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We report here the facile substitution of aromatic iodides with non-activated fluoroarenes through radical-promoted reaction conditions. Applying the recently-popularized BHAS methodology, catalytic 1,10-phenanthroline and KO t Bu and the desired fluorobenzene as reactant and solvent, various fluorinated biaryls can be synthesized in moderate to good yields. The method provides a simple access to generate potentially many ‘F n Ar’-substituted derivatives from a single haloarene synthetic intermediate, using relatively cheap and non-toxic fluoroarene substrates directly from the bottle, and may therefore be of use for medicinal chemistry campaigns. Although the method has a limitation in that it is not compatible with substrates featuring base-sensitive substituents, especially 1,4-difluorobiaryls are accessible in good yields. These investigations facilitate the exploitation of the potential of this protocol to synthesize biologically active fluorinated biaryls, e.g. WNT-active molecules.

Two series of fluorine-substituted benzoate ester type rod-shaped liquid crystals incorporating the azobenzene as side arm linked with terminal double bonds as polymerizable functional groups were synthesized and characterized by polarized-light optical microscopy (POM), differential scanning calorimetry (DSC) and UV–visible spectroscopy investigations. Thus, rod-shaped monomers, namely 4a and 4b having odd and even number of carbon in the terminal group exhibited nematic phase and SmA type phase was found at lower temperature. Compound 5 showed nematic phase whereas compound 6 showed SmA phase. These rod-shaped molecules exhibit strong photoisomerization behaviour in solution. The photoswitching properties of the compounds showed trans to cis isomerization in about 10 s, whereas the reverse process takes place about 120 min in solutions. Proposed materials may have potential to use it in optical storage devices.

Relative stabilities, dipole moments and response electric properties of fluorinated benzenes have been studied using Hartree–Fock (HF) and correlated second-order Moller–Plesset perturbation theory (MP2) with the Sadlej's POL basis set. At the highest MP2/POL level, on passing from benzene to hexafluorobenzene the electronic mean polarizability value increases by only 3%, whereas the difference on the polarizability anisotropy is comparatively larger (+19%). The polarizability anisotropy of fluorobenzenes depends on the fluorination, increasing progressively with the increases of the number of fluorine atoms, following a near-additive atomic contribution law. Dipole moments and first-order hyperpolarizabilities among the investigated isomers differ up to a factor of two, these properties being potentially useful to discriminate the fluorobenzene isomers. Hyperpolarizability differences between the fluorinated isomers have been elucidated using hyperpolarizability density analyses. Electron correlation effects evaluated at the MP2 level are especially important for the first-order hyperpolarizabilities, increasing the HF values by 20–30%.

The recycle of fluoride ion generated from the degradation of 1-methyl-3-butylimidazolium tetrafluoroborate, diethyl methyl methoxyethylammonium tetrafluoroborate in the presence of Tris–HCl buffer solution and/or the biodegradation of fluorobenzene and benzotrifluoride, was described. The generated fluoride ion was reused to produce 5′-fluoro-5′-deoxyadenosine (5′-FDA), fluoroacetate and/or 4-fluorothreonine.

A variety of theoretical methods have been used to study the gas-phase acidity of benzene and its eleven fluorine-substituted derivatives: fluorobenzene, three isomers of difluorobenezene, three isomers of trifluorobenzene, three isomers of tetrafluorobenzene and 1,2,3,4,5-pentafluorobenzene. The high-level ab initio methods, G3//B3-LYP and CBS-QB3, are shown to reproduce experimental data to within an average of 1.9 and 1.4 kcal mol −1 , respectively. Of the lower-cost methods studied, M05-2X and MP2 showed the best overall performance with mean absolute deviations of just 1.2 and 1.1 kcal mol −1 , respectively. The effect of substitution and position on the acidity of the protons in the various compounds are studied and the structure–reactivity trends in these heterolytic C–H bond dissociation energies (BDEs) are compared with the corresponding homolytic C–H BDEs for the same species.

Isolation of bacterial strains capable of degrading fluorinated materials was described. 8 strains of Actinobacteria exhibited degradability of ethyl difluoroacetate (DFAc) was accumulated by bacteria, giving difluoroacetic acid and then fluoride ion. Further, 13 strains of Actinobacteria exhibited degradability of fluorobenzene and/or benzotrifluoride. In batch culture, growth of strains on fluorinated materials led to the release of fluoride ion.

