Urea → (2S)-6-Amino-2-hydroxyhexanoic acid

Participants

Reaction Steps

The crude L-lysine.2H2SO4 was taken up in 10% H2SO4 (250 ml) and treated dropwise with a solution of sodium nitrite (25.9 gm, 0.36 mole) in water (100 ml) at 45°-50° C. (bath temperature) over a period of 2 hours. When the addition was complete, the mixture was stirred at 45°-50° C. for an additional 4.5 hours, the excess nitrous acid decomposed with urea and the mixture poured onto an AG-50-X8 ion exchange column (H+ form, 200 ml bed volume). The column was eluted with water and then aqueous NH4OH (conc. NH4OH--H2O; 1:3) to elute the product. The ninhydrin positive fractions were combined and evaporated to give a pink semi-solid which was recrystallized from H2O--EtOH to give title compound (8.20 gm, 56%) as white crystals, m.p. 197°-199° C. [α]D =-12.2° (c=1.2, H2O)[Lit m.p. 203°-206° C., [α]D =-12.1° (c=1.16, H2O)]. TLC (i-iPrOH-conc. NH4OH--H2O; 7:2:1) Rf =0.16 (contains trace of lysine, Rf =0.02).

Provenance & Evidence