Ammonia → 2-(Fluoromethyl)benzoic acid

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Reaction Steps

4-Bromomethylbenzoic acid was converted to t-butyl 4-bromomethylbenzoate using isobutylene in sulfuric acid [16], in 50% yield. The product, an oil, had the following NMR spectrum in CDCl3 : 6 7.96 and 7.43 (each d, 2H, J=8Hz), 4.50 (s, 2H), 1.59 (s, 9H, t-Bu). The chemical ionization mass spectrum (NH3) showed peaks at 211 (m+1), 228. The bromomethyl compound was fluorinated as above using tetrabutylammonium fluoride in acetonitrile, in 90% yield. NMR spectrum in CDCl3 : 6 8.01 and 7.41 (each d, 2H, J-8Hz), 5.44 (d, 2H, J=47Hz), 1.60 (s, 9H, t-Bu). The t-butyl ester was removed quantitatively upon 10 min exposure to neat trifluoroacetic acid. The product, α-fluorotoluic acid, was obtained as a white solid, melting at 178°-181°. The chemical ionization mass spectrum (NH3) showed a peak at 172=m+1+17). NMR spectrum in CDCl3 : δ 8.12 and 7.47 (each d, 2H, J=8Hz), 5.47 (d, 2H, J=47Hz).

Provenance & Evidence