Disulfones reduction

Disulfonate esters of vicinal diols sometimes undergo reductive elimination on treatment with sodium iodide in acetone at elevated temperature and pressure (usually l(X)-200°). This reaction derived from sugar chemistry has been used occasionally with steroids, principally in the elimination of 2,3-dihy-droxysapogenin mesylates. The stereochemistry of the substituents and ring junction is important, as illustrated in the formation of the A -olefins (133) and (134). 

The reduction of the surface tension between water and heptane brought about by homologous alkanesulfonates and by some disulfonates is demonstrated in Fig. 25 [39]. On comparing Figs. 24 and 25 it is obvious that the adsorption energy of a methylene group at the water-oil interface is greater than at the water-air interface. 

Humic acid and the corresponding fulvic acid are complex polymers whose structures are incompletely resolved. It is accepted that the structure of humic acid contains oxygenated structures, including quinones that can function as electron acceptors, while reduced humic acid may carry out reductions. These have been observed both in the presence of bacteria that provide the electron mediator and in the absence of bacteria in abiotic reactions, for example, reductive dehalogenation of hexachloroethane and tetrachloromethane by anthrahydroquininone-2,6-disulfonate (Curtis and Reinhard 1994). Reductions using sulfide as electron donor have been noted in Chapter 1. Some experimental aspects are worth noting ... 

Bacteria have been isolated using reduced anthraquinone-2,6-disulfonate (HjAQDS) as electron donor and nitrate as electron acceptor (Coates et al. 2002). The organisms belonged to the a-, p-, y-, and 5-subdivision of the Proteobacteria, and were able to couple the oxidation of H AQDS to the reduction of nitrate with acetate as the carbon source. In addition, a number of C2 and C3 substrates could be used including propionate, butyrate, fumarate, lactate, citrate, and pyruvate. 

Curtis GP, M Reinhard (1994) Reductive dehalogenation of hexachloroethane, carbon tetrachloride, and bromoform by anthrahydroquinone disulfonate and humic acids. Environ Sci Technol 28 2393-2401. 

Since long retention times are often applied in the anaerobic phase of the SBR, it can be concluded that reduction of many azo dyes is a relatively a slow process. Reactor studies indicate that, however, by using redox mediators, which are compounds that accelerate electron transfer from a primary electron donor (co-substrate) to a terminal electron acceptor (azo dye), azo dye reduction can be increased [39,40]. By this way, higher decolorization rates can be achieved in SBRs operated with a low hydraulic retention time [41,42]. Flavin enzyme cofactors, such as flavin adenide dinucleotide, flavin adenide mononucleotide, and riboflavin, as well as several quinone compounds, such as anthraquinone-2,6-disulfonate, anthraquinone-2,6-disulfonate, and lawsone, have been found as redox mediators [43—46]. 

Anaerobic bio-reduction of azo dye is a nonspecific and presumably extracellular process and comprises of three different mechanisms by researchers (Fig. 1), including the direct enzymatic reduction, indirect/mediated reduction, and chemical reduction. A direct enzymatic reaction or a mediated/indirect reaction is catalyzed by biologically regenerated enzyme cofactors or other electron carriers. Moreover, azo dye chemical reduction can result from purely chemical reactions with biogenic bulk reductants like sulfide. These azo dye reduction mechanisms have been shown to be greatly accelerated by the addition of many redox-mediating compounds, such as anthraquinone-sulfonate (AQS) and anthraquinone-disulfonate (AQDS) [13-15],... 

Dos Santos AB, Cervantes FJ, Van Lier JB (2004) Azo dye reduction by thermophilic anaerobic granular sludge, and the impact of the redoxmediator anthraquinone-2,6-disulfonate (AQDS) on the reductive biochemical transformation. Appl Microbiol Biotechnol 64 62-69... 

