Abstract
d-trans-8-Oxocamphor is used widely as a cardiotonic but its crystal is extremely unstable and is oxidized in the air, almost completely loosing its pharmacological effect in about 24 hours. A methanolic solution of this substance and thiourea separates some needle crystals on being cooled and the newly formed substance is composed of 8-oxocamphor and thiourea in 1:3 molar ratio. From X-ray diffraction and infrared absorption spectrum, the crystal is a rhombohedral and the substance was proved to be the so-called inclusion compound by Schlenk and others. Such 8-oxocamphor included in thiourea is extremely stable and residual ratio after 8 months at room temperature was 97.5%, that after 6 months at 40° being 93%. Extraction of this adduct in a Soxhlet extractor with warm ether was found to give 100% of 8-oxocamphor and the residual thiourea formed the original rhombic crystals. When this adduct is dissolved in water, it dissociated into the original two components, the solution showing the chemical properties of 8-oxocamphor, as well as its toxicity and pharmacological effect. There was no difference in its effect as a medicinal from the corresponding 8-oxocamphor.
