Part 18 (1/2)
~Acetone~ (CH_{3}COCH_{3}), or dimethyl ketone, is formed when iso-propyl alcohol is oxidised with potassium bi+chromate and sulphuric It is also produced in considerable quantities during the dry distillation of wood, and anic compounds Crude wood spirit, which has been freed from acetic acid, consists in the main of a mixture of acetone and hly separated by the addition of calcium chloride, which combines with the methyl-alcohol On subsequent distillation crude acetone passes over, and may be purified by conversion into the bisulphite compound
Acetone is usually prepared, however, by the dry distillation of crude calcium or barium acetate
(CH_{3}COO)_{2}Ca = CH_{3}COCH_{3} + CaCO_{3}
The distillate is fractionated, and the portion, boiling between 50 and 60 C,solution of sodium bisulphite The crystalline cake of acetone sodiu, is well pressed, to free it from impurities, decomposed by distillation with dilute sodium carbonate, and the aqueous distillate of pure acetone dehydrated over calciur 792 at 20 C, it boils at 565 C, has a peculiar, pleasant, ethereal odour, and is mixible ater, alcohol, and ether in all proportions
The acetone used in thespecification:--
SPECIFICATION FOR ACETONE
1 The acetone to be not ravity at 60 F When mixed with distilled water it must show no turbidity, and must leave no residue on evaporation at 212 F On distillation, four-fifths by volume of the quantity taken138 F The residual matter left after this distillation redient that is not a bye-product incidental to the manufacture of acetone
2 One cc of 010 per cent solution in distilled water of pure peranate of potash, added to 100 cc of the acetone, must retain its distinctive colour for not less than 30 minutes This test should be made at a temperature of 60 F
3 The acetone tested by the following method must not show more than 0005 per cent of acid, calculated to acetic acid:--
To 50 cc of the sample diluted with 50 cc of distilled water, with 2 cc of phenol-phthalein solution (1 gramme to 1,000 cc of 50 per cent
alcohol) added as an indicator, add froramme acetic acid), and calculate to acetic acid in the usual manner
The water used for the dilution of the acetone must be carefully tested for acidity, and the pipettes used forshould not be blown out, as it would be possible thus to neutralise nearly 2 cc of the soda solution
The presence of water in a sawitz's method (_Cheether equal volu point, 40 to 60 C), when if present a separation of the liquid in layers will take place
~Estimation of Acetone~--Kebler (_Jour Amer Chem Soc_, 1897, 19, 316- 320) has improved Squibb's modification of Robineau and Rollins'solutions are required:--
(1) A 6 per cent solution of hydrochloric acid
(2) A decinormal solution of sodium thiosulphate
(3) Alkaline potassiurms
of potassiurms of sodium hydroxide (by alcohol) in water, likewisethe latter to stand, 800 cc of the clear solution are added to the litre of KI
(4) Sodiu powder (35 per cent) are mixed with 400 cc of water: to this is added a hot solution of 120 grms of crystallised sodiu, the clear liquid is decanted, the remainder filtered, and the filtrate made up to a litre; to each litre is added 25 cc of sodiur 129)
(5) An aqueous solution of the acetone, containing 1 or 2 per cent of acetone
(6) Bicarbonated starch solution prepared by treating 0125 gr 20 cc of boiling water, boiling a few rms of sodium bicarbonate
To 20 cc of the potassium iodide solution are added 10 cc of the diluted aqueous acetone, an excess of the sodium hypochlorite solution is then run in from a burette and well shaken for a minute The mixture is then acidified with the hydrochloric acid solution, and while agitated, an excess of sodiu afterwards allowed to stand a few minutes The starch indicator is then added, and the excess of thiosulphate re-titrated The relation of the sodiu known, the percentage of acetone can be readily calculated[A]
[Footnote A: See ”The Testing of Acetone,” Conroy, _Jour Soc Chem
Ind_, 31st March 1900, vol xix]
Dr SJM Auld has recently (_Jour Chem Soc_, Feb 15, 1906, vol xxv) worked out a volu on the formation of bromoform, and its subsequent hydrolysis with alcoholic potash The hydrolysis is probably expressed thus--
3CHBr_{3} + 9KOH + C_{2}H_{5}OH = 3CO + C_{2}H_{4} + 9KBr + 7H_{2}O