Sodium Hydroxide → potassium sodium D-glucarate

Aqueous sodium hydroxide solution (21 mL, 2 M) was added to a slurry of monopotassium D-glucarate (10.0 g, 40.3 mmol) in water (50 mL) until all of the solid dissolved and a constant pH of 10 was reached. The volume of the solution was reduced to 20 mL by rotary evaporator. Methanol (15 mL) was added, producing a cloudy solution which cleared upon heating. The solution was allowed to sit undisturbed at 5° C. Crystals grew from the solution over a 48 h period. The crystals were isolated by filtration, washed with cold 1:1 methanol/water (3×5 mL), and dried under reduced pressure to give sodium potassium D-glucarate as colorless crystals (10.2 g, 33.2 mmol as the dihydrate, 82.4%).