Catalytic hydrodefluorinations of organofluorine compounds by low-valent niobium catalyst were developed. In the presence of niobium(V) chloride (typically, 5 mol%), fluorobenzenes, α,α,α-trifluorotoluenes and (trifluoromethyl)pyridines were hydrodefluorinated with lithium aluminum hydride to give the corresponding benzenes, toluenes and methylpyridines in good yields, respectively.

Catalytic Friedel-Crafts acylation of benzene and unactivated benzenes, such as chlorobenzene and fluorobenzene, was successfully accomplished using rare earth(III) perfluorooctane sulfonates (RE(OPf)3), RE = Sc, Y, La ∼ Lu) and perfluorooctanesulfonic acid (PfOH) as catalysts in fluorous solvents. Solutions of Yb(OPf)3 and PfOH in perfluorodecalin (C10F18, cis and trans-mixture) are the most suitable catalytic system, with catalyst loading as low as 0.4%mol leading to clean, high-yielding benzoylation of a variety of unactivated benzenes. By simple separation of the fluorous phase containing only catalyst, acylation can be repeated several times.

In this work, we accomplished for the first time the Suzuki cross-coupling reaction between fluorobenzene and phenylboronic acid with different heterogeneous catalysts and bases. The conversion values obtained are similar to those provided by homogeneous catalysts and activated aryl fluorides.

Photochemically induced reaction of fluorobenzene and a range of polyfluorobenzenes, both in an excess of the arene and with fluorotrichloromethane as solvent, gave isolable adducts only with fluorobenzene, the isomeric difluorobenzenes, and in very small yield with 1,3,5-tri-fluorobenzene. These adducts were identified by combustion analysis, mass spectrometry, and n.m.r. techniques (1H, 19C, 19F). In every case, the expected substitution products accompanied these adducts, and in the more fully fluorinated benzene derivatives substitution was the only process observed. Fluorotrichloromethane encouraged the formation of adducts, but the concurrent formation of substantial amounts of substitution products suggested that adducts are not the necessary precursors of the substitution products, in contrast with other systems.

Perfluoro-[ N -fluoro- N -(4-pyridyl)methanesulphonamide] (III), synthesised via direct fluorination of the sodio derivative of perfluoro-[ N -(4-pyridyl)methanesulphonamide] (I), readily converts diethyl sodio(phenyl)malonate and anisole to diethyl fluoro(phenyl)malonate and ortho - plus para -fluoroanisole respectively at ambient temperature; at 60 °C it quickly converts benzene to fluorobenzene. The sodio-precursor (I) of the N-F compound (III) is easily made from pentafluoropyridine and trifluoromethanesulphonamide.

Nucleophilic attack on hexafluorobenzene by sodium formanilides gave N,N′-diphenyl-2,3,5,6-tetrafluorophenylene-1,4-diamine as the main product at elevated temperature and N,N′-diformyl-N,N′-diphenyl-2,3,5,6-tetrafluorophenylene-1,4-diamine as the main compound at ambient temperature. Metallation of formanilide with lithium hydroxide instead of sodium hydride gave only 2,3,4,5,6-pentafluorodiphenylamine.

A new synthetic method of obtaining 4-fluorophenol starting from fluorobenzene is reported. The process involves three steps: 1. formation of 4-F,4′-Z-benzophenones by a Friedel-Crafts condensation between fluorobenzene and 4-Z-benzoyl chlorides; 2. oxidation of the benzophenone-derivatives to the corresponding arylesters by peracetic acid; 3. alkaline hydrolysis of the esters giving the final 4-fluorophenol. The influence on the reaction selectivity deriving from the electrophilic character of the different Z-substituents in the benzoyl chlorides moiety has been also investigated.

Fluorobenzene and derivatives 1 can be easily and selectively prepared by fluorodecarboxylation from the corresponding haloformates 2 in a hydrogen fluoride media under gaseous conditions over a mineral catalyst (1). A large number of compounds were prepared and most of the case, the yields are high (fluorobenzene; fluorotoluenes; 1,4 difluorobenzene; halofluorobenzenes). The reactivity of substrates over different catalysts will be discussed.

