Chemical shifts for carboxyl OH protons usually appear down around 10-12 because they are so deshielded. Deshielding is basically what causes acidity so shouldn't more acidic carboxylic acids have chemical shifts greater than 11? Acetic acid has a peak at around 11.5 ppm: http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/cre_frame_disp.cgi?spectrum_type=hnmr&sdbsno=306 Benzoic acid has a peak at around 12 ppm which makes sense since the benzene ring delocalises the charge on the proton and increases its acidity. I can't find a HNMR spectrum for trifluoroacetic acid but heres one for dichloroacetic acid: http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/cre_frame_disp.cgi?spectrum_type=hnmr&sdbsno=5238 it contains a peak at around 9.4 ppm. I don't get it. The fluorine atoms are strongly electron withdrawing which is why difluoroacetic acid is more acidic than acetic acid. Why does the peak appear at 9.4 ppm? The proton should be far more deshielded than acetic acid so I would have expected its peak to be higher than 11.5 ppm. What am I missing here?