| Revision as of 21:10, 16 January 2014 editPlasmic Physics (talk | contribs)Extended confirmed users, Rollbackers19,174 edits Undid revision 590984138 by 193.113.135.112 (talk)← Previous edit | Revision as of 19:04, 26 February 2014 edit undoSmokefoot (talk | contribs)Autopatrolled, Extended confirmed users, Pending changes reviewers, Rollbackers74,700 edits expand with ref to eEROS, move pretty obscure systematic names to other names slot on table, give examples and describe structure, CAS# for the ones readers probably more care about, new image emphasizing H3O+ partNext edit → | ||
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| | Verifiedfields = changed | | Verifiedfields = changed | ||
| | verifiedrevid = 476998855 | | verifiedrevid = 476998855 | ||
| | ImageFile = |
| ImageFile = H3OBF4.png | ||
| | ImageFile_Ref = {{chemboximage|correct|??}} | | ImageFile_Ref = {{chemboximage|correct|??}} | ||
| | ImageName = Canonical, skeletal formula of fluoroboric acid | | ImageName = Canonical, skeletal formula of fluoroboric acid | ||
| | PIN = Tetrafluoroboric acid{{Citation needed|date = October 2011}} | | PIN = Tetrafluoroboric acid{{Citation needed|date = October 2011}} | ||
| | OtherNames = |
| OtherNames = tetrafluoroboric acid, oxonium tetrafluoroboranuide, oxonium tetrafluoridoborate(1-) | ||
| Hydrofluoroboric acid{{Citation needed|date = October 2011}}<br /> | |||
| Hydrogen Tetrafluoroborate{{Citation needed|date = October 2011}} | |||
| | Section1 = {{Chembox Identifiers | | Section1 = {{Chembox Identifiers | ||
| | CASNo = 14219-41-1 (for H<sub>3</sub>OBF<sub>4</sub>), 16872-11-0 (solvent free), 80628-99-5 (for H<sub>5</sub>O<sub>2</sub>BF<sub>4</sub>) | |||
| | CASNo = 16872-11-0 | |||
| | CASNo_Ref = {{cascite|correct|CAS}} | | CASNo_Ref = {{cascite|correct|CAS}} | ||
| | PubChem = 28118 | | PubChem = 28118 | ||
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| }} | }} | ||
| '''Fluoroboric acid''' or ''' |
'''Fluoroboric acid''' or '''tetrafluoroboric acid''' is an ] with the ] {{Chem|H|3|OBF|4}}. It is mainly produced as a precursor to other fluoroborate salts.<ref>Gregory K. Friestad, Bruce P. Branchaud "Tetrafluoroboric Acid" E-Eros Encyclopedia of Reagents for Organic Synthesis. {{DOI|10.1002/047084289X.rt035}}</ref> It is a strong acid. Fluoroboric acid is corrosive and attacks the skin. It is available commercially as a solution in water and other ]s such as ]. With a strength comparable to ], fluoroboric acid is a strong acid with a ], non-oxidizing conjugate base. | ||
| ==Structure and production == | |||
| It is available commercially as a solution in water and other ]s such as ]. With a strength comparable to ], fluoroboric acid is a strong acid with a ], non-oxidizing conjugate base. | |||
| Although the solvent-free HBF<sub>4</sub> has not been isolated, its solvates are well characterized. These salts consist of protonated solvent as a cation, e.g., H<sub>3</sub>O<sup>+</sup> and H<sub>5</sub>O<sub>2</sub><sup>+</sup>, and the tetrahedral BF<sub>4</sub><sup>-</sup> anion. The anion and cations are strongly hydrogen-bonded.<ref>Mootz, D.; Steffen, M. "Crystal structures of acid hydrates and oxonium salts. XX. Oxonium tetrafluoroborates H3OBF4, BF4, and BF4" Zeitschrift fuer Anorganische und Allgemeine Chemie (1981), vol. 482, pp. 193-200. {{DOI|10.1002/zaac.19814821124}}</ref> | |||
| ⚫ | Aqueous solutions of HBF<sub>4</sub> are produced by dissolving ] in aqueous ] solution.<ref>{{ OrgSynth | author = Flood, D. T. | title = Fluorobenzene | year = 1933 | volume = 13 | page = 46 | collvol = 2 | collvolpages = 295 | prep = CV2P0295 | url = http://www.orgsyn.org/orgsyn/pdfs/CV2P0295.pdf | format = pdf }}</ref> Three equivalents of HF react to give the intermediate ] and the fourth gives fluoroboric acid: | ||
| <!--==History== | |||
