Sultones hydrolysis

The reaction of sulfur trioxide with of-olefines in molecular ratios gives rise to two main products, i.e. isomeric alkenesulfonates and sultones. The 1,2-sulfone is produced first, followed by transformation into the 1,3- and 1,4-sultones. Hydrolysis then leads to hydrox-yalkanesulfonates. The overall synthesis is a four-stage process of sulfonation, transformation, neutralization and hydrolysis. The complex mixture of isomeric alkenesulfonates and hydroxyalkanesulfonates is known under the collective term of of-olefinesulphonates , an anionic surfactant that is itself a blend of different... 

Table 8 Hydrolysis rates of C and D sultones at various lemperatur C sultones (1,3) (Gamma sultones) hydrolysis rates...

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. 

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. 

The next stage is neutralization of the alkenesulfonic acids with NaOH yielding water-soluble sodium alkenesulfonates, and hydrolysis of the sultones leading to sodium 3-hydroxyalkanesulfonates and sodium 4-hydroxyalkanesulfon-ates. The proportion of the latter two compounds in the mixture will depend on the conditions employed in the aging step. A hydrolysis temperature of 150-160°C and a hydrolysis time of 40-45 min ensures virtually complete hydrolysis of sultones 1,3-sultones will be present in ppb quantities and 1,4-sultones in ppm quantities. 

Similarly, the presence of sulfonate esters also indicates incomplete hydrolysis. Residual saponifiable material in a final AOS product is then a measure of the quality of the surfactant. In practice, such material can be extracted, subjected to drastic conditions of saponification, and the quantity of residual saponifiable material calculated. Methods have been developed which can be used for the determination of 10 or more ppm of saponifiable material in the neutral oil of AOS. Unfortunately, the procedures outlined below are now of historic interest only, since they give unrealistically high values for residual saponifiable material content. Methods listed in the sultones section are now the analyses of choice. 

The amount of residual sulfonate ester remaining after hydrolysis can be determined by a procedure proposed by Martinsson and Nilsson [129], similar to that used to determine total residual saponifiables in neutral oils. Neutrals, including alkanes, alkenes, secondary alcohols, and sultones, as well as the sulfonate esters in the AOS, are isolated by extraction from an aqueous alcoholic solution with petroleum ether. The sulfonate esters are separated from the sultones by chromatography on a silica gel column. Each eluent fraction is subjected to saponification and measured as active matter by MBAS determination measuring the extinction of the trichloromethane solution at 642 nra. (a) Sultones. Connor et al. [130] first reported, in 1975, a very small amount of skin sensitizer, l-unsaturated-l,3-sultone, and 2-chloroalkane-l,3-sultone in the anionic surfactant produced by the sulfation of ethoxylated fatty alcohol. These compounds can also be found in some AOS products consequently, methods of detection are essential. 

Roberts et al. [131,132] investigated the formation of sultones in the production of AOS. In the initial sulfonation stage, these include 1,2-, 1,3-, and 1-4-sultones. As indicated earlier, the 1,2 and 1,3 derivatives are easily hydrolyzed to produce sulfonates. The 1,4-sultone (8 sultone) is fairly resistant to saponification, and severe conditions are required for complete conversion to sulfonates. The presence, then, of 1,4-sultone is an indication of the degree of hydrolysis. 

Neutralization of the sulfonation product from a-olefins is more complex than neutralization of the corresponding products of alkylbenzenes. This is because the S03-a-olefin acid product contains about 50% free sulfonic acid, the rest being C(l,3) and D(l,4) sultones, assuming that with acid aging the 0(1,2) sultones have disappeared. In the case of a-olefins an excess of caustic (1.5-2.0% excess) must be added to neutralize both the sulfonic acid initially present and that formed on subsequent hydrolysis of the C(l,3) and D(l,4) sultones. The sultones (ring-structured esters) cannot be converted to their proper salts by a simple neutralization but need a hydrolysis step. 

Commonly employed base hydrolysis of sultones at 150°C leads to about 60-70% hydroxyalkanesulfonate and 30-40% alkanesulfonate (see Sec. V.H). 

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... 

Another example of preferred linear displacement in ring openings can be found in the study of the hydrolysis of sultones (2). For a chelate ring to open it must have an angular displacement with a minimum arc to avoid the repulsions from... 

Along with the hydrolysis of tropylium salts (see above), the tautomeriza-tion of sulfonate 279 to give sultone 602 (Scheme 162) exemplifies the attack by an oxygen nucleophile (89BCJ1158). 

The enzyme also catalyses the hydrolysis of various esters such as 4-nitrophenyl acetate and sultones. A number of slightly different enzymes, carbonic anhydrases A, B and C occur in different organisms. The most well characterised enzymes are the bovine and human carbonic anhydrases B, which are monomeric and contain one tightly bound zinc per 30000 molecular weight. 

Synthesis o/eslra-l,3,5(10)-(rieiie-17-oii . Nicolaou and Barnette report that sultone 1 is metalated with KH in DME to afford a clear yellow solution of the anion 2. Alkylation of 2 with tosylate 3 followed by acid hydrolysis affords 4 as a mixture of diastereomers in 77% yield. Thermolysis of 4 affords estra-1,3,5(10)-triene-17-one (5) directly in 85% yield, probably by way of an intermediate o-quinone methide a. This sequence constitutes an exceedingly short and efficient synthesis of the steroid nucleus. 

Ring opening of sultones 91 by hydrolysis in aqueous acetone produced acyclic y-hydroxy-lated sulfonates 92 [83,84] (O Scheme 22). Furthermore, the Sn2 reaction of 91 with NaN3... 

The hydrolysis of the tropolone methyl ether 360 with concentrated HCl in boiling EtOH results in the hydroxyfluorenone 361 (equation 172) °. Thermal rearrangement with loss of sulfur dioxide occurs on heating the y-sultones 362 in dioxane, DMSO, dioxane-water or THE at 90 °C for 6-10 h to give 90% of the styrene derivatives 363 in a highly stereospecific manner (equation 173). ... 

These compounds are prepared starting from chloroace-tic acid or its ethyl ester. For chains longer than acetic, cya-noethylation and hydrolysis of the nitrile obtained leads to the propionic chain, alkylation with ethyl 4-bromobutyrate and saponification leads to the butyric chain. The propane-sulfonic chains are particularly accessible by means of ring opening of propane-sultone. 

The sultone cycloadducts could be further manipulated by ring-opening with various nucleophiles, such as alcohols and amines, at the y-position [41]. When optically active (S)-(-)-a-methylbenzylamine reacted with the racemic sultone cycloadduct 76 in ethanol at room temperature, one of the diastereomeric ammonium sulfonates precipitated from the reaction mixture (Scheme 17). Although the absolute stereochemistry of 77 had not been determined, cyclization of optically pure 77 with phosphorus oxychloride gave an optically pure sultam 78. Formic acid debenzylation followed by base hydrolysis of the N-formyl group afforded the optically pure sultam 80 in good yield [40]. 

The 1,3-dipolar cycloaddition of 80 with nitrile oxides and nitrones to give products such as 81 has been reported <03JHC1071, 03TL395>. Diastereoselectuve hydrolysis of y-sultones 82 to give products including homotaurine derivatives has been examined <045590,... 

A. The Energetics of Sultones The Hydrolysis of Some Benzo[[Pg.301]

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