Benzenesulfonates, reduction

Thiophene-2-sulfonic acid is a strong acid, similar to benzenesulfonic acid. It forms a sulfonyl chloride with phosphoryl chloride which on reduction with zinc yields thiophene-2-sulfinic acid. 

Principally the same, but chemically simpler, sequence was used to prepare arylnitro anion-radicals from arylamines, in high yields. For instance, aqueous sodium nitrite solution was added to a mixture of ascorbic acid and sodium 3,5-dibromo-4-aminobenzenesulfonate in water. After addition of aqueous sodium hydroxide solution, the cation-radical of sodium 3,5-dibromo-4-nitro-benzenesulfonate was formed in the solution. The latter was completely characterized by its ESR spectrum. Double functions of the nitrite and ascorbic acid in the reaction should be underlined. Nitrite takes part in diazotization of the starting amine and trapping of the phenyl a-radical formed after one-electron reduction of the intermediary diazo compound. Ascorbic acid produces acidity to the reaction solution (needed for diazotization) and plays the role of a reductant when the medium becomes alkaline. The method described was proposed for ESR analytical determination of nitrite ions in water solutions (Lagercrantz 1998). 

In case (a), labelled secondary alkyl benzenesulfonates (alkyl = 2-adamantyl, 2-propyl, cyclopentyl, etc.) with 18-28% of lsO in the sulfonyl group were partially solvolysed in a range of solvents (SOH), and recovered unreacted alkyl benzenesulfonates were then subject to reductive cleavage of the O—S bond of the sulfonate ester [39]. For water as solvent, the... 

Orthanilic acid was first made by the reduction of nitro-benzenesulfonic acid by ammonium sulfide.2 This reduction has also been carried out electrolyticallv, and by the use of iron or zinc.3 The acid has also been made by the rearrangement of phenylsulfamic acid,4 by the action of sodium hypobromite upon potassium o-carbaminebenzenesulfonate,5 by the reduction of the mixed nitrobenzenesulfonic acids followed by separation of the isomers,6 by the action of methyl alcohol upon o-nitro-phenylsulfurchloride,7 by the action of acid upon diacetyl diphenylsulfamide,8 by the debromination of />-bromoaniline-e-sulfonic acid,9 by the reduction of 1,2,6-aminothiophenolsulfonic acid,10 and by the hydrolysis and reduction of e-nitrobenzene-sulfonyl chloride, which was obtained from di-o-nitrophenyl-disulfide.11... 

Remarks. Ferrous sulfate can be used advantageously instead of salt to precipitate the m-nitrobenzenesulfonic acid. The iron salt is very difficultly soluble in 20 per cent sulfuric acid and can be filtered off directly without further treatment. The reduction is carried out exactly as described above. If benzene is sulfonated with 100 per cent sulfuric acid, and then the benzenesulfonic acid is nitrated at 100°, there are formed, according to the work of Obermiller, besides the meta sulfonic acid, considerable quantities of the ortho and para isomers. The latter can be separated quite easily tluough the magnesium salts, and this affords a method for obtaining the valuable o-aminobenzenesulfonic acid. The preparation of orthanilic acid starting with o-m trochlorobenzene has also been described. ... 

Fuchs has used this reaction type for the construction of an 11-membered ring in the course of model studies for the [ll]cytochalasin synthesis. These cytostatic compounds, e.g. cytochalasin C (109), are metabolites of microorganisms. Reductive fragmentation of the benzenesulfonates (110 Scheme 37) produces the dienols (111). In contrast, both the sulfonates (112) on treatment with LDA afford the tricyclic ketones (113), the products of internal alkylation. Less than 1% of (111) is formed. In conclusion, the author points out that the enolate conformation (Scheme 37, in parentheses) appears to be all important in determining the reaction products of the four diastereoisomers (110) and (112). Whenever the enolate can easily assume a folded conformation, the tricyclic cyclobutane (113) will result. Models of the enolates of (110), where the intraannular fragmentation successfully occurs, show that the folded conformations are more strained than are the extended conformations. 

The role of the surfactant was further studied in sonochemical reduction [20, 21] processes of Pt (IV) ions in water. It was investigated in the presence of various kinds of surfactants such as sodium dodecylsulfate (SDS) and sodium dodecyl-benzenesulfonate (DBS) as anionic surfactants, polyethylene glycol monostearate (PEG-MS) as non-ionic, and dodecyltrrmethylammonium chloride (DTAG) and bromide (DTAB) as cationic surfactants. An improved colorimetric determination reveals that Pt (IV) ion is reduced to zero-valent metal in two steps step (1) Pt (IV) ion to Pt (II) ion, and step (2) Pt (II) ion to Pt (0), and after the completion of step (1), step (2) sets in. 

Reductive oxidation of />-nitrotoluene to -aminobenzaldehyde, 31, 6 Reformatsky reaction, 37, 38 Reissert s compound, 38, 58 Reissert reaction, 38, 58 Replacement, benzenesulfonate groups by bromine atoms, 31, 82 bromine, by a thiol group, 30, 35 by fluorine, 36, 40 chlorine, by an amino group, 31,45 by a thiol group, 32, 101 by iodine, 30, 11 by methoxyl, 32, 79 by nitrile, 36, 50 in an imido-chloride group by an anilino group, 31, 48 chlorine and nitro by ethoxyl radicals, 32,68... 

Benzenesulfonamide, Ar,AT-dibromo-4-methyl-(TsNBr2) bromohydrination with, 287 Benzenesulfonamides reductive cleavage, 247 synthesis of drugs, 301, 307-308 Benzenesulfonic acids. See Sulfonic acids Benzenesulfonic acid, 4-methyl-, esters (tosylates) alkyl a-synthons, 16, 24, 47, 93 fragmentation of, 89 rearrangement of, 32 reductive cleavage of, 114, 202-203 —, 4-methyl-, hydrazide (tosylhydrazine) hydrazones of fragmentation, 89 reduction, 109... 

The reactions of benzenesulfonic acid have been of interest in connection with questions of valence for some time. On hydrolysis with acid, benzene and sulfuric acid are formed, with alkali, phenol and sulfite. The question of oxidation and reduction in these reactions can be approached best by considering first the structure of the benzene sulfonic acid as developed from simple principles and analogies. 

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