It is not necessary to wash the crystals in the centrifuge until
they are white. A small amount of chromic salt will not interfere
with the subsequent purification.

Commercial sodium dichromate is hygroscopic and contains varying
amounts of water. The 375 g. required in these directions are
equivalent to 319 g. of anhydrous material.

The total time required for the oxidation is twenty-four hours.
It is convenient to start the reaction in the morning.
In this way the last part of the reaction, which requires
no attention, will be accomplished during the night.
The regulation of the temperature is necessary, as the reaction
proceeds very slowly below 20'0; on the other hand, the dichloroacetone
itself is oxidized at a somewhat higher temperature than 25'0. 3.
Other Methods of Preparation

The preparation of dichloroacetone by the following methods
is described in the literature: the direct chlorination of
acetone;[1] the oxidation of dichlorohydrin;[2] the action of silver
chloride on diiodoacetone;[3] the action of dichloropropene
(CH2Cl-CCl=CH2) and hypochlorous acid;[4] the action of hydrochloric
acid on ethoxymonochloroacetoacetic ester;[5] and the hydrolytic
cleavage of dichloroacetoacetic ester.[6]


[1] Jahresb. 1859, 345; 1871, 531; J. prakt. Chem. (2)4, 52
(1871); Ber. 7, 467 (1874); 8, 1330, 1438 (1875); 26, 598
(1893); 42, 3233 (1909); Ann. 279, 315 (1894)