Ammonia → 2-Chloro-4,5-dihydroxyphenylglycine

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Reaction Steps

Aqueous ammonia (Sp.Gr 0.88, 37.5 ml) was added dropwise to an ice bath cooled 50% w/v aqueous glyoxylic acid solution (11.25 ml) at <10°. When the addition was complete the solution was heated at 50° for 15 minutes, 4-chlorocatechol (21.7 g) and more aqueous ammonia (12.5 ml) added, then heated at 60° for 4 hours. The solution was allowed to cool, reduced to ca. half volume in vacuo, washed with ethyl acetate (3×40 ml), adjusted to pH 5.5(conc, HCl) and set aside at 0° overnight. The solid was collected, washed with water and methanol, then dried, 2.76 g. The crude product was suspended in water (30 ml), conc. hydrochloric acid added to give a clear solution, treated with decolourising charcoal, filtered, adjusted to pH 5.5(40% sodium hydroxide solution) and left to crystallise at 0°. The product was collected, washed with water and acetone then dried, 2.53 g, 16% δ(CF 3 CO2H), 5.5-5.8(1H, m, CH), 7.10(2H, s, Ar), 7.70 (3H, broad, NH3) Found: C, 40.48; H, 4.27 Cl, 15.03; N, 5.91%. C8H8ClNO4. H2O requires: C, 40.78; H, 4.28; Cl, 15.05; N, 5.95%.

Provenance & Evidence