TABLE OF CONTENTS As mentioned in Chapter 2, chlorosulfonic acid is a valuable reagent for the conversion of organic compounds into their sulfonyl chlorides. The latter are of considerable importance because they are valuable synthetic intermediates in the preparation of a wide range of sulfonyl derivatives.1 The synthetic utility of sulfonyl chlorides depends on their ability to undergo substitution reactions with various nucleophilic reagents. Organic sulfonyl chlorides are generally liquids or low melting solids and they are not easily purified by recrystallization or distillation. The relatively low melting point makes crystallization difficult and they tend to decompose on distillation even under reduced pressure. Sulfonyl chlorides are also prone to hydrolysis when traces of moisture are present, since this results in the formation of hydrogen chloride which catalyses further hydrolytic decomposition. Sulfonyl chlorides are therefore generally characterized by condensation with amines to form the corresponding sulfonamides which are stable, well-defined, crystalline solids with fairly high, sharp melting points. The sulfonyl transfer reaction is illustrated by the condensation of an arylsulfonyl chloride 1 with nucleophilic reagents, e.g. water, alcohols, phenols, amines, hydrazine, hydroxylamine and azide ion to yield the corresponding sulfonic acids 2, sulfonates 3, sulfonamides 4, sulfonyl hydrazides 5, sulfonyl hydroxylamines 6 and sulfonyl azides 7 (Equations 1 6).
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| (6) |  |
In the reactions with amines or amino derivatives (Equations 3 5), either an excess of the amino compound is employed or the reaction is carried out in the...
