Sulphonyl chloride, reaction + alkali

Mixtures of primary, secondary and tertiary amines can usually be separated by Hinsberg s method. This is based on the fact that reaction with benzene-sulphonyl (or toluene-p-sulphonyl) chloride converts primary amines into alkali-soluble sulphonamides, secondary amines into alkali-insoluble sulphon-amides and leaves tertiary amines unaffected. 

Arenesulphinic acids and their alkali metal salts have long been used as precursors for the preparation of sulphonyl chlorides. This oxidation has most often been performed in either water or aqueous acetic acid solution, with chlorine or copper halides, as shown in equation 143263.553,555-564 jn some cases side-reactions occur, causing ring chlorination565. 

Alkyl- and aryl-sulphonyl derivatives are readily obtained by reaction of an amine with the sulphonyl chloride in aqueous alkali (Schotten-Baumann) or in the presence of pyridine. 

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