Sulfonation/desulfonation

Sulfonation—Desulfonation of Chlorobenzenes. Sulfonation of chlorobenzenes can also be used to produce chlorophenols. Sulfonation is carried out at 60—80°C using oleum at 15—20%. The subsequent desulfonation usually calls on aqueous alkaU solutions at 15—20% at temperatures between 170 and 230°C. 

Groups other than H can be displaced during electrophilic aromatic attack. The acid-catalyzed reversal of sulfonation (desulfonation) exemplifies such a reaction here, displaces SOjH as SOj and H". 

The analysis of surfactants by GC and GLC is difficult because surfactants are not volatile. To overcome the problem of volatility, the surfactants can be either derivatized to yield more volatile products, or pyrolyzed to hydrocarbons. In the case of alkyl(aryl)sulfonates desulfonation is often used [31]. The resulting chromatograms usually contain several peaks and may be difficult to use for quantification. 

Use in Synthesis. Sulfonation-desulfonation is a useful tool for preparing ortho isomer derivatives of benzene. The sulfonic group is introduced to block the 4 position opposite a methyl, hydroxyl, or acetylamino group then a chlorine or alkyl group is introduced ortho to the methyl or hydroxyl group. Finally, the sulfonic group is removed for the case of 2-chlorotol-uene, the reaction is as follows ... 

While this approach afforded gram quantities of a heparin-like polysaccharide with anticoagulant activity, unnatural saccharide units, such as 3-0-sulfo-D-glucuronic acid, were present in their product, suggesting a limitation in the selectivity of chemical sulfonation/desulfonation in HS synthesis. 

Sulfonation-desulfonation is a useful tool in syntheses involving eleotrophilio aromatio substitution. 

Bromination 4. Sulfonation/desulfonation 7. Reduction 10. Clemmensen reduction... 

The synthesis of 2,4-dihydroxyacetophenone [89-84-9] (21) by acylation reactions of resorcinol has been extensively studied. The reaction is performed using acetic anhydride (104), acetyl chloride (105), or acetic acid (106). The esterification of resorcinol by acetic anhydride followed by the isomerization of the diacetate intermediate has also been described in the presence of zinc chloride (107). Alkylation of resorcinol can be carried out using ethers (108), olefins (109), or alcohols (110). The catalysts which are generally used include sulfuric acid, phosphoric and polyphosphoric acids, acidic resins, or aluminum and iron derivatives. 2-Chlororesorcinol [6201-65-1] (22) is obtained by a sulfonation—chloration—desulfonation technique (111). 1,2,4-Trihydroxybenzene [533-73-3] (23) is obtained by hydroxylation of resorcinol using hydrogen peroxide (112) or peracids (113). 

Many aminonaphthalenesulfonic acids are important in the manufacture of azo dyes (qv) or are used to make intermediates for azo acid dyes, direct, and fiber-reactive dyes (see Dyes, reactive). Usually, the aminonaphthalenesulfonic acids are made by either the sulfonation of naphthalenamines, the nitration—reduction of naphthalenesulfonic acids, the Bucherer-type amination of naphtholsulfonic acids, or the desulfonation of an aminonaphthalenedi-or ttisulfonic acid. Most of these processes produce by-products or mixtures which often are separated in subsequent purification steps. A summary of commercially important aminonaphthalenesulfonic acids is given in Table 4. 

Another example of manufacture in this series is the sulfonation of an aminonaphthalenesulfonic acid, followed by selected desulfonation, to make 6-amino-l,3-naphthalenedisulfonic acid (21). Thus, 2-amino-l-naphthalenesulfonic acid made by amination of 2-hydroxy-1-naphthalenesulfonic acid is added to 20 wt % oleum at ca 35°C. At this temperature, 65 wt % oleum is added and the charge is stirred for 2 h, is then slowly heated to 100°C and is maintained for 12 h to produce 6-amino-l,3,5-naphthalenetrisulfonic acid. The mass is diluted with water and maintained for 3 h at 105°C to remove the sulfo group adjacent to the amino group. After cooling to ca 20°C and filtration, 6-amino-l,3-naphthalenedisulfonic acid is obtained in 80% yield (55). 

Naphthalenediol. This diol is made by the hydrolytic desulfonation of 2,3-naphthalenediol-6-sulfonic acid at ca 180°C. It is used as a coupler forming a2o dyes which are appHed in reprographic processes. 

