Proresid,Sandoz,W. Germany,1966
500 g of podophyllinic acid hydrazide are heated together with 150 cc of
acetaldehyde with 2,200 cc of methanol to 40°C. The solution obtained is
filtered and then cooled. The product which crystallizes out is filtered off with
suction and washed with methanol. Together with a second fraction obtained
after concentration of the mother liquors there are produced 450 g of
podophyllinic acid ethylidene hydrazide, having a melting point of 222°C to
224°C and a specific rotation of [α]D = -285° (c. = 0.5 in ethanol).
The product is hydrogenated in 4,000 cc of ethanol at room temperature and
under normal atmospheric pressure with a catalyst prepared in the usual
manner from 400 g of Raney nickel alloy. The calculated amount of hydrogen
is taken up in approximately 75 hours. After filtration and evaporation to a
small volume, the residue is distributed between 1,000 cc of chloroform and
water each. The chloroform solution is then dried over sodium sulfate and
evaporated toa small volume. Precipitation of the hydrogenation product with
petroleum ether yields an amorphous white powder which is filtered by
suction, washed with petroleum ether and dried at 50°C in a high vacuum. 1-
ethyl-2-podophyllinic acid hydrazide is obtained in a practically quantitative
yield.