A variety of (per- and polyfluoroalkyl)phenyl- and p-fluorophenyliodonium triflates 3 were synthesized in good yields by the oxidation of the corresponding iodofluoroalkanes with trifluoroperacetic acid followed by the treatment with benzene or fluorobenzene and triflic acid. It was also shown that elemental fluorine was used as a substitute for the peracid. The use of fluorosulfonic, sulfuric, and methanesulfonic acids instead of triflic acid afforded the fluoroalkylaryliodonium fluorosulfonates 5 , sulfates 6 , and methanesulfonate 7 , respectively. Similarly perfluoroalkylene-α,ω-bisaryliodonium triflates 10 were synthesized from α,ω-diiodoperfluoroalkanes. On the other hand, the treatment of (perfluoroalkyl)-p-tolyliodonium chlorides with silver sulfonates gave the iodonium benzenesulfonate 13 , methanesulfonate 12 , and triflate 14 , and bisiodonium sulfate 15 . Thermolysis of (perfluorooctyl)phenyliodonium triflate at about 150°C afforded perfluorooctyl triflate, iodobenzene, and (perfluorooctyl)iodobenzene in 73, 63, and 25% yields, respectively.

The rates of methoxydefluorination of all twelve polyfluorobenzenes in dimethyl sulphoxide-methanol mixtures (DMSO-MeOH; 9:1, v/v; 298.2 K) have been measured. Three substituent rate factors (fo, 60; fm, 180; fp, 0.75) are sufficient to reproduce the effect of the fluorine substituent in this reaction upon each member of the series. The solvent effect, comparing these results with an earlier and more limited study in methanol is predominantly a simple acceleration. The effects of substituents upon the rate of methoxydefluorination of fluorobenzene itself are slightly greater (ϱ−, 6.9) than in the corresponding reaction of pentafluorobenzene derivatives (ϱ−, 5.8), but the change in sensitivity is much less than that found with nitrobenzene derivatives.

The reaction of atomic fluorine with fluorobenzene under cold plasma conditions leads to the formation of three difluorobenze isomers. The isomer distributions confirm the selective introduction of atomic fluorine into the aromatic ring as previously found in the reaction of atomic fluorine and bromobenzene. A comparison of the isomer distribution indicates that the presence of a fluorine atom in a ring has greater inhibiting effect on ortho substitution than the corresponding bromine atom.

Room -temperature fluorination of benzene with cesium fluoroxysulphate in the presence of boron trifluoride as catalyst resulted in the formation of fluorobenzene, while reaction with naphthalene gave 1-fluoro and 2-fluoronaphthalene in the ratio 5:1, the overall yield being between 38 and 42%. The fluorination of phenanthrene and pyrene should be carried out at higher dilution and needs no catalyst. Phenanthrene gave 9-fluorophenanthrene and 9, 9-difluoro-10-keto-9, 10-dihydrophenanthrene in the ratio 1:6 in a yield of about 70%, while pyrene gave 1-fluoro and 4-fluoropyrene in the ratio 7.5:1.

(1,l-Dihydroperfluoroalkyl)phenyl- and - p -fluorophenyliodonium triflates 2 and 3 were synthesized by the reaction of l-bis(trifluoroacetoxy)iodo-1,l-dihydroperfluoroalkanes 1 with triflic acid and benzene or fluorobenzene in 1,1,2-trichlorotrifluoroethane. The use of fluorosulfonic acid and sulfuric acid instead of triflic acid afforded (1,l-dihydroperfluoroalkyl) phenyliodonium fluorosulfonate 4 and sulfate 5 , respectively. Similarly, (1,1,ω-trihydroperfluoroalkyl)phenyliodonium triflate 7 and 1,1,5,5-tetrahydroperfluoropentane-l,5-bisphenyliodonium triflate 9 were synthesized.

Reaction of the oxadiazapentane (CF 3 ) 2 NON(CF 3 ) 2 (I) with chlorobenzene or bromobenzene affords mainly the substitution products (CF 3 ) 2 NC 6 H 4 X (X=Cl or Br; para > ortho > meta ). In contrast reaction with fluorobenzene gives mainly addition products, i.e. cyclohexenes, and the compound 4-(CF 3 ) 2 NOC 6 H 4 N(CF 3 ) 2 , while reaction with iodobenzene yields the compounds (CF 3 ) 2 NH and 4-IC 6 H 4 I and tar.

