Checked by Nathan L. Drake and Ralph Mozingo.
1. Procedure
Caution! The product is toxic. The reaction should be carried out in a hood.
In a
250-ml. Erlenmeyer flask provided with a
two-holed stopper which has a slit cut in one edge to serve as an air vent and which holds a
thermometer, the bulb of which reaches almost to the bottom of the flask, is placed
31.5 g. (0.5 mole) of anhydrous nitric acid (Note
1). The flask is cooled below 10° in ice water, and
51 g. (0.5 mole) of acetic anhydride (Note
2) is slowly added from a
buret through the second hole in the stopper in portions of about 0.5 ml. at a time. The temperature of the reaction mixture is never allowed to rise above 10° (Note
3). After about
5 ml. of the acetic anhydride has been added the reaction becomes less violent, and larger portions, increasing gradually from 1 to 5 ml., may be introduced at a time with constant shaking. After all the
acetic anhydride has been added, the stopper and the thermometer are removed. The neck of the flask is wiped clean with a towel, and the flask is then covered with an inverted
beaker and allowed to come up to room temperature in the original
ice bath (Note
4).
The mixture is allowed to stand at room temperature for 7 days (Note
5), and the
tetranitromethane is separated by pouring the mixture into 300 ml. of water in a
500-ml. round-bottomed flask and steam distilling (Note
6). The
tetranitromethane passes over with the first 20 ml. of the distillate. The heavy product is separated from the upper layer of water, washed first with dilute alkali, finally with water, and dried over anhydrous
sodium sulfate. The yield of
tetranitromethane is
14–16 g. (
57–65%).
The product should not be distilled, as it may decompose with explosive violence. Tetranitromethane must be kept out of contact with aromatic compounds except in
very small test portions, since violently explosive reactions can occur (Note
7).
2. Notes
1. The anhydrous
nitric acid (sp. gr. > 1.53) is most easily obtained by slowly distilling ordinary fuming
nitric acid from its own bulk of concentrated
sulfuric acid. If ordinary concentrated
nitric acid (sp. gr. 1.42) is used, it is advisable to distil twice from equal volumes of
sulfuric acid. A
technical grade of fuming nitric acid having a specific gravity of 1.60 was found to give satisfactory yields when used without further treatment; but an equivalent amount of a weaker commercial acid, corresponding to
98% nitric acid by gravity, gave considerably lower yields. The use of more than the calculated amount of
nitric acid decreases the yield of
tetranitromethane.
3. If the flask is not cooled, the reaction proceeds more and more vigorously as the temperature rises and may, if unchecked, become violent.
4. If the flask is removed from the ice bath after the addition of the anhydride, and allowed to stand at room temperature, the reaction may become violent with great loss of product.
5. The yield is only
35% after 2 days and no greater than
65% after 10–15 days. If it should be necessary to obtain the product in shorter time, the reaction mixture may be allowed to stand at room temperature for 48 hours and then slowly heated to 70° during an interval of 3 hours and maintained at 70° for 1 hour longer before pouring into water. The yield of a run carried out in this way was, according to the submitter,
40%.
6. It is most convenient to use a
50-ml. graduated separatory funnel as the receiver during the steam distillation, if it is desired to estimate roughly the yield of
tetranitromethane, the density of which is 1.65 at 15°.
7.
Tetranitromethane is a valuable reagent for detecting the presence of double bonds, especially those which do not give the ordinary reactions of such linkages.
1
3. Discussion
The procedure described is essentially that of Chattaway.
2 Tetranitromethane has also been prepared by nitrating
nitroform,
3 from
acetic anhydride by the action of
diacetylorthonitric acid,
4 from
iodopicrin and
silver nitrite,
5 from
acetyl nitrate by heating with
acetic anhydride or
glacial acetic acid,
6 from
nitrobenzene by distilling with a mixture of
nitric acid and fuming sulfuric acid,
7 by adding
acetic anhydride to
nitrogen pentoxide or a mixture of
nitrogen pentoxide and nitrogen peroxide,
8 by the action of
acetic anhydride on highly concentrated
nitric acid,
9 from
toluene by nitration,
10 from
acetylene by the action of
nitric acid,
11 from
nitrobenzene and a mixture of nitric and fuming nitric acids,
12 and from
acetylene and
ethylene by the action of
nitric acid in the presence of a catalyst.
13
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