Trifluoromethanol is a synthetic organic compound with the formula . It is also referred to as perfluoromethanol or trifluoromethyl alcohol. The compound is the simplest

perfluoroalcohol Fluoroalcohols are organofluorine compounds consisting of an alcohol functional group with at least one C-F bond. These compounds often have distinctive solvent properties. Perfluoroalcohols Most primary and secondary perfluoroalcohols are unstab ...

. The substance is a colorless gas, which is unstable at room temperature.

Synthesis

Like all primary and secondary perfluoroalcohols, trifluoromethanol eliminates

hydrogen fluoride Hydrogen fluoride (fluorane) is an Inorganic chemistry, inorganic compound with chemical formula . It is a very poisonous, colorless gas or liquid that dissolves in water to yield hydrofluoric acid. It is the principal industrial source of fluori ...

in an

endothermic reaction An endothermic process is a chemical or physical process that absorbs heat from its surroundings. In terms of thermodynamics, it is a thermodynamic process with an increase in the enthalpy (or internal energy ) of the system.Oxtoby, D. W; Gillis, ...

and forms

carbonyl fluoride Carbonyl fluoride is a chemical compound with the formula . It is a carbon oxohalide. This gas, like its analog phosgene, is colourless and highly toxic. The molecule is planar with ''C''2v symmetry, bond lengths of 1.174 Å (C=O) and 1.312 Å ( ...

. : (I) At temperatures in the range of −120 °C, trifluoromethanol can be prepared from

trifluoromethyl hypochlorite The trifluoromethyl group is a functional group that has the formula . The naming of is group is derived from the methyl group (which has the formula ), by replacing each hydrogen atom by a fluorine atom. Some common examples are trifluoromethane ...

and

hydrogen chloride The Chemical compound, compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hyd ...

: : (II) 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,

, and

chlorotrifluoromethane Chlorotrifluoromethane, R-13, CFC-13, or Freon 13, is a non-flammable, non-corrosive, nontoxic chlorofluorocarbon (CFC) and also a mixed halomethane. It is a man-made substance used primarily as a refrigerant. When released into the environment, ...

, 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 Methanol (also called methyl alcohol and wood spirit, amongst other names) is an organic chemical compound and the simplest aliphatic Alcohol (chemistry), alcohol, with the chemical formula (a methyl group linked to a hydroxyl group, often ab ...

. This fact can be explained by the absence of intramolecular H—F bonds, which are also not visible in the infrared gas phase spectrum. A simpler synthesis uses the reaction (I); an equilibrium can be shifted to the thermodynamically preferred trifluoromethanol at lower temperatures. If the synthesized trifluoromethanol is protonated by superacids, for example (

fluoroantimonic acid Fluoroantimonic acid is a mixture of hydrogen fluoride and antimony pentafluoride, containing various cations and anions (the simplest being and ). This mixture is a superacid stronger than pure sulfuric acid, by many orders of magnitude, acco ...

), the equilibrium can be further shifted to the left towards the desired product. Similar to reaction (I), trifluoromethoxides () can be prepared from saline-type fluorides (e.g., NaF) and

. However, if the ion is, for example, in an aqueous solution displaced by an acid, trifluoromethanol 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 and radicals by reaction with and 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.

References

{{Alcohols Trifluoromethyl compounds Primary alcohols Organic compounds with 1 carbon atom Substances discovered in the 1970s

Synthesis

Occurrence in upper layers of atmosphere

See also

References