Sulfuric Acid → HCID 131711319, compound

Participants

Reaction Conditions

Reaction Steps

207.2 g (0.5 mole) of calcium hydrogen L-malate 6 hydrate (C8H10O10.Ca.6H2O) are suspended in 300 ml of water, and 55 ml of 60% (by weight) sulfuric acid are added thereto. The precipitates of calcium sulfate are removed by filtration. The filtrate is passed through a column of about 100 ml of a cation exchange resin [manufactured by Rohm & Haas Co. under the trade name "Amberlite IR-120 (H+ type)] and then a column of about 30 ml of an anion exchange resin [manufactured by Rohm & Haas Co. under the trade name "Amberlite IR-45 (OH- type)] to remove calcium sulfate completely therefrom. 79.2 g (1.4 moles) of potassium hydroxide (purity: 85%) are added gradually to the aqueous L-malic acid solution thus obtained. Insoluble materials are removed by filtration, and the filtrate (pH 4.4) is concentrated under reduced pressure to make the total weight thereof about 300 g. The concentrated filtrate is cooled to 10° C. and the mixture (i.e., the mixture of the concentrated filtrate and crystals precipitated) is stirred at the same temperature for 2 hours. After stirring the mixture had a pH of 5.6. The crystalline precipitates are collected by filtration, washed with an aqueous 80% methanol solution and dried overnight in air at 35° C. 133.6 g of monopotassium L-malate monohydrate are obtained as crystals. Yield: 70.2% The product loses its intramolecular water at 99° to 101° C. and decomposes at 183.5° to 185° C.

Provenance & Evidence