Malic Acid → HCID 131711319, compound

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Reaction Steps

As a result of our investigations, we have now found that when L-malic acid and potassium ion are dissolved in an aqueous solvent at a pH higher than 6.8, a malic acid salt contained in the solution exists substantially in the form of dipotassium L-malate and can not be crystallized out from the aqueous solvent. In this connection, however, we have also found that crystals of monopotassium L-malate monohydrate or crystals composed of L-malic acid and monopotassium L-malate are obtained by cooling an aqueous solution of L-malic acid and potassium ion at a pH of 6.8 or less. Namely, pure crystals of monopotassium L-malate monohydrate are obtained by cooling an aqueous solution of L-malic acid and potassium ion having a pH of 6.8 or less, to initiate crystallization of a potassium salt of L-malic acid, and continuing said crystallization at a pH of 5.3 to 6.8, especially at a pH of 5.3 to 6.5. On the other hand, when the crystallization step described above is continued at a pH lower than 5.3, the crystals obtained as the solid phase are composed of L-malic acid and monopotassium L-malate. Moreover, we have found that pure crystals of monopotassium L-malate monohydrate can also be prepared from impure crystals composed of L-malic acid and monopotassium L-malate by allowing said impure crystals to stand in a small amount of water at a pH of 5.3 to 6.8 until liquid-solid equilibrium is substantially achieved.

Provenance & Evidence