acetone

(Ph Eur monograph 0872)




C3H6O 58.08 67-64-1
Ph Eur
DEFINITION
Acetone is propan-2-one.
CHARACTERS
A volatile clear , colourless liquid, miscible with water, with alcohol and with ether. The vapour is flammable.
IDENTIFICATION
A. To 1 ml, add 3 ml of dilute sodium hydroxide solution R and 0.3 ml of a 25 g/l solution of sodium nitroprusside R. An intense red colour is produced which becomes violet with the addition of 3.5 ml of acetic acid R.
B. To 10 ml of a 0.1 per cent V/V solution in alcohol (50 per cent V/V) R, add 1 ml of a 10 g/l solution of nitrobenzaldehyde R in the same solvent and 0.5 ml of strong sodium hydroxide solution R. Allow to stand for about 2 min and acidify with acetic acid R. A greenish-blue colour is produced.
TESTS
Appearance of solution
To 10 ml add 10 ml of water R. The solution is clear (2.2.1) and colourless (2.2.2, Method II).
Acidity or alkalinity
To 5 ml add 5 ml of carbon dioxide-free water R, 0.15 ml of phenolphthalein solution R and 0.5 ml of 0.01 M sodium hydroxide . The solution is pink. Add 0.7 ml of 0.01 M hydrochloric acid and 0.05 ml of methyl red solution R. The solution is red or orange.
Relative density (2.2.5)
0.790 to 0.793.
Related substances
Examine by gas chromatography (2.2.28).
Test solution The substance to be examined.
Reference solution To 0.5 ml of methanol R add 0.5 ml of 2-propanol R and dilute to 100.0 ml with the test solution. Dilute 1.0 ml to 10.0 ml with the test solution.
The chromatographic procedure may be carried out using:
—a fused-silica column 50 m long and 0.3 mm in internal diameter coated with a film (0.5 mm) of macrogol 20 000 R,
— helium for chromatography R as the carrier gas with a split ratio of about 50:1 and at a linear flow of 21 cm/s,
—a flame-ionisation detector,
maintaining the temperature of the column at 45°C until injection, then raising the temperature at a rate of 5°C per minute to 100°C and maintaining the temperature of the injection port at 150°C and that of the detector at 250°C.
Inject 1 ml of the test solution and 1 ml of the reference solution.
When the chromatograms are recorded in the conditions described above, the substances are eluted in the following order: acetone, methanol, 2-propanol.
Continue the chromatography for three times the retention time of acetone (which is about 5.3 min).
The test is not valid unless, in the chromatogram obtained with the reference solution, the resolution between the peaks corresponding to methanol and 2-propanol is at least 1.0.
In the chromatogram obtained with the test solution: the area of any peak corresponding to methanol or 2-propanol is not greater than the difference between the areas of the corresponding peaks in the chromatogram obtained with the reference solution and the areas of the corresponding peaks in the chromatogram obtained with the test solution (0.05 per cent V/V for each impurity); the area of any peak, apart from the principal peak and any peaks corresponding to methanol and 2-propanol, is not greater than the difference between the area of the methanol peak in the chromatogram obtained with the reference solution and the area of the corresponding peak in the chromatogram obtained with the test solution (0.05 per cent V/V for each of the additional impurities).
Matter insoluble in water
To 1 ml add 19 ml of water R. The solution is clear (2.2.1).
Reducing substances
To 30 ml add 0.1 ml of 0.02 M potassium permanganate and allow to stand in the dark for 2 h. The mixture is not completely decolourised.
Residue on evaporation
Evaporate 20.0 g to dryness on a water-bath and dry at 100°C to 105°C. The residue weighs not more than 1 mg (50 ppm).
Water (2.5.12)
Not more than 3 g/l, determined on 10.0 ml by the semi-micro determination of water. Use 20 ml of anhydrous pyridine R as solvent.
STORAGE
Store protected from light.
IMPURITIES
A. CH3-OH: methanol,
B. propan-2-ol.

Ph Eur