Magnesium chlorate refers to inorganic compounds with the chemical formula Mg(ClO3)2(H2O)x. The anhydrous (x = 0), dihydrate (x = 2), and hexahydrate (x = 6) are known. These are thermally labile white solids. The hexahydrate has been identified on the Martian surface.[1]
Samples of magnesium chlorate were first claimed in 1920 as the result of treating magnesium oxide with chlorine. A more modern method involves electrolysis of magnesium chloride.[2] The magnesium chlorate can be purified by exploiting its solubility in acetone.
The hexahydrate Mg(ClO3)2·6H2O decomposes to the tetrahydrate at 35 °C. At 65 °C, it dehydrates to the dihydrate, then at 80 °C forms a basic salt. If further heated to 120 °C it decomposes to water, oxygen, chlorine, and magnesium oxide.[3]
As confirmed by X-ray crystallography, the di- and hexahydrates feature octahedral Mg2+ centers. The other ligands are water, exclusively in the hexahydrate. In the dihydrate, chlorate is also coordinated and functions as a bridging ligand.[4]
Magnesium(II) chlorate is used as a powerful desiccant and a defoliant for cotton, potato, and rice. It is also found as a lubricant in eye drops as an inactive ingredient.[5]
Magnesium chlorate is an oxidizer and can in principle form explosive mixtures.