The invention discloses a preparation method of
prednisone. The method comprises the following steps of: (a) preparing
prednisone by taking a mold
oxide (I) as a starting
raw material, and undergoing a Platts oxidation reaction on the mold
oxide to obtain a Platts substance (II); (b) undergoing a
bromine addition reaction on the Platts substance (II) to obtain a
bromine-added substance (III); (c) undergoing a
bromine removing reaction on the bromine-added substance (III) to obtain a bromine-removed substance (IV); (d) undergoing a 21-bit
iodine addition reaction on the bromine-removed substance (IV) to obtain
prednisone (IV); and (k) undergoing a 21-bit replacement reaction on the substance (XI) obtained in the step (d) to obtain a replacement substance (IV). The preparation method has the advantages that: 1, after
chromium waste water is treated,
chromium can be used repeatedly, and the recovering cost of
acetic acid can be reduced simultaneously; 2, totally-enclosed treatment is performed, waste water is drained after being concentrated, and all
chromium is recovered, so that chromium
pollution is avoided basically, and the concentration of
acetic acid in water is reduced greatly simultaneously; and 3, a method for treating chromium waste water is simple, chromium is qualified, and adverse effects on a reaction are avoided.