563. Solutions in sulphuric acid. Part XXV. Cryoscopic measurements on some phenols

Addition of sulfur trioxide to acid halides and esters

“…A second product, trisulfuryl fluoride, FS020S020S02F, bp 64°(120 mm), 2.04 g (12%), was identified by ir and NMR (singlet 19F NMR peak at +49.8 ppm). 16 m-Trifluoromethylbenzoyl Fluorosulfate (6). Addition of 7.5 g (0.094 mol) of S03 over a 10-min period to 19.2 g (0.10 mol) of m -trifluoromethylbenzoyl fluoride proceeded exothermically.…”

Aromatic sulphonation. Part 92. Sulphonation of the three methylphenols and the six dimethylphenols in concentrated aqueous sulphuric acid; and the lsomerization of some of the resulting sulphonic acids and of m-xylene-2-and o-xylene-3-sulphonic acid

“…First, the sulphonation proceeds via the sulphate as intermediate; secondly, the 3-sulphonic acid results from sulphonation of the oxygen protonated species of (8), and thirdly, the substantial substitution at the 3-position is due to electronic and steric effects (inhibition of resonance). The first explanation is rendered unlikely, as (i) 2,6-dimethylanisole (1 1) (the sulphation of which is impossible), in 84.5% H2S04 is mainly sulphonated at the 3-p0sition,~~ and (ii) phenyl methanesulphonate (12) (which is an analogue of phenyl hydrogen sulphate) in 86-99% H,SO, yields exclusively the 4-sulphonic acid.' The second explanation can also be refuted, as it has been shown previously that a large number of orthoand para-substituted phenols and anisoles are sulphonated via the unprotonated species, which is very much more reactive than the protonated species (which is the predominant substrate species present).'…”