Aromatic Sulphonation Research Articles

Photochemical dissociation of p-nitrobenzyl 9,10-dimethoxyanthracene-2-sulphonate via intramolecular electron transfer

While o-nitrobenzyl aromatic sulphonates are known to photodissociate via an intramolecular rearrangement, photodissociation of p-nitrobenzyl aromatic sulphonates has not been reported. In this study, we report that p-nitrobenzyl 9,10-dimethoxyanthracene-2-sulphonate is photochemically dissociated to give 9,10-dimethoxyanthracene-2-sulphonic acid, 9,10-dimethoxy-2-(p-nitrobenzyl)-anthracene, and p,p′-dinitrobibenzyl. The dissociation is considered to proceed via an intramolecular electron transfer from the 9,10-dimethoxyanthracene moiety to the p-nitrobenzyl moiety. The quantum yield of the photodissociation in acetonitrile is 0.11 and the spectral response extends to 450 nm. The quantum yield is much higher than those of o-nitrobenzyl esters.

The cathodic cleavage of aromatic sulphones. When the fragmentation process is followed by an aromatic substitution by means of electrogenerated sulphinate as nucleophile

Anion radicals from aromatic sulphones also substituted by cleavable electrodonating groups may possess an astonishing stability. However, t-butyl aryl sulphones of those series behave quite differently. A very fast and unexpected scission of the aromatic carbon—sulphur bond occurs and is followed by an attack of the sulphonate ion towards the substrate— via an aromatic substitution—with the formation of a symmetrical disulphone.

The reversal of the diamagnetic anisotropy in amphiphilic nematic liquid crystals using the aromatic counterions phenyl sulphonate and benzoate

Abstract Proton N.M.R. is used to investigate the inclusion of the phenylsulphonate and the benzoate ion as counterions in samples of amphiphilic nematic liquid crystals. When these aromatic counterions are substituted in sufficient amounts the sign of the diamagnetic anisotropy is reversed. The orientation parameters are also shown to be dependent upon the micelle shape, as well as the sign of the diamagnetic anisotropy.

Conductivity of polypyrrole films doped with aromatic sulphonate derivatives

The conductivity of polypyrrole films doped with various kinds of aromatic sulphonate derivatives has been studied. The conductivity of polypyrrole films could be varied by more than an order of magnitude by the current density chosen in the film preparation, and the highest conductivity was achieved at moderate current densities such as 0.2 mA cm–2. The film conductivity was also influenced greatly by the number of sulphonate groups of a dopant molecule in such a manner that an increase in the number caused the conductivity to decrease. This effect was especially noticeable for polypyrrole films prepared at relatively low current densities such as 0.005 mA cm–2.

The surface photo-degradation of bisphenol A polysulphone

ESCA has been used to monitor the changes in surface composition of polysulphone films irradiated in nitrogen and in low vacuum ( λ > 290 nm). A photo-reduction of the sulphone group to a sulphide was observed. The extent of sulphide formation is dependent on both irradiation time and the partial pressure of oxygen. Comparison with results obtained from the irradiation of polyethylene and polycarbonate in sulphur dioxide atmospheres indicated that the photo-reduction is associated only with aromatic sulphones.

Nucleophilic aromatic substitution: effect of complexation on the alkaline hydrolysis of 4-aminophenylazobenzothiazolium dyes

Nucleophilic attack by hydroxide ion on 2-(4-dimethylaminophenophenylazo)-3,6-dimethylbenzothiazolium iodide to expel the dimethylamino function is inhibited in aqueous solution by aromatic carboxylate, aromatic sulphonate, and phenolate ions. The inhibition is demonstrated to involve complexation of dye with solute to to form an unreactive species. The dissociation constant of the complex is relatively insensitive to structure except in the case of phenolate ions where electron-withdrawing substituents favour stability. Both charge transfer and electrostatic effects are necessary for efficient complexing ability of the additive. Complexation of cyclodextrin with the dye is followed by reaction to yield a dye–cyclodextrin covalent species; the intermediate slowly decomposes to give quinone imine, the regular product of dye hydrolysis.

Orthanilic Acid and Analogues as Carbon Sources for Bacteria: Growth Physiology and Enzymic Desulphonation

Summary: Carbon-limited aerobic batch enrichment cultures were grown and 17 bacteria able to degrade orthanilic acid (2-aminobenzenesulphonic acid), sulphanilic acid, sulphonamide, 4-sulphobenzoic acid, and benzene-, toluene- and phenolsulphonic acids were isolated. The organisms could each use one to three of the substances. Strain O-1, a Pseudomonas sp., which utilized three of these compounds, was studied in detail. A complete mass balance was obtained for the growth of the organism in medium containing, for example, orthanilic acid, and a specific growth rate of 0·1 h-1 was observed. Cell extracts desulphonated six aromatic sulphonates. The enzyme(s) was soluble and was not synthesized in succinate-grown cells. Enzyme activity [about 40 μkat (kg protein)-1] was dependent on the presence of catalytic amounts of NAD(P)H.

