アロキサン一水和物

純化方法Recrystallisation from H2O gave the tetrahydrate in large prisms or rhombs. On heating at 100o, or on exposure to air, this is converted to the monohydrate. Dissolve it in its own weight of boiling H2O and cool it for several days below 0o; the tetrahydrate crystallises from solution much more slowly when free from HNO3. It is less soluble in bicarbonate solutions than in H2O. Drying the solid over H2SO4 yields the monohydrate. The anhydrous crystals can be obtained by recrystallisation from dry Me2CO or AcOH followed by washing with dry Et2O, or by sublimation in a vacuum. On heating it turns pink at 230o and decomposes at ca 256o. It is acidic to litmus. [Hartman & Sheppard Org Synth Coll Vol III 37 1955.] It forms a compound with urea which crystallises from H2O in yellow needles that become red at 170o and decompose at 185-186o. [Beilstein 24 H 500, 24 I 428, 24 II 301, 24 III/IV 2137.]