Substrate selectivity and orientation in aromatic substitution by molecular fluorine

Journal Article · Wed May 07 00:00:00 EDT 1980 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00530a034· OSTI ID:5069151

Cacace, F ^[1]; Giacomello, P; Wolf, A P

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1. Univ. of Rome, Italy

Direct elemental fluorination of representative aromatic substrates, including PhH, PhCH/sub 3/, PhF, PhCl, PhBr, PhNO/sub 2/, PhCN, and PhOCH/sub 3/, has been investigated in inert solvents, e.g., CCl/sub 3/F and other fluorocarbons, over the temperature range -154 to 40/sup 0/C. In order to achieve the necessary control of the extremely reactive electrophile, and to minimize unwanted modifications of the reaction environment, the fluorination has been carried out at extremely low rates and correspondingly low conversions, generally below 0.01%, using as a reagent gaseous mixtures of F/sub 2/ highly diluted (<1 mol%) in N/sub 2/ or Ar. The partial rate factors, calculated from a consistent set of relative reactivity and orientation data measured at -78/sup 0/C in CCl/sub 3/F, correlate smoothly with the sigma/sup +/ constants for all the substituents investigated, giving a rho/sup +/ value of -2.45 for aromatic substitution by elemental fluorine with a correlation coefficient of 0.993. These results characterize F/sub 2/ as a highly reactive, and correspondently unselective, reagent, and support a polar electrophilic substitution mechanism that is discussed and compared with other plausible fluorination pathways.

• OSTI ID: 5069151
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 102:10; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical &amp; Physicochemical Properties-- (-1987)
ANISOLE
AROMATICS
BENZENE
BROMINATED AROMATIC HYDROCARBONS
CHEMICAL REACTIONS
CHLORINATED AROMATIC HYDROCARBONS
ETHERS
FLUORINATED AROMATIC HYDROCARBONS
FLUORINATION
HALOGENATED AROMATIC HYDROCARBONS
HALOGENATION
HYDROCARBONS
NITRILES
NITRO COMPOUNDS
NITROBENZENE
ORGANIC BROMINE COMPOUNDS
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC FLUORINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
TOLUENE