Abstract
Codeine phosphate forms crystals with 1.5, 1.0, and 0.5 mole of water of crystallization and the formation of these three kinds of crystals depends on the kind of solvent used, concentration of the solution, and temperature at the time of crystallization at the time of preparation of codeine phosphate. Codeine phosphate with less moisture is more easily soluble in water and is stable to periodic change when heated. The crystal with 1.5 moles of water easily liberates water at a low temperature of 40°, but those with 0.5 and 1.0 mole of water do not. These three kinds of hydrated crystals, dried to a lower hydrate or anhydrate state, were found to return to the corresponding hydrated molecules in the air.
X-Ray diffraction of these codeine phosphate crystals showed that the crystals formed by hydration of the anhydrate crystals regain the same crystal form as the original hydrated crystals. It follows, therefore, that codeine phosphate crystals with 1.5, 1.0, and 0.5 mole of water of crystallization are all in stable form.
