Sodium monofluorophosphate

Last updated
Sodium monofluorophosphate
Sodium monofluorophosphate.svg
Names
IUPAC name
Disodium phosphorofluoridate
Other names
Sodium fluorophosphate, disodium monofluorophosphate
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.030.381 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 233-433-0
PubChem CID
RTECS number
  • TE6130000
UNII
  • InChI=1S/FH2O3P.2Na/c1-5(2,3)4;;/h(H2,2,3,4);;/q;2*+1/p-2 Yes check.svgY
    Key: BFDWBSRJQZPEEB-UHFFFAOYSA-L Yes check.svgY
  • InChI=1/FH2O3P.2Na/c1-5(2,3)4;;/h(H2,2,3,4);;/q;2*+1/p-2
    Key: BFDWBSRJQZPEEB-NUQVWONBAA
  • [Na+].[Na+].[O-]P([O-])(F)=O
Properties
Na2PFO3
Molar mass 143.95 g/mol
Appearancewhite powder
Melting point 625 °C (1,157 °F; 898 K)
25 g/100 mL
Solubility insoluble in ethanol, ether
Pharmacology
A01AA02 ( WHO ) A12CD02 ( WHO )
Hazards
NFPA 704 (fire diamond)
NFPA 704.svgHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
2
0
1
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
0,9g/kg (rat, oral) [1]
Safety data sheet (SDS) Sigma-Aldrich
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Sodium monofluorophosphate, commonly abbreviated SMFP, is an inorganic compound with the chemical formula Na2PO3F. Typical for a salt, MFP is odourless, colourless, and water-soluble. This salt is an ingredient in some toothpastes. [2]

Contents

Uses

MFP is best known as an ingredient in some toothpastes. [3] It functions as a source of fluoride via the following hydrolysis reaction: [2]

PO3F2− + OH → HPO42− + F

Fluoride protects tooth enamel from attack by bacteria that cause dental caries (cavities). Although developed by a chemist at Procter and Gamble, its use in toothpaste (Colgate toothpaste and Ultra Brite) was patented by Colgate-Palmolive, as Procter and Gamble was engaged in the marketing of Crest toothpaste (containing stannous fluoride, marketed as "Fluoristan"). In the early 1980s, Crest was reformulated to use MFP, under the trademark "Fluoristat"; today Crest toothpastes use sodium fluoride or stannous fluoride. Compared to straight fluorides, sodium monofluorophosphate has slightly less aftertaste.

MFP is also used in some medications for the treatment of osteoporosis. [2]

In 1991, sodium monofluorophosphate was found by Calgon to inhibit the dissolution of lead in drinking water when used in concentrations between 0.1 mg/L and 500 mg/L. [4]

Tooth decay

Tooth decay is caused by bacteria naturally present in one's mouth. These bacteria form a sticky, colorless soft film on the teeth called plaque. When foods containing carbohydrates (starches and sugars) are eaten, the bacteria that form plaque use the sugar as a form of energy. They also turn it into a glue-like substance that helps them stick to the surface of the tooth. The plaque produces acid, which attacks the enamel. [5]

Chemistry of decay

Tooth enamel consists mostly of calcium hydroxyphosphate, Ca5(PO4)3OH, also known as the mineral hydroxyapatite. Apatite is a hard, insoluble compound. Acid (H+), produced especially after a high-sugar meal, attacks the apatite:

Ca5(PO4)3OH(s) + H+(aq) → Ca5(PO4)3+(aq) + H2O(ℓ)

Chemistry of enamel fluoridation

The degradation of apatite by loss of OH causes the enamel to dissolve. The process is reversible as saliva supplies back OH to reform apatite. If fluoride, F, ions are present in saliva, fluorapatite, Ca5(PO4)3F, also forms.

Ca5(PO4)3+(aq) + F(aq) → Ca5(PO4)3F(s)

Fluorapatite resists attacks by acids better than apatite itself, so the tooth enamel resists decay better than enamel containing no fluoride. [6]

Preparation and structure

Sodium monofluorophosphate is produced industrially by the reaction of sodium fluoride with sodium metaphosphate: [2]

NaPO3 + NaF → Na2PO3F

The process involves scission of a pyrophosphate bond, analogous to hydrolysis. NaMFP can also be prepared by treating tetrasodium pyrophosphate or disodium phosphate with hydrogen fluoride. [2]

In the laboratory, MFP can be prepared by hydrolysis of difluorophosphate ions with dilute sodium hydroxide:

PO2F2 + 2 NaOH → Na2PO3F + H2O + F

Structure

The structure of the fluorophosphate anion consists of phosphorus at the center of a tetrahedron defined by three oxygen atoms and one fluorine. Formal representations depict a double bond between one oxygen atom and phosphorus, with single bonds for the other two oxygen atoms and the fluorine. In this very formal depiction, negative charge is localized on the O atoms of the single P-O bonds. MFP is similar to and isoelectronic with Na2 SO4. The anion has C3v symmetry.

