Organic Syntheses, CV 4, 977
Submitted by Daniel Swern and E. F. Jordan, Jr.
1.
Checked by William S. Johnson and Leland J. Chinn.
1. Procedure
In a
500-ml. round-bottomed three-necked flask provided with a
thermometer, a
reflux condenser, and a
gas inlet tube through which a stream of
nitrogen is passed (Note
1) are placed
206 g. (2.4 moles) of freshly distilled vinyl acetate (Note
2) and
80 g. (0.4 mole) of lauric acid (Note
3). The
lauric acid is dissolved by warming, and
1.6 g. of mercuric acetate is added. The mixture is shaken by hand for about 30 minutes, and
0.15 ml. of 100% sulfuric acid is added dropwise (Note
4). The solution is heated under reflux for 3 hours, then
0.83 g. of sodium acetate trihydrate is added to neutralize the
sulfuric acid. The excess
vinyl acetate is recovered by distillation at atmospheric pressure (vapor temperature about 70–80°) until the pot temperature reaches 125° (Note
5). The distillation is completed at 10 mm. or lower (Note
5), and, after the collection of a small quantity of low-boiling material, fairly pure
vinyl laurate (Note
6) is obtained as a colorless liquid, b.p.
142–143°/10 mm. (
138–139°/8 mm.;
124–126°/3 mm.). The yield is
50–57 g. (
55–63%). Redistillation (Note
7) yields
48–53 g. (
53–59%) of pure
vinyl laurate, b.p.
142–142.5°/10 mm. (
120–120.5°/2 mm.);
n25D 1.4387 (Note
8) and (Note
9).
2. Notes
1. All operations should be conducted in a
nitrogen atmosphere to minimize the formation of polymer.
2. An
Eastman Kodak Company practical grade of vinyl acetate is satisfactory. It was distilled immediately before use through a
48 by
in. column packed with 3/32-in. single-turn Pyrex glass helices. The checkers employed material obtained from the Niacet Chemicals Division, Niagara Falls, New York, distilled once through a
12-in. Vigreux column, b.p.
73°/746 mm.
3.
Lauric acid, m.p. 44°, was prepared from the commercial acid obtained from Armour and Company, Chicago, Illinois. The acid was recrystallized twice from
acetone at −40°
(10 ml. of acetone per gram of acid) and distilled under reduced pressure through a well-insulated, electrically heated
30 by 1 in. column packed with
-in. Berl saddles. Pure
lauric acid has a boiling point of
167–168°/8 mm. and
n45D 1.4316. The
Eastman Kodak Company grade of lauric acid melting at
43–44° is satisfactory.
5. An electrically heated
18 by
in. Vigreux column was employed.
6. The
vinyl laurate, which has an acid number of about 2, usually contains a small quantity of
mercury at this stage, from which it can be separated by decantation.
7. Sufficient
sodium bicarbonate is added to the pot charge to neutralize the free acid present (Note
6).
8. Additional properties of
vinyl laurate are
n35D 1.4345 and
d304 0.8639. If the
iodine number is determined by the Wijs method, a 200% excess of
iodine chloride solution and a 1-hour reaction period should be employed in order to obtain values which are 97–99% of the theoretical value.
9.
Vinyl caproate, caprylate, pelargonate, caprate, myristate, palmitate, stearate, 10-hendecenoate (undecylenate) and oleate can be prepared in a similar manner, except that in the preparation of the
palmitate and
stearate the fatty acids are added to a solution of
mercuric acetate and
sulfuric acid in
vinyl acetate.
Vinyl stearate is not redistilled, but the once-distilled product is recrystallized from
acetone at 0° (
3 ml. of acetone per gram of
vinyl stearate). The amount of
mercuric acetate employed was 2%, and the amount of
100% sulfuric acid was 0.3–0.4%, of the weight of the
stearic acid. Average yields and properties of these vinyl esters are given in the table.
|
Vinyl Ester |
Yield, % |
Boiling Point |
n30D |
d304 |
°C. |
mm. |
|
Caproate |
40 |
98–99 |
100 |
1.4159 |
0.8837 |
Caprylate |
55 |
134–135 |
100 |
1.4256 |
0.8719 |
Pelargonate |
55 |
133–133.5 |
50 |
1.4291 |
0.8689 |
Caprate |
45 |
148 |
50 |
1.4320 |
0.8670 |
Myristate |
60 |
147–148 |
4.8 |
1.4407 |
0.8617 |
Palmitate (m.p. 26.7–27.1°) |
35 |
168–169 |
4.5 |
1.4438 |
0.8602 |
Stearate (m.p. 35–36°) |
30 |
187–188 |
4.3 |
1.4423 (at 40°) |
0.8517 (at 40°) |
10-Hendecenoate |
70 |
124–124.5 |
10 |
1.4442 |
0.8799 |
Oleate |
60 |
178 |
2.8 |
1.4533 |
0.8691 |
|
The acids used for preparing the vinyl esters tabulated were Eastman Kodak Company pure grade except for the following, which were obtained from the companies indicated and purified by fractionation through an
efficient fractionating column:
caproic acid, b.p. 96°/8 mm., Carbide and Carbon Chemicals Corporation, New York;
caprylic acid, b.p.
124–125°/8 mm.,
capric acid, b.p. 145–146°/8 mm., Armour and Company, Chicago, Illinois;
pelargonic acid, b.p. 176°/64 mm., Emery Industries, Cincinnati, Ohio;
10-hendecenoic (undecylenic) acid, b.p. 177–180°/25 mm., Baker Castor Oil Company, New York.
Oleic acid was prepared from olive-oil fatty acids by low-temperature crystallization and distillation.
2
3. Discussion
The procedure described is substantially that of Toussaint and MacDowell,
3 with minor modifications.
4 Vinyl esters of long-chain aliphatic acids have also been prepared by the reaction of
acetylene with the appropriate acids,
5,6,7,8 but this reaction is not so convenient for small-scale laboratory preparations.
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