Shriadah and Ohzeki [350] determined iron in seawater by densitometry after enrichment as a bathophenanthroline disulfonate complex on a thin layer of anion exchange resin. Seawater samples (50 ml) containing iron (II) and iron (III) were diluted to 150 ml with water, followed by sequential addition of 20% hydrochloric acid (100 xl), 10% hydroxyl-ammonium chloride (2 ml), 5 M ammonium solution (to pH 3.0 for iron (III) reduction), bathophenanthroline disulfonate solution (1.0 ml), and 10% sodium acetate solution (2.0 ml) to give a mixture with a final pH of 4.5. A macroreticular anion exchange resin in the... 

The persistent and distinctive structural features of the GS network effectively reduce crystal engineering to the last remaining (third) dimension. These features prompted our laboratory to synthesize related materials in which the monosulfonate components were replaced with disulfonates. We surmised that this would lead to a two-fold reduction in the amount of space occupied by the organic residues between the GS sheets, creating frameworks... 

Hydrazine salts have been prepared by the action of hypochlorites on ammonia1 or urea 2 by the hydrolysis of salts of sulfohydrazimethylene disulfonic acid 3 by the hydrolysis of triazoacetic acid 4 by the reduction of diazoacetic ester 5 by the reduction of nitroguanidine followed by hydrolysis 6 by the reduction of the nitroso derivatives of hexamethylene tetramine 7 by the reduction of nitrates or nitrites with zinc in neutral solution 8 by the action of sodium bisulfite on hyponitrous acid... 

Other disulfones like (32) and (33) were studied (see Ref [6]). They exhibit surprisingly stable anion radicals (and even a stable dianion with (32)). Such charged species could be used as redox mediators, tiowever, reduction of alkyl halides RX by (33) did not permit the formation of alkylated products presumably because of the strong steric strain induced by alkylation of the corresponding carbon atoms in the cyclobutene ring. 

Titanium ions can also he used as redox catalysts for the indirect cathodic reduction of nitro compounds (417). The electroreduction is carried out in an H20-H2S04/Ti(S04)2-(Pb/Cu) system at 45 80°C under 5 20Am . Nitrobenzene, dinitrobenzene, nitrotoluene, 2,4-dinitrotoluene, 2-nitro-m-xylene, nitro-phenol, 2,4-dinitrophenol, nitrophenetole, o-nitroanisole, 4-nitrochlorotoluene, ni-trobenzenesulfonic acid, and 4,4 -dinitro-stilbene-2,2 -disulfonic acid can all be reduced by this procedure to the corresponding amino compounds (418) in good yields (Scheme 146) [513-516]. Tin... 

Tab. 12.8 Per cent reduction of three Fe oxides by Shewanella putrefaciens in the absence (-) and presence (-h) of anthraquinone-2,6-disulfonate (AQDS) (Zachara et al. 1998).

Diaminoamhraquinone is prepared from 1.5-dmitroanlhraquinone by ammonnlysis, by catalytic hydrogenation, or by reduction with sodium sulfide. It is also prepared From anthraquinone-],5-disulfonic acid by ammonolysis. 1.5-Diaminoanlhraquinone is an important intermediate lor manufacturing vat dyes. 

Sunset yellow was separated from its subsidiary dye l-p-sulfophenylazo-2-naphthol-3,6-disulfonic acid trisodium salt (195) and from its intermediates sulfanilic acid and Schaeffer s salt (194) by means of ion-pair HPLC. Ion-pair chromatography has also been used to determine free and bound nonsulfonated aromatic amines in sunset yellow after reduction with dithionite, diazotization with sodium nitrite, and coupling with R-salt (202). 

There is surprisingly little reliable information on the sulfonation of benzo[6]thiophene or its derivatives. Benzo[6]thiophene is more readily sulfonated than naphthalene.699 Reaction with concentrated sulfuric acid at 80° gives a mixture of mono-, di-, and trisulfonic acids, reaction with 70% sulfuric acid at 80° gives a monosulfonic acid,699 and reaction with 18% oleum gives a disulfonic acid 86 in each case the orientation of the products is unknown. Treatment of benzo[6]thiophene with concentrated sulfuric acid in acetic anhydride at 20° gives 3-acetylbenzo[6]thiophene (ca. 10%) and a sulfonation product (isolated as the potassium salt), which was believed to be the 3-sulfonic acid.660 Recently, the sulfonation product has been shown to contain the 2- (8%) and 3-isomer (92%), by conversion into the sulfonyl chlorides and reduction to a separable mixture of 2- and 3-mercaptobenzo[6]thiophene.84... 