Discovery and development

Sodium monofluorophosphate was first described in 1929 by the German chemist Willy Lange, who was then with the University of Berlin. His fruitless attempts to prepare the free monofluorophosphoric acid led him to check the stability of its esters. Together with Gerda von Krüger, one of his students, Lange thus synthesized diethyl fluorophosphate and some analogs, which proved to be quite toxic, being related to nerve agents. In the 1930s, Gerhard Schrader, working for the German company IG Farben, tried to develop synthetic insecticide. His work focused on esters of phosphoric acid and resulted in an accidental discovery of some other nerve agents such as DFP (diisopropyl fluorophosphate), Tabun, Soman, and Sarin. In the meantime, Lange, who was married to a Jewish woman, emigrated from Germany to the United States and started work for Procter and Gamble Company. In 1947, he and Ralph Livingston of Monsanto Company published the preparation of the free fluorophosphoric acids and mentioned the use of some toxic esters of monofluorophosphoric acid (like DFP) in the treatment of glaucoma and myasthenia gravis. The well known toxicity of these esters led to fears that the simple salts might also be toxic, and such fears precluded any large scale commercial use of the salts. In 1950, under sponsorship of the manufacturer of the compounds, Ozark Chemical Company, the toxicity of sodium monofluorophosphate was studied by Harold Hodge at the University of Rochester who included anti-cavity testing. In 1967 Colgate-Palmolive filed several patents on the use of sodium monofluorophosphate in toothpaste. [4]

Safety

The usual content of MFP in toothpaste is 0.76%. The compound is used in place of sodium fluoride, particularly in children's toothpastes, because it is less acutely toxic, although both have modest toxicities. The LD50 in rats is 0.9 g/kg. [7]

Related Research Articles

<span class="mw-page-title-main">Apatite</span> Mineral group, calcium phosphate

Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH, F and Cl ion, respectively, in the crystal. The formula of the admixture of the three most common endmembers is written as Ca10(PO4)6(OH,F,Cl)2, and the crystal unit cell formulae of the individual minerals are written as Ca10(PO4)6(OH)2, Ca10(PO4)6F2 and Ca10(PO4)6Cl2.

<span class="mw-page-title-main">Toothpaste</span> Substance to clean and maintain teeth

Toothpaste is a paste or gel dentifrice used with a toothbrush to clean and maintain the aesthetics and health of teeth. Toothpaste is used to promote oral hygiene: it is an abrasive that aids in removing dental plaque and food from the teeth, assists in suppressing halitosis, and delivers active ingredients to help prevent tooth decay and gum disease (gingivitis). Owing to differences in composition and fluoride content, not all toothpastes are equally effective in maintaining oral health. The decline of tooth decay during the 20th century has been attributed to the introduction and regular use of fluoride-containing toothpastes worldwide. Large amounts of swallowed toothpaste can be poisonous. Common colors for toothpaste include white and blue.

Crest is an American brand of toothpaste and other oral hygiene products made by American multinational Procter & Gamble (P&G) and sold worldwide. In many countries in Europe, such as Germany, Bulgaria, Serbia, Ukraine, Belarus, Russia, Poland, Hungary, Latvia, Romania, Estonia and Lithuania, it is sold as Blend-A-Med, the name of an established German toothpaste acquired by P&G in 1987. In France, Italy, Israel, Sweden, Finland, Argentina, Belgium, the Netherlands, Brazil, the United Kingdom, the Republic of Ireland, Australia, Nigeria, Greece, Uruguay and Colombia, P&G markets similar toothpaste formulations under the Oral-B brand.

<span class="mw-page-title-main">Calcium phosphate</span> Chemical compound

The term calcium phosphate refers to a family of materials and minerals containing calcium ions (Ca2+) together with inorganic phosphate anions. Some so-called calcium phosphates contain oxide and hydroxide as well. Calcium phosphates are white solids of nutritional value and are found in many living organisms, e.g., bone mineral and tooth enamel. In milk, it exists in a colloidal form in micelles bound to casein protein with magnesium, zinc, and citrate–collectively referred to as colloidal calcium phosphate (CCP). Various calcium phosphate minerals are used in the production of phosphoric acid and fertilizers. Overuse of certain forms of calcium phosphate can lead to nutrient-containing surface runoff and subsequent adverse effects upon receiving waters such as algal blooms and eutrophication (over-enrichment with nutrients and minerals).

