Sodium fluoride Chemical Properties

Melting point:

993 °C (lit.)

Boiling point:

1700 °C

Density 

1.02 g/mL at 20 °C

vapor pressure 

1.4 mm Hg ( 0 °C)

refractive index 

1.336

Flash point:

1704°C

storage temp. 

2-8°C

solubility 

H₂O: 0.5 M at 20 °C, clear, colorless

form 

powder

color 

White to off-white

Specific Gravity

2.558

PH

7.0-10.0 (25℃, 0.5M in H2O)

Odor

Odorless

Water Solubility 

4 g/100 mL (25 ºC)

Sensitive 

Hygroscopic

Crystal Structure

NaCl type

crystal system

Cube

Merck 

14,8618

Space group

Fm3m

Lattice constant

a/nm	b/nm	c/nm	α/o	β/o	γ/o	V/nm3
0.4633	0.4633	0.4633	90	90	90	0.09945

Exposure limits

ACGIH: TWA 2.5 mg/m3
NIOSH: IDLH 250 mg/m3; TWA 2.5 mg/m3

Stability:

Stable. Hydrolyzed by water. Reacts with mineral acids to generate highly toxic hydrogen fluoride. Incompatible with glass.

CAS DataBase Reference

7681-49-4(CAS DataBase Reference)

NIST Chemistry Reference

Sodium fluoride(7681-49-4)

EPA Substance Registry System

Sodium fluoride (7681-49-4)

Safety Information

Hazard Codes 

T,Xn

Risk Statements 

25-32-36/38-22

Safety Statements 

23-24/25-45-36-22

OEB

B

OEL

TWA: 2.5 mg/m3 [*Note: The REL also applies to other inorganic, solid fluorides (as F).]

RIDADR 

UN 1690 6.1/PG 3

WGK Germany 

1

RTECS 

WB0350000

F 

10

Hazard Note 

Toxic/Hygroscopic

TSCA 

Yes

HS Code 

2826 19 10

HazardClass 

6.1

PackingGroup 

III

Hazardous Substances Data

7681-49-4(Hazardous Substances Data)

Toxicity

LD50 orally in rats: 0.18 g/kg (Smyth)

MSDS

• Language:English Provider:SigmaAldrich
• Language:English Provider:ACROS
• Language:English Provider:ALFA

Sodium fluoride Usage And Synthesis

Chemical Properties

It is colorless crystals or shiny white powder, belongs to tetragonal system, is positive hexahedral or octahedral crystals. It is slightly soluble in alcohol, soluble in water. Aqueous solution is acidic. It dissolves in hydrofluoric acid to form sodium hydrogen fluoride.

Solubility in water

Dissolved Amount per 100 ml of water at different temperatures (℃) in grams:
3.66g/0 ℃; 4.06g/20 ℃; 4.22g/30 ℃; 4.4g/40 ℃
4.68g/60 ℃; 4.89g/80 ℃; 5.08g/100 ℃

Uses

1. Sodium fluoride is mainly used as Inlaid steel for mechanical blade and planer to enhance weld strength. Secondly, it is used as wood preservatives, fungicides in brewing industry, agricultural pesticides (should be infected with blue), medical preservatives, welding flux, fluorine agent for drinking water. Also used for producing other fluoride and casein glue, sodium fluoride toothpaste, as adhesives, also used in paper and metallurgical industries. In the production of elemental fluorine, it is used for removing trace amounts of hydrogen fluoride. In addition, it is also used in enamels and pharmaceutical industries.
2.  Sodium fluoride is used as disinfectants, preservatives, pesticides, also used in enamel, wood preservation, medicine, metallurgy, manufacturing of fluorides and so on.
3.  Used for determination of scandium in microanalysis, determination of phosphorus in photoelectric colorimetric analysis, used as reagent, the masking agents, preservatives of iron and steel.
4.  As food supplements. According to Chinese regulations for salt, the maximum usage is 0.1g/kg.
5.  It is used as wood preservatives, pharmaceutical preservative, welding flux and used in paper industry, this company's products are specific level toothpastes, can also be used as purifying agent for drinking water, and used for hides and skin processing in tanning industry, for smelting and refining of light metal, and protection layer of light metal, for adhesive corrosion, and manufacturing boiling steel.
6.  Sodium fluoride is used as the Phosphate accelerator in coating industry, makes phosphating solution stability, phosphate refinement, improves the performance of phosphate coating. Aluminum and its alloys phosphate can close negative catalytic Al3 + of great danger, and make phosphating smoothly. It is used as wood preservatives, agricultural pesticides, fungicides in brewing industry, pharmaceutical preservative, welding flux, alkaline zincate zinc additives and enamel, paper and so on.

