A Publication
of Reliable Methods
for the Preparation
of Organic Compounds
Annual Volume
Org. Synth. 1935, 15, 11
DOI: 10.15227/orgsyn.015.0011
Submitted by G. H. Coleman and David Craig.
Checked by John R. Johnson and H. B. Stevenson.
1. Procedure
In a 3-l. three-necked, round-bottomed flask, fitted with a 500-cc. separatory funnel, a liquid-sealed mechanical stirrer, and a reflux condenser, are placed 36.5 g. (1.5 gram atoms) of magnesium turnings and 500 cc. of absolute ether. A solution of 206 g. (1.5 moles) of n-butyl bromide (Org. Syn. Coll. Vol. I, 1941, 28, 37) in 250 cc. of absolute ether is placed in the separatory funnel. The stirrer is started, and 10–15 cc. of the bromide solution is allowed to flow into the flask from the funnel; the reaction generally begins within a few minutes (Note 1). As soon as refluxing is vigorous, the flask is surrounded by ice and water and the rate of addition of the bromide is adjusted so that moderate refluxing occurs. After all the solution has been added (thirty to forty minutes), the cooling bath is removed. Stirring is continued for fifteen minutes longer, after which only a small residue of unreacted magnesium remains.
The flask is cooled in an ice bath and a solution of 55.5 g. (0.75 mole) of pure ethyl formate (Note 2) in 100 cc. of absolute ether is placed in the separatory funnel. The stirrer is started and the ethyl formate solution is added at such a rate that the ether refluxes gently. This addition requires about one-half hour. The cooling bath is then removed and stirring is continued for ten minutes.
With vigorous stirring (Note 3), 100 cc. of water is added through the separatory funnel at such a rate that rapid refluxing occurs. Following this, a cold solution of 85 g. (46 cc., 0.85 mole) of concentrated sulfuric acid in 400 cc. of water is added. After the addition of the acid, the two layers become practically clear. A large part of the ethereal layer is decanted into a 1-l. round-bottomed flask, and the remainder, together with the aqueous layer, is transferred to a separatory funnel. The solid remaining in the flask is washed with two 25-cc. portions of ether, which are added to the material in the separatory funnel. The ethereal layer is separated and combined with the decanted portion. The flask is fitted with an efficient fractionating column, and the ether is distilled from a steam bath until the temperature of the vapor reaches about 50°. To the residual impure carbinol (Note 4) is added 75 cc. of 15 per cent aqueous potassium hydroxide solution and the flask is fitted with a reflux condenser. The mixture is boiled vigorously under reflux for three hours, after which the purified carbinol is removed by steam distillation, the volume in the flask being kept at 250–300 cc. The distillate is collected in a separatory funnel so that the lower aqueous layer can be drawn off periodically. The distillation is complete when about 1.5 l. of water has been collected.
The upper layer of di-n-butylcarbinol is separated and allowed to stand over 10 g. of anhydrous potassium carbonate for one hour. The liquid is decanted into a 500-cc. Claisen flask, and the residual potassium carbonate is washed with three 10-cc. portions of dry ether, which are added to the material in the distilling flask. After removing a small fraction of low-boiling material, there is obtained 90–92 g. (83–85 per cent of the theoretical amount) of pure di-n-butylcarbinol, b.p. 97–98°/ 20 mm. (Note 5).
2. Notes
1. The reaction between the ethereal solution of n-butyl bromide and the magnesium generally starts without any assistance; if necessary, a small amount of a previously prepared Grignard reagent or a crystal of iodine may be used to start the reaction.
2. It is best to use freshly distilled ethyl formate, which may be purified in the following way: To 100 g. of commercial ethyl formate is added 15 g. of anhydrous potassium carbonate, and the mixture is allowed to stand for one hour with occasional shaking. The ester is decanted into a dry 200-cc. flask, and 5 g. of phosphorus pentoxide is added. The flask is provided with an efficient fractionating column, and the ethyl formate is distilled into a receiver protected from atmospheric moisture. A fraction boiling at 53–54° was used in this preparation.
3. During the addition of the water it is necessary to stir efficiently so that the solid which is produced will be precipitated in a finely divided form and not in large aggregates.
4. The formic ester of di-n-butylcarbinol is present as an impurity in the crude product and is hydrolyzed by refluxing with potassium hydroxide solution.
5. Di-n-butylcarbinol can be distilled at atmospheric pressure without appreciable decomposition (b.p. 193–194°/743 mm.) but it is preferable to distil under diminished pressure. The following boiling points were observed under various pressures: 97°/20 mm., 104°/30 mm., 109°/40 mm., 117°/60 mm., 130°/100 mm.
3. Discussion
Di-n-butylcarbinol has been prepared by the action of n-butylmagnesium bromide upon n-valeraldehyde1 and upon ethyl formate.1, 2 It has also been obtained by the catalytic hydrogenation of di-n-butyl ketone in the presence of platinum.3

References and Notes
  1. Malengreau, Bull. acad. roy. Belg. cl. sei. 1906, 802 [C. A. 1, 1970 (1907)].
  2. Dillon and Lucas, J. Am. Chem. Soc. 50, 1713 (1928).
  3. Vavon and Ivanoff, Compt. rend. 177, 453 (1923).

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

potassium carbonate (584-08-7)

sulfuric acid (7664-93-9)

ether (60-29-7)

magnesium turnings (7439-95-4)

n-butyl bromide (109-65-9)

platinum (7440-06-4)

iodine (7553-56-2)

potassium hydroxide (1310-58-3)

ethyl formate (109-94-4)

n-butylmagnesium bromide (693-03-8)


di-n-butyl ketone (502-56-7)

phosphorus pentoxide (1314-56-3)

n-valeraldehyde (110-62-3)