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Sodium fluoride
Identifiers
CAS number 7681-49-4 Yes check.svgY
PubChem 5235
EC number 231-667-8
UN number 1690
RTECS number WB0350000
ATC code A01AA01
Properties
Molecular formula NaF
Molar mass 41.988713 g/mol
Appearance White solid
Odor odorless
Density 2.558 g/cm3
Melting point

993 °C

Boiling point

1695 °C

Solubility in water 4.13 g/100 g (25 °C)
Solubility soluble in HF
insoluble in ethanol
Hazards
MSDS Sodium fluoride MSDS
EU Index 009-004-00-7
EU classification Toxic (T)
Irritant (Xi)
R-phrases R25, R32, R36/38
S-phrases (S1/2), S22, S36, S45
NFPA 704
NFPA 704.svg
0
3
0
Flash point Non-flammable
LD50 52–200 mg/kg (oral in rats, mice, rabbits)[1]
Related compounds
Other anions Sodium chloride
Sodium bromide
Sodium iodide
Other cations Lithium fluoride
Potassium fluoride
Rubidium fluoride
Caesium fluoride
Related compounds TASF reagent
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Sodium fluoride is the inorganic compound with the formula NaF. This colorless solid is a source of the fluoride ion in diverse applications. Sodium fluoride is less expensive and less hygroscopic than the related salt potassium fluoride.

Contents

Structure, general properties, occurrence

Sodium fluoride is an ionic compound, dissolving to give separated Na+ and F ions. It crystallizes in the cubic (sodium chloride) motif where both Na+ and F occupy octahedral coordination sites.[2][3]

The mineral form of NaF, villiaumite, is moderately rare. It is known from plutonic nepheline syenite rocks.[4]

Production

NaF is prepared by neutralizing hydrofluoric acid or hexafluorosilicic acid (H2SiF6), byproducts of the production of superphosphate fertilizer. Neutralizing agents include sodium hydroxide and sodium carbonate. Alcohols are sometimes used to precipitate the NaF:

HF + NaOH → NaF + H2O

From solutions containing HF, sodium fluoride precipitates as the bifluoride salt NaHF2. Heating the latter releases HF and gives NaF.

HF + NaF NaHF2

In a 1986 report, the annual, worldwide consumption of NaF was estimated to be several million tonnes.[5]

Applications

Sodium fluoride is sold in tablets for cavity prevention.

Fluoride salts are used to enhance the strength of teeth by the formation of fluorapatite, a naturally occurring component of tooth enamel. Although sodium fluoride is also used to fluoridate water, hexafluorosilicic acid (H2SiF6) and its salt sodium hexafluorosilicate (Na2SiF6) are more commonly used additives in the U.S.[6] Toothpaste often contains sodium fluoride to prevent cavities.[7]

Alternatively, sodium fluoride is used as a cleaning agent, e.g. as a "laundry sour".[5] A variety of specialty chemical applications exist in synthesis and extractive metallurgy. The fluoride is the reagent for the synthesis of fluorocarbons. Representative substrates include electrophilic chlorides including acyl chlorides, sulfur chlorides, and phosphorus chloride.[8] Like other fluorides, sodium fluoride finds use in desilylation in organic synthesis.

In medical imaging, fluorine-18-labelled sodium fluoride is used in positron emission tomography (PET). Relative to conventional bone scintigraphy carried out with gamma cameras or SPECT systems, PET offers more sensitivity and spatial resolution. A disadvantage of PET is that fluorine-18 labelled sodium fluoride is less widely available than conventional technetium-99m-labelled radiopharmaceuticals.

Sodium fluoride is used to conserve tissue samples in biochemistry and medicinal testing as fluoride ions stop glycolysis by inhibiting the enzyme enolase[citation needed]. Sodium fluoride is often used together with iodoacetic acid, which inhibits the enzyme aldolase[citation needed]. It also is used in RIPA lysis buffer as phosphatase inhibitor along with Na3VO4.

