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HEXAFLUOROSILIC ACID

HEXAFLUOROSİLİC ACID

CAS No .: 16961-83-4

EC No .: 241-034-8

Hexafluorosilic acid is an inorganic compound with the chemical formula H, also spelled SiF ₆ ₂ [SiF ₆]. It is a colorless liquid most commonly encountered as a diluted aqueous solution, from which the second chemical representation is also recommended. Hexafluorosilic acid has a pronounced sour taste and pungent odor.

Water fluoridation, Wood preservative, Sterilization of equipment, Electroplating, Tanning, Glass etching, Cement Hardening, Oil acidizing, Rust Removal in textile field, lead refining and fluorosilicate salt manufacture.Not combustible. Gives off irritating or toxic fumes (or gases) in a fire.

SYNONYM

Hexafluorosilicic acid;Fluorosilic acid;16961-83-4;Dihydrogen hexafluorosilicate;MFCD00036289;Silicate (2-), hexafluoro-, dihydrogen;hexafluorosilicon (2 -); hydron;Fluosilic acid, 25% by weight aqueous solution;UNII-53V4OQG6U1;hexafluorosilicon (2-); hydron;Hexafluorosilic acid;Kieselfluorwasserstoffsaure;53V4OQG6U1;DTXSID2029741;hexakis (fluororanyl) silicone (2-); hydron;SC-47078;DB-064742;FT-0626488;A811126;Q411250;J-521443;241-034-8;Fluorosilic acid;Fluorosilic acid solution;Fluosilic acid;Hexafluorosilicic acid;Hydrofluoric acid, compound. with tetrafluorosilane;Hydrogen hexafluorosilicate;MFCD00036289;Tetrafluorosilane dihydrofluoride;Tetrafluorosilane, difluorhydrate;Tetrafluorylanhydrofluoride;[16961-83-4];1216463-25-0;ACTH (1-39), HUMAN;Dihydrogen hexafluorosilicate;Fluorosilic acid, 22-25% in water;H2SiF6;Hexafluorosilicic acid, 23% aqueous solution;hexafluorosilic acid;CAS Names: Silicate (2-), hexafluoro-, hydrogen (1: 2); hexafluorosilicon(2-);hydron; Dihydrogen hexafluorosilicate; Kieselfluorwasserstoffsaure

Hexafluorosilicic acid is generally assumed to consist of oxonium ions charge balanced by hexafluorosilicate dianions as well as water. In aqueous solution, the hydronium cation (H3O+) is traditionally equated with a solvated proton, and as such, the formula for this compound is often written as H2SiF6. Extending that metaphor, the isolated compound is then written as H2SiF6·2H2O, or (H3O)2SiF6.The situation is similar to that for chloroplatinic acid, fluoroboric acid, and hexafluorophosphoric acid. Hexafluorosilicate is an octahedral anion; the Si–F bond distances are 1.71 Hexafluorosilicic acid is only available commercially as solution.

The majority of the hexafluorosilicic acid is converted to aluminium fluoride and synthetic cryolite.These materials are central to the conversion of aluminium ore into aluminium metal. The conversion to aluminium trifluoride is described as:

H2SiF6 + Al2O3 → 2 AlF3 + SiO2 + H2O

Hexafluorosilicic acid is also converted to a variety of useful hexafluorosilicate salts. The potassium salt, Potassium fluorosilicate, is used in the production of porcelains, the magnesium salt for hardened concretes and as an insecticide, and the barium salts for phosphors.Hexafluorosilicic acid is also used as an electrolyte in the Betts electrolytic process for refining lead.Hexafluorosilicic acid (identified as hydrofluorosilicic acid on the label) along with oxalic acid are the active ingredients used in Iron Out rust-removing cleaning products, which are essentially varieties of laundry sour.

The major use of sodium hexafluorosilicate and hexafluorosilic acid is as fluoridation agents for drinking water. Sodium hexafluorosilicate has also been used for caries control as part of a silicophosphate cement, an acidic gel in combination with monocalcium phosphate monohydrate, and a two-solution fluoride mouth rinse. Both chemicals are also used as a chemical intermediate (raw material) for aluminum trifluoride, cryolite (Na3AlF6), silicon tetrafluoride, and other fluorosilicates and have found applications in commercial laundry. Other applications for sodium hexafluorosilicate include its use in enamels/enamel frits for china and porcelain, in opalescent glass, metallurgy (aluminum and beryllium), glue, ore flotation, leather and wood preservatives, and in insecticides and rodenticides. It has been used in the manufacture of pure silicon, as a gelling agent in the production of molded latex foam, and as a fluorinating agent in organic synthesis to convert organodichlorophosphorus compounds to the corresponding organodifluorophosphorus compound. In veterinary practice, external application of sodium hexafluorosilicate combats lice and mosquitoes on cattle, sheep, swine, and poultry, and oral administration combats roundworms and possibly whipworms in swine and prevents dental caries in rats.

