Sodium fluoride
| Sodium fluoride | |
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IUPAC name
Sodium fluoride
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Other names
Florocid
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| Identifiers | |
| CAS number | 7681-49-4  |
| PubChem | 5235 |
| EC number | 231-667-8 |
| UN number | 1690 |
| RTECS number | WB0350000 |
| ATC code | A01 |
| 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 |
 0
3
0
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| 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 |
 (what is this?) (verify)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Sodium fluoride is an inorganic chemical compound with the formula NaF. A colorless solid, it 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
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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.23
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
Fluoride salts are used to enhance the strength of teeth by the formation of fluorapatite, a naturally occurring component of tooth enamel6 7. Although sodium fluoride is also used to fluoridate water and, indeed, is the standard by which other water-fluoridation compounds are gauged, hexafluorosilicic acid (H2SiF6) and its salt sodium hexafluorosilicate (Na2SiF6) are more commonly used additives in the U.S.8 Toothpaste often contains sodium fluoride to prevent cavities.9 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. It reacts with electrophilic chlorides including acyl chlorides, sulfur chlorides, and phosphorus chloride.10 Like other fluorides, sodium fluoride finds use in desilylation in organic synthesis. The fluoride is the reagent for the synthesis of fluorocarbons.
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.
Safety
The lethal dose for a 70 kg human is estimated at 5–10 g.5 Sodium fluoride is classed as toxic by both inhalation (of dusts or aerosols) and ingestion.11 In high enough doses, it has been shown to affect the heart and circulatory system.
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.12 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.13
See also
- Fluorine
- Caries
- Cryolite
- Light metals
- Mouthwash
References
- ^ Martel, B.; Cassidy, K. (2004), Chemical Risk Analysis: A Practical Handbook, Butterworth–Heinemann, p. 363, ISBN 1903996651
- ^ Wells, A.F. (1984), Structural Inorganic Chemistry, Oxford: Clarendon Press, ISBN 0-19-855370-6
- ^ "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
- ^ "Mineral Handbook" (PDF). Mineral Data Publishing. 2005. http://rruff.geo.arizona.edu/doclib/hom/villiaumite.pdf.
- ^ 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
- ^ Bourne, Geoffrey Howard (1986), Dietary research and guidance in health and disease, Karger, p. 153, ISBN 3-805-5434-17, http://books.google.com/?id=OW0gAAAAMAAJ, Snippet view from page 153
- ^ Klein, Cornelis; Hurlbut, Cornelius Searle; Dana, James Dwight (1999), Manual of Mineralogy (21 ed.), Wiley, ISBN 0-471-31266-5
- ^ 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.
- ^ "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.
- ^ Halpern, D.F. (2001), "Sodium Fluoride", Encyclopedia of Reagents for Organic Synthesis, John Wiley & Sons, doi:10.1002/047084289X.rs071
- ^ http://www.jtbaker.com/msds/englishhtml/S3722.htm NaF MSDS
- ^ 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.
- ^ 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
- Chemical profile for sodium fluoride at Scorecard, the pollution information site
- International Chemical Safety Card 0951Sodium fluoride’s effect on the male reproductive system
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