Safety

Sodium fluoride is classed as toxic by both inhalation (of dusts or aerosols) and ingestion.[9] In high enough doses, it has been shown to affect the heart and circulatory system, and the lethal dose for a 70 kg human is estimated at 5–10 g.[5]

In the higher doses used to treat osteoporosis, plain sodium fluoride can cause pain in the legs and incomplete stress fractures when the doses are too high; it also irritates the stomach, sometimes so severely as to cause ulcers. Slow-release and enteric-coated versions of sodium fluoride do not have gastric side effects in any significant way, and have milder and less frequent complications in the bones.[10] In the lower doses used for water fluoridation, the only clear adverse effect is dental fluorosis, which can alter the appearance of children's teeth during tooth development; this is mostly mild and is unlikely to represent any real effect on aesthetic appearance or on public health.[11]

See also

References

  1. ^ Martel, B.; Cassidy, K. (2004). Chemical Risk Analysis: A Practical Handbook. Butterworth–Heinemann. p. 363. ISBN 1903996651. 
  2. ^ Wells, A.F. (1984). Structural Inorganic Chemistry. Oxford: Clarendon Press. ISBN 0-19-855370-6. 
  3. ^ "Chemical and physical information" (PDF), Toxicological profile for fluorides, hydrogen fluoride, and fluorine, Agency for Toxic Substances and Disease Registry (ATDSR), September 2003, pp. 187, http://www.atsdr.cdc.gov/toxprofiles/tp11.pdf, retrieved 2008-11-01 
  4. ^ "Mineral Handbook" (PDF). Mineral Data Publishing. 2005. http://rruff.geo.arizona.edu/doclib/hom/villiaumite.pdf. 
  5. ^ a b c Aigueperse, Jean; Paul Mollard, Didier Devilliers, Marius Chemla, Robert Faron, Renée Romano, Jean Pierre Cuer (2005), "Fluorine Compounds, Inorganic", in Ullmann, Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a11_307 
  6. ^ Division of Oral Health, National Center for Prevention Services, CDC (1993) (PDF). Fluoridation census 1992. http://cdc.gov/fluoridation/pdf/statistics/1992.pdf. Retrieved 2008-12-29. 
  7. ^ "Sodium fluoride, Molecule of the week". American Chemical Society. 2008-02-19. http://portal.acs.org/portal/acs/corg/content?_nfpb=true&_pageLabel=PP_ARTICLEMAIN&node_id=841&content_id=WPCP_008239&use_sec=true&sec_url_var=region1. Retrieved 2008-11-01. 
  8. ^ Halpern, D.F. (2001), "Sodium Fluoride", Encyclopedia of Reagents for Organic Synthesis, John Wiley & Sons, doi:10.1002/047084289X.rs071 
  9. ^ http://www.jtbaker.com/msds/englishhtml/S3722.htm NaF MSDS
  10. ^ Murray TM, Ste-Marie LG. Prevention and management of osteoporosis: consensus statements from the Scientific Advisory Board of the Osteoporosis Society of Canada. 7. Fluoride therapy for osteoporosis. CMAJ. 1996;155(7):949–54. PMID 8837545.
  11. ^ National Health and Medical Research Council (Australia). A systematic review of the efficacy and safety of fluoridation [PDF]. 2007. ISBN 1864964154. Summary: Yeung CA. A systematic review of the efficacy and safety of fluoridation. Evid Based Dent. 2008;9(2):39–43. doi:10.1038/sj.ebd.6400578. PMID 18584000. Lay summary: NHMRC, 2007.

External links


Simple English

File:Sodium fluoride
Sodium fluoride tablets taken to prevent tooth decay

Sodium fluoride is a chemical compound. It is made of sodium and fluoride ions. Its chemical formula is NaF. It tastes bitter and is toxic. It is made by reacting hydrofluoric acid with sodium hydroxide. It is used in toothpaste to prevent tooth decay. It is a white crystalline solid.

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