Sulfonic group, detection

It is illuminating to note that only very minor (and probably insignificant) differences can be detected as far as the r(SO) and sulfone groups in the thiirene series (i.e. I8a and 19a), compared with that of the acyclic analogues [i.e. (CH3)2SO and (CH3)2S02, respectively]. 

Ionomer membranes are used in fuel cells in order to separate the anode and cathode compartment and to allow the transport of protons from the anode to the cathode. The typical membrane is Nation , which consists of a perfluorinated backbone and side chains terminated by sulfonic groups. In the oxidizing environment of fuel cells, Nation , as well as other membranes, is attacked by reactive oxygen radicals, which reduce the membrane stability. Direct ESR was used recently in our laboratory to detect and identify oxygen radicals as well as radical intermediates formed in perfluorinated membranes upon exposure to oxygen radicals [73,74]. The three methods used to produce oxygen radicals in the laboratory and the corresponding main reactions are shown below. 

Bisulfite modification of cytosine residues also can be used to add permanently a sulfone group to the C-6 position. In this scheme, the sulfone functions as a hapten recognizable by specific anti-sulfone antibodies. At high concentrations of bisulfite and in the presence of methyl-hydroxylamine, cytosines are transformed into N4-methoxy-5,6-dihydrocytosine-6-sulphonate derivatives (Herzberg, 1984 Nur et al., 1989). Labeled antibodies can then be used to detect the hybridization of such probes. 

Reduction of dibenzothiophene with sodium in liquid ammonia has been shown to be sensitive to the experimental methods employed however, the major product is usually 1,4-dihydrodibenzothiophene. 27 -28i The electrochemical reduction of dibenzothiophene in ethylene-diamine-lithium chloride solution has been shown to proceed via stepwise reduction of the aromatic nucleus followed by sulfur elimination. In contrast to the reduction of dibenzothiophene with sodium in liquid ammonia, lithium in ethylenediamine, or calcium hexamine in ether, electrolytic reduction produced no detectable thiophenol intermediates. Reduction of dibenzothiophene with calcium hexamine furnished o-cyclohexylthiophenol as the major product (77%). Polaro-graphic reduction of dibenzothiophene 5,5-dioxide has shown a four-electron transfer to occur corresponding to reduction of the sulfone group and a further site. ... 

Double-chain surfactants with two sulfonate groups were proposed for micellar elec-trokinetic chromatography (MEC) analysis of phenolic pollutants in water °. CE with ESI-MS detection was applied to the analysis of phenolic compounds in olive mill wastewaters. Quantitative analysis was performed in the negative SIM mode, using p-chlorophenol as internal standard. LOD ranged from 1 pg for 4-hydroxybenzaldehyde and protocatechuic acid (27) to 386 pg for vanillic acid (38) °". A modified montmorillonite served for SPE preconcentration of phenols, followed by EtOH desorption and CE end analysis . 

For Na and Li counterions the shift of the -S03 stretching frequency begins when the water content falls below about 5 H20 per sulfonate group. For K counterions, the water content must fall below 2 H20 per sulfonate before a barely detectable frequency shift occurs (1.5 cm 1), while for Rb and Cs no shift is observed even for completely dried material. 

The catalyst was a sulfonated derivative of Wilkinson s catalyst which did not appear to affect the structure of bilayers with respect to their permeability barrier properties [2]. The catalyst was found to hydrogenate oil-in-water emulsions and two-phase oil-water systems without the need for organic co-solvents [3]. The reaction rate could be increased significantly by screening the electrostatic charge on the sulfonate groups with inorganic cations added to the aqueous phase. This allowed the catalyst to penetrate into the substrate at the interface partition of the catalyst from the aqueous into the lipid phase could not be detected. 

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