Benzene, toluene, and nitrobenzene interact rapidly with NF 4 BF 4 in anhydrous HF to give, almost exclusively, fluorine substituted aromatic derivatives. Up to four hydrogens can be replaced in a rapid reaction, before a much slower addition reaction takes over. The direction of the substitution in C 6 H 6 , C 6 H 5 CH 3 and C 6 H 5 NO 2 and the lack of side chain fluorination in C 6 H 5 CH 3 support an electrophillic substituion mechanism. These rapid substitution reactions are followed by much slower fluorine addition reactions to give the corresponding cyclo-hexadienes and -hexenes. These addition reactions were also studied separately using tetra-, penta- and hexa- fluorobenzene as the starting materials. In these addition reactions, almost no hydrogen substitution occured. The addition of the first pair of fluorines always gave 1,4-cyclohexadienes in which CF 2 group was adjacent to hydrogen on the ring. The addition of the second pair of fluorines resulted in the formation of cyclohexenes. These reactions occured in high yield and offer a controlled, high yield path to dienes. All products were characterized spectroscopically and by comparison to literature data.

The catalytic decarboxylation of phenyl fluoroformate to fluorobenzene has been achieved with yields of 70–80% in a flow system using alumina or alumina-based catalysts. The reaction occurs in short space times ( Pd/Al2O3>Rh/Al2O3≈Al2O 3. 2,4,6-Trimethlyphenyl flouroformate, a new material, was found to decarboxylate similarly to give 1-flouro-2,4,6-trimethylbenzene, but 4-chlorophenyl flouroformate was noted to produce only low yields (∼10%) of the corresponding arly flouride

The thermal decomposition of benzoyl peroxide in a range of polyfluorobenzenes at 80° gives biaryls arising from both the displacement of fluorine and hydrogen. Phenyldefluorination predominated only in the attack of 1,2,3,4-tetrafluorobenzene and of pentafluorobenzene, but was evident even in the attack of o -difluorobenzene. The relative rates of displacement, as shown by the isomer distributions, were generally well reflected by the application of partial rate factors found in the phenylation of fluorobenzene; however, phenyldefluorination was not so easily amenable to this treatment, a possible consequence of complex formation between radical precursor and substrate.

In contrast to limited substitutive fluorination of aromatics with halogen fluorides such as ClF, ClF3, BrF3 and IF5, fluorination is the predominant reaction path with ClF5. Under non-catalytic liquid phase conditions, benzene was converted to fluorobenzene (54% yield) and chlorobenzene (37% yield), respectively. For a heterocyclic substrate, i.e. 2,4,6-trifluoropyrimidine, substitutive fluorination predominated over chlorination. Three possible fluorination mechanisms are discussed. A transition complex of ClF5 with benzene is favored. Enhanced exchange fluorination of CCl4 was effected with ClF5 (CF2Cl2>>CFCl3>CF3Cl) as compared with ClF3 (CFCl3>>CF2Cl2).

The reactions of fluorine and acetyl hypofluorite with trimethylaryltin, -germanium, and -silicon compounds were studied using fluorine-18 (T12 = 110 min) as a radiochemical tracer. The fluorodemetallation of phenyl derivatives by sub-stoichiometric F2 to yield fluorobenzene was almost independent of temperature (−78° to 22°C), reaction time (2 to 200 min) and substrate concentration (2 to 150 mM). The reactions of both fluorination agents were not affected by perhalogenated methanes as solvents, but completely suppressed in solvents with active hydrogens. In a series of p-substituted phenyl derivatives (CH3O-, CH3-, H-, F-, Br-, CF3-,O2N-), a decrease in the fluorodemetallation yield was observed in the order Sn > Ge > Si, and with rings containing electron-withdrawing groups. The reactivity of CH3CO2F with stannylated arenes was equal to that of F2, but much lower than that of F2 when arylgermanium or -silicon derivatives were used. These findings are in agreement with a substitution mechanism involving a σ-complex. The only side-products which formed from the corresponding metallated anisyl- and toluyl- compounds were 2-fluoroanisole (< 16%) and benzylfluoride (< 5.5%). No direct hydrogen substitution was observed in the other substrates investigated. The high regiospecific fluorination yields obtained make aromatic fluorination of group IVb metallated arenes (especially of tin) a very attractive preparative fluorination and radio-labelling method.

Passage of undiluted elemental fluorine gas through a radiofrequency discharge region is known to produce atomic fluorine. Reaction of atomic fluorine with bromobenzene vapor gave the corresponding bromofluorobenzene isomers and small amounts of fluorobenzene and difluorobenzene isomers. From the isomer distributions the substitution of the atomic fluorine in observed to be more selective than previously thought.

The arylation of fluorobenzene with pentafluorophenyl radicals obtained by the reaction of the corresponding aniline with pentyl nitrite is described. The reaction involves attact at the 2t-,3t-and 4t-positions. The composition of the mixture and the nature of its components were determined by 19 F NMR spectroscopy and were confirmed by gas-liquid chromatography.