Boron trifluoride
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Systematic name	Boron trifluoride
Molecular formula	BF3
Molar mass	67.8062 g mol−1
Density	2.178 g dm−3
Relative density (air = 1)	2.42
Solubility (water)	decomposes
Melting point	−126°C
Boiling point	−100.3°C
CAS number	[7637-07-2]
Disclaimer and references

Boron trifluoride is the chemical compound with the formula BF₃. This pungent colourless toxic gas forms white fumes in moist air. It is a useful Lewis acid and a versatile building block for other boron compounds. IUPAC nomenclature is a systematic way of naming organic chemical compounds. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... Molar mass is the mass of one mole of a chemical element or chemical compound. ... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is... Layers of Atmosphere (NOAA) Air redirects here. ... Solubility refers to the ability for a given substance, the solute, to dissolve in a solvent. ... “HOH” redirects here. ... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... A chemical compound is a chemical substance consisting of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. ... This article does not cite its references or sources. ... Toxic redirects here, but this is also the name of a song by Britney Spears; see Toxic (song) Look up toxic and toxicity in Wiktionary, the free dictionary. ... In chemistry, a Lewis acid can accept a pair of electrons and form a coordinate covalent bond, after the American chemist Gilbert Lewis. ... General Name, Symbol, Number boron, B, 5 Chemical series metalloids Group, Period, Block 13, 2, p Appearance black/brown Standard atomic weight 10. ...

Structure and bonding

Unlike the aluminium trihalides, the boron trihalides are all monomeric. They do undergo rapid dimerization as indicated by the high rate of the halide exchange reactions:

BF₃ + BCl₃ → BF₂Cl + BCl₂F

Because of the facility of this exchange process, the mixed halides cannot be obtained in pure form.

The geometry of a molecule of BF₃ is described as trigonal planar. The D_3h symmetry conforms with the prediction of VSEPR theory. Although featuring three polar covalent bonds, the molecule has no dipole moment by virtue of its high symmetry. Although isoelectronic with carbonate, CO₃^2-, BF₃ is commonly referred to as " electron deficient," a description that is reinforced by its exothermic reactivity toward Lewis bases. In science, a molecule is a group of atoms in a definite arrangement held together by chemical bonds. ... ǃǁɚɵ A generic trigonal planar molecule showing ideal bond angle. ... The symmetry group of an object (e. ... Valence shell electron pair repulsion theory (VSEPR) (1957) is a model in chemistry that aims to generally represent the shapes of individual molecules [1] . To achieve this, it is necessary to construct a valid Lewis structure that shows all of the bonds within the molecule and the locations of lone... Two or more molecular entities (atoms, molecules, ions) are described as isoelectronic if they have the same number of valence electrons and the same structure (number and connectivity of atoms), but may differ in the elements involved. ... Electron deficiency occurs when a compound has too few valence electrons for the connections between atoms to be described as covalent bonds. ... In thermodynamics, the word exothermic describes a process or reaction that releases energy in the form of heat. ... A Lewis base is any molecule or ion that can form a new covalent bond by donating a pair of electrons. ...

In the boron trihalides, BX₃, the length of the B-F bonds (1.30 Å) is shorter than would be expected for single bonds,^{[citation needed]} and this shortness may indicate stronger B-X π-bonding in the fluoride. A facile explanation invokes the symmetry-allowed overlap of a p orbital on the boron atom with the in-phase combination of the three similarly oriented p orbitals on fluorine atoms. ^[1] Electron atomic and molecular orbitals, showing a Pi-bond at the bottom right of the picture In chemistry, pi bonds (Ï€ bonds) are bonds with a single nodal plane containing the line segment between the two atoms. ...

Synthesis

BF₃ is manufactured by the reaction of boron oxides with hydrogen fluoride: Hydrogen fluoride is the chemical compound with the formula HF. It is the only fluoride of hydrogen. ...

B₂O₃ + 6 HF → 2 BF₃ + 3 H₂O

Typically the HF is produced in situ from sulfuric acid and fluorite (CaF₂).^[2] Fluorite (also called fluor-spar) is a mineral composed of calcium fluoride, CaF2. ...

On a laboratory scale, BF₃ is produced by the thermal decomposition of diazonium salts:^[3]

PhN₂BF₄ → PhF + BF₃ + N₂

Fluorobenzene is the chemical compound with the formula C6H5F, often abbreviated PhF. This species is a derivative of benzene, with a single fluorine atom attached. ... General Name, Symbol, Number nitrogen, N, 7 Chemical series nonmetals Group, Period, Block 15, 2, p Appearance colorless gas Standard atomic weight 14. ...

