Trifluorotoluene
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| Template:Longitem | C6H5CF3 |
| Molar mass | 146.11 g/mol |
| Appearance | colorless liquid |
| Odor | aromatic |
| Density | 1.19 g/mL at 20 °C |
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| Solubility | soluble in ether, benzene, ethanol, acetone miscible in n-heptane, CCl4 |
| Template:Longitem | 1.41486 (13 °C) |
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Trifluorotoluene is an organic compound with the formula of C6H5CF3. This colorless fluorocarbon is used as a specialty solvent in organic synthesis and an intermediate in the production of pesticides and pharmaceuticals.[1]
Synthesis
For small-scale laboratory preparations, trifluorotoluene is synthesized by coupling an aromatic halide and trifluoromethyl iodide in the presence of a copper catalyst:[2]
- PhX + CF3I → PhCF3 (where X = I, Br)
Industrial production is done by reacting benzotrichloride with hydrogen fluoride in a pressurized reactor.[3]
- PhCCl3 + 3 HF → PhCF3 + 3 HCl
Uses
Trifluorotoluene has a variety of niche uses.
Dichloromethane alternative
According to Ogawa and Curran, trifluorotoluene is similar to dichloromethane in standard acylation, tosylation, and silylation reactions.[4] The dielectric constants for dichloromethane and trifluorotoluene are 9.04 and 9.18, respectively, indicating similar solvating properties. Dipole moments compare less favorably: 1.89 and 2.86 D for dichloromethane and trifluorotoluene, respectively. Replacing dichloromethane is advantageous when conditions require higher boiling solvents, since trifluorotoluene boils at 103 °C it has a higher boiling point than dichloromethane, which has a boiling point of ~40 °C.
As a solvent, trifluorotoluene is useful in mild Lewis-acid catalyzed reactions, such as the Friedel-Crafts preparations. The most common catalyst, aluminium trichloride reacts with trifluorotoluene at room temperature; however, zinc chloride does not.
Synthetic intermediate
A second and perhaps more valuable use of trifluorotoluene is as a synthetic intermediate. A derivative of trifluorotoluene, 3-aminobenzotrifluoride, is the precursor to the urea herbicide fluometuron.[3] It is synthesized via nitration followed by reduction to meta-H2NC6H4CF3. This aniline is then converted to the final urea.
Flumetramide (6-[4-(trifluoromethyl)phenyl]morpholin-3-one), a skeletal muscle relaxant, is also prepared from trifluorotoluene.[1]
Analytics
Trifluorotoluene appears in 19F NMR as a singlet at -63.2 ppm.[5]
References
- ↑ a b Banks, R.E. Organofluorine Chemicals and their Industrial Applications, Ellis Horwood LTD, Chichester, 1979.
- ↑ Ogawa, Akiya; Tsuchii, Kaname "α,α,α-Trifluorotoluene" in Encyclopedia of Reagents for Organic Synthesis 2005, John Wiley and Sons. Script error: No such module "CS1 identifiers".
- ↑ a b Siegemund, Günter "Aromatic Compounds with Fluorinated Side-Chains" in Ullmann’s Encyclopedia of Industrial Chemistry 2005, Wiley-VCH. Script error: No such module "CS1 identifiers"..
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