Hydroxylamines sulphonyl

A test for sulphonic acids is based on conversion to the sulphonyl chloride and then reaction with hydroxylamine. The reaction product can be converted with a drop of acetaldehyde to a hydroxamic acid which is detected in the classical way through the brown-violet colour with a drop of a Fe3+ reagent264. 

Though, strictly speaking, they are outside the scope of the review, a number of other interesting structures have been reported recently. They include potassium hydroxylamine-iV,iV-disulphonate (7)17 and the sulphonylated sulphamate cyclohexyl N-benzyl-iV-(p-bromophenylsulphonyl)sulphamate (8)18. 

Sulphonamides.— Oxidative amidation of sulphinic acids gives primary sulphon-amides, though the severe reaction conditions (18% oleum with NaNj) restrict the potential of this route. Selective amino sulphonation of anilines, using CISOjNCO and AlClj, depends on the formation of cyclic A-carbamoyl-sulphonamides. More conventional preparative methods are covered in the conversion of naphthalene-1-thiol into 4-(2-hydroxyethylsulphonyl)naphthalene-1-sulphonamide (an assessment of standard routes has been made), and in the preparation of alkanesulphonyl- and trifluoromethanesulphonyl-hydroxyl-amines from hydroxylamines and the sulphonyl chlorides. In the latter study,conditions favouring N- rather than 0-sulphonylation were established. 

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