Tetramethylammonium fluoride
Tetramethylammonium fluoride is the quaternary ammonium salt with the formula (CH3)4NF. This colorless solid is a source of “naked fluoride", that is fluoride ions not connected to a metal atom in a complex. Most other soluble salts of fluoride are in fact bifluorides, HF2–. Tetramethylammonium fluoride is produced by combining tetramethylammonium hydroxide and hydrogen fluoride in isopropanol. Due to the high basicity of the fluoride anion, the salt reacts slowly with acetonitrile, inducing its dimerization to CH3C(NH2)=CHCN, which co-crystallizes.[1]
| Names | |
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| IUPAC name
tetramethylazanium;fluoride | |
| Identifiers | |
3D model (JSmol) |
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| Properties | |
| C4H12FN | |
| Molar mass | 93.145 g·mol−1 |
| Appearance | white solid |
| Hazards | |
| GHS pictograms |  |
| GHS Signal word | Warning |
| H302, H312, H315, H319, H332, H335 | |
| P261, P264, P270, P271, P280, P301+312, P302+352, P304+312, P304+340, P305+351+338, P312, P321, P322, P330, P332+313, P337+313, P362, P363, P403+233, P405, P501 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Related salts
- Tetramethylphosphonium fluoride (CH3)4PF forms stable solutions in acetonitrile. It is prepared by reaction of the ylide with potassium bifluoride:
- (CH3)3P=CH2 + KHF2 → (CH3)4PF + KF
- In the gas phase, tetramethylphosphonium fluoride exists as the phosphorane, but in acetonitrile solution, it dissociates into ions.[2]
- A more elaborate phosphazenium salt ([(CH3)2N)3P]2N+F−) is also known.[3]
- Tetrabutylammonium fluoride has been prepared by the reaction of hexafluorobenzene and tetrabutylammonium cyanide. This salt was once suspected of being unstable owing to Hofmann degradation.[4]
References
- Christe, K. O.; Wilson, W. W.; Wilson, R. D.; Bau, R.; Feng, J. A. (1990). "Syntheses, Properties, and Structures of Anhydrous Tetramethylammonium Fluoride and Its 1:1 Adduct with trans-3-Amino-2-butenenitrile". Journal of the American Chemical Society. 112 (21): 7619–7625. doi:10.1021/ja00177a025.CS1 maint: uses authors parameter (link)
- Kornath, Andreas; Neumann, F.; Oberhammer, H. (2003). "Tetramethylphosphonium Fluoride: "Naked" Fluoride and Phosphorane". Inorganic Chemistry. 42 (9): 2894–2901. doi:10.1021/ic020663c. PMID 12716181.CS1 maint: multiple names: authors list (link)
- Schwesinger, Reinhard (2001). "1,1,1,3,3,3-Hexakis(dimethylamino)-1λ5,3λ5-diphosphazenium Fluoride". e-EROS Encyclopedia of Reagents for Organic Synthesis. pp. 1–2. doi:10.1002/047084289X.rh014m. ISBN 0471936235.
- Haoran Sun & Stephen G. DiMagno (2005). "Anhydrous Tetrabutylammonium Fluoride". Journal of the American Chemical Society. 127 (7): 2050–1. doi:10.1021/ja0440497. PMID 15713075.
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