Org. Synth. 1926, 6, 28
DOI: 10.15227/orgsyn.006.0028
DIACETONAMINE HYDROGEN OXALATE
[Diacetonamine, acid oxalate]
Submitted by P. R. Haeseler
Checked by Roger Adams and G. S. Hiers.
1. Procedure
A mixture of
200 g. (2 moles) of mesityl oxide (p. 345) and
280 cc. of aqueous ammonia (27 per cent) is placed in a
1-l. round-bottomed flask which is equipped with an
efficient mechanical stirrer. The stirrer should be inserted through a
stopper in such a way that the flask is nearly air-tight. Because of the heat generated during the reaction it is desirable to keep tap water running over the flask. After stirring for several hours
(Note 1) the system becomes homogeneous. When this point is reached the stirring is discontinued, and the
well-stoppered flask is allowed to stand at room temperature for three days
(Note 2).
Dry air is blown through the solution to remove the excess of ammonia, and the solution is then dissolved in its own volume of absolute alcohol. A sample of this solution is titrated with standard oxalic acid, litmus being used as an outside indicator (Note 3). The amount of oxalic acid (Note 4) necessary to form the acid salt is placed in a large evaporating dish and dissolved in 4 l. of 95 per cent alcohol. The amine solution is then slowly run into the acid with constant stirring. During the addition of the last half of the amine solution, the container must be cooled in order to avoid the formation of the neutral oxalate.
The resulting mixture is then heated on a steam cone or an air bath with constant stirring until the temperature of the mixture reaches 70°. The mixture is filtered, while hot, through a previously heated Büchner funnel. The filtrate is immediately placed in a large beaker or evaporating dish for the crystallization of the diacetonamine hydrogen oxalate (Note 5). The residue is treated with boiling alcohol and filtered, the filtrate containing a small additional quantity of the amine hydrogen oxalate. The mother liquor is distilled until nothing further passes over at 78° (Note 6), and the residue is allowed to stand for a day in a cool place. The crystals that separate are washed with cold absolute alcohol and dried. A total yield of 285–320 g. (63–70 per cent of the theoretical amount) of product that melts at 126–127° is obtained (Note 7).
2. Notes
1.
The time required varies between three and eight hours, and the lower time limit is very materially favored when the reaction is carried out in the sunlight.
2.
The period of three days seems to be the most desirable length of time to allow the reaction mixture to stand; the reaction is not complete in less time and the yields tend to become smaller if a much longer time is employed.
3.
The volume of the diluted amine is usually between 800 and 860 cc. A 10-cc. portion of this may be conveniently drawn off with a
pipette and usually requires from
35 to 50 cc. of 0.5 N oxalic acid.
4.
The end point to litmus occurs when the neutral salt is formed. As the acid salt is desired, twice the amount of
oxalic acid calculated above is used. This is usually between 230 and 260 g.
5.
If the crystals are allowed to remain in contact with the mother liquor for several hours without filtering, they become somewhat dark in color. This color may be removed by washing with hot absolute
alcohol.
6.
The
alcohol recovered in this way may be used as a solvent in subsequent runs. When about
3.5 l. of alcohol has been distilled, the residue gives a small yield (
10–15 g.) of dark crystals which must be washed several times with warm absolute
alcohol to remove most of the color.
7.
The product is entirely free from
triacetonamine,
triacetondiamine, and other troublesome condensation products, thus making its purification very simple. There is, however, a small quantity of
ammonium hydrogen oxalate (1–1.2 per cent) mixed with this salt, but since it offers no difficulty when the product is used for synthetic purposes it is usually ignored. A small amount of
ammonium salt has practically no effect on the melting point. It is possible to get pure
diacetonamine hydrogen oxalate by recrystallizing from absolute
alcohol.
3. Discussion
Diacetonamine can be prepared from a mixture of commercial
acetone and
calcium chloride by treatment with anhydrous
ammonia;
1 from
acetone and
ammonia in the presence of a "promoter" such as
ammonium nitrate;
2 and from
mesityl oxide with aqueous
ammonia3 or liquid
ammonia.
4
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
ammonium salt
Diacetonamine, acid oxalate
alcohol (64-17-5)
calcium chloride (10043-52-4)
ammonia (7664-41-7)
Oxalic acid (144-62-7)
acetone (67-64-1)
DIACETONAMINE HYDROGEN OXALATE (53608-87-0)
Mesityl oxide (141-79-7)
oxalate
amine hydrogen oxalate
triacetonamine
triacetondiamine
ammonium hydrogen oxalate (5972-72-5)
Diacetonamine
ammonium nitrate
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