Application in toothpaste

Sodium fluoride was added to toothpaste which can play against dental caries, since enamel interacts with fluoride to form fluorapatite on the enamel surface, which improves the hardness and acid resistance of enamel, and reduces formation of plaque, reduces the incidence of dental caries.
Fluoride toothpaste does have some anti-caries effects. As early as the mid-19th century,  pregnant women took orally calcium fluoride for anti-caries in Europe. In the 20th century, fluoride is recognized worldwide as an effective anti-caries agent. Usually in fluoride toothpaste, the content of sodium fluoride is 0.22-0.33%, the content of sodium monofluorophosphate is 0.76%. Although small amount, it has a good protective effect on people's teeth, can reduce the caries prevalence rate of 28%.
According to different content of fluoride in toothpaste, fluoride toothpaste is divided into the following categories: sodium fluoride toothpaste, monofluorophosphate toothpaste, stannous fluoride toothpaste, amine fluoride toothpaste and so on. Currently the most common fluoride toothpaste on the market are sodium fluoride toothpaste and monofluorophosphate dentifrice, or double fluorine toothpaste containing both sodium fluoride and sodium monofluorophosphate. Different types of fluoride toothpastes, and whether the toothpastes contain single fluorine or double fluorides, their effects of anti-caries are the same.

Production method

Melt immersion method
Calcine the fluorite, quartz sand and soda ash at high temperature (800~900 ℃), followed by water leaching, and then by evaporation, crystallization, drying to prepare products.
CaF2 + Na2CO3 + SiO2 → 2NaF + CaSi03 + C02 ↑
Neutralizational process
It is derived from neutralization of soda ash or caustic soda with hydrofluoric acid,
2HF + Na2CO3 → 2NaF + H2O + CO2 ↑
Dissolve soda in the pot liquor, and then add 30% hydrofluoric acid to neutralize to a pH value of 8-9, until CO2 gas evolution, hydrofluoric acid often contains fluosilicate impurities, and after neutralization to generate sodium fluosilicate, heating for 1h at 90~95 ℃, sodium fluosilicate decomposes:
Na2SiF6 + 2Na2CO3 → 6NaF + SiO2 + 2C02 ↑
And during the process of neutralization, pH value is not less than 8, otherwise sodium fluoride is difficult to decompose by base, and neutralization solution is allowed to stand for 1h, serum is cooled and concentrated to precipitate sodium fluoride crystals and then separated by centrifugation, drying, crushing to obtain products.
Sodium fluosilicate method
As the byproduct of the wet process of phosphoric acid and phosphate fertilizer, fluosilicic acid may prepare 99.87% sodium fluoride by conventional methods. The reaction lasts 160~180min at 84~95 ℃ and 0.15MPa conditions, with an excess of 5% to 8% alkaline solution (pH value 8-9) to prepare sodium fluoride.
Na2SiF6 + 2Na2Co3 → 6NaF + SiO2 + 2C02 ↑
After standing and clarification of neutralization solution, the supernatant was concentrated by evaporation, cooling crystallization, after separation, wash with hot water of 50~60 ℃, indirectly dry to obtain products.

Toxicity

Sodium fluoride is an acute toxicant. Ingestion of large quantites (5 to 10g) can cause death in humans. Smaller quantities can produce nausea, vomiting, diarrhea, stupor, and weakness. Other symptoms are tremor, muscular weakness, and dyspnea. Mottling of teeth can occur from chronic exposure.