| Aqueous fluroboric acid has been used since the late 1920s in the synthesis of ] fluoroborates. Christian A. Wamser expressed a particular interest in fluoroboric acid with several journal publications on the subject, however there is no indication as to how far back this compound may be dated. Unsourced and uninformative? --> | |||
| == Production == | |||
| ⚫ | |||
| :: B(OH)<sub>3</sub> + 4 HF → H<sub>3</sub>O<sup>+</sup> + BF<sub>4</sub><sup>−</sup> + 2 H<sub>2</sub>O | :: B(OH)<sub>3</sub> + 4 HF → H<sub>3</sub>O<sup>+</sup> + BF<sub>4</sub><sup>−</sup> + 2 H<sub>2</sub>O | ||
| Aqueous solutions of fluoroboric acid can also be prepared by treating |
Aqueous solutions of fluoroboric acid can also be prepared by treating ] with solid boric acid followed by removal of precipitated ].{{Citation needed|date=September 2007}} Anhydrous solutions can be prepared by treatment of aqueous fluoroboric acid with ].<ref>{{ cite encyclopedia | author = Friestad, G. K.; Branchaud, B. P. | title = Tetrafluoroboric Acid | encyclopedia = Encyclopedia of Reagents for Organic Synthesis | year = 2001 | publisher = John Wiley & Sons | doi = 10.1002/047084289X.rt035 }}</ref> | ||
| == Applications == | |||
| {{main|Tetrafluoroborate}} | |||
| Fluoroboric acid is the principal precursor to ] salts, which are typically prepared by acid-base reactions. The inorganic salts are intermediates in the manufacture of flame-retardant materials and glazing frits, and in electrolytic generation of ]. HBF<sub>4</sub> is also used in aluminum etching and acid pickling. | Fluoroboric acid is the principal precursor to ] salts, which are typically prepared by acid-base reactions. The inorganic salts are intermediates in the manufacture of flame-retardant materials and glazing frits, and in electrolytic generation of ]. HBF<sub>4</sub> is also used in aluminum etching and acid pickling. | ||
| == Applications == | |||
| === Organic chemistry === | === Organic chemistry === | ||
| HBF<sub>4</sub> is used as a ] for ]s and ]. In carbohydrate protection reactions, ethereal fluoroboric acid is an efficient and cost-effective catalyst for transacetalation and isopropylidenation reactions. ] solutions cleave ] and some ], while neat{{Citation needed|date=September 2007}} fluoroboric acid removes ] groups. | HBF<sub>4</sub> is used as a ] for ]s and ]. In carbohydrate protection reactions, ethereal fluoroboric acid is an efficient and cost-effective catalyst for transacetalation and isopropylidenation reactions. ] solutions cleave ] and some ], while neat{{Citation needed|date=September 2007}} fluoroboric acid removes ] groups. Many reactive cations have been obtained using fluoroboric acid, e.g. ] (C<sub>7</sub>H<sub>7</sub><sup>+</sup>BF<sub>4</sub><sup>-</sup>), ] (Ph<sub>3</sub>C<sup>+</sup>BF<sub>4</sub><sup>-</sup>), ] ((Et<sub>3</sub>O<sup>+</sup>BF<sub>4</sub><sup>-</sup>), and ] (PhN<sub>2</sub><sup>+</sup>BF<sub>4</sub><sup>-</sup>). | ||
| === Galvanic cells === | === Galvanic cells === | ||
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| {{reflist}} | {{reflist}} | ||
| ==Further reading== | |||
| * {{ cite journal | author = Albert, R.; Dax, K.; Pleschko, R.; Stütz, A. E. | title = Tetrafluoroboric acid, an efficient catalyst in carbohydrate protection and deprotection reactions | journal = Carbohydrate Research | year = 1985 | volume = 137 | pages = 282–290 | doi = 10.1016/0008-6215(85)85171-5 }} | * {{ cite journal | author = Albert, R.; Dax, K.; Pleschko, R.; Stütz, A. E. | title = Tetrafluoroboric acid, an efficient catalyst in carbohydrate protection and deprotection reactions | journal = Carbohydrate Research | year = 1985 | volume = 137 | pages = 282–290 | doi = 10.1016/0008-6215(85)85171-5 }} | ||
