Arenesulfonates

For coupling, the cheaper aryl fluorosulfonate 713 is used as an alternative to the expensive aryl triflates to give the same results[473]. The arenesulfonates 714 are active for the reaction with vinylstannanes when dppp and LiCI are used in DMSO[583], The bromide 715 attacks the arylstannane moiety selectively without reacting with the organoboron moiety in 716 in the absence of a base[584]. 

Reaction conditions depend on the reactants and usually involve acid or base catalysis. Examples of X include sulfate, acid sulfate, alkane- or arenesulfonate, chloride, bromide, hydroxyl, alkoxide, perchlorate, etc. RX can also be an alkyl orthoformate or alkyl carboxylate. The reaction of cycHc alkylating agents, eg, epoxides and a2iridines, with sodium or potassium salts of alkyl hydroperoxides also promotes formation of dialkyl peroxides (44,66). Olefinic alkylating agents include acycHc and cycHc olefinic hydrocarbons, vinyl and isopropenyl ethers, enamines, A[-vinylamides, vinyl sulfonates, divinyl sulfone, and a, P-unsaturated compounds, eg, methyl acrylate, mesityl oxide, acrylamide, and acrylonitrile (44,66). 

Di(arenesulfonyl) peroxides (24, = ryl) react with aromatic solvents to form aryl arenesulfonates (33) ... 

The cleavage products of several sulfonates are utilized on an industrial scale (Fig. 3). The fusion of aromatic sulfonates with sodium hydroxide [1310-73-2J and other caustic alkalies produces phenohc salts (see Alkylphenols Phenol). Chlorinated aromatics are produced by treatment of an aromatic sulfonate with hydrochloric acid and sodium chlorate [7775-09-9J. Nitriles (qv) (see Supplement) can be produced by reaction of a sulfonate with a cyanide salt. Arenesulfonates can be converted to amines with the use of ammonia. This transformation is also rather facile using mono- and dialkylamines. 

Where X is Br or Q, the free acids may be obtained by acidification of the alkaline solution, but where X is I, the acids must be isolated as salts to avoid reduction of the arsonic acids by HI. Rather than using alkyl haUdes, alkyl or dialkyl sulfates or alkyl arenesulfonates can be used. Primary alkyl haUdes react rapidly and smoothly, secondary haUdes react only slowly, whereas tertiary haUdes do not give arsonic acids. AHyl haUdes undergo the Meyer reaction, but vinyl hahdes do not. Substituted alkyl haUdes can be used eg, ethylene chlorohydrin gives 2-hydroxyethylarsonic acid [65423-87-2], C2H2ASO4. Arsinic acids, R2AsO(OH), are also readily prepared by substituting an alkaU metal arsonite, RAs(OM)2, for sodium arsenite ... 

The iso)tazole ring is rather resistant to sulfonation. However, on prolonged heating with chlorosulfonic acid, 5-methyl-, 3-methyl- and 3,5-diraethyl-isoxazoles are converted into a mixture of the sulfonic acid and the corresponding sulfonyl chloride. The sulfonic acid group enters the 4-position even when other positions are available for substitution. The sulfonation of the parent isoxazole occurs only under more drastic conditions (20% oleum) than that of alkyl isoxazoles isoxazole-4-sulfonic acid is obtained in 17% yield. In the case of 5-phenylisoxazole (64), only the phenyl nucleus is sulfonated to yield a mixture of m-and p-arenesulfonic acid chlorides (65) and (66) in a 2 1 ratio (63AHC(2)365). 

The solvolysis of 4-arylbutyl arenesulfonates in nonnucleophilic media leads to the formation of tetralins ... 

Tetrabutylammonium iodide in trifluoroacetic anhydride is an effective reducing reagent [dS] This system can be used for direct reduction of arenesulfonic acids to the corresponding thiols or disulfides m moderate yields under mild conditions (equation 18) Alkanesulfonic acids are reduced by this system to disulfides with 30-57% yields [dfi]... 

Of these the most important are the sulfonic acids. In general, however, sulfonic acids are not prepared by oxidation of thiols. Arenesulfonic acids (ArS03H), for example, are prepared by sulfonation of arenes (Section 12.4). 

