Disulphonate

Forms water-soluble alkali and alkaline earth metal salts. Heating with KCN gives benzonitrile and phenol is formed by fusion with NaOH or KOH. Further sulphonation at 250°C gives benzene-1,3-disulphonic acid. 

Naphthalene disulphonic acids are prepared by more prolonged sulphonation than in the preparation of the monosulphonic acids. Four isomeric acids are obtained. 

Naphthalene (risulphonic acids can be obtained by more drastic sulphonation of naphthalene or its mono- and disulphonic acids. Only the 1,3,5-, 1,3,6- and 1,3,7-acids are obtained. The most important of the iri-sulphonic acids is the 1,3,6-acid which is used for the preparation of H-acid, a dyestufT intermediate. 

Supplement 1955 3634-3793 Sulphonic acids Indigo-disulphonic acid (indigocarmine), 304. Amines, 308. Keto-ammes Pyramidone, 452. Allan-toin, 474. Murexide, 499. Amino-carboxylic acids Histidine, 513. j Hydrazines, 531. Azo compounds, 535. 1... 

Nitration in the presence of strong acids or Lewis acids Solutions of dinitrogen pentoxide in sulphuric acid nitrate 1,3-dimethyl-benzene-4,6-disulphonic acid twice as fast as a solution of the same molar concentration of nitric acid. This is consistent with Raman spectroscopic and cryoscopic data, which establish the following ionisation ... 

Calcichrome. This indicator, cyclotris-7-( l-azo-8-hydroxynaphthalene-3,6-disulphonic acid), is very selective for calcium. It is in fact not very suitable as an indicator for EDTA titrations because the colour change is not particularly sharp, but if EDTA is replaced by CDTA (see Section 2.26), then the indicator gives good results for calcium in the presence of large amounts of barium and small amounts of strontium.13... 

Discussion. An excellent method for the colorimetric determination of minute amounts of cobalt is based upon the soluble red complex salt formed when cobalt ions react with an aqueous solution of nitroso-R-salt (sodium 1-nitroso-2-hydroxynaphthalene-3,6-disulphonate). Three moles of the reagent combine with 1 mole of cobalt. 

Conant and Peterson123 made the first kinetic study of the coupling of diazonium ions with aromatics, and measured the rates of reaction of diazotised aniline and its 2-MeO, 4-Me, 4-Br and 4-S03H derivatives with the sodium salts of 4-hydroxybenzenesulphonic acid, 2-naphthol-3,6-disulphonic acid, 1-naphthol-3,8-disulphonic acid, and l-naphthol-4-sulphonic acid. The reaction was second-order, viz. 

For coupling with 2-naphthol-6,8-disulphonic-l-isotope effects (kK/kD) varied with the substituent in the benzenediazonium ion as follows 4-C1 (6.55) 3-C1 (5.48) 4-N02 (4.78), i.e. the reactivity of the ion was increased so that i correspondingly decreased. Base catalysis was observed127, 129, and there was a free energy relationship between this catalytic effect and the basicity of pyridine, 3- and 4-picoline. However, for 2-picoline and 2,6-lutidine, the catalysis was 3 times and 10 times less than expected from their basicities showing that, in this particular proton transfer, steric hindrance is important. 

Christen and Zollinger303 have made an extensive study of kinetic isotope effects in bromination of the disodium salt of 2-naphthol-6,8-disulphonic acid with hypobromous acid and with bromine in aqueous buffers at 20 °C. Both bro-minating agents give the same rate (within 20 %) and the reactions are first-order... 

If 30% hydrogen peroxide is used as the oxidant then stepwise oxidation occurs leading to the a-disulphone (equation 80)195. In this study the trioxide, RS02S0R, was not found but was assumed to be produced. 

The oxidation of disulphones with iodine in aqueous perchloric acid apparently produces the corresponding sulphonic acid (equation 95)212. 

FIGURE 3. Voltammetric curves at a stationary mercury microelectrode for anthracene in the presence of 17b (a) anthracene alone, 6.5 x 10 3m (b, c, d) previous solution with 2.3, 5.1 and 7.6 x 10"3m of 17b (e) disulphone 17b without anthracene. Medium, DMF-Bu4NC104 0.14m sweep rate, 10mVs 1 (after Reference 25). 

Thus, 9,10-diphenylanthracene ( p = — 1.83 V vs. SCE) is reduced at too positive a potential and hence its rate of reaction with the sulphonyl moieties is too low. On the other hand, pyrene (Ep = — 2.04 V) has a too negative reduction potential and exchanges electrons rapidly both with allylic and unactivated benzenesulphonyl moieties. Finally, anthracene Ev = —1.92 V) appears to be a suitable choice, as illustrated in Figure 3 (curves a-d). Using increasing concentrations of the disulphone 17b, the second reduction peak of XRY behaves normally and gives no indication of a fast electron transfer from A. 

Sulphones - see also Acetoxysulphones, /1-Acyloxysulphones, a-Alkoxysulphones, a-Aminosulphones, Azidosulphones, Azosulphones, Azoxysulphones, co-Cyanosulphones, Dialkoxysulphones, a-Diazosulphones, Disulphones, Episulphones, Epoxysulphones, a-Halosulphones, Hydroxysulphones, / -Iminosulphones, Ketosulphones, a-Lithiosulphones, a-Nitrosulphones, /1-Oxosulphones, Poly(olefin suphonejs, Polysulphones, y-Siloxysulphones, Tetrahalosulphones, Trisulphones addition reactions of 642-649, 774-809 alkadienyl - see Alkadienyl sulphones alkenyl - see Alkenyl sulphones alkyl aryl - see Alkyl aryl sulphones alkylthiomethyl - see Alkylthiomethyl sulphones... 

Dinitra-sym-diphenyl urea 550 Dinitro stilbene disulphonic 450... 

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