Melibiose crystallises as a hydrate from water or aqueous EtOH. The anomer is obtained by recrystallising 1g from a mixture of 0.35mL of H2O and 0.2mL of EtOH. It crystallises easily with m 179o and mutarotates from [] D 20 +166o to +142.3o (220minutes, c 4, H2O). Crystallisation from MeOH gives the anhydrous form which hydrates to the monohydrate in air. The anomer dihydrate m 85-86o mutarotates from [] D 20 +123.5o to +143.1o (c 4, H2O for anhydrous). [Fletcher & Diehl J Am Chem Soc 74 5774 1952, Beilstein 1 7 III/IV 3075, 17/7 V 206.]