Hydroxynaphthalenesulfonic acids are important as intermediates either for coupling components for a2o dyes or a2o components, as well as for synthetic tanning agents. Hydroxynaphthalenesulfonic acids can be manufactured either by sulfonation of naphthols or hydroxynaphthalenesulfonic acids, by acid hydrolysis of arninonaphthalenesulfonic acids, by fusion of sodium naphthalenepolysulfonates with sodium hydroxide, or by desulfonation or rearrangement of hydroxynaphthalenesulfonic acids (Table 6). 

H. Cerfontain, Mechanisticdspects in Aromatic Sulfonation and Desulfonation, Wiley-Interscience, New York, 1968. 

Thermal stabihty of the foaming agent in the presence of high temperature steam is essential. Alkylaromatic sulfonates possess superior chemical stabihty at elevated temperatures (205,206). However, alpha-olefin sulfonates have sufficient chemical stabihty to justify their use at steam temperatures characteristic of most U.S. steamflood operations. Decomposition is a desulfonation process which is first order in both surfactant and acid concentrations (206). Because acid is generated in the decomposition, the process is autocatalytic. However, reservoir rock has a substantial buffering effect. 

Pigment Red 177 [4051-63-2] 65300 anthraquinone bimolecular debromination of l-amino-4-bromoanthraquiQone-2-sulfonic acid, foUowed by desulfonation... 

Sulfonic acids are prone to reduction with iodine [7553-56-2] in the presence of triphenylphosphine [603-35-0] to produce the corresponding iodides. This type of reduction is also facile with alkyl sulfonates (16). Aromatic sulfonic acids may also be reduced electrochemicaHy to give the parent arene. However, sulfonic acids, when reduced with iodine and phosphoms [7723-14-0] produce thiols (qv). Amination of sulfonates has also been reported, in which the carbon—sulfur bond is cleaved (17). Ortho-Hthiation of sulfonic acid lithium salts has proven to be a useful technique for organic syntheses, but has Httie commercial importance. Optically active sulfonates have been used in asymmetric syntheses to selectively O-alkylate alcohols and phenols, typically on a laboratory scale. Aromatic sulfonates are cleaved, ie, desulfonated, by uv radiation to give the parent aromatic compound and a coupling product of the aromatic compound, as shown, where Ar represents an aryl group (18). 

Sulfonic acids may be hydrolytically cleaved, using high temperatures and pressures, to drive the reaction to completion. As would be expected, each sulfonic acid has its own unique hydrolytic desulfonation temperature. Lower alkane sulfonic acids possess excellent hydrolytic stability, as compared to aromatic sulfonic acids which ate readily hydrolyzed. Flydrolytic desulfonation finds use in the separation of isomers of xylene sulfonic acids and other substituted mono-, di-, and polysulfonic acids. 

As in the nitration of naphthalene, sulfonation gives the 1-substituted naphthalene. However, because the reverse reaction (desulfonation) is appreciably fast at higher temperatures, the thermodynamically controlled product, naphthalene-2-sulfonic acid, can also be obtained. Thus it is possible to obtain either of the two possible isomers of naphthalene sulfonic acid. Under kineticaHy controlled conditions naphthalene-l-sulfonic acid [85-47-2] (82) is obtained thermodynamic control gives naphthalene-2-sulfonic acid [120-18-3] (83). 

The sulfonation of an aromatic ring with SO3 and H2S04 is reversible. That is, heating benzenesulfonic acid with H2SO4 yields benzene. Show the mechanism of the desulfonation read ion. What is the electrophile ... 

Allylic sulfones and a, /5-unsaturated sulfones are known to be in equilibrium314-319. Allylic sulfones, such as 242, isomerize to a, /5-unsaturated sulfones 243 upon treatment with a catalytic amount of potassium t-butoxide in dry THF. The a, /5-unsaturated sulfones can be converted to the corresponding olefins upon desulfonation with sodium amalgam320 or aluminium amalgam294,321. Since treatment of allylic sulfones with potassium-graphite gives 2-alkenes, alkylation of allylic sulfones and subsequent desulfonation is a useful process for the synthesis of olefins, as shown in Scheme 6. 

Although anaerobic desulfonation of arene sulfonates, in which the sulfonate is used as a source of sulfur, has been described in a Clostridium sp., the product was not identified (Denger et al. 1996,... 

The thermal degradation of alkylbenzene sulfonates in alkaline media is important because of the application at elevated temperatures. The half-lives, with respect to thermal degradation, of several commercially available sulfonates were estimated at hundreds to thousands of years at 204° C. The degradation mechanism was predominately a clipping of the alkyl chain to yield an alkylbenzene sulfonate with the phenyl group attached to the a-carbon however, desulfonation also occurred [1624]. 

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