Dithionate, from oxidation

The direct sulphur to sulphur linking in the first formula is in harmony with the formation of the salt by reduction of the sulphite and with the stability of the salt in the presence of alkalis,1 but it is discounted by the absence of dithionate from the oxidation products, and by the easy fission of the substance into sulphite and sulphoxylate on treatment with an aldehyde. 

In dithionic acid and dithionates, 8205 , the oxidation state of the 2 8 atoms has been reduced from VI to V by the formation of an 8-8 bond (Table 15.18, p. 705). The free acid has not been obtained pure, but quite concentrated aqueous solutions can be prepared by treatment of the barium salt with the stoichiometric amount of H28O4 ... 

The yield of the photocathodic dissolution of CdS in a solution containing 1 x 10" M SOi" is only 0.005 molecules dissolved per photon absorbed. In the presence of 5 X 10 M excess Cd " ions it amounts to 0.05. Sulfate and dithionate are formed in the ratio 2.2 to 1. The oxidation of SO3" is effected by the positive holes produced upon illumination, two holes being necessary to convert one SO ion into SO " or 1/2 SjOg . If the SOj anion captured the two holes from the same colloidal particle ( two-hole mechanism ), only sulfate would appear as the oxidation product. However, if SO3" captured only one hole to form the radical SOj", the final products would be formed bj reactions of two such radicals, and these two radicals could even originate from different colloidal particles ( one-hole mechanism )... 

A quinazoline-2,4-dithione complex [Pd(LH)3(PPh3)] has been isolated from the reaction of the free ligand LH (51) with [Pd(PPh3)4], Unidentate co-ordination of the ligand via a sulphur atom was confirmed from the i.r. spectrum. Oxidative addition with iodine is reported. ... 

Anodic oxidation of heterocyclic thiones leads generally to disulfides. Thus cyclic voltammetric data at a pyrolytic graphite anode of purine-2,6-dithione show three peaks. The first and second correspond to a disulfide formation from the 6- and 2-thione groups, respectively, whereas the third is due to an oxidation to purine-2,6-disulfonic acid.432 Similarly, the electrochemical oxidation of benzthiazole-2-thione and benzimidazole-2-thione in CH3CN-NaC104 at a platinum electrode afforded the corresponding disulfides in good yield.433... 

Mesomeric 1,3,5-triazine-dione, -one-thione and -dithione betaines may be synthesized from N,N -disubstituted acetamidines (Scheme 73) (75JHC187). Huffman and Schaefer have reported the synthesis of the triazine 1-oxide (137) in 45% yield from methyl N-cyanoacetimidate and benzamidoxime (equation 70) (63JOC1816). 

Because the benzene resonance energy is much higher than that of an isolated double bond, the oxidation of an ethylenedithiolate to the butadiene-like dithione is easier to accomplish than the oxidation of a benzenedithiolate to the corresponding dithio-or /io-benzoquinone there is a difference in stability between the dianionic ligands (44) and (46) relative to the dithioketone forms (45) and (47) derived from them by a two-electron oxidation. 

It is of interest that there are reducing agents that may be oxidized to one product by two-electron oxidants and to a different product by one-electron oxidants. One of the simolest of these is SOI , which is oxidized to S024 by T1+8, JOr, or Br2. However, when MnOt> Ce(IV), Co(III), or Fe(III) is used as an oxidant, the dithionate ion, SaOjj" is formed, and may be made to predominate. The dithionate almost certainly results from the dimerization of the SOj radical ion, formed in an initial one-electron transfer ... 

Sodium selenate, Na2Se04.—The selenate is prepared from sodium selenite by electrolytic oxidation with platinum electrodes at ordinary temperature.13 A by-product analogous to the dithionate obtained in the electrolytic oxidation of sodium sulphite is not formed.14... 

Dithionic acid, H2S2O6, can be obtained in quite concentrated aqueons solutions (equation 31) from barium dithionate. The metal dithionates are usually obtained by oxidizing the corresponding sulfite or metathesis. 

Sulfate is the ultimate product of the oxidation of SO2. We might expect small concentrations of other species, such as dithionates that are intermediates in the oxidation process, although these have not been detected. Concentrations of sulfate particles in the remote atmosphere are typically at a few nanomoles per cubic meter. In the marine atmosphere the sulfate is found both in coarse particles where it derives from seasalt and in fine particles around a micron in diameter as... 

A useful conversion of a nucleoside 2,6-dithione into a 6-methylamino-adenosine via oxidation with dimethyldioxirane, illustrates several instructive points. The presumed intermediates are sulfinic acids the 2-sulfinic acid loses sulfur dioxide to leave hydrogen at C-2, and nucleophilic displacement of the 6-sulfinic acid (or possibly the sulfonic acid after further oxidation) introduces the amino group. Similar reactions can be carried out on pyrimidine thiones. The scheme shows intermediates derived from a disulfinic acid - it is not clear in what order oxidations/loss of sulfur dioxide/displacements take place. 

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