Lewis acidity and related reactions

Boron trifluoride is a versatile Lewis acid that forms adducts with such Lewis bases as fluoride and ethers: Wikipedia does not yet have an article with this exact name. ... A Lewis base is any molecule or ion that can form a new covalent bond by donating a pair of electrons. ... Fluoride is the ionic form of fluorine. ... Ether is the general name for a class of chemical compounds which contain an ether group — an oxygen atom connected to two (substituted) alkyl groups. ...

CsF + BF₃ → CsBF₄

O(C₂H₅)₂ + BF₃ → BF₃O(C₂H₅)₂

Tetrafluoroborate salts are commonly employed as non-coordinating anions. The adduct with diethyl ether is a conveniently handled liquid and consequently is a widely encountered as a laboratory source of BF₃. Overview Caesium fluoride (cesium fluoride in North America), is an ionic compound usually found as a hygroscopic white solid. ... Diethyl ether, also known as ether and ethoxyethane, is a clear, colorless, and highly flammable liquid with a low boiling point and a characteristic smell. ... The structure of the tetrafluoroborate anion, BF4− Tetrafluoroborate is the anion BF4−. This tetrahedral species is isoelectronic with many stable and important species including tetrafluomethane, CF4, and the closely related anion perchlorate, ClO4−. It arises by the reaction of fluoride salts with the Lewis acid BF3. ... A magnified crystal of a salt (halite/sodium chloride) Salt covering the floor of Bad Water in Death Valley, CA, the lowest point in the US. A salt, in chemistry, is defined as the product formed from the neutralisation reaction of acids and bases. ... In chemistry, a non-coordinating anion is an anion that only weakly interacts with its cation. ... A liquid will usually assume the shape of its container A liquid is one of the main states of matter. ...

Comparative Lewis acidity

All three lighter boron trihalides, BX₃ (X = F, Cl, Br) form stable adducts with common Lewis bases. Their relative Lewis acidities can be evaluated in terms of the relative exothermicities of the adduct-forming reaction. Such measurements have revealed the following sequence for the Lewis acidity:

BF₃ < BCl₃ < BBr₃ (strongest Lewis acid)

This trend commonly attributed to the degree of π-bonding in the planar boron trihalide that would be lost upon pyramidalization of the BX₃ molecule.^[4] which follows this trend: Electron atomic and molecular orbitals, showing a Pi-bond at the bottom right of the picture In chemistry, pi bonds (Ï€ bonds) are bonds with a single nodal plane containing the line segment between the two atoms. ...

BF₃ > BCl₃ > BBr₃ (most easily pyramidalized)

The criteria for evaluating the relative strength of π-bonding are not clear, however.^[1]
In an alternative explanation, the low Lewis acidity for BF₃ is attributed to the relative weakness of the bond in the adducts F₃B-L.^[5][6] Electron atomic and molecular orbitals, showing a Pi-bond at the bottom right of the picture In chemistry, pi bonds (Ï€ bonds) are bonds with a single nodal plane containing the line segment between the two atoms. ...

Hydrolysis

Boron trifluoride reacts with water to give boric acid and fluoroboric acid: The reaction commences with the formation of the aquo adduct, H₂O-BF₃, which then loses HF: Boric acid, also called boracic acid or orthoboric acid or Acidum Boricum, is a mild acid often used as an antiseptic, insecticide, flame retardant, in nuclear power plants to control the fission rate of uranium, and as a precursor of other chemical compounds. ... Fluoroboric acid is the conjugate acid of tetrafluoroborate, which is a weakly-coordinating anion. ...

4 BF₃ + 3 H₂O → 3 HBF₄ + "B(OH)₃"

The heavier trihalides do not undergo analogous reactions, possibly the lower stability of the tetrahedral ions BX₄^- (X = Cl, Br). Because of the high acidity of fluoroboric acid, the fluoroborate ion can be used to isolate particularly electrophilic cations, such as diazonium ions, that are otherwise difficult to isolate as solids. Phenyldiazonium cation Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group with the characteristic structure of R-N2+ X- where R can be any organic residue such alkyl or aryl and X is an inorganic or organic anion such as a halogen. ...