Apparently, all pesticidal products had their registrations cancelled or they were discontinued by the early 1990s. Fluorosilicic acid is used in the tanning of animal hides and skins, in ceramics and glass, in technical paints, in oil well acidizing, in the manufacture of hydrogen fluoride, for the sterilization of equipment (e.g., in brewing and bottling establishments and for copper and brass vehicles), and in electroplating. It is also employed as an impregnating ingredient to preserve wood and harden masonry and for the removal of mold as well as rust and stain in textiles.

Acid Characteristics: Hexafluorosilic acid is a transparent, straw colored, corrosive liquid having the chemical formulation of H2SiF6. It is manufactured in modern rubber lined equipment producingan acid of high commercial purity. Commercial water solutions of the acid are available, having concentration of between 20% and 25% H2SiF6. Hexafluorosilic acid is generally believed not to exist in the vapor phase, but only in solution. Upon vaporizing, it decomposes into hydrofluoric acid (HF) and silicon tetrafluoride. This equilibrium exists at the surface of strong solutions of Hexafluorosilic acid and if stored in glass containers, the small concentration of hydrofluoric acid may very slowly attack the glass above the solution level. For this reason, it is generally shipped in polyethylene containers rather than glass carboys. A 23% fluorosilicic acid water solution weighs 10.2 pounds per gallon at 60ºF, and has a fluoride (F) content of 17.41%.

Hexafluorosilic acid is available generally as a 20 to 40 percent aqueous solution.
60-70% solution will be solidified at 19 C to form a dihydrate crystalline.,

Fumes in air. Soluble in water with release of heat and corrosive fumes.

SELF

Hexafluorosilicic acid is a type of inorganic acid. It is largely used for fluoridation of water in the United States to minimize incidence of dental caries and dental flora. For chemical synthesis, it is largely used in the production of aluminum fluoride and cryolite, as well as many types of hexafluorosilicate salts. It can also be used in the production of silicon and silicon dioxide. It can also be used as an electrolyte in the Betts electrolytic process to refine lead. It is also a special reagent in organic synthesis to break down Si - O bonds of silyl ethers.

Hexafluorosilicic acid is an inorganic compound with chemical formula H.

2SiF6 is also (H3O) 2 [SiF6]. It is a colorless liquid that is often encountered as diluted aqueous solution, from there the second chemical notation has also been proposed. Hexafluorosilicic acid has a distinctive sour taste and a pungent odor. It is naturally produced on a large scale in volcanoes. It is produced as a by-product in the production of phosphate fertilizers. The resulting hexafluorosilic acid is consumed almost exclusively as a precursor for aluminum trifluoride and synthetic cryolite used in aluminum processing. Salts derived from hexafluorosilic acid are called hexafluorosilicates. Hydrofluorosilic acid is a chemical commonly known by other names such as Hexafluorosilic acid , fluosilic acid, silicofluoride, and silicofluoric acid, and is often abbreviated as HSA or FSA. It is a colorless chemical that is formed when you take phosphoric rock from the ground and convert it into soluble fertilizer. In this process, two highly toxic fluorine gases are liberated, one of which is hydrogen fluoride; the other is silicon tetrafluoride. Condensate from this hydrogen fluoride is collected, then purged with water. In the past, the phosphate industry would allow these two gases to freely enter the atmosphere. However, this has caused serious environmental damage to windsurfed communities, including widespread cattle poisoning, parched vegetation, and various human health complaints. Eventually, as a result of both lawsuits and regulations, the phosphate industry used "wet scrubbers" to capture fluoride gases. founded. The liquid collected in these scrubbers (hydrofluorosilic acid) is entered into storage tanks and shipped to water departments across the country. Depending on the manufacturer, impurities (arsenic, lead) may be present and are often not removed. While there are measures to regulate water safety, contaminants can be a factor over time for your storage container, which we'll cover below.

