Methane sulphinic acid

Sulphur dioxide. Methane sulphinic acid. Hobson, Annahn 1858,106, 288,... 

Trichloronitroso methane, obtained by the action of nitric acid on the sodium salt of trichloromethyl sulphinic acid, is a liquid boiling at 5° C. at 70 mm. pressure. 

The sulphonic acids are now known to be stronger than was supposed up to ten years ago. Methane-sulphonic acid has a pKg of —1 20, as determined by proton magnetic resonance (Covington and Lilley, 1967), or —1 86, as determined by Raman spectrometry (Clarke and Woodward, 1966) both values were obtained in water at 25°. Thus this substance is comparable in strength to nitric acid (Table 8.12). Similarly p-toluenesulphonic acid was shown to have a pKg of - 1 - 34 (Dinius and Choppin, 1962) by p.m.r. measurements in water at 25° (cf. —1 06 for Raman measurement by Bonner and Torres, 1965). Table 8.5 contains values for these substances, and organic sulphinic and boric acids (see Table 8.6 for corresponding phosphorus and arsenic derivatives). 

A very violent reaction takes place and the yield of trichloro nitroso methane is low. This compound is more conveniently obtained by the action of an aqueous solution of sodium trichloro methyl sulphinate, potassium nitrate and sodium nitrite on sulphuric acid. ... 

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