radium chloride
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 464379743
| Name = Radium chloride
| ImageFile = US_radium_standard_1927.jpg
| ImageCaption1 = An ampoule containing radium chloride
| Section1 = {{Chembox Identifiers
|InChI = 1/2ClH.Ra/h2*1H;/q;;+2/p-2
|InChIKey = RWRDJVNMSZYMDV-NUQVWONBAG
|SMILES = Cl[Ra]Cl
|StdInChI_Ref = {{stdinchicite|correct|chemspider}}
|StdInChI = 1S/2ClH.Ra/h2*1H;/q;;+2/p-2
|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
|StdInChIKey = RWRDJVNMSZYMDV-UHFFFAOYSA-L
|CASNo_Ref = {{cascite|changed|??}}
|CASNo = 10025-66-8
|EINECS = 233-035-7
|UNII_Ref = {{fdacite|correct|FDA}}
|UNII = KKO873WR2Z
|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
|ChemSpiderID =20138060
}}
| Section2 = {{Chembox Properties
|Appearance = Colorless solid, glows blue-green{{r|KirbySalutsky1964|p=5}}
|Formula = {{chem2|RaCl2}}
|Density = 4.9 g/cm3{{r|KirbySalutsky1964|p=5}}
|MolarMass = 296.094 g/mol
|Solubility = 245 g/L (20 °C){{r|KirbySalutsky1964|p=6}}
|MeltingPtC = 900
|MeltingPt_ref = {{r|KirbySalutsky1964|p=5}}
}}
| Section7 = {{Chembox Hazards
|MainHazards = radioactive, highly toxic, corrosive
|GHSPictograms = {{GHS06}}{{GHS08}}{{GHS09}}
|HPhrases = {{H-phrases|300|310|330|350|370|373|410}}
|NFPA-H = 4
|NFPA-F = 0
|NFPA-R = 1
|NFPA-S = RA}}
| Section8 = {{Chembox Related
|OtherAnions = Radium bromide
|OtherCations = Beryllium chloride
Magnesium chloride
Calcium chloride
Strontium chloride
Barium chloride
|OtherFunction_label =
}}
}}
Radium chloride is an inorganic compound with the chemical formula {{chem2|RaCl2|auto=1}}. It is a radium salt of hydrogen chloride. It was the first radium compound isolated in a pure state. Marie Curie and André-Louis Debierne used it in their original separation of radium from barium. The first preparation of radium metal was by the electrolysis of a solution of this salt using a mercury cathode.{{Cite journal |title=RADIOACTIVITÉ. Sur le radium métallique. Note de Mme P. CURIE et M. A. DEBIERNE |trans-title=RADIOACTIVITY. On metallic radium. Note by Mrs. P. CURIE and Mr. A. DEBIERNE |last1=Curie |first1=Marie |author-link1=Marie Curie |last2=Debierne |first2=André-Louis |author-link2=André-Louis Debierne |journal=C. R. Hebd. Séances Acad. Sci. |date=5 September 1910 |access-date=22 November 2024 |url=https://gallica.bnf.fr/ark:/12148/bpt6k31042/f523 |volume=151 |pages=523–25 |language=fr}}{{r|KirbySalutsky1964|p=3}}
Preparation
Radium chloride crystallises from aqueous solution as the dihydrate. The dihydrate is dehydrated by heating to 100 °C in air for one hour followed by 5.5 hours at 520 °C under argon.{{cite journal|author1=Weigel, F. |author2=Trinkl, A. |year=1968|title=Crystal Chemistry of Radium. I. Radium Halides|journal=Radiochimica Acta|volume=9|pages=36–41|doi=10.1524/ract.1968.9.1.36 |s2cid=201843329 }} If the presence of other anions is suspected, the dehydration may be effectuated by fusion under hydrogen chloride.{{cite journal | doi =10.1002/zaac.19342210113 | title =Revision des Atomgewichtes des Radiums | year =1934 | last1 =Hönigschmid| first1 =O. | last2 =Sachtleben | first2 =R. | journal =Zeitschrift für anorganische und allgemeine Chemie | volume =221 | pages =65–82}}
Radium chloride can also be prepared by heating radium bromide in a flow of dry hydrogen chloride gas. It can be produced by treating radium carbonate with hydrochloric acid.
