Aromatic Fluorine Compounds. VII. Replacement of Aromatic -Cl and -NO₂ Groups by -F^1,2

Controlled variation of monomer sequence distribution in the synthesis of aromatic poly(ether ketone)s

“…Candidate nucleophiles in the system include the carbonate and fluoride anions, and indeed potassium carbonate has previously been shown to induce a small degree of sequence randomization in an aromatic PEK, albeit requiring very high reaction temperatures (340 C) and long reaction times (6 h). 15 The fluoride ion can be a very strong nucleophile in dipolar aprotic solvents, 16,17 but its effectiveness in the present context would depend both on the solubility of the fluoride salt involved and on the extent of pairing with its counterion in solution. The larger the counterion, the weaker the ion pairing and the more soluble the salt, so RbF should be much more effective than sodium fluoride, with potassium fluoride somewhere in between (r ionic ¼ 1.16, 1.52, 1.66 Å for 6-coordinate Na þ , K þ , and Rb þ , respectively).…”

6.06 Synthesis of Fluorides

“…152 Subsequently, the substitution of chloride in 1-chloro-2,4-dinitrobenzene with fluoride via S N Ar at 200°C was established as an approach for the synthesis of aryl fluorides, 153 which was later more generally established for electron-deficient arenes with leaving groups such as chloride or nitro groups (Scheme 45). 154 More recent work in this area has allowed for the fluorination of electron-poor, chloro-or nitroarenes with anhydrous TBAF at room temperature in up to 495% yield. 155 Nucleophilic fluorodemetallation of toxic organothallium 156 and organomecury 157 substrates as well as diaryliodonium 158 substrates were investigated as well, but are less widely used.…”

Activation and Formation of Aromatic C–F Bonds

“…The difficulty associated with C-F bond synthesis may be due to electronic features of the carbon substituent, as well as fluorine's potential reactivity with other functionality [5]. Traditional carbon-fluorine bond synthesis methodologies include direct fluorination [6], nucleophilic substitution of electron-poor bromine or chlorine arenes using KF [7], and transforming aryl iodides to their aryl fluorine counterparts using CuF 2 as the F-source [8]. These methods generally require harsh conditions and are usually not compatible with diverse functional groups, which limit the scope of fluorinated molecules that can be produced [9].…”