<span class="mw-page-title-main">Sodium fluoride</span> Ionic compound (NaF)

Sodium fluoride (NaF) is an inorganic compound with the formula NaF. It is a colorless or white solid that is readily soluble in water. It is used in trace amounts in the fluoridation of drinking water to prevent tooth decay, and in toothpastes and topical pharmaceuticals for the same purpose. In 2021, it was the 291st most commonly prescribed medication in the United States, with more than 600,000 prescriptions. It is also used in metallurgy and in medical imaging.

<span class="mw-page-title-main">Dental erosion</span> Medical condition

Acid erosion is a type of tooth wear. It is defined as the irreversible loss of tooth structure due to chemical dissolution by acids not of bacterial origin. Dental erosion is the most common chronic condition of children ages 5–17, although it is only relatively recently that it has been recognised as a dental health problem. There is generally widespread ignorance of the damaging effects of acid erosion; this is particularly the case with erosion due to consumption of fruit juices because they tend to be considered as healthy. Acid erosion begins initially in the enamel, causing it to become thin, and can progress into dentin, giving the tooth a dull yellow appearance and leading to dentin hypersensitivity.

<span class="mw-page-title-main">Hydroxyapatite</span> Naturally occurring mineral form of calcium apatite

Hydroxyapatite is a naturally occurring mineral form of calcium apatite with the formula Ca5(PO4)3(OH), often written Ca10(PO4)6(OH)2 to denote that the crystal unit cell comprises two entities. It is the hydroxyl endmember of the complex apatite group. The OH ion can be replaced by fluoride or chloride, producing fluorapatite or chlorapatite. It crystallizes in the hexagonal crystal system. Pure hydroxyapatite powder is white. Naturally occurring apatites can, however, also have brown, yellow, or green colorations, comparable to the discolorations of dental fluorosis.

<span class="mw-page-title-main">Fluoride therapy</span> Medical use of fluoride

Fluoride therapy is the use of fluoride for medical purposes. Fluoride supplements are recommended to prevent tooth decay in children older than six months in areas where the drinking water is low in fluoride. It is typically used as a liquid, pill, or paste by mouth. Fluoride has also been used to treat a number of bone diseases.

<span class="mw-page-title-main">Bioglass 45S5</span>

Bioglass 45S5 or calcium sodium phosphosilicate, is a bioactive glass specifically composed of 45 wt% SiO2, 24.5 wt% CaO, 24.5 wt% Na2O, and 6.0 wt% P2O5. Typical applications of Bioglass 45S5 include: bone grafting biomaterials, repair of periodontal defects, cranial and maxillofacial repair, wound care, blood loss control, stimulation of vascular regeneration, and nerve repair.

<span class="mw-page-title-main">Tricalcium phosphate</span> Chemical compound

Tricalcium phosphate (sometimes abbreviated TCP), more commonly known as Calcium phosphate, is a calcium salt of phosphoric acid with the chemical formula Ca3(PO4)2. It is also known as tribasic calcium phosphate and bone phosphate of lime (BPL). It is a white solid of low solubility. Most commercial samples of "tricalcium phosphate" are in fact hydroxyapatite.

<span class="mw-page-title-main">Diisopropyl fluorophosphate</span> Chemical compound

Diisopropyl fluorophosphate (DFP) or Isoflurophate is an oily, colorless liquid with the chemical formula C6H14FO3P. It is used in medicine and as an organophosphorus insecticide. It is stable, but undergoes hydrolysis when subjected to moisture.

Gleem is an American brand of oral hygiene products, including toothpastes and electric toothbrushes, owned by the Procter & Gamble. It was introduced as a toothpaste in the United States in 1952 and discontinued in 2014. Procter & Gamble later revived Gleem toothpaste as a flavor variant of Crest toothpaste. In 2019, Procter & Gamble expanded the brand to include a line of electric toothbrushes.

<span class="mw-page-title-main">Tin(II) fluoride</span> Chemical compound

Tin(II) fluoride, commonly referred to commercially as stannous fluoride (from Latin stannum, 'tin'), is a chemical compound with the formula SnF2. It is a colourless solid used as an ingredient in toothpastes.

