Potassium → 2782-04-9

Participants

Reaction Steps

Acid form cation exchange resin (20 mL, 40 meq. of total exchange capacity, Rexyn 100(H), Fisher) that had been prewashed with deionized water was added to a mixture of monopotassium D-glucarate (10.00 g, 39.89 mmol, Sigma) and deionized water (100 mL). The potassium salt dissolved within 10 min, the mixture was stirred for 3 h and the resin was removed by filtration and washed with deionized water (3×10 mL). The resin was left aside for regeneration to its acid form and the filtrate was concentrated to a syrup at 60° C. The syrup was seeded with pure D-glucaro-3,6-lactone and solidified as a cake in two-three days. The cake was triturated with acetone (15 mL), the white solid was removed by filtration and air-dried to yield D-glucaro-6,3-lactone (4,851 g, 63.3%). When this experiment was scaled up to 50.00 g of monopotassium D-glucarate, D-glucaro-6,3-lactone was obtained in 69.1% yield (26.49 g, 137.9 mmol): mp 130°-135° C. [Smith, J. Chem. Soc., 633 (1944); 138-142 ° C.]; IR (KBr) 3365 cm-l (broad, OH), 2913 cm-1 (C--H, stretch), 1780 cm-l (C=O, five membered ring lactone), 1725 cm-l (C=O, acid); 1H NMR (CD3OD) δ4.59 (dd, 1H, H-3, J2,3 = 6.73 Hz, J3,4 =2.12), 4.53 (m, 2H, H-2, H-5,), 4.51 (m, 1H, H-2); proton decoupled 13C NMR (D2O)δ178.8 (lactone C=O), 174.5 (acid C=O), 81.61 (C-3), 71.65 (C-5), 71.31 (C-2), and 69.89 (C-4).

Provenance & Evidence