Uses: Most hexafluorosilic acid is converted into aluminum fluoride and synthetic cryolite. These materials are central to the conversion of aluminum ore to aluminum metal. Conversion to aluminum trifluoride is defined as follows:

H2SiF6 + Al2O3 → 2 AlF3 + SiO2 + H2O

Hexafluorosilicate acid is also converted into various useful hexafluorosilicate salts. Potassium salt, Potassium fluorosilicate is used in the production of porcelain, as a magnesium salt and insecticide for hardened concrete and in barium salts for phosphors.

Hexafluorosilicic acid is also used as an electrolyte to refine lead in the Betts electrolytic process.

H2SiF6 is a reagent in organic synthesis for cleaving Si-O bonds of silyl ethers. It is more reactive for this purpose than HF. It reacts faster with t-butyldimethysilyl (TBDMS) ethers than triisopropylsilyl (TIPS) ethers.

Hexafluorosilicic acid and the salts are used as wood preservation agents. The aluminium and magnesium hexafluorosilicate are two used compounds.

Hexafluorosilicic acid releases hydrogen fluoride when evaporated, so it has similar risks. It is corrosive and may cause fluoride poisoning; inhalation of the vapors may cause lung edema. Like hydrogen fluoride, it attacks glass and stoneware.

Hexafluorosilicic acid can react with strong acids (such as sulfuric acid) to release fumes of toxic hydrogen fluoride. Attacks glass and materials containing silica. Reacts exothermically with chemical bases (examples: amines, amides, inorganic hydroxides). Reacts with active metals, including iron and aluminum to dissolve the metal and liberate hydrogen and/or toxic gases. Can initiate polymerization in certain alkenes. Reacts with cyanide salts and compounds to release gaseous hydrogen cyanide. Flammable and/or toxic gases are also often generated by reactions with dithiocarbamates, isocyanates, mercaptans, nitrides, nitriles, sulfides, and weak or strong reducing agents. Additional gas-generating reactions may occur with sulfites, nitrites, thiosulfates (to give H2S and SO3), dithionites (SO2), and carbonates. Can catalyze (increase the rate of) chemical reactions. Decomposes when heated to the boiling point to produce very toxic and corrosive hydrogen fluoride gas.

Hexafluorosilic acid (defined as hydrofluorosilic acid on the label) along with oxalic acid are the active ingredients used in Iron Out rust remover cleaning products, which are mainly laundry sour varieties.

Natural salts: Some rare minerals encountered in volcanic or coal-fire fumaroles are hexafluorosilic acid salts. Examples include naturally occurring ammonium hexafluorosilicate as two polymorphs: cryptohalite and bararite.

Production and basic reactions: Commodity chemical hydrogen fluoride is produced from fluoride by treating it with sulfuric acid. As a by-product, about 50 kg of (H3O) 2SiF6 is produced per tonne of HF due to reactions involving silica-containing mineral impurities. (H3O) 2SiF6 is also produced as a by-product from the production of phosphoric acid from apatite and fluorapatite. Again, some of the HF reacts with silicate minerals, an inevitable component of mineral feedstock, to give silicon tetrafluoride. The silicon tetrafluoride formed in this way reacts more with HF. The exact process can be defined as: SiO2 + 6 HF → SiF2−6 + 2 H3O + Hexafluorosilic acid can also be produced by treating silicon tetrafluoride with hydrofluoric acid Hydrolysis to water, hexafluorosilic acid, hydrofluoric acid and various forms of amorphous and hydrated silica ("SiO2") happens. At the concentration generally used for water fluoridation, 99% hydrolysis occurs and the pH drops. The rate of hydrolysis increases with pH. At the pH of the drinking water, the degree of hydrolysis is essentially 100%. H2SiF6 + 2 H2O → 6 HF + "SiO2" Neutralization of hexafluorosilic acid solutions with alkali metal bases produces the corresponding alkali metal fluorosilicate salts: (H3O) 2SiF6 + 2 NaOH → Na2SiF6 + 4 H2O The resulting salt Na2SiF6 is mainly used in water fluoridation. The corresponding ammonium and barium salts are produced similarly for other applications. Near neutral pH, hexafluorosilicate salts hydrolyze rapidly according to this equation: SiF2−6 + 2 H2O → 6 F− + SiO2 + 4 H +

STRUCTURE: Hexafluorosilic acid is generally assumed to be composed of a charge of oxonium ions balanced with hexafluorosilicate dianions as well as water. In aqueous solution, the hydronium cation (H3O +) is conventionally equated with a solvated proton, and therefore the formula for this compound is often written as H. 2SiF6. By expanding this metaphor, the isolated compound is then written as H. 2SiF6. 2H2O or (H3O) 2SiF6. The situation is similar to that for chloroplatinic acid, fluoroboric acid and hexafluorophosphoric acid. Hexafluorosilicate is an octahedral anion; Si - F bond distances are 1.71 Å. Hexafluorosilic acid is commercially available only as a solution.

