Names | |||
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IUPAC name Sulfur(IV) fluoride | |||
Other names Sulfur tetrafluoride | |||
Identifiers | |||
3D model (JSmol) | |||
ChEBI | |||
ChemSpider | |||
ECHA InfoCard | 100.029.103 | ||
PubChem CID | |||
RTECS number |
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UNII | |||
UN number | 2418 | ||
CompTox Dashboard (EPA) | |||
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Properties | |||
SF4 | |||
Molar mass | 108.07 g/mol | ||
Appearance | colorless gas | ||
Density | 1.95 g/cm3, −78 °C | ||
Melting point | −121.0 °C | ||
Boiling point | −38 °C | ||
reacts | |||
Vapor pressure | 10.5 atm (22 °C) [1] | ||
Structure | |||
Seesaw (C2v) | |||
0.632 D [2] | |||
Hazards | |||
Occupational safety and health (OHS/OSH): | |||
Main hazards | highly toxic corrosive | ||
NFPA 704 (fire diamond) | |||
NIOSH (US health exposure limits): | |||
PEL (Permissible) | none [1] | ||
REL (Recommended) | C 0.1 ppm (0.4 mg/m3) [1] | ||
IDLH (Immediate danger) | N.D. [1] | ||
Safety data sheet (SDS) | ICSC 1456 | ||
Related compounds | |||
Other anions | Sulfur dichloride Disulfur dibromide Sulfur trifluoride | ||
Other cations | Oxygen difluoride Selenium tetrafluoride Tellurium tetrafluoride | ||
Related sulfur fluorides | Disulfur difluoride Sulfur difluoride Disulfur decafluoride Sulfur hexafluoride | ||
Related compounds | Thionyl fluoride | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Sulfur tetrafluoride is the chemical compound with the formula S F4. It is a colorless corrosive gas that releases dangerous HF upon exposure to water or moisture. Despite these unwelcome characteristics, this compound is a useful reagent for the preparation of organofluorine compounds, [3] some of which are important in the pharmaceutical and specialty chemical industries.
Sulfur in SF4 is in the formal +4 oxidation state. Of sulfur's total of six valence electrons, two form a lone pair. The structure of SF4 can therefore be anticipated using the principles of VSEPR theory: it is a see-saw shape, with S at the center. One of the three equatorial positions is occupied by a nonbonding lone pair of electrons. Consequently, the molecule has two distinct types of F ligands, two axial and two equatorial. The relevant bond distances are S–Fax = 164.3 pm and S–Feq = 154.2 pm. It is typical for the axial ligands in hypervalent molecules to be bonded less strongly. In contrast to SF4, the related molecule SF6 has sulfur in the 6+ state, no valence electrons remain nonbonding on sulfur, hence the molecule adopts a highly symmetrical octahedral structure. Further contrasting with SF4, SF6 is extraordinarily inert chemically.
The 19F NMR spectrum of SF4 reveals only one signal, which indicates that the axial and equatorial F atom positions rapidly interconvert via pseudorotation. [4]
At the laboratory scale, fluorination of elemental sulfur with cobaltic fluoride suffices: [5]
For larger-scale syntheses, SF4 is produced by the reaction of SCl2 and NaF in acetonitrile: [6]
At higher temperatures (e.g. 225–450 °C), the solvent is superfluous. Moreover, sulfur dichloride may be replaced by elemental sulfur (S) and chlorine (Cl2). [7] [8]
A low-temperature (e.g. 20–86 °C) alternative to the chlorinative process above uses liquid bromine (Br2) as oxidant and solvent: [9]
In organic synthesis, SF4 is used to convert COH and C=O groups into CF and CF2 groups, respectively. [10] The efficiency of these conversions are highly variable.
In the laboratory, the use of SF4 has been superseded by the more conveniently handled diethylaminosulfur trifluoride, Et2NSF3, "DAST": [11] This reagent is prepared from SF4: [12]
Sulfur chloride pentafluoride (SF
5Cl), a useful source of the SF5 group, is prepared from SF4. [13]
Hydrolysis of SF4 gives sulfur dioxide: [14]
This reaction proceeds via the intermediacy of thionyl fluoride, which usually does not interfere with the use of SF4 as a reagent. [6]
When amines are treated with SF4 and a base, iminosulfur difluorides result. [15]
SF
4 reacts inside the lungs with moisture, generating sulfur dioxide and hydrogen fluoride: [16]
In organic chemistry, an acyl halide is a chemical compound derived from an oxoacid by replacing a hydroxyl group with a halide group.
Boron trifluoride is the inorganic compound with the formula BF3. This pungent, colourless, and toxic gas forms white fumes in moist air. It is a useful Lewis acid and a versatile building block for other boron compounds.
A trimethylsilyl group (abbreviated TMS) is a functional group in organic chemistry. This group consists of three methyl groups bonded to a silicon atom [−Si(CH3)3], which is in turn bonded to the rest of a molecule. This structural group is characterized by chemical inertness and a large molecular volume, which makes it useful in a number of applications.
Thionyl fluoride is the inorganic compound with the formula SOF
2. This colourless gas is mainly of theoretical interest, but it is a product of the degradation of sulfur hexafluoride, an insulator in electrical equipment. The molecule adopts a distorted pyramidal structure, with Cs symmetry. The S-O and S-F distances are 1.42 and 1.58 Å, respectively. The O-S-F and F-S-F angles are 106.2 and 92.2°, respectively. Thionyl chloride and thionyl bromide have similar structures, although these compounds are liquid at room temperature. Mixed halides are also known, such as SOClF, thionyl chloride fluoride.