<span class="mw-page-title-main">Fluorapatite</span> Phosphate mineral

Fluorapatite, often with the alternate spelling of fluoroapatite, is a phosphate mineral with the formula Ca5(PO4)3F (calcium fluorophosphate). Fluorapatite is a hard crystalline solid. Although samples can have various color (green, brown, blue, yellow, violet, or colorless), the pure mineral is colorless, as expected for a material lacking transition metals. Along with hydroxylapatite, it can be a component of tooth enamel, but for industrial use both minerals are mined in the form of phosphate rock, whose usual mineral composition is primarily fluorapatite but often with significant amounts of the other.

Olaflur is a fluoride-containing substance that is an ingredient of toothpastes and solutions for the prevention of dental caries. It has been in use since 1966. Especially in combination with dectaflur, it is also used in the form of gels for the treatment of early stages of caries, sensitive teeth, and by dentists for the refluoridation of damaged tooth enamel.

<span class="mw-page-title-main">Remineralisation of teeth</span>

Tooth remineralization is the natural repair process for non-cavitated tooth lesions, in which calcium, phosphate and sometimes fluoride ions are deposited into crystal voids in demineralised enamel. Remineralization can contribute towards restoring strength and function within tooth structure.

<span class="mw-page-title-main">Monofluorophosphate</span> Chemical compound

Monofluorophosphate is an anion with the formula PO3F2−, which is a phosphate group with one oxygen atom substituted with a fluoride atom. The charge of the ion is −2. The ion resembles sulfate in size, shape and charge, and can thus form compounds with the same structure as sulfates. These include Tutton's salts and langbeinites. The most well-known compound of monofluorophosphate is sodium monofluorophosphate, commonly used in toothpaste.

<span class="mw-page-title-main">Fluorophosphoric acid</span> Chemical compound

Fluorophosphoric acid is the inorganic compound with the formula H2PO3F. It is a colorless viscous liquid that solidifies to a rigid glass upon cooling at −78 °C (−108 °F).

Topical fluorides are fluoride-containing drugs indicated in prevention and treatment of dental caries, particularly in children's primary dentitions. The dental-protecting property of topical fluoride can be attributed to multiple mechanisms of action, including the promotion of remineralization of decalcified enamel, the inhibition of the cariogenic microbial metabolism in dental plaque and the increase of tooth resistance to acid dissolution. Topical fluoride is available in a variety of dose forms, for example, toothpaste, mouth rinses, varnish and silver diamine solution. These dosage forms possess different absorption mechanisms and consist of different active ingredients. Common active ingredients include sodium fluoride, stannous fluoride, silver diamine fluoride. These ingredients account for different pharmacokinetic profiles, thereby having varied dosing regimes and therapeutic effects. A minority of individuals may experience certain adverse effects, including dermatological irritation, hypersensitivity reactions, neurotoxicity and dental fluorosis. In severe cases, fluoride overdose may lead to acute toxicity. While topical fluoride is effective in preventing dental caries, it should be used with caution in specific situations to avoid undesired side effects.

<span class="mw-page-title-main">William Harrison Nebergall</span> American inorganic chemist (1914–1978)

William Harrison Nebergall was an inorganic chemist who synthesized the fluoride compatible polishing agent calcium pyrophosphate. This discovery combined with stannous fluoride led to the development and release of the first fluoride containing toothpaste, Crest, in 1955. In 1960 Crest became the first toothpaste to be endorsed by the American Dental Association as an effective decay-preventing agent. In 1959 he cowrote one of the first widely used textbooks of college chemistry titled General Chemistry, which was published in six editions.

References

  1. "Safety (MSDS) data for sodium fluorophosphate". Archived from the original on 2009-01-11. Retrieved 2009-07-06.
  2. 1 2 3 4 5 Klaus Schrödter, Gerhard Bettermann, Thomas Staffel, Friedrich Wahl, Thomas Klein, Thomas Hofmann "Phosphoric Acid and Phosphates" in Ullmann’s Encyclopedia of Industrial Chemistry 2008, Wiley-VCH, Weinheim. doi : 10.1002/14356007.a19_465.pub3
  3. Wolfgang Weinert "Oral Hygiene Products" in Ullmann’s Encyclopedia of Industrial Chemistry 2000, Wiley-VCH, Weinheim. doi : 10.1002/14356007.a18_209
  4. 1 2 Peter Meiers Monofluorophosphate History
  5. "HealthyTeeth - Healthy Sleep Tips, News and Product Reviews". HealthyTeeth. Retrieved 19 April 2018.
  6. Davis, R. E., Ph.D., Metcalfe, H. C., Williams, J. E., Castka, J. F. (1999). Modern Chemistry. Austin, TX: Harcourt Brace & Company.
  7. "Safety (MSDS) data for sodium fluorophosphate". Archived from the original on 2009-01-11. Retrieved 2009-07-06.