Sulphonic acids iodination

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

Sulphonation, like iodination, is reversible and is believed to take place in concentrated sulphuric acid via the pathway ... 

The mercury in tiiese compounds may be replaced by iodine, when 2 iodotoIuen -4-sulphonic acid is obtained. 

Radiolabelling is often performed by oxidation of iodide by different agents for iodination of tyrosine and histidine residues in peptides. However, unfavourable oxidation reactions can occur simultaneously, e.g., cysteine and methionine can be oxidized to their corresponding sulphone or sulphonic acid, so that neutral amino acids are converted to highly acidic groups, thus changing the electrostatic distribution within the structme of the... 

Selenium has been determined with 5,5-dimethyl-1,3-cyclohexanedione [51], 6-amino-1-hydroxynaphthalenesulphonic acid [52,53], and l-aminonaphthalene-7-sulphonic acid [54], Determinations of Se involved also the following dyes Rhodamine B [55], Methylene Blue [56], Xylenol Orange [57], and Rhodamine 6G (by the amplification method, in iodide medium, after oxidation of iodide to iodine, and reaction of the I03 with the dye) [58]. 

Selenium has been determined in tellurium with the aid of dithizone [46]. Selenium present in anodic slimes has been determined after the reaction with iodide and extraction of the liberated iodine [74], In pharmaceutical products selenium was determined with the use of l-aminonaphthalene-7-sulphonic acid [54]. 

Sulphonic acids may normally be obtained in 65-75% yields upon oxidation of thiols, thiolates or disulphides with 30% hydrogen peroxide234-240. Higher yields are realized if a tertiary thiol is used. The same products may also be realized by reaction of either thiols or disulphides with aqueous dimethyl sulphoxide (equation 37), in the presence of a catalytic amount of bromine, iodine or a hydrogen halide241,242. In this latter oxidation, dimethyl sulphide is formed as a by-product, but is easily removed by aspiration. 

Figure 8.1. Thickness dependence of total Shielding Efficiency (SE,) of highly conducting polymers measured at 6.5 GHz (from [23c]) sample A stretched heavily iodine doped Tsukamoto polyacetylene (dotted line is obtained by using calculation of Se, with approximated values of a absorption coefficient and n) sample B unstretched heavily iodine doped Tsukamoto polyacetylene sample C camphor sulphonic acid doped polyaniline in m-cresol solvent sample D PFe doped polypyrrole sample E TSO doped polypyrrole Inset comparison of (microwave conductivity), c, and tan 6, Reprinted from ref. 23c with permission. Copyright American Institute of Physics.

The work on isotope eifects in the iodination of p-nitrophenol, and on the bromination and bromodesulphonation of anisole-4-sulphonic acid not only excludes mechanisms (10-11), (12-13) and (14-15), but also shows that the mechanism (6-2) does not involve a rapid and reversible first step and a slow proton transfer, but a typical steady-state intermediate ( iPa]... 

Iodine-mediated oxidation has been applied in conjunction with 5-Xan, S-Tmob, S-Mmt, S-Trt, and 5-Acm protection (5, 8, 26-28, 38). Optimal solvents include ACOH-H2O (4 1), MeOH-HjO (4 1), and DMF-H2O (4 1) (39). The main caution with iodine is to avoid over-oxidation of the thiol functionality to the corresponding sulphonic acid, as well as to prevent or minimize modification of other sensitive amino acid side-chains (Tyr, Met, Trp) (5, 8, 38), It is advisable to monitor reactions, e.g. by HPLC once complete oxidation is verified, quenching should be carried out so as to lessen the extent of any possible side reactions. Other oxidizing agents, such as cyanogen iodide (97) or iV-iodosuccinimide (98), can be used. 

Cyclization of the unsaturated epoxy-ester (100), to a-pyrone (101), has been effected using iodine and toluene-p-sulphonic acid in benzene. ... 

Some of the volumetric methods described above may also be adapted to the electrometric determination of arsenic. Such methods have been described for titration of arsenites with ceric sulphate,9 iodine in the presence of sodium bicarbonate,10 chloramine (p-toluene-sulphone chloramide),11 alkaline potassium ferricyanide solution,12 potassium bromate13 or potassium iodate14 in the presence of hydrochloric acid, silver nitrate15 (by applying a secondary titration with 01N alkali to maintain the desired low H+-ion concentration), and with... 

Sulphides are oxidized readily by most hypervalent iodine reagents. IOB alone is not suitable, since mixtures of sulphoxides and sulphones are formed under drastic conditions. However, in the presence of catalytic amounts of p-toluenesulphonic acid [49] or benzeneseleninic acid [50] various sulphides were cleanly oxidized to sulphoxides in excellent yields. Using a chiral catalyst asymmetric oxidation was highly successful [51]. 

Diaminodiphenyl sulphone and related drugs are chromatographed as 4,4 -diiodo derivatives. The amino groups are diazotized by treatment with nitrous acid and substituted with iodine, and the resulting derivative provides a high ECD response [568]. 

---