Trifluorotoluene

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Trifluorotoluene
Benzotrifluoride.png
Trifluorotoluene-3D-balls.png
Names
Other names
Benzotrifluoride (BTF)
α,α,α-Trifluorotoluene
CF3Ph
PhCF3
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.002.396
EC Number 202-635-0
Properties
C6H5CF3
Molar mass 146.11 g/mol
Appearance colorless liquid
Odor aromatic
Density 1.19 g/mL at 20 °C
Melting point −29.05 °C (−20.29 °F; 244.10 K)
Boiling point 103.46 °C (218.23 °F; 376.61 K)
<0.1 g/100 mL at 21 ºC
Solubility soluble in ether, benzene, ethanol, acetone
miscible in n-heptane, CCl4
1.41486 (13 °C)
Hazards
NFPA 704
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g., gasolineHealth code 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g., sodium chlorideReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
3
0
0
Flash point 12 °C (54 °F; 285 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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[edit]

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 via reacting benzotrichloride with hydrogen fluoride in a pressurized reactor.[3]

PhCCl3 + 3 HF → PhCF3 + 3 HCl

Uses[edit]

Trifluorotoluene has a variety of niche uses.

Low toxicity alternative to dichloromethane[edit]

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 62 °C higher than dichloromethane (b.p. 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[edit]

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 herbicide fluometuron.[3] It is synthesized via nitration followed by reduction to meta-H2NC6H4CF3. This aniline is then converted to the urea.

Flumetramide (6-[4-(trifluoromethyl)phenyl]morpholin-3-one), a skeletal muscle relaxant, is also prepared from trifluorotoluene.[1]

Analytics[edit]

Trifluorotoluene appears in 19F NMR as a singlet at -63.2 ppm.[5]

References[edit]

  1. ^ a b Banks, R.E. Organofluorine Chemicals and their Industrial Applications, Ellis Horwood LTD, Chichester, 1979.
  2. ^ Ogawa, Akiya; Tsuchii, Kaname "α,α,α-Trifluorotoluene" in Encyclopedia of Reagents for Organic Synthesis 2005, John Wiley and Sons. doi: 10.1002/047084289X.rn00653
  3. ^ a b Siegemund, Günter "Aromatic Compounds with Fluorinated Side-Chains" in Ullmann’s Encyclopedia of Industrial Chemistry 2005, Wiley-VCH. doi:10.1002/14356007.a11_349.
  4. ^ Ogawa, Akiya; Curran, Dennis P. "Benzotrifluoride: A Useful Alternative Solvent for Organic Reactions Currently Conducted in Dichloromethane and Related Solvents" Journal of Organic Chemistry 1997, volume 62, pp. 450-451. doi:10.1021/jo9620324
  5. ^ Denmark, Scott E.; Smith, Russell C. (3 February 2010). "Mechanistic Duality in Palladium-Catalyzed Cross-Coupling Reactions of Aryldimethylsilanolates. Intermediacy of an 8-Si-4 Arylpalladium(II) Silanolate (Supplementary Material, referenced as PhCF3)". Journal of the American Chemical Society. 132 (4): 1243–1245. doi:10.1021/ja907049y. PMC 2812642.