Reversed Phase Ion-Pair Chromatographic Separation of Acetyl Choline and Choline

Abstract A reversed phase High-Performance Liquid Chromatographic procedure for the separation of choline and acetyl choline is described. The method employs a mobile phase containing aromatic sulphonates as counter ions for ion-pair chromatography and for U.V. Visualisation of choline and acetyl choline at 254 nm. The method enables the separation of the two compounds in the 1-10 ug concentration range in six minutes. The separations are better achieved on a PRP-I resin column.

Aromatic sulphonation. Part 94. Sulphonation and sulphation of the three 2- and 4-hydroxy- and 2- and 4-methoxy-benzenesulphonic acids in concentrated sulphuric acid

The sulphonation of 2-methoxy-(1) and 4-methoxy-benzene sulphonate (2) and 1-(3), 3-(4), and 4-hydroxybenzenesulphonate (5) in 86.9–98.5% H2SO4 at 25 °C has been studied. Substrates (1)–(3) and (5) all yield the corresponding 2,4-disulphonic acid as the exclusive product, whereas (4) yields a mixture of 2-hydroxybenzene-1,4- and 4-hydroxybenzene-1,2-disulphonic acid. 3- and 4-Hydroxybenzenesulphonic acids in sulphuric acid (>87% H2SO4) are present in part as their hydrogen sulphates and the sulphuric acid concentration of 50% sulphation is 97.5 and 100.5 ± 0.2% H2SO4. The sulphonation is first order in the aromatic substrate. From the rate dependence on the sulphuric acid concentration it is concluded that the substrate species undergoing ring sulphonation is the –O3SC6H4OR (R = H; Me) species with H2S2O7 as the sulphonating entity. From the observed proportionality between [–O3SC6H4OSO3H]/[–O3SC6H4OH] and aSO3 it is concluded that the aromatic species undergoing sulphation is again –O3SC6H4OH.

Aromatic sulphonation. Part 92. Sulphonation of the three methylphenols and the six dimethylphenols in concentrated aqueous sulphuric acid; and the lsomerization of some of the resulting sulphonic acids and of m-xylene-2-and o-xylene-3-sulphonic acid

The isomer distributions for the mono- and di-sulphonation of the three methylphenols in 81.6–90.0% sulphuric acid and of the six dimethylphenols in 84.9% sulphuric acid at 35 °C have been determined by means of 1H n.m.r. spectroscopy. Products that would result from demethylation, disproportionation, or ipso-substitution have not been observed. The monosulphonation isomer distribution of each of the three methylphenols is independent of the sulphuric acid concentration. 2,4-Dimethylphenol in 84.9% H2SO4yields 19% 5- and 79% 6-sulphonic acid, and 2,6-dimethylphenol yields 28% 3- and 72% 4-sulphonic acid. With the phenols (2), (3), (5), and (7), which have positions both ortho and para to the –OH substituent available for sulphodeprotonation, the yield of ortho-substitution is relatively high, viz. 44, 45,36, and 27%, respectively. The mono- and di-sulphonic acids of which the sulpho group is between the –OH and an –Me group are unstable under the reaction conditions employed, with the exception of the 3,5-dimethylphenol-2-sulphonic acid. It is proposed that their isomerization proceeds by protiodesulphonation followed by resulphonation to yield the more stable sulphonic acid isomer(s). From a kinetic analysis of the calculated first-order rate coefficients for protiodesulphonation, it is concluded that the unprotonated substrate species is the entity undergoing the protiodesulphonation.

Aromatic sulphonation. Part 91. The sulphonation of anisole, phenol, phenyl methanesulphonate, potassium phenyl sulphate, and a series of methyl-, bromo-, and chloro-substituted anisoles and phenols in concentrated aqueous sulphuric acid

