ANTIMONY PENTAFLUORIDE

Description

This week’s molecules combine to make “magic”. The first, fluorosulfuric acid (HSO3F; also called fluorosulfonic acid) is an extremely strong Br?nsted acid that has been known since the late 19th century. It is ≈1000 times stronger than pure sulfuric acid, which puts it in the class of superacids. It can protonate and dissolve almost all organic compounds and has several industrial uses, including catalysis and hydrofluorination.
The second molecule, antimony pentafluoride (SbF5), was first reported in 1904. This strong Lewis acid is nasty: It reacts violently with water, attacks the skin and eyes, and corrodes metals. Its chief use is the fluorination of organic compounds.
So where’s the magic? In the 1960s, George A. Olah and co-workers, first at Dow Chemical (Midland, MI), then at Case Western Reserve University (Cleveland), were seeking ways to make and study stable carbocations. To extract hydride groups (hydrogen anions) from organic compounds, they needed a strong, but poorly nucleophilic, acid.
At Case Western, the researchers discovered that a mixture of HSO3F and SbF5easily dissolves paraffins. NMR spectra of the solutions showed that the acidic combination cleaved the long-chain alkanes, and the fragments isomerized to form stable?tert-butyl cations (Me3C+). This result was so spectacular that the chemists dubbed the mixture “magic acid”. The usual molar ratio of the components is 1:1, but other combinations have also been useful.
Olah went on to do extensive research on carbocations at Case Western and then the University of Southern California (Los Angeles). He received the Nobel Prize in Chemistry in 1994 for his pioneering work.

Description

Antimony pentafluoride is a noncombustible,oily, colorless liquid with a pungent odor. Molecularweight= 216.75; Boiling point= 143℃; Melting/Freezingpoint=8.3℃; Specific gravity: 2.340 at 30℃; Liquidsurface tension= 5 (estimate) 0.020 N/m at 20℃; Latentheat of vaporization= (estimate) 1.8 3 105 J/kg; Vaporpressure= 1.33 kPa at 25℃. Hazard Identification (basedon NFPA-704 M Rating System): Health 3, Flammability 0,Reactivity 1. Soluble in water.

Chemical properties

colourless oily liquid

Chemical properties

Antimony pentafluoride is a noncombustible, oily, colorless liquid with a pungent odor.

Physical properties

Colorless oily liquid; highly viscous; hygroscopic; freezes at 8.3°C; boils at 149.5°C; density 2.99 g/cm³ at 23°C; soluble in excess water (with violent reaction) and glacial acetic acid; also soluble in potassium fluoride.

The Uses of ANTIMONY PENTAFLUORIDE

HF/SbF5 is an excellent medium for the preparation of alkylidene oxonium salts.1

The Uses of ANTIMONY PENTAFLUORIDE

In the fluorination of organic Compounds, see the monograph Preparation, Properties and Technology of Fluorine and Organic Fluoro Compounds, C. Slesser, S. R. Schram, Eds. (McGraw-Hill, New York, 1951) 868 pp.

Preparation

Antimony pentafluoride is prepared by the reaction of antimony pentachloride with anhydrous hydrogen fluoride:
SbCl₅ +5 HF → SbF₅ +5 HCl
It may also be prepared from antimony trifluoride and fluorine, or by treating antimony pentaoxide with aqueous hydrofluoric acid and evaporing water.

Definition

ChEBI: Antimony pentafluoride is an antimony molecular entity and an inorganic fluoride salt. It has a role as a Lewis acid.

Production Methods

Antimony pentafluoride is prepared by treating antimony pentachloride with excess anhydrous hydrogen fluoride. The antimony pentafluoride is separated from the volatile byproducts by fractional distillation. It can also be prepared by allowing fluorine to react with antimony powder or molten antimony trifluoride. The main use of antimony pentafluoride is as a fluorinating agent.

General Description

A colorless, oily liquid. Fumes irritate the eyes and mucous membranes. Toxic. Corrosive to metals and tissue. Extremely dangerous to tissue; its burns may be followed by gangrene. Only shipped in cylinders. Under prolonged exposure to heat cylinders may violently rupture and rocket. Used to make other chemicals as well as a catalyst in the manufacture of other chemicals.

Reactivity Profile

ANTIMONY PENTAFLUORIDE is strongly acidic. Reacts vigorously with bases. When heated to decomposition, ANTIMONY PENTAFLUORIDE emits highly toxic fumes of fluorides and metallic antimony. Reacts with ammonia to form a diammoniate.

Hazard

Corrosive to skin and tissue.

Health Hazard

The compound is irritating to eyes, skin, and lungs. Contact with eyes or skin causes severe burns. The compound is extremely toxic with a probable oral lethal dose of 5-50 mg/kg or between 7 drops and one teaspoonful for a 150 pound person (antimony salts).

Fire Hazard

Reacts violently with water, to form poisonous hydrogen fluoride fumes. If confined and wet can cause explosion. May cause fire in contact with combustible material. Hazardous polymerization may not occur.

Safety Profile

A poison by inhalation. A very reactive, corrosive liquid to skin, eyes, mucous membranes. See also FLUORIDES and ANTIMONY COMPOUNDS. Violent reaction with phosphates. When heated to decomposition it emits very toxic fumes of F and Sb.

Potential Exposure

It is used as a catalyst in chemical reactions or as a source of fluorine (fluorinating reagent) in fluorination reactions.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. If victim is conscious, administer water ormilk. Do not induce vomiting. Medical observation isrecommended for 24°48 h after breathing overexposure, aspulmonary edema may be delayed. As first aid for pulmonary edema, a doctor or authorized paramedic may consideradministering a corticosteroid spray.

storage

Color Code—Blue: Health Hazard/Poison: Store ina secure poison location. Prior to working with this chemicalyou should be trained on its proper handling and storage.Antimony pentafluoride must be stored to avoid contactwith phosphorus, phosphates, siliceous, and combustible ororganic materials since violent reactions occur. Store intightly closed containers in a cool, well-ventilated area awayfrom water or moisture and heat. Outside or detached storage is preferred.

Shipping

UN1732 Antimony pentafluoride, Hazard class: 8; Labels: 8-Corrosive material, 6.1-Poisonous materials.

Purification Methods

Purify it by vacuum distillation, preferably in a quartz apparatus, and store it in quartz or aluminum bottles. It is a hygroscopic viscous liquid which reacts violently with H2O and is hydrolysed by alkalis. It is POISONOUS and attacks the skin. [Woolf & Greenwood J Chem Soc 2200 1950, Kwasnik in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 200 1965.]

Incompatibilities

Water and other forms of moisture releases hydrofluoric acid, combustible organic and siliceous materials, phosphorus, and phosphate materials. Attacks glass, ceramic, lead, and metals, including copper in the presence of moisture. 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. Antimony pentafluoride, if confined and wet may cause explosion. Antimony pentafluoride appears to have oxidizing properties; may cause fire in contact with combustible or organic materials. May react with metals, including lead, releasing flammable hydrogen gas.

Waste Disposal

Consult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform with EPA regulations governing storage, transportation, treatment, and waste disposal.