| * {{ cite journal | author = Bandgar, B. P.; Patil, A. V.; Chavan, O. S. | title = Silica supported fluoroboric acid as a novel, efficient and reusable catalyst for the synthesis of 1,5-benzodiazepines under solvent-free conditions | journal = Journal of Molecular Catalysis A: Chemical | year = 2006 | volume = 256 | issue = 1–2 | pages = 99–105 | doi = 10.1016/j.molcata.2006.04.024 }} | * {{ cite journal | author = Bandgar, B. P.; Patil, A. V.; Chavan, O. S. | title = Silica supported fluoroboric acid as a novel, efficient and reusable catalyst for the synthesis of 1,5-benzodiazepines under solvent-free conditions | journal = Journal of Molecular Catalysis A: Chemical | year = 2006 | volume = 256 | issue = 1–2 | pages = 99–105 | doi = 10.1016/j.molcata.2006.04.024 }} | ||
Revision as of 19:04, 26 February 2014
| |
| Names | |
|---|---|
| Preferred IUPAC name Tetrafluoroboric acid | |
| Other names tetrafluoroboric acid, oxonium tetrafluoroboranuide, oxonium tetrafluoridoborate(1-) | |
| Identifiers | |
| CAS Number | |
| 3D model (JSmol) | |
| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.037.165 
|
| EC Number |
|
| Gmelin Reference | 21702 |
| MeSH | Fluoroboric+acid |
| PubChem CID | |
| RTECS number |
|
| UN number | 1775 |
| CompTox Dashboard (EPA) | |
InChI
| |
SMILES
| |
| Properties | |
| Chemical formula | BF4H |
| Molar mass | 87.81 g·mol |
| Appearance | Colourless liquid |
| Melting point | −90 °C (−130 °F; 183 K) |
| Boiling point | 130 °C (266 °F; 403 K) |
| Acidity (pKa) | -0.4 |
| Basicity (pKb) | 14.4 |
| Hazards | |
| NFPA 704 (fire diamond) |
 |
| Related compounds | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa).
 N verify (what is ?)
Infobox references
| |
Fluoroboric acid or tetrafluoroboric acid is an inorganic compound with the chemical formula H
3OBF
4. It is mainly produced as a precursor to other fluoroborate salts. It is a strong acid. Fluoroboric acid is corrosive and attacks the skin. It is available commercially as a solution in water and other solvents such as diethyl ether. With a strength comparable to nitric acid, fluoroboric acid is a strong acid with a weakly coordinating, non-oxidizing conjugate base.
Structure and production
Although the solvent-free HBF4 has not been isolated, its solvates are well characterized. These salts consist of protonated solvent as a cation, e.g., H3O and H5O2, and the tetrahedral BF4 anion. The anion and cations are strongly hydrogen-bonded.
Aqueous solutions of HBF4 are produced by dissolving boric acid in aqueous hydrofluoric acid solution. Three equivalents of HF react to give the intermediate boron trifluoride and the fourth gives fluoroboric acid:
- B(OH)3 + 4 HF → H3O + BF4 + 2 H2O
Aqueous solutions of fluoroboric acid can also be prepared by treating hexafluorosilicic acid with solid boric acid followed by removal of precipitated silicon dioxide. Anhydrous solutions can be prepared by treatment of aqueous fluoroboric acid with acetic anhydride.
Applications
Fluoroboric acid is the principal precursor to fluoroborate salts, which are typically prepared by acid-base reactions. The inorganic salts are intermediates in the manufacture of flame-retardant materials and glazing frits, and in electrolytic generation of boron. HBF4 is also used in aluminum etching and acid pickling.
Organic chemistry
HBF4 is used as a catalyst for alkylations and polymerizations. In carbohydrate protection reactions, ethereal fluoroboric acid is an efficient and cost-effective catalyst for transacetalation and isopropylidenation reactions. Acetonitrile solutions cleave acetals and some ethers, while neat fluoroboric acid removes tert-butoxycarbonyl groups. Many reactive cations have been obtained using fluoroboric acid, e.g. tropylium tetrafluoroborate (C7H7BF4), triphenylmethyl tetrafluoroborate (Ph3CBF4), triethyloxonium tetrafluoroborate ((Et3OBF4), and benzenediazonium tetrafluoroborate (PhN2BF4).
