Perfluorobenzene reaction with

Preparation of Bis-1, 4-(disubstituted)perfluorobenzene and Bis-4,4 (disubstituted)perfluorobiphenyl. To a solution of 4.85 mmole of HFB or PFB and 9.65 mmole of 4-isopropylphenol or 4- -butylthiophenol in 20 ml of solvent was added 20.8 mmole of K2CO3 and 1.34 mmole of 18-crown-6 ether. The magnetically stirred heterogeneous mixture was heated to reflux or to 80 with DMAc and maintained under dry N2 for 4-24 hr. For reactions with... 

Perfluorobenzene on reaction with potassium 4-hydroxybenzoate yields product 16 with substitution of two fluorine atoms in positions 1 and 4.92... 

Photochemical chlorination of perfluorobenzene [170] and perfluoropyridine [171], and reactions with bistrifluoromethyl nitroxide [171], give addition products, although the C=N bond is very resistant to radical attack (Figure 9.71). 

Thus, aromatic sulphonic acids are readily produced. For example, benzenesulphonic acid is formed by reaction of sulphur trioxide in chloroform with benzene (equation 15) in higher yield and at a lower temperature (0-10 °C) compared with sulphonation with concentrated sulphuric acid105. The sulphonation of a wide structural variety of aromatic compounds with concentrated sulphur trioxide and its derivatives has been extensively studied by Cerfontain and coworkers21,23,45,47,52,55,56,58,59,62,64,66,80,81,106"130 and by others5,105,131"137. In two rather interesting reports, mono-, di- and trisulphonation of perfluorobenzene was performed by reaction with liquid sulphur dioxide138,139. 

The nature of the transient qiecies formed from the reactitm of Oaq whh perfluorobenzene can be determined frtim electron transfer studies whh a suitable electron acceptor. Based on these studies h was concluded diat the reaction of eaq with perfluoroacett henone or perfluorobenzaldd e formed radical anions whereas the reaction with hexafluorobenzene, pentafluon hmol or pentafluoroaniline resulted in the frxmation of a radical species vtidi fluoride ion eliminatioa Similarly, the reaction of electron with all rl halides (RX) lead to the formation of the allQrl radical and the halide ioa... 

McBroy, A., and F. P. TuUy (1993), Kinetic study of OH reactions with perfluoropropene and perfluorobenzene, J. Phys. Chem., 97, 610-614. 

Perfluorobenzene undergoes Sf Ar reactions readily with dimethylarmne, aniline, N methylaniline [AS], piperidine, A/-tnmethylsilyliminotnmcthylphos-phorane [69], and bthinm aniUde [70], but the reactions are often accompanied by sigmficant amounts of di- or polysubstitubon However, with the lithium salt of A -tnmethylsilylanilme, only one fluorine atom in pcrfluorobenzeneis replaced [71] (equation 36)... 

Takenaka and Lemal subsequently undertook an extensive study of the perfluorobenzene oxide (3)/perfluorooxepin (4) system.13,14 After considerable effort, benzene oxide 3 was successfully prepared by ozonization of tricyclic precursor 5 and photolytic decomposition of the resultant ozonides. Oxepin 4 was not observed directly, but was estimated by NMR computer simulations to be present in small proportion (3 %) at 55"C. The principal reaction of 3 is its rearrangement to cyclohexadienone 2, which occurs at room temperature in polar solvents, by heating in nonpolar solvents, or in the presence of Lewis acids. Photolysis of 3 with benzophenone as triplet sensitizer also produces 2. Furthermore, attempts to trap the oxepin, for example by treatment with bromine in the dark, result in cyclohexadienone 2. 

The elimination of only one fluorine of unsubstituted perfluoroarencs yielding monothiolated pentafluorobenzenes and heptafluoronaphthalenes is rather difficult to perforin. The reactivity of the respective perfluoroarenes is not very high and because of enhanced reactivity of fluorine in position 4 (benzene) or 6 (naphthalene) of the mono(alkylsulfanyl) compounds, the reaction tends to proceed further. When perfluorobenzene is reacted with the hydrosulfide anion, the pcrfluorobenzenethiolate anion formed is a very strong competitor to the hydrosulfidc anion ... 

Other well-known reactions are those offluorinated olefins with fluoride ion and negatively substituted aromatic compounds leading to the formation of per-fluoroalkylated aromatic compounds The reaction may be considered an anionic version ot a Friedel Crafts process and can result m introduction of one or several perfluoroalkyl substituents [HI] Aromatic substrates include substituted and unsubstituted perfluorobenzenes [131, 212, 213, 214], fluorinated heterocycles [131, 203, 215, 216, 217, 218, 219, 220, 221, 222, 223], perchlonnated heterocycles [224] (equation 44), and other activated aromatic compounds [225] (equation 45) The fluorinated olefins can be linear or cyclic [208] (equation 46)... 

OFCOT. No evidence was obtained for oxidative addition of a C—F bond to the nickel center, in contrast to the reported reaction of perfluorobenzene with [Ni(COD)(PEt3)2] (see Section III,F). 

We are mainly concerned here with general processes but two specific reactions are of some interest. Fragmentation occurs in the pyrolysis of CFBrs, giving perfluorobenzene (Figure 9.3) [3-5] this was probably the first synthesis of this compound, although it was not reported for some time. Trimerisation of hexafluoro-2-butyne leads to hexakis(trifluoro-methyl)benzene [6,7], areaction that was referred to in Chapter 7, Section lllB, Subsection 1. 

Fig. 3. a) the adsorption isotherms and b) the characteristic adsorption isotherms of benzene on supermicroporous active carbon prepared by the chemical reaction of perfluorobenzene with lithium amalgame, at 20 C (O), 4,0°C (A) and 60°C (Q). The full points - desorption. 

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