Hexafluorosilicic acid is commonly used as a source of fluoride. It is converted to a variety of useful hexafluorosilicate salts. It is also used as an electrolyte in the Betts electrolytic process for refining lead. It is an important organic reagent for cleaving Si-O bonds of silyl ethers. Further, it is used as wood a preservation agent and also used in surface modification of calcium carbonate.

Application: Hexafluorosilicic acid is also converted to a variety of useful hexafluorosilicate salts. The potassium salt is used in the production of porceleins, the magnesium salt for hardened concretes and as an insecticide, and the barium salts for phosphors.

Notes

Incompatible in strong oxidizing agents, metals, alkalis, strong acids, stoneware and glass.

Chemicals: The following chemicals were analytical grade and used as they were taken without further purification: hexadecyltrimethylammonium bromide (Sigma-Aldrich, CTAB, 98% w / w), ethyl acetate (Sigma-Aldrich, EA, 99.8% w / w), ammonia solution Sigma- Aldrich, 30% w / w), tetraethyl orthosilicate (Sigma-Aldrich, TEOS, 98% w / w), ethanol (Sigma-Aldrich, EtOH, 96% v / v), calcium hydroxide (Ca (OH) 2 Carlo Erba 95% w / w). The FSA solution (Honeyweel, 34% w / w) was diluted to 23.8% w / w with double distilled water, and the concentration was determined by a titration method according to ref (30). Double distilled water was used throughout the experiments.

The most widely discussed application for this chemical is water fluorination in water treatment plants. This process helps prevent periodontal problems and is added to drinking water. Another common chemical added to drinking water for the same purpose is sodium fluoride, but it can be five times more expensive. However, storage of hydrofluorosilicic acid can be more dangerous, so it's important to have a reliable and safe storage solution.

Another use of the FSA is to etch glass; The highly corrosive nature of the chemical is effective for this desired application. We'll cover storage options in the next section, but glass or fiberglass tanks are therefore not good storage solutions when the goal is "not" glass food.

Hydrofluorosilic acid is also used in the production of salts that may contain porcelain.

Storage Problems and Solutions:

Hydrofluorosilic acid is the most dangerous chemical in your local water treatment plant. When vaporized, it can release hydrogen fluoride, is corrosive and can injure the lungs when inhaled, making it particularly dangerous for plant workers if stored incorrectly.

The FSA also negatively interacts with metals to generate a flammable hydrogen gas, which means that a stainless steel chemical storage tank is not a viable option. It attacks glass, eats concrete, and creates a serious storage concern. Before rotomolded plastic became a viable storage option, fiberglass tanks built with a resin-rich cover were often used for storage. However, the resin-rich cover usually only provides 1/8 chemical barrier protection from the incompatible fiberglass (cut glass) structure itself. Since the FSA eats glass, it is truly incredibly dangerous to store the FSA from a structural support container made of glass in a location that provides only minimal safety barrier.

In these cases, a high density cross-linked polyethylene (XLPE) storage tank is the safest option, and it is best to choose one with secondary containment in case of a problem. With linear polyethylene (HDPE) it is possible to unzip (or tear the side of the tank destructively), but with XLPE it will hold up even if the structural integrity of the tank is compromised. A secondary containment XLPE tank such as Poly Processing's SAFE-Tank can contain the chemical as well as the transition outlet from the primary tank to the pump. Otherwise, not including your fixture, which is the most vulnerable part of a robust system, is like not having a housing in the first place. Another option is to place the pump armature above the tank where the chemical cannot escape when the armature fails. However, this requires special design in the pumping system.

With the popularity of fluorination occurring in most American water treatment plants, a tank with NSF-61 certification from the tank manufacturer (and specifically for hydrofluorosilic acid and not just for drinking water) should be included. XLPE tanks are available with this certificate. Always ensure that the NSF61 specifications are for the specific chemicals (not just water) tested, as NSF certifies the exact chemical to Maximum Permissible Levels .