Galvanic cells
Aqueous HBF4 is used as an electrolyte in galvanic cell oxygen sensor systems, which consist of an anode, cathode, and oxygen-permeable membrane. The solution of HBF4 is able to dissolve lead(II) oxide from the anode in the form of lead tetrafluoroborate while leaving the rest of the system unchanged.
Metal plating
A mixture of CrO3, HBF4, and sulfonic acids in conjunction with a cathode treatment give tin-plated steel. Tin(I) fluoroborate/fluoroboric acid mixtures and organic reagents are used as the electrolyte in the cathode treatment of the tin plating process. Similar processes of electrodeposition and electrolytic stripping are used to obtain specific metal alloys.
Other fluoroboric acids
A series of fluoroboric acids is known in aqueous solutions. The series can be presented as follows:
- H
- H
- H
- H
- H
See also
References
- Gregory K. Friestad, Bruce P. Branchaud "Tetrafluoroboric Acid" E-Eros Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rt035
- Mootz, D.; Steffen, M. "Crystal structures of acid hydrates and oxonium salts. XX. Oxonium tetrafluoroborates H3OBF4, BF4, and BF4" Zeitschrift fuer Anorganische und Allgemeine Chemie (1981), vol. 482, pp. 193-200. doi:10.1002/zaac.19814821124
- Flood, D. T. (1933). "Fluorobenzene" (PDF). Organic Syntheses. 13: 46; Collected Volumes, vol. 2, p. 295.
- Friestad, G. K.; Branchaud, B. P. (2001). "Tetrafluoroboric Acid". Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons. doi:10.1002/047084289X.rt035.
{{cite encyclopedia}}: CS1 maint: multiple names: authors list (link) - Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
Further reading
- Albert, R.; Dax, K.; Pleschko, R.; Stütz, A. E. (1985). "Tetrafluoroboric acid, an efficient catalyst in carbohydrate protection and deprotection reactions". Carbohydrate Research. 137: 282–290. doi:10.1016/0008-6215(85)85171-5.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - Bandgar, B. P.; Patil, A. V.; Chavan, O. S. (2006). "Silica supported fluoroboric acid as a novel, efficient and reusable catalyst for the synthesis of 1,5-benzodiazepines under solvent-free conditions". Journal of Molecular Catalysis A: Chemical. 256 (1–2): 99–105. doi:10.1016/j.molcata.2006.04.024.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - Heintz, R. A.; Smith, J. A.; Szalay, P. S.; Weisgerber, A.; Dunbar, K. R. (2002). "Homoleptic Transition Metal Acetonitrile Cations with Tetrafluoroborate or Trifluoromethanesulfonate Anions". Inorganic Syntheses. 33: 75–83. doi:10.1002/0471224502.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - Housecroft, C. E.; Sharpe, A. G. (2004). Inorganic Chemistry (2nd ed.). Prentice Hall. p. 307. ISBN 978-0-13-039913-7.
- Meller, A. (1988). "Boron". Gmelin Handbook of Inorganic Chemistry. Vol. 3. New York: Springer-Verlag. pp. 301–310.
- Perry, D. L.; Phillips, S. L. (1995). Handbook of Inorganic Compounds (1st ed.). Boca Raton: CRC Press. p. 1203. ISBN 9780849386718.
{{cite book}}: CS1 maint: multiple names: authors list (link) - Wamser, C. A. (1948). "Hydrolysis of Fluoboric Acid in Aqueous Solution". Journal of the American Chemical Society. 70 (3): 1209–1215. doi:10.1021/ja01183a101.
- Wilke-Dörfurt, E.; Balz, G. (1927). "Zur Kenntnis der Borfluorwasserstoffsäure und ihrer Salze". Zeitschrift für Anorganische und Allgemeine Chemie. 159 (1): 197–225. doi:10.1002/zaac.19271590118.
{{cite journal}}: CS1 maint: multiple names: authors list (link)
External links
- "Fluoroboric Acid ICSC: 1040". INCHEM.