Org. Synth. 1940, 20, 40
DOI: 10.15227/orgsyn.020.0040
DIMETHYLETHYNYLCARBINOL
[3-Butyn-2-ol, 2-methyl-]
Submitted by Donald D. Coffman
Checked by C. F. H. Allen and Alan Bell.
1. Procedure
In a
2-l. round-bottomed flask fitted with a
three-holed stopper bearing a
mechanical stirrer, a
separatory funnel, and a gas outlet tube leading to a
hood (Note 1) are placed
1 l. of anhydrous ether (Note 2) and
156 g. (4 moles) of finely ground sodium amide (p. 778) (Note 3). The flask is surrounded by a well-packed
ice-salt bath. To the vigorously stirred mixture
232 g. (4 moles) of dry acetone (Note 4) is added, dropwise, during a period of 3 hours. With the flask cooled to −10°
(Note 5), a slow current of
acetylene (Note 6) is passed through the reaction mixture for 2 hours to sweep out the
ammonia. The three-holed stopper is then replaced by a two-holed stopper having a stopcock and an inlet tube reaching to the bottom of the flask and connected with a cylinder of
acetylene. The stopper is wired in. The mixture is placed in an ice-salt mixture
(Note 5), the whole being mounted on a shaking machine and agitated vigorously for 10 hours; the mixture is kept under a pressure of 10 lb. of
acetylene. Every 30 minutes the pressure is released by means of the stopcock, to sweep out
ammonia formed from small amounts of previously unreacted
sodium amide.
The reaction mixture is poured cautiously into 800 g. of crushed ice and acidified in the cold by the addition of 400 ml. of 10 N sulfuric acid (Note 7). The ether layer is separated and the aqueous layer extracted twice with 100-ml. portions of ether. The combined ethereal solutions are dried over 100 g. of anhydrous potassium carbonate, and the filtered solution is fractionated (Note 8). The portion boiling at 103–107° is collected; any low-boiling fraction is dried and redistilled. The total yield is 135–155 g. (40–46%) of a colorless product that boils at 103–107° (Note 9), (Note 10), and (Note 11).
2. Notes
1.
In cold weather, it is convenient to carry out the reaction out-of-doors. This minimizes the attention needed to replace the ice. The outlet tube then opens to the air.
2.
A commercial grade of anhydrous
ether was dried over
sodium.
3.
The
sodium amide, moistened by the
heptane, was rapidly ground and the solvent allowed to evaporate.
4.
An Eastman grade of
acetone was used, after standing over anhydrous
potassium carbonate.
5.
It was found convenient to add Dry Ice to the freezing mixture, thus decreasing the frequency of packing. The temperature never rose above −10° and was usually considerably less.
6.
Commercial
acetylene used for welding was dried by passing over anhydrous
calcium chloride.
7.
This is prepared by adding
110 ml. of concentrated sulfuric acid to 290 ml. of water.
8.
The checkers used a
modified Widmer column.
9.
There is a considerable quantity of high-boiling material; the quantity and boiling-point range are greater when the shaking is insufficient.
10.
The reaction may be interrupted at several points. After the
ammonia has been swept out by
acetylene, it is usually convenient to place the mixture in a
refrigerator overnight and start the shaking the next day. The shaking period need not be continuous; in this event the chilled mixture is placed in the
icebox.
11.
By the same procedure the submitter obtained
methylethylethynylcarbinol, b.p.
119–123° (
33% yield), using
methyl ethyl ketone,
1,2 and
1-ethynylcyclohexanol-1, b.p.
53–55°/2 mm. (
50% yield), using
cyclohexanone and double the amount of
ether.
3. Discussion
Dimethylethynylcarbinol has usually been prepared by the addition of
acetylene to the
sodium derivative of
acetone,
3,4,5,6,7,8 but
potassium metal
9 and
sodium ethoxide10 have also been used. The above method is based upon that described by Sung Wouseng.
3 Other methods use
potassium hydroxide with
calcium carbide,
11 or with
acetylene and an immiscible alcohol such as
butanol12 or
amyl alcohol.
13 Dimethylethynylcarbinol has also been prepared by the action of
sodium acetylide on the
bisulfite addition compound of
acetone.
14
A modified procedure, involving the addition of
acetone to
sodium acetylide in liquid
ammonia, has been reported to give a 67% yield.
15The general procedure of Campbell, Campbell, and Eby
16 gives excellent yields of ethynylcarbinols.
This preparation is referenced from:
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
calcium carbide
calcium chloride (10043-52-4)
potassium carbonate (584-08-7)
sulfuric acid (7664-93-9)
acetylene (74-86-2)
ammonia (7664-41-7)
ether (60-29-7)
Cyclohexanone (108-94-1)
butanol (71-36-3)
acetone (67-64-1)
potassium hydroxide (1310-58-3)
sodium (13966-32-0)
sodium ethoxide (141-52-6)
potassium (7440-09-7)
amyl alcohol (71-41-0)
bisulfite (7782-99-2)
methyl ethyl ketone (78-93-3)
sodium amide (7782-92-5)
heptane (142-82-5)
1-ethynylcyclohexanol-1 (78-27-3)
Dimethylethynylcarbinol,
3-Butyn-2-ol, 2-methyl- (115-19-5)
methylethylethynylcarbinol (77-75-8)
sodium acetylide
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