Nowadays, Sulfur tetrafluoride has become a topic of general interest in society. With the advancement of technology and access to information, more and more people are interested in learning more about Sulfur tetrafluoride and how it impacts their lives. Whether Sulfur tetrafluoride is a person, place, event or phenomenon, its relevance in today's world is undeniable. In this article, we will explore different aspects of Sulfur tetrafluoride to understand its importance and influence in different areas. From its history to its impact today, Sulfur tetrafluoride is a topic that invites us to reflect and understand its meaning in our modern world.
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Names | |||
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IUPAC name
Sulfur(IV) fluoride
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Other names
Sulfur tetrafluoride
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Identifiers | |||
3D model (JSmol)
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ChEBI | |||
ChemSpider | |||
ECHA InfoCard | 100.029.103 | ||
PubChem CID
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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) | ||
Structure | |||
Seesaw (C2v) | |||
0.632 D | |||
Hazards | |||
Occupational safety and health (OHS/OSH): | |||
Main hazards
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highly toxic corrosive | ||
NFPA 704 (fire diamond) | |||
NIOSH (US health exposure limits): | |||
PEL (Permissible)
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none | ||
REL (Recommended)
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C 0.1 ppm (0.4 mg/m3) | ||
IDLH (Immediate danger)
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N.D. | ||
Safety data sheet (SDS) | ICSC 1456 | ||
Related compounds | |||
Other anions
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Sulfur dichloride Disulfur dibromide Sulfur trifluoride | ||
Other cations
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Oxygen difluoride Selenium tetrafluoride Tellurium tetrafluoride | ||
Related sulfur fluorides
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Disulfur difluoride Sulfur difluoride Disulfur decafluoride Sulfur hexafluoride | ||
Related compounds
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Thionyl fluoride | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa).
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Sulfur tetrafluoride is the chemical compound with the formula SF4. 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, 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.
At the laboratory scale, fluorination of elemental sulfur with cobaltic fluoride suffices:
For larger-scale syntheses, SF4 is produced by the reaction of SCl2 and NaF in acetonitrile:
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).
A low-temperature (e.g. 20–86 °C) alternative to the chlorinative process above uses liquid bromine (Br2) as oxidant and solvent:
In organic synthesis, SF4 is used to convert COH and C=O groups into CF and CF2 groups, respectively. 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": This reagent is prepared from SF4:
Sulfur chloride pentafluoride (SF
5Cl), a useful source of the SF5 group, is prepared from SF4.
Hydrolysis of SF4 gives sulfur dioxide:
This reaction proceeds via the intermediacy of thionyl fluoride, which usually does not interfere with the use of SF4 as a reagent.
When amines are treated with SF4 and a base, iminosulfur difluorides result.
SF
4 reacts inside the lungs with moisture, generating sulfur dioxide and hydrogen fluoride: