1,3-sultones alkaline hydrolysis

By the alkaline hydrolysis of the sultone formed on boiling an aqueous solution of the diazonium salt of S-amino-l-naphthalenesulfonic acid or its appropriate derivatives. 

Cyclic five-membered sulfates and sultones are known to undergo hydrolysis from 105 to 107 faster than their acyclic analogs. Thus, for example, catechol sulfate [54] undergoes alkaline hydrolysis 2 x 107 faster than diphenyl sulfate (Kaiser et al., 1965), and l-naphthol-8-sulfonic acid sultone [55] hydrolyzes 5 x 105 faster than phenyl cr-toluenesulfonate (Kaiser et al., 1967). In contrast... 

A study of the rates of alkaline hydrolysis of a series of 5-substituted 2-hydroxytoluene-a-sulphonic acid sultones showed them to be moderately sensitive to substituent effects (p = + 1.23) but does not provide a method of distinguishing between a concerted mechanism and one involving a covalent intermediate143. The rates of hydrolysis and methanolysis of sultone 41 in strongly basic media have been correlated with H and HM respectively and lead to the conclusion that an addition-elimination mechanism would involve a monoionic intermediate 49 rather than the dianionic species 50144. 

It seems likely, therefore, that although the major cause of enthalpy strain observed in the alkaline hydrolysis of sultones arises from angle strain, other factors such as 1,3-lone-pair-lone-pair interactions and possibly conjugative effects also contribute to destabilisation of the five-membered ring. 

Alkene monosulphonates may be extracted as the sulphonic acids from strongly acid solution and determined by titration with alkali. Under these conditions the hydroxyalkane sulphonates are converted back to the sultones from which they were derived, and although these are also extracted, they are not titrated by alkali. Alternatively the alkene sulphonates in the extract may be titrated with benzethonium chloride. The hydroxyalkane sulphonates may be determined by alkaline hydrolysis followed either by measurement of the alkali consumed or by a second titration with benzethonium chloride. The following method is adapted from those of Ranky and Battaglini [20] and Martinsson and Nilsson [21]. The alkali used for hydrolysis of the sultones is alcoholic simply to prevent excessive foaming. 

Sultenes, Sultines, and Sultones.—Further reports have appeared on the formation of sultones from SO3 and dienes and from the cycloaddition of c-amino-methylene-ketones and sulphene. Unusual sultone formations occurred during the reaction of a ketose derivative with mesyl chloride and during the rearrangements of bicyclic ketones that were induced by sulphuric acid, respectively. The kinetics of reactions of sultones (181) with nucleophiles and the enthalpy changes accompanying their alkaline hydrolysis," which allow an estimation of differences in ring strain between the five- and six-membered sultones, have been studied. 

The major sulfonation process uses sulfur trioxide as the reactant and yields alkene sulfonic acids as preliminary products, together with various sultones (mainly 1,3 and 1,4 sultones corresponding to the more probable positions of the intermediate carbonium ion in the successive molecular rearrangements). Further alkaline hydrolysis of sultones yields hydroxyalkane sulfonates and alkene sulfonates (illustrated belo for 1,3 alkane sultone). An acidic hydrolysis of sultones produces alkene sulfonates as major products. 

Conditions for hydrolysis (82) of the intermediate sultone mixture also help modify the ratio of alkenesulfonate to -hydroxyalkanesulfonate, distribution of alkenesulfonate positional isomers, and completeness of conversion. Caustic hydrolysis using a slight stoichiometric excess of base is employed to ensure alkaline conditions throughout the hydrolysis phase of AOS production. The rate of hydrolysis depends a great deal on temperature. The 5-sultone requires the most time for conversion to 4-hydroxyalkanesulfonate. P-Sultones and y-sultones hydrolyze so rapidly to 2-hydroxyalkanesulfonate and 3-hydroxyalkanesulfonate that temperatures below 100°C can be used. 5-Sultone completely hydrolyzes between 120 and 175°C in 1—30 minutes. The quaUty of the final product mixture is ultimately determined by the choice of conditions. 

In the following stage, the reaction mixture is neutralized by caustic soda solution. In this neutralization step, only the free sulfonic acid component will be dissolved. The water-insoluble mixture of sultones must undergo an alkaline or acid hydrolysis. This takes place in a reactor at a hydrolysis temperature of 150-160°C for ca. 30 min. This leads to a nearly complete hydrolysis of the sultones to sodium 3-hydroxyalkanesulfonates and sodium 4-hydroxyalkanesulfonates. 

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