Sulphonate salts

The preparation and isolation of S-benzylisothiouronium chloride by the interaction of benzyl chloride and thiourea is described in Expt 5.203. On recrystallisation the compound separates in either, or sometimes as both, of two dimorphic forms, m.p. 150 and 175 °C respectively. The former may be converted into the higher m.p. form by dissolving it in ethanol and seeding with crystals of the form, m.p. 175 °C the low m.p. form when warmed to 175 °C gives, after solidification, a m.p. of 175 °C. The compound is of particular interest as a reagent for the characterisation of carboxylic acids or sulphonic acids with which it forms the S-benzylisothiouronium carboxylate (or sulphonate) salts (Sections 9.6.15, p. 1264, and 9.6.26, p. 1285). Both dimorphic forms give identical derivatives. 

After preparation of sulphonate salt, a second deprotonation step effects the ring closure ... 

In these examples it was not possible to visualise any chiral structure with a microscope, but when PANI was prepared using poly(acrylic acid) as an in situ template, helical microwires were visualised [65]. In an even more general sense, helical fibres of PANI, poly(ethylenedioxythiophene) (PEDOT), and poly(pyrrole) were prepared using synthetic lipids as templates [66,67]. The synthetic lipid molecules used are shown in Fig. 6 along with some of the helical fibres of PEDOT that are formed when the sulphonate salt is used to shape the fibres during the polymerisation. The procedure involves growing the fibres by electrochemical polymerisation onto an ITO electrode with the lipid molecules in the electrolyte. 

Although ethylmethylphenylphosphine oxide was the first tetrahedral phosphorus compound to be resolved , only negative results were obtained when attempts were made to resolve methyl(a-naphthyl)phenylarsine oxide (142) by protonation and separation of (-i-)-a-bromocamphor-jc-sulphonate salts, or (c>-carboxyphenyl)methylphenyl-arsine oxide (143) or its anhydride 144 after protonation and use of (—)-brucine or (-l-)-morphine . The reversible combination of a tertiary arsine oxide with water was recognized at the outset and it is this property that is responsible for the racemization - ... 

The effects of sulphonate salt concentration and chain length on the retention factor k ) were studied by measuring k using only berenil as the diamidine, with a mobile phase consisting of 25.0 mM citrate buffer, pH=3.25, 45.0% methanol, T=30.0°C, with pentane sulphonate, hexane sulphonate, heptane sulphonate, octane sulphonate, and decane sulphonate sodium salts at concentrations of 0.00, 1.00, 2.00, 3.00, 4.00, 5.00, 6.00, 9.00, and 12.00 mM. The resultant data are shown in Fig. 4, where it may be observed that retention times and hence k increase as the concentration of the ion pairforming agent increases. This increase is much more... 

Preparation of Typical Phenolic Adhesives Containing Calcium and Copper Sulphonate Salts... 

Results. Phenolic adhesives are usually manufactured with little or no fillers because of their applications. They are soluble in solvents and dilution methods can be readily applied to the analysis of these products but if trace analysis is required for health or environmental reasons destructive methods may be necessary. Excellent results can be obtained for the determination of calcium and copper sulphonate salts added to products using the internal standard method. These low density adhesives can be analysed without resorting to destructive methods (Table 6.22). 

This conclusion has been confirmed by a total synthesis of macronecine (7), which involves successive reductions of the racemic pyrrolizidine ester (8) by zinc and acetic acid, followed by lithium aluminium hydride. Resolution was achieved via the a-bromo-D-camphor-n-sulphonate salts. The conclusion concerning the relative stereochemistry in macronecine was substantiated by the preparation of the other three racemates having the same gross structure as macronecine, and a detailed comparison of their n.m.r. spectra. In consequence of this work, the complete structure of macrophylline is as given in (9). ... 

Methods for analysis of the free acids are considered first followed by methods used primarily for sulphonate salts. This distinction is arbitrary but convenient. Clearly, many methods used for free acids can be applied to salts in the presence of added (mineral) acid and methods used for salts can be applied to acid samples after prior neutralization. 

The displacement of aromatic amino groups by sulphite, to form a sulphonic acid (or a sulphonate salt), gives rise to the genetic hazard of sulphites. Deamination or dehalogen-ation of the aromatic rings in nucleosides is a very facile reaction in which sulphonic acid salts are produced, either in vivo or in vitro192 199. For example, cytosine reacts with sodium sulphite to form the 6-sulphonate, by deamination, as shown in equation 28. 

Sulphonate salts may be formed by oxidation of aromatic thiocarbamates with hydrogen peroxide, in 50-60% yield243, as shown in equation 38. The thiocarbamates may be readily formed from phenols by reaction with dimethylthiocarbamyl chlorides244. A similar reaction also occurs on oxidation of thioacetates with hydrogen peroxide or peracids245,246. Thioacetates are readily prepared by several routes, for example, by reaction of alkenes with thioacetic acid. 

Finally, a rather trivial but noteworthy process is the conversion of a sulphonic acid or a salt into a sulphonate salt. This may be accomplished by the use of an ion-exchange resin. For example, sodium sulphonates have been converted into silver sulphonates by first passing them through an ion-exchange resin (in the H+ form) followed by reaction with silver carbonate319, as shown in equation 68. 

Other sulphonic acid derivatives react with amines to give sulphonamides. Sulphonate esters react with primary amines to give a sulphonamide and an alcohol as shown in equation 122495. Anhydrides undergo a similar reaction496,497 and in this case the second product is an ammonium sulphonate salt (equation 123). 

In marked contrast to the above results, sodium benzene- 1,3-disulphonate (32) reacts with sodium hydroxide at temperatures up to 360 °C to give the resorcinol salt 34 in over 80% yield along with some phenol126. Presumably the intermediate phenol-3-sulphonate salt 33 is no longer deactivated by the phenolate anion (equation 26). 

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