Org. Synth. 1931, 11, 98
DOI: 10.15227/orgsyn.011.0098
[3-Pentanol, 3-ethyl-]
Submitted by W. W. Moyer and C. S. Marvel.
Checked by Frank C. Whitmore and D. J. Loder.
1. Procedure
In a 3-l. three-necked flask, fitted with a mechanical stirrer, a 500-cc. separatory funnel, and an efficient reflux condenser to which a calcium chloride tube is attached, are placed 107 g. (4.4 gram atoms) of magnesium turnings and 800 cc. of anhydrous ether. The reaction is started by adding 5 cc. (7 g., 0.06 mole) of ethyl bromide (Note 1) without stirring. The stirrer is started, and a solution of 480 g. (4.4 moles) of ethyl bromide in 1 l. of anhydrous ether is added as rapidly as the refluxing of the ether allows. The addition requires about two hours (Note 2). The reaction is practically complete when all the halide has been added, but stirring should be continued for fifteen minutes longer.
A solution of 156 g. (1.32 moles) of ethyl carbonate (Note 3) in 200 cc. of ether is added to the Grignard reagent, with rapid stirring, over a period of approximately three hours. The reaction is vigorous, and the ether refluxes continually. After all the diethyl carbonate has been added, the flask is heated on a water bath and stirring is continued for another hour.
The reaction mixture is hydrolyzed by pouring it, with frequent shaking, into a 5-l. round-bottomed flask containing 1.5 kg. of cracked ice and a solution of 300 g. of ammonium chloride in 600 cc. of water. The ether layer is separated in a large separatory funnel, and the aqueous residue is extracted with two 500-cc. portions of ether (Note 4).
The ether is distilled from the combined extracts, and the crude triethyl carbinol is dried with 10 g. of anhydrous potassium carbonate. The alcohol is then distilled at atmospheric pressure, and the portion (80–90 g.) boiling at 139–142° is collected. The low-boiling distillate is treated with 5 g. of anhydrous potassium carbonate, filtered, and redistilled, whereby another portion (about 25 g.) of triethyl carbinol boiling at 139–142° is obtained. The process is repeated once, or twice if necessary, and an additional 20 g. is collected (Note 5). The total yield is 125–135 g. (82–88 per cent of the theoretical amount) (Note 6). Triethyl carbinol is a viscous liquid with a penetrating, camphor-like odor.
2. Notes
1. The ethyl bromide used in this preparation was dried over calcium chloride and then distilled from phosphorus pentoxide. The fraction boiling at 38–39° was collected. Directions for preparing ethyl bromide are given in Org. Syn. Coll. Vol. I, 1941, 29, 36.
2. The time of addition may be decreased by cooling the flask externally. A towel is folded in a narrow strip and wrapped about the flask above the ether line, and cracked ice is packed on top of the flask. This arrangement allows the ether vapor to be condensed without appreciable cooling of the reaction mixture.
3. The commercial "99 per cent" ester was used. It was purified according to the description given in Note 2 on p. 283 above.
4. The ether used for extraction may be obtained by distilling the ether from the triethyl carbinol solution.
5. In checking this preparation the first drying was allowed to continue for fifteen hours. The first fractionation of the carbinol yielded 122 g., the second 10 g., and the third yielded none.
6. The preparation of homologous trialkyl carbinols by use of the Grignard reagent and ethyl carbonate was found to be very satisfactory. The following compounds were prepared: tri-n-propyl carbinol (b.p. 89–92°/20 mm.) in 75 per cent yield; tri-n-butyl carbinol (b.p. 129–131/20 mm.) in 84 per cent yield; tri-n-amyl carbinol (b.p. 160–164°/19 mm.) in 75 per cent yield; and tri-n-heptyl carbinol (b.p. 195–200°/6 mm.) in 72 per cent yield.
3. Discussion
Triethyl carbinol has been prepared by the action of zinc on a mixture of ethyl iodide and diethyl ketone;1 by the action of magnesium on ethyl bromide in diethyl ketone solution;2 by the action of sodium and ethyl bromide on diethyl ketone or ethyl propionate;3 as a by-product in the reaction between ethylmagnesium bromide and carbon oxysulfide;4 and by the action of ethylmagnesium bromide on ethyl propionate,5 ethyl chloroformate, 6 ethyl cyanoformate, 7 or ethyl carbonate.8

References and Notes
  1. Barataeff and Saytzeff, J. prakt. Chem. (2) 34, 463 (1886).
  2. Davies and Kipping, J. Chem. Soc. 99, 298 (1911).
  3. Morton and Stevens J. Am. Chem. Soc. 53, 2247 (1931).
  4. Weigert, Ber. 36, 1009 (1903).
  5. Schreiner, J. prakt. Chem. (2) 82, 295 (1910); Böeseken and Wildschut, Rec. trav. chim. 51, 169 (1932).
  6. Mazurewitsch, J. Russ. Phys.-Chem. Soc. 42, 1582 (1910) (Chem. Zentr. 1911, I, 1500).
  7. Bruylants, Bull. soc. chim. Belg. 33, 529 (1924).
  8. Whitmore and Badertscher, J. Am. Chem. Soc. 55, 1560 (1933).

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

carbon oxysulfide

Grignard reagent

calcium chloride (10043-52-4)

potassium carbonate (584-08-7)

ether (60-29-7)

ammonium chloride (12125-02-9)

magnesium turnings (7439-95-4)

Ethyl bromide (74-96-4)

zinc (7440-66-6)

sodium (13966-32-0)

ethyl chloroformate (541-41-3)

ethylmagnesium bromide (925-90-6)

Ethyl iodide (75-03-6)

ethyl carbonate

ethyl propionate (105-37-3)

ethyl cyanoformate (623-49-4)

3-Pentanol, 3-ethyl- (597-49-9)

diethyl carbonate (105-58-8)

diethyl ketone (96-22-0)

phosphorus pentoxide (1314-56-3)

tri-n-propyl carbinol (2198-72-3)

tri-n-butyl carbinol (597-93-3)

tri-n-amyl carbinol

tri-n-heptyl carbinol