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Radium-223 chloride is one of the most potent ((antineoplastic drugs)) known. Bayer received FDA approval for this drug to treat prostate cancer osteoblastic bone metastases in May 2013. Radium-223 dichloride ( USP, radium chloride Ra 223), tradename Xofigo (formerly Alpharadin), is an alpha-emitting radiopharmaceutical. It was also used in medicine to produce radon gas which in turn was used as a brachytheraputic cancer treatment. The large quantities of material involved (to extract a gram of pure radium metal, about 7 tonnes of pitchblende is required) favour this less costly (but less efficient) method over those based on radium bromide or radium chromate (used for the later stages of the separation). Radium chloride is still used for the initial stages of the separation of radium from barium during the extraction of radium from pitchblende.
It also differs from barium chloride by the flame color, which is red as opposed to green for barium chloride. Ĭontrary to diamagnetic barium chloride, radium chloride is weakly paramagnetic with a magnetic susceptibility of 1.05 ×10 6. The gas shows strong absorptions in the visible spectrum at 676.3 nm and 649.8 nm (red): the dissociation energy of the radium–chlorine bond is estimated as 2.9 eV, and its length as 292 pm. Gaseous radium chloride exists as RaCl 2 molecules, as with other alkaline earth metal halides. Radium chloride is only sparingly soluble in azeotropic hydrochloric acid and virtually insoluble in concentrated hydrochloric acid. This property is used in the first stages of the separation of radium from barium by fractional crystallization. It is less soluble in water than other alkaline earth metal chlorides – at 25 ☌ its solubility is 245 g/L whereas that of barium chloride is 307 g/L, and the difference is even larger in hydrochloric acid solutions. Its color gradually changes to yellow with aging, whereas contamination by barium may impart a rose tint. Radium chloride is a colorless-white salt with a blue-green luminescence, especially when heated. Radium chloride can also be prepared by heating radium bromide in a flow of dry hydrogen chloride gas, or can be isolated from uranium and thorium ores by treating radium sulfate with sodium carbonate, leaving radium carbonate and then reacting the radium carbonate in hydrochloric acid. If the presence of other anions is suspected, the dehydration may be effectuated by fusion under hydrogen chloride. It may be dehydrated by heating to 100 ☌ in air for one hour followed by 5 + 1⁄ 2 hours at 520 ☌ under argon. Radium chloride crystallises from solution as the di hydrate.
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