The (homogeneous) sulphonation of a number of aromatic ethers and alcohols, viz. anisole (1), 3- methyl-(2), 4-methyl-(3). 2-bromo-(4), 4-bromo-(5), 2-chloro-(6), and 4-chloro-anisole (7), phenol (8), 2-methyl-(9), 3-methyl-(10), 4-methyl-(11), 4-bromo-(12), 2-chloro-(13), and 4- chloro-phenol (14), phenyl methanesulphonate (15), and potassium phenyl sulphate (16) in concentrated aqueous sulphuric acid at 25.0 °C has been studied, and rates and isomer distributions have been determined. The sulphonation is first-order in the aromatic substrate, and from the rate measurements it is concluded that the species undergoing sulphonation in the phenyl ring is an unprotonated substrate species. In the lower acid concentrations the sulphonating entity is H3SO4+. With increasing sulphuric acid concentration there is a gradual change-over in the sulphonating entity from H3SO4+ to H2S2O7. The acid concentrations of equal rate contribution by the two entities for anisole and phenol are 87 and 90 ± 1%, respectively. Sulphonation on the oxygen atom (i.e., sulphation) does not occur. The o/p-ratios for (1) and (8) do not vary over the studied sulphuric acid range of 75–90% H2SO4. Partial rate factors for the 2- and 4-position of (1) and (8) are reported. The very low partial rate factors for the 4-substitution of (1) and (8) and the observed extreme suppression and compression of the reactivities of the substrates (1)–(14) are ascribed to hydrogen bonding of the substrates with the acidic solvent species present. It is tentatively suggested that the relatively high contents of sulphonation ortho to –OR with anisole (36%) and phenol (48%) are due to specific complexation of the substrates with the sulphonating electrophile.

Aromatic sulphonates and the hydrolysis of 2-(p-nitrophenoxy)tetrahydropyran

The rate of hydrolyis of 2-(p-nitrophenoxy)tetrahydropyran was measured in a variety of buffers in water at 30 °C. At low ionic strength (μ = 0.05), 3,6-disulphonaphthoxyacetic acid catalysed the reaction. The second-order rate constant was 20 times faster than predicted from pKa. At high ionic strength (μ = 0.5), plots of kobs vs. total buffer concentration for both 3,6-disulphonaphthoxyacetic acid and 6,8-disulphonaphthyoxyacetic acid go through a maximum. Polyacrylic acid catalysed the reaction. The results are discussed in terms of aggregation and salt effects.

Trennung stellungsisomerer aromatischer sulfonate durch hochspannungselektrophorese in dimethylformamid

Electrophoretic separations of position-isomeric aromatic sulphonates which are not possible in aqueous buffers can be achieved using dimethylformamide as buffer solvent. Examples are the separations of naphthol sulphonates, of food colours Orange 1 and Orange 2, and of azo dyes derived from the naphthol sulphonates. An additional improvement of the separations is possible by using a temperature gradient along the migration path.

Some aspects of homogeneous and two‐phase aromatic sulphonation

AbstractThe two‐phase sulphonation of benzene and toluene with concentrated sulphuric acid solutions at 30°C has been studied in a continuous stirred tank reactor (1.06 dm3 capacity). The rates of reaction, as a function of sulphuric acid concentration and the overall mass transfer coefficient times, and the interfacial area per unit volume of the acid phase as a function of agitation speed, have been determined. In homogeneous systems, the kinetic rate constants and the relative rates of sulphonation of a series of aromatic hydrocarbons have been measured in the range of 13–16 mol dm−3 sulphuric acid. It has been shown that the rates of sulphonation of compounds, with levels of reactivity beyond that of m‐xylene, are likely to be affected by diffusional phenomena.

Some aspects of homogeneous and two-phase aromatic sulphonation

Some aspects of homogeneous and two-phase aromatic sulphonation

ChemInform Abstract: Aromatic Sulphonation. Part 72. Behaviour of Some 9‐Alkylanthracenes Containing 2 α‐Hydrogens and 0‐3 β‐Hydrogens in the Side‐chain with Dioxan‐Sulphur Trioxide in Dioxan as Sulphonating Medium; Mechanism for Alkyl Side‐chain Reduction and Subsequent Sulphonation.

AbstractReaktionen der Alkylanthracene (I) mit äquimolaren Sog‐Mengen in Dioxan liefern Gemische der α‐Sulfonsäuren (II) mit den (α,β‐ungesättigten v‐Sulfonsäuren (III) (1H‐NMR‐Spektren; Mechanismus).

Aromatic sulphonation. Part 72. Behaviour of some 9-alkylanthracenes containing 2 α-hydrogens and 0–3 β-hydrogens in the side-chain with dioxan–sulphur trioxide in dioxan as sulphonating medium; mechanism for alkyl side-chain reduction and subsequent sulphonation

The reactions at 17 °C of seven 9-alkylanthracenes, with two alkyl α-hydrogens, with dioxan–SO3 in dioxan has been studied. With the exception of 9-ethyl- and 9-neopentyl-anthracene these substrates yield products having a side-chain structure with (i) the sulphonate group at C-α(α-sulphonic acids) and/or (ii) a double bond at C-α with the sulphonate group at C-γ(α-alkene-γ-sulphonic acids). 9-Ethylanthracene yields, besides the α-sulphonic acid, an α-alkene-β-sulphonic acid, whereas 9-neopentylanthracene leads to sulphonation of the anthryl group at the 10- and 4-positions. It is proposed that the α-sulphonic acids are formed as suggested for the formation of 9-anthrylmethanesulphonic acid from 9-methylanthracene, and that the α-alkene-γ-sulphonic acids are produced by sulphonation of 9-(alk-1-enyl)anthracenes, which intermediates result from a redox reaction between the 9-alkylanthracenes and SO3.