The boundary between all oxidized forms and all reduced forms of a substance can be drawn from Equation (18) by expanding Q (Equation (17)) to include acid/base speciation. Figure 16.1 shows this for five substances that exhibit moderately complex, but well characterized, speciation as a function of pH (uncomplexed Fe(II)/Fe(III), iron porphyrin, juglone, lawsone, and anthraquinone disulfonate). The resulting Eh-pH diagram shows, for example, that the hydroquinone of lawsone is a reductant relative to anthraquinone disulfonate, below pH 7.5, but the relationship is inverted at higher pH. A similar crossing... 

Walther obtained the first direct dyes by self-condensation of 4-nitrotoluene-2-sulfonic acid. So-called Sun Yellow is a mixture of different components, depending on the concentration of sodium hydroxide, the temperature, and the duration of the reaction. Oxidation of the intermediate dye and subsequent reduction with iron and hydrochloric acid gives 4,4 diaminostilbene-2,2 -disulfonic acid, which is used for fluorescent whitening agents and azo dyes. The shades are mostly yellow to red. The structure of Direct Yellow 11, 40000 [65150-80-3] (13 is one of the main components) probably contains a mixture of stilbene, azo, and/or azoxy groups. 

The starting compound for all triazinylaminostilbenes is 4,4 -dinitrostilbene-2,2 -disulfonic acid [128-42-7], which is obtained by oxidizing 4-nitrotoluene-2-sulfonic acid with aqueous sodium hypochlorite in the presence of sodium hydroxide or, more recently, by atmospheric oxidation in an aqueous ammoniacal medium [39], The Bechamps reduction using iron filings etched with hydrochloric acid yields 4,4 -diaminostilbene-2,2 -disulfonic acid [81-11-8] (DAS). 

Electrolysis of benzalacetophenone in the presence of C02 gave a-phenylben-zoylpropionic acid 306 Reduction of stilbene in the presence of C02 yielded 92% meso-2,3-diphenylsuccinic acid 307 The reduction of anthracene at -2,3 V in the presence of S02 and 02 yields 9,10-dihydroanthracene-9,10-disulfonic acid 307a) An interesting intramolecular addition was found in the reduction of the thiocyanato steroid 77 to the mercaptoimine 78 308 ... 

In the previous subsection, it was shown that the Ferrier reaction offers an opportunity to convert glycal derivatives into unsaturated sugar derivatives, which have an isolated double bond between C(2) and C(3). The Tipson-Cohcn reaction is another important reaction for the introduction of isolated double bonds.29 In this procedure, a cis or tram diols are converted into disulfonates (mesylates or tosylates) which are reductively eliminated with sodium iodide and zinc in refluxing DMF (Scheme 3.6a). In this reaction, the C(3) sulfonate is substituted by an iodide, which then is reductively removed by zinc with concomitant elimination of the second sulfonate moiety, introducing a double bond. Stereoelectronic effects make nucleophilic substitutions at C(3) more favourable than similar reactions at C(2) (see Section 3.2.3). Probably, the elimination proceeds through a boat conformation. In this case, the iodide and tosylate are in a syn relation. In most cases, E2 elimination proceeds via a transition state involving an anti orientation. Nevertheless, syn elimination becomes the dominant mode of reaction when structural features prohibit an anti orientation. 

The steps in Eqs. (21.5) and (21.6) consist of the reduction of ammonium nitrite with SO2 at about 5°C to the disulfonate, which is then hydrolyzed at 100°C to hydroxylamine sulfate. One mole of (NH SC is formed for each mole of hydroxylamine sulfate46. 

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