Properties
Radium chloride is a colorless salt with a blue-green luminescence, especially when heated. Its color gradually changes to yellow with aging, whereas contamination by barium may impart a rose tint.{{r|KirbySalutsky1964|p=5}} It is less soluble in water than other alkaline earth metal chlorides – at 25 °C 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. This property is used in the first stages of the separation of radium from barium by fractional crystallization.{{r|KirbySalutsky1964|p=6}} Radium chloride is only sparingly soluble in azeotropic hydrochloric acid and virtually insoluble in concentrated hydrochloric acid.{{cite journal | doi = 10.1002/cber.19300630120 | title = Löslichkeits-Bestimmungen einiger Radiumsalze | year = 1930 | last1 = Erbacher | first1 = Otto | journal = Berichte der Deutschen Chemischen Gesellschaft (A and B Series) | volume = 63 | pages = 141–156}}
Gaseous {{chem2|RaCl2}} 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,Lagerqvist, A. (1953). Arkiv Fisik 6:141–42. and its length as 292 pm.Karapet'yants, M. Kh.; Ch'ing, Ling-T'ing (1960). Zh. Strukt. Khim. 1:277–85; J. Struct. Chem. (USSR) 1:255–63.
Contrary to diamagnetic barium chloride, radium chloride is weakly paramagnetic with a magnetic susceptibility of 1.05{{e|6}}. Its flame color is red.{{r|KirbySalutsky1964|p=5}}
Uses
Radium chloride is still used for the initial stages of the separation of radium from barium during the extraction of radium from pitchblende. 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).
It was also used in medicine to produce radon gas which in turn was used as a brachytheraputic cancer treatment.{{Cite journal | doi = 10.1001/archderm.1975.01630180085013 | last1 = Goldstein | first1 = N. | title = Radon seed implants. Residual radioactivity after 33 years | journal = Archives of Dermatology | volume = 111 | issue = 6 | pages = 757–759 | year = 1975 | pmid = 1137421}}{{cite journal|last=Winston|first=P.|title=Carcinoma of the Trachea Treated by Radon Seed Implantation|journal=The Journal of Laryngology & Otology|date=June 1958|volume=72|issue=6|pages=496–499|doi=10.1017/S0022215100054232|pmid=13564019|s2cid=36790323 }}
Radium-223 dichloride (USP, radium chloride Ra 223), tradename Xofigo (formerly Alpharadin), is an alpha-emitting radiopharmaceutical. Bayer received FDA approval for this drug to treat prostate cancer osteoblastic bone metastases in May 2013. Radium-223 chloride is one of the most potent ((antineoplastic drugs)) known.{{citation needed|date=December 2013}} One dose (50 kBq/kg) in an adult is about 60 nanograms; this amount is 1/1000 the weight of an eyelash (75 micrograms).
References
{{reflist|35em|refs=
{{cite report |last1=Kirby |first1=H. W. |last2=Salutsky |first2=Murrell L. |title=The Radiochemistry of Radium |date=December 1964 |url=https://sgp.fas.org/othergov/doe/lanl/lib-www/books/rc000041.pdf |publisher=Subcommittee on Radiochemistry, National Research Council, National Academy of Sciences |docket=NAS-NS-3057 |doi=10.2172/4560824 |osti=4560824}}
}}
Bibliography
- Gmelins Handbuch der anorganischen Chemie (8. Aufl.), Berlin:Verlag Chemie, 1928, pp. 60–61.
- {{Cite book |last1=Weigel |first1=Fritz |author-link=:de:Fritz Weigel |url=https://books.google.com/books?id=Lmg6AQAAIAAJ&q=%22radium+chloride%22 |title=Gmelin Handbuch der anorganischen Chemie (8. Aufl. 2. Ergänzungsband) |series=Gmelin Handbook of Inorganic Chemistry |edition=8th |date=1977 |publisher=Springer |location=Berlin |isbn=978-3-540-93335-9 |page=362–364 |language=en}}
{{Radium compounds}}
{{Chlorides}}