A Publication
of Reliable Methods
for the Preparation
of Organic Compounds
Annual Volume
Org. Synth. 1935, 15, 27
DOI: 10.15227/orgsyn.015.0027
Submitted by P. A. Levene
Checked by W. W. Hartman, L. A. Smith, and J. B. Dickey.
1. Procedure
In a 2-l. round-bottomed flask, fitted with a liquid-sealed mechanical stirrer, a gas inlet tube, and a tube to carry off hydrogen chloride and acetic acid vapors (Note 1), are placed 915 cc. of glacial acetic acid, 327 g. (5 gram atoms) of zinc dust, and 352 g. (1 mole) of cetyl iodide (m.p. 20–22°) (p. 322). The mixture is saturated with dry hydrogen chloride and then stirred and heated on a steam bath. At the end of every five hours of heating, the mixture is again saturated with hydrogen chloride. After the reaction has proceeded for twenty-five hours, the mixture is allowed to cool, and the layer of hexadecane, which rises to the top of the reaction mixture, is separated. The residue is poured into 3 l. of water and filtered on a Büchner funnel to remove the zinc dust. The zinc dust is washed with 500 cc. of water and then with 250 cc. of ether. The combined water layers are extracted with two 500-cc. portions of ether. The ether extracts are combined and added to the hexadecane, and the resulting solution is washed with two 250-cc. portions of 20 per cent sodium hydroxide and then with water until free of alkali. The ether solution is dried with 150 g. of anhydrous sodium sulfate, filtered, and distilled from a 500-cc. modified Claisen flask with a fractionating side arm. The yield of n-hexadecane boiling at 156–158°/14 mm. and melting at 16–17° is 192 g. (85 per cent of the theoretical amount).
2. Notes
1. If the reaction is run in a hood, an open flask may be used.
3. Discussion
n-Hexadecane has been prepared by the reduction of cetyl iodide with zinc and hydrochloric acid in alcohol1 or acetic acid,2, 3 with the zinc-copper couple,3 and with hydrogen and a palladium catalyst.3 The hydrocarbon has also been prepared by treating octyl iodide with sodium;4 by heating mercury dioctyl alone or with zinc dust;5 by heating palmitic acid with hydriodic acid and red phosphorus;6 and by reducing 1-hexadecene.7
n-Hexadecane has been obtained as a by-product from the preparation of octylmagnesium bromide8 and from the action of sodium on a mixture of octyl bromide and ethyl bromide,9 and it is one of the products formed on heating sodium stearate10 or cetyl ether.11

References and Notes
  1. Sorabji, J. Chem. Soc. 47, 38 (1885).
  2. Levene, West, and van der Scheer, J. Biol. Chem. 20, 523 (1915).
  3. Carey and Smith, J. Chem. Soc. 1933, 346.
  4. Zincke, Ann. 152, 15 (1869).
  5. Eichler, Ber. 12, 1882 (1879).
  6. Krafft, ibid. 15, 1701 (1882).
  7. Wibaut and collaborators, Rec. trav. chim. 58, 360 (1939).
  8. v. Braun, Deutsch, and Schmatloch, Ber. 45, 1254 (1912).
  9. Lachowicz, Ann. 220, 180 (1883).
  10. Grün and Wirth, Ber. 53, 1310 (1920).
  11. Oddo, Gazz. chim. ital. 31 (I) 346 (1901).

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

red phosphorus

zinc-copper couple

mercury dioctyl

hydrogen chloride,
hydrochloric acid (7647-01-0)

acetic acid (64-19-7)

ether (60-29-7)

hydrogen (1333-74-0)

sodium hydroxide (1310-73-2)

Ethyl bromide (74-96-4)

Octyl bromide (111-83-1)

sodium sulfate (7757-82-6)

zinc (7440-66-6)

sodium (13966-32-0)

palladium (7440-05-3)

hydriodic acid (10034-85-2)

cetyl iodide (544-77-4)

n-HEXADECANE (544-76-3)

octyl iodide (629-27-6)

palmitic acid (57-10-3)

1-hexadecene (629-73-2)

octylmagnesium bromide (17049-49-9)

sodium stearate (822-16-2)

cetyl ether (4113-12-6)