Sulfur dichloride is the chemical compound with the formula SCl2. This cherry-red liquid is the simplest sulfur chloride and one of the most common, and it is used as a precursor to organosulfur compounds. It is a highly corrosive and toxic substance, and it reacts on contact with water to form chlorine-containing acids.
Hexafluorosilicic acid is an inorganic compound with the chemical formula H
2SiF
6. Aqueous solutions of hexafluorosilicic acid consist of salts of the cation and hexafluorosilicate anion. These salts and their aqueous solutions are colorless.
Xenon difluoride is a powerful fluorinating agent with the chemical formula XeF
2, and one of the most stable xenon compounds. Like most covalent inorganic fluorides it is moisture-sensitive. It decomposes on contact with water vapor, but is otherwise stable in storage. Xenon difluoride is a dense, colourless crystalline solid.
Selenium tetrafluoride (SeF4) is an inorganic compound. It is a colourless liquid that reacts readily with water. It can be used as a fluorinating reagent in organic syntheses (fluorination of alcohols, carboxylic acids or carbonyl compounds) and has advantages over sulfur tetrafluoride in that milder conditions can be employed and it is a liquid rather than a gas.
Carbonyl fluoride is a chemical compound with the formula COF2. It is a carbon oxohalide. This gas, like its analog phosgene, is colourless and highly toxic. The molecule is planar with C2v symmetry, bond lengths of 1.174 Å (C=O) and 1.312 Å (C–F), and an F–C–F bond angle of 108.0°.
Organofluorine chemistry describes the chemistry of organofluorine compounds, organic compounds that contain a carbon–fluorine bond. Organofluorine compounds find diverse applications ranging from oil and water repellents to pharmaceuticals, refrigerants, and reagents in catalysis. In addition to these applications, some organofluorine compounds are pollutants because of their contributions to ozone depletion, global warming, bioaccumulation, and toxicity. The area of organofluorine chemistry often requires special techniques associated with the handling of fluorinating agents.
In inorganic chemistry, sulfonyl halide groups occur when a sulfonyl functional group is singly bonded to a halogen atom. They have the general formula RSO2X, where X is a halogen. The stability of sulfonyl halides decreases in the order fluorides > chlorides > bromides > iodides, all four types being well known. The sulfonyl chlorides and fluorides are of dominant importance in this series.
Diethylaminosulfur trifluoride (DAST) is the organosulfur compound with the formula Et2NSF3. This liquid is a fluorinating reagent used for the synthesis of organofluorine compounds. The compound is colourless; older samples assume an orange colour.
Fluorination by sulfur tetrafluoride produces organofluorine compounds from oxygen-containing organic functional groups using sulfur tetrafluoride. The reaction has broad scope, and SF4 is an inexpensive reagent. It is however hazardous gas whose handling requires specialized apparatus. Thus, for many laboratory scale fluorinations diethylaminosulfur trifluoride ("DAST") is used instead.
Fluorination with aminosulfuranes is a chemical reaction that transforms oxidized organic compounds into organofluorine compounds. Aminosulfuranes selectively exchange hydroxyl groups for fluorine, but are also capable of converting carbonyl groups, halides, silyl ethers, and other functionality into organofluorides.
Sulfur chloride pentafluoride is an inorganic compound with the formula SF5Cl. It exists as a colorless gas at room temperature and is highly toxic, like most inorganic compounds containing the pentafluorosulfide functional group. The compound adopts an octahedral geometry with C
4v symmetry. Sulfur chloride pentafluoride is the only commercially available reagent for adding the –SF5 group to organic compounds.
Vanadium(V) fluoride is the inorganic compound with the chemical formula VF5. It is a colorless volatile liquid that freezes near room temperature. It is a highly reactive compound, as indicated by its ability to fluorinate organic substances.
Thiophosphoryl fluoride is an inorganic molecular gas with formula PSF3 containing phosphorus, sulfur and fluorine. It spontaneously ignites in air and burns with a cool flame. The discoverers were able to have flames around their hands without discomfort, and called it "probably one of the coldest flames known". The gas was discovered in 1888.
Fluorine forms a great variety of chemical compounds, within which it always adopts an oxidation state of −1. With other atoms, fluorine forms either polar covalent bonds or ionic bonds. Most frequently, covalent bonds involving fluorine atoms are single bonds, although at least two examples of a higher order bond exist. Fluoride may act as a bridging ligand between two metals in some complex molecules. Molecules containing fluorine may also exhibit hydrogen bonding. Fluorine's chemistry includes inorganic compounds formed with hydrogen, metals, nonmetals, and even noble gases; as well as a diverse set of organic compounds. For many elements the highest known oxidation state can be achieved in a fluoride. For some elements this is achieved exclusively in a fluoride, for others exclusively in an oxide; and for still others the highest oxidation states of oxides and fluorides are always equal.
Difluoroamino sulfur pentafluoride is a gaseous chemical compound of fluorine, sulfur, and nitrogen. It is unusual in having a hexa-coordinated sulfur atom with a link to nitrogen. Other names for this substance include difluoro(pentafluorosulfur)amine, pentafluorosulfanyldifluoramine, and pentafluorosulfanyl N,N-difluoramine.
1,1,1,2-tetrafluorodisulfane, also known as 1,2-difluorodisulfane 1,1-difluoride or just difluorodisulfanedifluoride (FSSF3) is an unstable molecular compound of fluorine and sulfur. The molecule has a pair of sulfur atoms, with one fluorine atom on one sulfur, and three fluorine atoms on the other. It has the uncommon property that all the bond lengths are different. The bond strength is not correlated with bond length but is inversely correlated with the force constant (Badger's rule). The molecule can be considered as sulfur tetrafluoride in which a sulfur atom is inserted into a S-F bond.