Hydrochloric Acid → L-Aspartic Acid

Participants

Reaction Steps

N6-Carbobenzyloxy-L-lysine (6.15 g) and excess maleic acid (17.6 g) were dissolved in 2 M NaOH (35 mL). The solution was refluxed for 24 hr and allowed to cool to ambient. The pH was adjusted to 3 with 6 M HCl and chilled. The mixture was filtered to remove the unreacted maleic acid which was washed with water (15 mL). The filtrate and washings were combined and evaporated. The residue was dissolved in 4% ammonium formate (120 mL) and degassed briefly. 10% Pd/C (600 mg) was added and the mixture was refluxed under Ar with stirring for 5 hr. The mixture was filtered through celite and the filtrate evaporated. The residue was dissolved in a solution of sodium hydroxide (1.3 g) and sodium carbonate (8.7 g) in dd H2O (40 mL). The final pH was adjusted to 11. This solution is added to the oxirane-derivatized resin (40 ml bed volume) prepared as described in Example 1. The mixture was stirred at 60° with mechanical stirring for 4hr and at ambient for 16 hr. The resin was collected by filtration, washed with ddH2O (6×100 mL), 10% HOAc (6×100 mL), and ddH2O (6×100 mL) or until the pH reached about 6 by litmus paper test. The C-Linked CM-Asp chelating resin was suction dried in preparation for metal loading.

Provenance & Evidence