Hazards & Safety Information

Category: Pesticide
Toxicity grading: Highly toxic
Acute toxicity
Oral-rat LD50: 52 mg/kg; Oral-Mouse LD50: c57 mg/kg
Stimulus data
Eyes-rabbit 20 mg/24 hours  moderate
Flammability hazard characteristics: It is non-combustible. In case of acid, it releases toxic hydrogen fluoride gas, heating may produce toxic fumes of fluoride and sodium oxide.
Storage Characteristics: Treasury ventilation low-temperature drying, stored separately from oxidants, food additives.
Occupational standards: TLV-TWA 2.5 mg (fluorine)/cubic meter, STEL 5 mg (fluorine)/cubic meter

Description

Sodium fluoride, NaF, is a binary salt that is a clear, lustrous crystal or white powder. The insecticide grade is frequently dyed blue. It is soluble in water and has a specific gravity of 2.558, which is heavier than water. Sodium fluoride is highly toxic by ingestion and inhalation, and is also strongly irritating to tissue. The TLV is 2.5 mg/m3 of air. The four-digit UN identification number is 1690. The primary uses are fluoridation of municipal water at 1 ppm, as an insecticide, rodenticide, and fungicide, and in toothpastes and disinfectants.

Chemical Properties

Sodium fluoride is a white powder or colorless crystals. Often used in a solution. Odorless. Pesticide grade is often dyed blue.

Physical properties

Colorless cubic or tetragonal crystals; density 2.78 g/cm³; melts at 993°C; vaporizes at 1,695°C; moderately soluble in water 4.22 g/100mL at 18°C; soluble in hydrofluoric acid; insoluble in ethanol.

Uses

Sodium fluoride is a versatile chemical reagent widely used in the fields of chemical industry, medicine, food, materials and electrochemistry. It can be used as a reagent in analytical chemistry and biological experiments (such as protein and enzyme analysis); adding 1 ppm NaF to drinking water can be used to prevent dental caries. It is also used to make adhesives, disinfectants and dental products, or for pesticide formulation components; used as a food preservative, such as preservatives and anti-fermentation agents in alcohol distilleries; used as a component of ceramic enamel and flux, or to make coated paper and frosted glass; used to preserve animal specimens.

Definition

ChEBI: Sodium fluoride is a metal fluoride salt with a Na(+) counterion. It has a role as a mutagen.

Preparation

Sodium fluoride is prepared by adding sodium hydroxide or sodium carbonate to a 40% solution of hydrofluoric acid. In excess hydrofluoric acid, sodium bifluoride, NaHF2 , is formed. NaF also is made by fusion of cryolite with caustic soda. Technical grade products are usually sold at 90 to 95% purity.

brand name

Fluorinse (Oral-B); Minute-Gel (Oral-B); Neutra Care (Oral-B); Pediaflor (Ross).

General Description

Sodium fluoride is a colorless crystalline solid or white powder, or the solid dissolved in a liquid. Sodium fluoride is formed by the reaction of sodium carbonate and hydrofluoric acid. Sodium fluoride is soluble in water. Sodium fluoride is noncombustible. Sodium fluoride is corrosive to aluminum. Sodium fluoride is used as an insecticide. Sodium fluoride is also used to fluorinate water supplies, as a wood preservative, in cleaning compounds, manufacture of glass, and for many other uses.

Hazard

Toxic by ingestion and inhalation, strong irritant to tissue.

Health Hazard

Ingestion may cause vomiting, abdominal pain, diarrhea, convulsions, collapse, thirst, disturbed color vision, acute toxic nephritis.

Health Hazard

The acute toxicity of fluorides is generally moderate. High exposures may cause irritation of the eyes and respiratory tract. Ingestion of fluoride may cause a salty or soapy taste, vomiting, abdominal pain, diarrhea, shortness of breath, difficulty in speaking, thirst, weak pulse, disturbed color vision, muscular weakness, convulsions, loss of consciousness, and death. In humans the approximate lethal dose of NaF by ingestion is 5 g. Repeated inhalation of fluoride dust may cause excessive calcification of the bone and calcification of ligaments of the ribs, pelvis, and spinal column. Repeated skin contact may cause a rash Fluorides have not been shown to be carcinogenic or to show reproductive or developmental toxicity in humans.

Fire Hazard

Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.

Fire Hazard

Fluorides are not combustible.

Flammability and Explosibility

Fluorides are not combustible.