Handling

Boron trifluoride is corrosive. Suitable metals for equipment handling boron trifluoride include stainless steel, monel, and hastelloy. In presence of moisture it corrodes steel, including stainless steel. It reacts with polyamides. Polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, and polypropylene show satisfactory resistance. The grease used in the equipment should be fluorocarbon based, as boron trifluoride reacts with the hydrocarbon-based ones.^[7] The 630 foot high, stainless-clad (type 304L) Gateway Arch defines St. ... Monel is a trademark comprising a series of rustless (stainless) metal alloys, primarily composed of nickel (up to 67%) and copper, with some iron and other trace elements. ... HASTELLOY is the registered trademark name of Haynes International, Inc. ... A polyamide is a polymer containing monomers joined by peptide bonds. ... Teflon is polytetrafluoroethylene (PTFE), a polymer of fluorinated ethylene. ... Polychlorotrifluoroethylene is a polymer with the following mer structure: ... PVDF, or PolyVinylidine DiFluoride, is a highly non-reactive and pure thermoplastic fluoropolymer. ... Polypropylene lid of a Tic Tacs box, with a living hinge and the resin identification code under its flap Micrograph of polypropylene Polypropylene or polypropene (PP) is a thermoplastic polymer, made by the chemical industry and used in a wide variety of applications, including food packaging, ropes, textiles, plastic parts... Grease is a lubricant of higher initial viscosity than oil, consisting originally of a calcium, sodium or lithium soap jelly emulsified with mineral oil. ... Some important fluorocarbons. ...

Uses

• applied as dopant in ion implantation
• p-type dopant for epitaxially grown silicon
• initiates polymerisation reactions of unsaturated compounds. Example polyethers
• as a catalyst in some isomerization, alkylation, esterification, condensation, and other reactions.
• used in sensitive neutron detectors

A dopant, also called doping agent and dope, is an impurity element added to a semiconductor lattice in low concentrations in order to alter the optical/electrical properties of the semiconductor. ... Ion implantation is a materials engineering process by which ions of a material can be implanted into another solid, thereby changing the physical properties of the solid. ... A P-type semiconductor is obtained by carrying out a process of doping, that is adding a certain type of atoms to the semiconductor in order to increase the number of free (in this case positive) charges. ... Epitaxy is a specialized thin-film deposition technique. ... It has been suggested that Silicons ranking be merged into this article or section. ... Polymerization is the formation of long, repeating organic polymer chains. ... In chemistry, saturation has four different meanings: In physical chemistry, saturation is the point at which a solution of a substance can dissolve no more of that substance and additional amounts of that substance will appear as a precipitate. ... A chemical compound is a chemical substance formed from two or more elements, with a fixed ratio determining the composition. ... Ether is the general name for a class of chemical compounds which contain an ether group &#8212; an oxygen atom connected to two (substituted) alkyl groups. ... In chemistry, isomerization is the transformation of a molecule into a different isomer. ... Alkylation is the transfer of an alkyl group from one molecule to another. ... Esterification is the general name for a chemical reaction in which two chemicals (typically an alcohol and an acid) form an ester as the reaction product. ... A condensation reaction is a chemical reaction in which two molecules or moieties combine to form one single molecule, together with the loss of a small molecule. ... This article or section does not adequately cite its references or sources. ...

References

1. ^ ^{a b} Greenwood, N. N.; A. Earnshaw (1997). Chemistry of the Elements, 2nd Edition, Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.
2. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
3. ^ Flood, D. T. “Fluorobenzene” Organic Syntheses Collective Volume 2, page 295. http://www.orgsyn.org/orgsyn/pdfs/CV2P0295.pdf.
4. ^ Cotton, F. A.; Wilkinson, G.; Murillo, C. A.; Bochmann, M. (1999). Advanced Inorganic Chemistry (6th Edn.) New York: Wiley-Interscience. ISBN 0-471-19957-5.
5. ^ Group V Chalcogenide Complexes of Boron Trihalides Boorman, P. M.; Potts, D. Canadian. Journal of Chemistry (Rev. can. chim.) volume 52, (1974) pp 2016-2020
6. ^ T. Brinck, J. S. Murray and P. Politzer (1993). "A computational analysis of the bonding in boron trifluoride and boron trichloride and their complexes with ammonia". Inorg. Chem. 32 (12): 2622-2625. DOI:10.1021/ic00064a008. 
7. ^ Air Liquide, Gas Encyclopedia — Boron trifluoride

Inorganic Chemistry is a peer-reviewed scientific journal, published since 1962 by the American Chemical Society. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Founded in 1902, Air Liquide is the world leader in industrial and medical gases and related services. ...

External links

• http://www.osha.gov/dts/chemicalsampling/data/CH_221700.html
• http://www.cdc.gov/niosh/ipcsneng/neng0231.html
• National Pollutant Inventory - Boron and compounds fact sheet
• National Pollutant Inventory - Fluoride and compounds fact sheet

• Links to external chemical sources