Aromatic sulphonation. Part 78. Behaviour of some α-chloro-substituted 9-methyl-, 9-ethyl-, 9-isopropyl-anthracenes, and of 1,4,9-trimethylanthracene in dioxan–sulphur trioxide complex in dioxan as sulphonating medium

The reaction of some α-chloro-substituted 9-methyl-, 9-ethyl-, 9-isopropyl-anthracenes and of 1,4,9-trimethyl-anthracene (3a–j), with dioxan–SO3 in dioxan has been studied at 25 °C. All the methylanthracene derivatives (3a–d) yield α-sulphonic acids (4a–d). 1,5-Dichloro-9-methyl- and 1,4,9-trimethyl-anthracene yield, in addition, the dimer (5c) and the sultones (6l and m) respectively.1-Chloro- and 1,5-dichloro-9-ethylanthracene yield the dimers (5e) and (5f) respectively. 4-Chloro-9-ethylanthracene yields the two sulphonic acids (4g) and (7g). 4,5-Dichloro-9-ethylanthracene does not react. 1-Chloro- and 1,5-dichloro-9-isopropylanthracene yield besides the dimeric products (5) and the sulphonic acids (9), products corresponding with those obtained in the sulphonation of 9-isopropylanthracene [viz. sultones (8), 9-allylanthracene derivatives (10), and the sulphonic acids (11) and (12)]. A mechanism for the formation of the products is presented. It is proposed that the dimeric products (5) and the sultone (6d) result from initial attack of SO3 at C-9 and C-1 respectively, whereas all other products result from attack of SO3 at C-10. The behaviour of the substrates (3a–j) in the sulphonation is compared with that in their protonation.

Aromatic sulphonation. Part 79. Sulphonation of some (poly)methylanthracenes with dioxan–sulphur trioxide complex in dioxan

The reactions of 2-MeA (2-methylanthracene), 2,3-Me2A, 2,3,6,7-Me4A, 1-MeA, 1,2-Me2A, 1,3-Me2A, and 1,4-Me2A with 1.5 equiv. dioxan–SO3 complex in dioxan at 40 °C lead in general to the formation of monosulphonic acids. The first three substrates yield the meso-sulphonic acids and 1-MeA and 1,2-Me2A products with the sulphonic acid group at the 4- and 10-position. The reaction of 1,3-Me2A at 17 °C leads to an equilibrium mixture of unconverted substrate and the 1,3-dimethylanthracenium-4-, -9-, and -10-sulphonate σ-complexes. On warming this reaction mixture to 40 °C, 1,3-dimethylanthracene-4- and -10-sulphonic acid and the sultone (1) are formed. 1,4-Me2A at 17 °C yields a mixture of unconverted substrate, and 1,4-dimethylanthracenium-9- and possibly -1-sulphonate σ-complexes. Warming this mixture to 40 °C leads to the formation of 1,4-dimethylanthracene-2-, -5-, and -6-sulphonic acid. The positional order for sulphonation is in agreement with that predicted by the localization energies, provided that allowance is made for steric factors.

Aromatic sulphonation. Part 75. Intramolecular kinetic isotope effects of hydrogen in the aprotic sulphonation of 1,2,4,5-tetramethylbenzene, naphthalene, and 1,6-methano[10]annulene. Implications for the mechanism of the sulphur trioxide sulphonation

The intramolecular substrate kinetic isotope effects of hydrogen for the sulphonation of 1,2,4,5-tetramethyl[3-2H]benzene and [1,4-2H2]naphthalene with sulphur trioxide in nitromethane as solvent at 0 °C have been determined as kH/kD= 5.6 ± 0.6 and 1.8 ± 0.1, respectively. With trichlorofluoromethane as solvent at –25 °C the intramolecular isotope effects for these two substrates are 3.1 ± 0.3 and 2.0 ± 0.1 respectively. For the sulphonation of 1,6-methano[2,7-2H2][10]annulene in dioxan at 12 °C kH/kD= 3.8 ± 0.3. The observed primary kinetic isotope effects are discussed in terms of the previously established σ,σ-mechanism for aromatic sulphonation with sulphur trioxide in aprotic solvents. They are ascribed to steric hindrance accompanying the intramolecular proton shift of the 1-arenium-1-pyrosulphonate σ-complex, yielding the arenepyrosulphonic acid. For trichlorofluoromethane as solvent the occurrence of an ‘encounter complex’ is discussed.