Industrial uses

Sodium fluoride is a white to yellowish powder, poorly soluble in water. The NaF solubility in water is 3.85% at 15 °C and 4.21% at 25 °C. Commercially, NaF is obtained by reacting hydrofluoric acid with sodium hydroxide. This reaction is a by-product during the production of superphosphates from fluoro-apatite. Sodium fluoride is an important depressant used exclusively during beneficiation of non-sulfide minerals, as well as the rare-earth minerals as a depressant alone or in combination with other depressants. It is used together with starch as co-depressant for rutile and ilmenite during zirconium– titanium separation or during reverse silicate flotation from rutile and ilmenite with cationic collectors. Although it is believed that Na₂F is a silicate depressant, studies have shown that it does not depress silicate minerals. In fact, it improves depression of oxides and silicates when used with other depressants.

Biochem/physiol Actions

Sodium fluoride (NaF) prevents dental caries, by catalysing the diffusion of calcium and phosphate and remineralizes the lesions. Fluoride affects spermatogenesis and capacitation process in the female reproductive tract. Fluoride induces oxidative stress, DNA damage in ovary ultimately affects the development of oocytes. Fluoride supplementation enhances bone mineral density. 18F-NaF is a radiotracer used in positron emission tomography (PET) to identify atherosclerotic lesions and other cardiac plaques.

Clinical Use

Sodium fluoride (NaF) promotes the proliferation and activity of osteoblasts and is classified as a nonhormonal bone-forming agent. Because treatment with NaF induces bone formation, it is essential that this therapy be coupled with oral calcium supplementation (1,000 mg/day). Additionally, NaF exhibits moderate antiresorptive activity, because it inhibits osteoclastic activity when it is absorbed into the bone matrix. In the treatment of osteoporosis, the therapeutic window for this agent is fairly narrow: Doses less than 45 mg/day are subtherapeutic, and doses in excess of 75 mg/day impair bone mineralization. In addition, the bone that is formed in the presence of NaF is neither as well mineralized nor as strong as normal bone tissue. In fact, some

Safety Profile

Human poison by ingestion. Experimental poison by ingestion, skin contact, intravenous, intraperitoneal, subcutaneous, and intramuscular routes. Human systemic effects: changes in teeth and supporting structures, cyanosis, diarrhea, EKG changes, fluid intake, headache, hypermotihty, increased immune response, muscle weakness, musculo-skeletal changes, nausea or vomiting, paresthesia, ptosis (drooping of the eyelid from sympathetic innervation), respiratory depression, salivary gland changes, tremors. Experimental teratogenic and reproductive effects. Human mutation data reported. A corrosive irritant to skin, eyes, and mucous membranes. Questionable carcinogen with experimental tumorigenic data. It is very phytotoxic. When heated to decomposition it emits toxic fumes of Fand NazO. Used in chemical cleaning, for fluoridation of drinking water, as a funglcide and insecticide. See also FLUORIDES

Potential Exposure

Widely used in the chemical industry; in water treatment and fluoridation of drinking water; as an insecticide, fungicide, and rodenticide; chemical cleaning; electroplating, glass manufacture; vitreous enamels; preservative for adhesives; toothpastes, disinfectant, dental prophylaxis; also used orally in the treatment of various bone diseases to increase bone density and to relieve bone pain.

Shipping

UN1690 Sodium fluoride, Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Purification Methods

Crystallise NaF from water by partial evaporation in a vacuum desiccator, or dissolve it in water, and precipitate ca half of it by adding EtOH. The precipitate is dried in an air oven at 130o for one day, and then stored in a desiccator over KOH. Its solubility in H2O is 4% at 15o and 4.3% at 25o. [Kwasnik in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 235 1963].

Incompatibilities

Contact with acids release toxic gas. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides.

Waste Disposal

In accordance with 40CFR165, follow recommendations for the disposal of pesticides and pesticide containers. Must be disposed properly by following package label directions or by contacting your local or federal environmental control agency, or by contacting your regional EPA office.

Sodium fluoride(7681-49-4)Related Product Information

• Sodium gluconate
• Sodium hydroxide
• Sodium benzoate
• TITANIUM(III) FLUORIDE
• Sodium chloride
• Sodium carbonate
• Sodium acetate
• Sodium bicarbonate
• Fluorinated carbon
• Potassium fluoride dihydrate
• Ammonium fluoride
• Lead fluoride
• Caesium fluoride
• Calcium fluoride
• Lithium fluoride
• Barium fluoride
• ALUMINUM FLUORIDE TRIHYDRATE
• Strontium fluoride