Hexafluorosilicic Acid is a water-insoluble Silicon source for use in oxygen sensitive applications such as metal fabrication. In extremely low concentrations (ppm), fluoride compounds are used in healthcare applications. Fluoride compounds also have important uses in synthetic organic chemistry. Usually they are also used for metal alloy and optical deposition. Some fluoride compounds can be produced in nanoscale and ultra-high purity forms. Hexafluorosilicic Acid is usually available immediately on most skins. Ultra high purity and high purity compositions improve both optical quality and usability as scientific standards. Basic powders and suspensions can be considered as nanoscale alternative high surface area forms. American Elements manufactures many standard grades, including Mil Spec (military grade), when applicable; ACS, Reactive and Technical Grade; Food, Agriculture and Pharmaceutical Grade; Optical Grade follows USP and EP / BP (European Pharmacopoeia / British Pharmacopoeia) and related ASTM testing standards.

Security

Hexafluorosilic acid can release hydrogen fluoride when evaporated, so it has similar risks. Inhalation of vapors can cause pulmonary edema. Attacks glass and stone objects like hydrogen fluoride. Hexafluorosilic acid has an LD50 of 430 mg / kg. Hydrofluorosilicic acid, or H2SiF6, is a demanding chemical as it has hazardous properties and certain storage concerns. Because of its widespread use in water treatment, it is important to be aware of the risks associated with storing this chemical inadvertently, let's take a closer look at the nature of hydrofluorosilic acid, its applications, specific storage issues, and available solutions and safety issues when working with this complex chemical.

Hexaflorosilic Acid Properties:

Chemical formula: F6H2Si

Molar mass: 144.091 gmol - 1

Appearance: transparent, colorless, smoky liquid

Odor: sour, pungent

Density: 1.22 g / cm3 (25% soln.)

1.38 g / cm3 (35% dissolved)

1.46 g / cm3 (61% dissolved)

Melting point ca: 19 ° C (66 ° F; 292 K) (60--70% solution)

<−30 ° C (22 ° F; 243 K) (35% solution)

Boiling point: 108.5 ° C (227.3 ° F; 381.6 K) (decomposes)

Solubility in water can be miscible

Refractive index: (nD) 1.3465

Hexaflorosilic Acid Hazards:

Safety data sheet External: MSDS, GHS pictograms GHS05: Corrosive, GHS Signal word: Danger, GHS hazard statements: H314, GHS precautionary statements: P260, P264, P280, P301 + 330 + 331, P303 + 361 + 353, P304 + 340, P305 + 351 + 338, P310, P321, P363, P405, P501, NFPA 704 (fire apple), NFPA 704 four-color diamond, 300, Flash point: Not flammable, Lethal dose or concentration (LD, LC):, LD50 (median dose) 430 mg / kg (oral, rat)

IUPAC Names:

Dihydrogen hexafluorosilicate, dihydrogen hexafluorosilicate, Dihydrogen hexafluorosilicate (2-), fluorosilic acid, H2SiF6, hexafluoro-bucket, hexafluorosilicate, Hexafluorosilicic acid, hexafluorosilic acid, hexafluorosilic acid-, hexafluorosilicon (2-); hydron

Trade Names:

Acid fluorosilicate; Acid fluosilicate; Acido fluosilicico; Dihydrogen; hexafluorosilicate; DIHYDROGEN; HEXAFLUOROSILICATE (2-); FLOROSILIC ACID; Fluorosilic Acid; Fluorosilic acid; fluorosilic acid; FLOROSILIC ACID; FLOROSILIC ACID;FLUOSILIC ACID; FSA; HEXAFLUORKIESELSAEURE HEXAFLUOROSILIC ACID; Hexafluorosilic Acid; hexafluorosilic acid; Hexafluosilicic acid; HFS; HYDROFLUOROSILIC ACID; Hydrofluorosilic acid; Hydrofluosilic acid; hydrofluosilic acid; Hydrogen fluorosilicate; HYDROGEN HEXAFLUOROSILICATE; Hydrogen hexafluorosilicate; KIESELFLUORWASSERSTOFFSAEURE; kwas; fluorokrzemowy Sand acid SILICATE (2-); HEXAFLORO-; DIHYDROGEN Silicate (2-); hexafluoro-; dihydrogen Silicic acid Silicofluoric Acid Silicofluoride Silicon hexafluoride dihydride