Salts of diazonium ions with certain arenesulfonate ions also have a relatively high stability in the solid state. They are also used for inhibiting the decomposition of diazonium ions in solution. The most recent experimental data (Roller and Zollinger, 1970 Kampar et al., 1977) point to the formation of molecular complexes of the diazonium ions with the arenesulfonates rather than to diazosulfonates (ArN2 —0S02Ar ) as previously thought. For a diazonium ion in acetic acid/water (4 1) solutions of naphthalene derivatives, the complex equilibrium constants are found to increase in the order naphthalene < 1-methylnaphthalene < naphthalene-1-sulfonic acid < 1-naphthylmethanesulfonic acid. The sequence reflects the combined effects of the electron donor properties of these compounds and the Coulomb attraction between the diazonium cation and the sulfonate anions (where present). Arenediazonium salt solutions are also stabilized by crown ethers (see Sec. 11.2). 

See also investigations by Bagal s group on diazonio-arenesulfonate zwitterions and their acid-base equilibria (Bagal et al., 1983 Malevanyi et al., 1992). 

An important role must be attributed to intermediate mixed anhydrides of sulfonic acids and mineral acids sulfonic acid anhydrides are reported to need Friedel-Crafts conditions to generate sulfones327,476. Instead of arenesulfonic acids, their methyl esters may undergo insertion of sulfur trioxide477,478 yielding mixed anhydrides, which in turn furnish... 

Hydrolyses of alkyl halides and arenesulfonates have long been known to be micelle-inhibited (Gani et al., 1973 Lapinte and Viout, 1973, 1979) but now k+/k < 1, except for hydrolysis of methyl benzenesulfonate which involves extensive bond making in the transition state (Al-Lohedan et al., 1982b Bunton and Ljunggren, 1984). Thus values of k+/k < 1 seem to be characteristic of hydrolyses in the SN1-SN2 mechanistic spectrum which involve considerable bond breaking in the transition state, and k+/k is very low for hydrolyses of diphenylmethyl halides where the transition state has considerable carbocation character (Table 8). 

It is reasonable to relate the values of k+fk at least qualitatively to the extents of bond making and breaking in the transition state. Bond making is all important in hydrolyses of carboxylic anhydrides, diaryl carbonates and methyl arenesulfonates. Bond breaking will be important in hydrolyses of alkyl halides and sulfonates, except for methyl derivatives, and especially so in water which can effectively solvate the leaving anion. 

The similarity for many reactions of second-order rate constants in aqueous and micellar pseudophases, and the observation that substrate hydrophobicity usually affects binding and not inherent reactivity in the micelle, suggests that substrate location or orientation is relatively unimportant. This conclusion is strongly supported by a quantitative analysis of the effects of CTABr micelles on the reaction of OH- and arylsulfonylalkyl arenesulfonates (16) (van der Langkruis and Engberts, 1984). 

V. A. Russell, M. D. Ward, Two-dimensional hydrogen-bonded assemblies the influence of sterics and competitive hydrogen bonding on the structures of guanidinium arenesulfonate networks , J. Mater. Chem 1997, 71123-1133. 

Sulfinic acids can be oxidized by a variety of reagents most frequently the product is the corresponding sulfonic acid (Stirling, 1971). Most of these oxidations have not been studied from a mechanistic point of view. Two that have, however, are those involving hydrogen peroxide and hypochlorite. Hydrogen peroxide oxidizes arenesulfinates to arenesulfonates (97) and study... 

Arenesulfinates are also oxidized to arenesulfonates by hypochlorite. In this case both HOC1 and OC1- can serve as the reactive oxidizing agent, but OC1-is about 300 times more reactive than HOC1 (Kice and Puls, 1977). The slower oxidation by HOC1 involves mechanism (99), akin to that for the oxidation... 

Fusion of arenesulfonates with sodium hydroxide leads to phenols. Although the exact mechanism for this well known reaction is not certain, a benzyne intermediate has been ruled out by showing that cine substitution does not occur (Buzbee, 1960 Oae et al., 1966). 

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