Sulphonacetamides

Sulphonacetamides. Sulphonacetamides are derivatives of sul-phonamides (Section IV.33A), but since the latter are readily prepared from the sulphonic acids or their salts, sulphonacetamides may be employed for the characterisation of sulphonic acids for this reason they are included in this Section. 

Sulphonamides upon heating with acetyl chloride are converted into the A -acetyl derivatives or sulphonacetamides ... 

Reflux 1 g. of the sulphonamide with 2-5 ml. of acetyl chloride for 30 minutes if solution is not complete within 5 minutes, add up to 2-5 ml. of glacial acetic acid. Remove the excess of acetyl chloride by distillation on a water bath, and pour the cold reaction mixture into water. Collect the product, wash with water and dissolve it in warm sodium bicarbonate solution. Acidify the Altered solution with glacial acetic acid Alter oflF the precipitated sulphonacetamide and recrystaUise it from aqueous alcohol. 

The melting points of a number of sulphonacetamides are —benzene-sulphonic acid, 125° p-toluenesulphonic acid, 137° p-bromobenzene-sulphonic acid, 203° m-nitrobenzenesulphonic acid, 189° p-nitroben-zenesulphonic acid, 192° naphthalene-a-sulphonic acid, 185° and naphthalene-p-sulphonic acid, 146°. 

Sulphonamides may also be characterised as sulphonacetamides for experimental details, see Section IV,33,d. 

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