is then added about 125 cc. of concentrated hydrochloric acid (Note 2).
The ether layer is separated and combined with a 200-cc. ether extract of the aqueous layer. The combined ether solution is washed once with about 100 cc. of water and then dried by shaking for a few minutes with about 10 g. of anhydrous potassium carbonate. After filtration, the ether is distilled on a water bath. When practically all the ether has been removed, about 5 g. of sodium, freshly cut and in thin slices, is added and the mixture is boiled for about two hours (Note 3). The solution is decanted and then distilled, using an efficient fractionating column. The fraction boiling at 190–210° is collected. This on redistillation yields 74–88 g. (50–59 per cent of the theoretical amount) of n-amylbenzene boiling at 198–202° (Note 4).
2. Notes
1. Directions for the preparation of n-butyl p-toluenesulfonate are given in Org. Syn. Coll. Vol. I, 1941, 145, and in Org. Syn. 20, 51.
2. The hydrolysis is preferably carried out in a 5-l. Erlenmeyer flask. The magnesium p-toluenesulfonate is sparingly soluble in hydrochloric acid, and complete solution is brought about by the subsequent addition of about 2 l. of water.
3. Refluxing with sodium helps to remove the small amount of benzyl alcohol formed by the atmospheric oxidation of benzylmagnesium chloride.
4. The major part of the n-amylbenzene distils at 199–201°. A careful fractionation of the distillate that comes over around 75° yields 24 g. (26 per cent of the theoretical amount) of n-butyl chloride boiling at 76–80°.
3. Discussion
n-Amylbenzene has been prepared by the action of sodium on a mixture of benzyl and butyl bromides;1 by the reaction between benzyl sodium and butyl chloride;2 by the reduction of n-valerophenone with formic acid over copper at 300°,3 or with zinc and hydrochloric acid;4 by the action of sodium ethoxide on the hydrazone5 and the semicarbazone6 of n-valerophenone; and by the procedure described, which is an adaptation of the directions of Gilman and Heck7 and Rossander and Marvel.8

References and Notes
  1. Schramm, Ann. 218, 388 (1883).
  2. Morton and Fallwell, Jr., J. Am. Chem. Soc. 60, 1429 (1938).
  3. Mailhe and de Godon, Bull. soc. chim. (4) 21, 62 (1917).
  4. Stenzl and Fichter, Helv. Chim. Acta 17, 677 (1934).
  5. Schmidt, Hopp, and Schoeller, Ber. 72, 1893 (1939).
  6. Ziegler, Dersch, and Wollthan, Ann. 511, 38 (1934).
  7. Gilman and Heck, J. Am. Chem. Soc. 50, 2223 (1928).
  8. Rossander and Marvel, ibid. 50, 1491 (1928).

Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)

benzyl and butyl bromides

hydrazone

semicarbazone

potassium carbonate (584-08-7)

hydrochloric acid (7647-01-0)

ether (60-29-7)

magnesium turnings (7439-95-4)

formic acid (64-18-6)

copper (7440-50-8)

zinc (7440-66-6)

sodium (13966-32-0)

sodium ethoxide (141-52-6)

benzyl chloride (100-44-7)

Benzyl alcohol (100-51-6)

Butyl chloride,
n-BUTYL CHLORIDE (109-69-3)

benzylmagnesium chloride (6921-34-2)

Benzene, amyl-,
n-AMYLBENZENE (538-68-1)

benzyl sodium

n-valerophenone (1009-14-9)

n-BUTYL p-TOLUENESULFONATE (778-28-9)

magnesium p-toluenesulfonate