Acetic Acid → Levodopa

Participants

Reaction Steps

1.8 g of tyrosine, 0.15 g of 9-methylphenazinium methylsulphate are placed into a reactor, dissolved in 1,000 ml of water. The resulting solution is acidified with acetic acid to the reaction medium pH of 4.5 and added with 30 ml of hydrazine hydrate and 5 g of Raney nickel. After filtering-off nickel, the resulting reaction mixture is evaporated to dryness under the pressure of 20 mm Hg, the residue is dissolved in 20 ml of methanol and the mixture is chromatographically separated into alumina and the desired product by eluting with a mixture consisting of n-propanol and a 34% aqueous ammonia taken in the ratio of 70:3. 1.1 g of 3,4-dihydroxyphenylalanine is thus obtained; the yield is 61% as calculated for the starting compound, m.p. of the product is 271°-272° C. The composition, in percent, is as follows:

Provenance & Evidence