Trifluoromethanol

Last updated
Trifluoromethanol
Trifluoromethanol.png
Names
Preferred IUPAC name
Trifluoromethanol
Other names
Trifluoromethyl alcohol, perfluoromethanol
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
  • InChI=1S/CHF3O/c2-1(3,4)5/h5H
    Key: WZCZNEGTXVXAAS-UHFFFAOYSA-N
  • C(O)(F)(F)F
Properties
CF3OH
Molar mass 86.013 g·mol−1
AppearanceColorless liquid
Density 1.5±0.1 g/cm3
Melting point −110.64 °C (−167.15 °F; 162.51 K)
Boiling point 22.4 °C (72.3 °F; 295.5 K) ±30.0°C
Hazards
Flash point 18.9 °C (66.0 °F; 292.0 K) ±15.6°
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Trifluoromethanol is a synthetic organic compound with the formula C F 3 O H . [1] It is also referred to as perfluoromethanol or trifluoromethyl alcohol. The compound is the simplest perfluoroalcohol. [2] The substance is a colorless gas, which is unstable at room temperature.

Contents

Synthesis

Trifluoromethanol eliminates hydrogen fluoride in an endothermic reaction [3] and forms carbonyl fluoride. [4]

CF3OH ⇌ COF2 + HF

The equilibrium can be shifted toward trifluoromethanol at lower temperatures. If the synthesized trifluoromethanol is protonated by superacids, for example HSbF6 (fluoroantimonic acid), the equilibrium can be further shifted to the left towards the desired product. Other primary and secondary perfluoroalcohols exhibit similar instability.

At temperatures in the range of −120 °C, trifluoromethanol can be prepared by treating trifluoromethyl hypochlorite with hydrogen chloride:

CF3OCl + HCl → CF3OH + Cl2

In this reaction, the recombination of a partially positively charged chlorine atom (in trifluoromethyl hypochlorite) with a partially negatively charged chlorine atom (in hydrogen chloride) is used as elemental chlorine. The undesired products, by-products chlorine, hydrogen chloride, and chlorotrifluoromethane, can be removed by evaporation at −110 °C. Trifluoromethanol has a melting point of −82 °C and a calculated boiling point of about −20 °C. The boiling point is thus about 85 K lower than that of methanol. This fact can be explained by the absence of intramolecular H—F bonds, which are also not visible in the infrared gas phase spectrum.

Trifluoromethoxide

Trifluoromethoxide (CF3O−) is the conjugate base of trifluoromethanol. Installing the trifluoromethoxy group, trifluoromethoxylation, is a well developed theme in agricultural and medicinal chemistry. [5]

Solutions or trifluoromethoxide can be prepared by treating carbonyl fluoride with sources of fluoride ion, e.g. NaF):

COF2 + F− → CF3O−

Some trifluoromethylethers can be cleaved to release trifluoromethoxide. [6]

CF3OAr + Nu → [Nu−Ar]+[CF3O]− (Nu = nucleophile, Ar = aryl group)

Trifluoromethyl benzoate is a related source of the trifluoromethoxide ion. [7]

In aqueous media, the CF3O− decomposes at the room temperature.

Occurrence in upper layers of atmosphere

While trifluoromethanol is unstable under normal conditions, it is generated in the stratosphere from CF−3 and CF3O− radicals by reaction with OF+ and F− radicals. In this case, decomposition of trifluoromethanol is negligible under the conditions prevailing in the atmosphere due to the high activation energy of the reaction. The expected lifetime of trifluoromethanol is several million years at altitudes below 40 km. [8] [9]

See also

References

  1. ↑ Kloeter, Gerhard; Seppelt, Konrad (January 1979). "Trifluoromethanol (CF3OH) and trifluoromethylamine (CF3NH2)". J. Am. Chem. Soc. 101 (2): 347–349. doi:10.1021/ja00496a012.
  2. ↑ Seppelt, Konrad (May 1977). "Trifluoromethanol, CF3OH". Angewandte Chemie International Edition in English. 16 (5): 322–323. doi:10.1002/anie.197703221.
  3. ↑ Schneider, W. F. (April 11, 1996). "Energetics and Mechanism of Decomposition of CF3OH". J. Phys. Chem. 100 (15): 6097–6103. doi:10.1021/jp952703m.
  4. ↑ Seppelt, K. (1977). "Trifluormethanol, CF3OH. In: , ". Angew. Chem. (in German). 325 (89): 325. Bibcode:1977AngCh..89..325S. doi:10.1002/ange.19770890509.
  5. ↑ Leroux, Frédéric; Jeschke, Peter; Schlosser, Manfred (2005). "α-Fluorinated Ethers, Thioethers, and Amines: Anomerically Biased Species". Chemical Reviews. 105 (3): 827–856. doi:10.1021/cr040075b. PMID   15755078.
  6. ↑ Bonnefoy, Clémence; Gallego, Adrien; Delobel, Clément; Raynal, Betty; Decourt, Maxime; Chefdeville, Emmanuel; Hanquet, Gilles; Panossian, Armen; Leroux, Frédéric R.; Toulgoat, Fabien; Billard, Thierry (2024). "Unlocking the Power of Acyl Fluorides: A Comprehensive Guide to Synthesis and Properties". European Journal of Organic Chemistry. 27 (18) e202400142. doi:10.1002/ejoc.202400142.
  7. ↑ Zhou, Min; Ni, Chuanfa; Zeng, Yuwen; Hu, Jinbo (2018). "Trifluoromethyl Benzoate: A Versatile Trifluoromethoxylation Reagent". Journal of the American Chemical Society. 140 (22): 6801–6805. Bibcode:2018JAChS.140.6801Z. doi:10.1021/jacs.8b04000. PMID   29787259.
  8. ↑ Schneider, W. F. (January 1995). "Atmospheric Chemistry of CF3OH: Is Photolysis Important?". Environmental Science & Technology. 29 (1): 247–250. Bibcode:1995EnST...29..247S. doi:10.1021/es00001a031. PMID   22200226.
  9. ↑ Wellington, T. J.; Schneider, W. F. (1994). "The Stratospheric Fate of CF3OH. In: Environmental Science & Technology 28/1994, S.". Environ. Sci. Technol. 28 (6): 1198–1200. doi:10.1021/es00055a036. PMID   22176252.
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