Oxy-acids of sulphur

Haight et al. ° have published a detailed account of the kinetics and stoichiometry of the oxidation of buffered bisulphite ion by chromic acid. The reaction is fast and its study requires a rapid mixing technique. The stoichiometry varies from a Cr(VI)/S(IV) molar ratio of 1 2 to 2 3 as the initial concentrations are changed in the range 0.12 [Cr(VI)]/[S(IV)] 1.4 and this was explained in terms of competition between two overall reactions 

The observed rate law, which applies only to (15) in 0.5 M sodium acetate buffer in the pH range 4.18-5.05 is 

The presence of the denominator term in the rate equation (17) suggests that the equilibrium (18) precedes the oxidation step. Two sequences of reactions are proposed (see below), depending on whether the sulphite radical ion dimerises (20) or attacks further acid chromate ion (21). It should be noted that of the species prevalent in dilute aqueous chromic acid, namely CrOj , Cr207, HCrO and H2Cr04, only the last is regarded as possessing oxidising powers. This fact, noted by Westheimer , is tacitly assumed in all recent discussion of 

The entity marked with a double dagger is regarded by the authors as an activated complex. Its breakdown (19) may well consist of a sequence of rapid steps rather than the single step implied, which involves a three-electron transfer and double protonation of a transition state subsequent to its formation. Steps (22)-(24 were invoked to explain the complete oxidation of S(IV) to S(VI) at higher Cr(VI) concentrations. 

The authors contrast this oxidation with those of As(III) and of alcohols, both of which involve analogous pre-equilibria (vide infra). 

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Lyons, D. Nickless, G. The lower oxy-acids of sulphur. In Inorganic Sulphur Chemistry Nickless, G.Ed. Elsevier New York, 1968 Chapter 14, pp. 519-522. 

The detection and determination ot the perchlorates.—The perchlorates give no precipitates with silver nitrate or barium chloride soln. cone. soln. give a white crystalline precipitate with potassium chloride. Unlike all the other oxy-acids of chlorine, a soln. of indigo is not decolorized by perchloric acid, even after the addition of hydrochloric acid and they do not give the explosive chlorine dioxide when warmed with sulphuric acid unlike the chlorates, the perchlorates are not reduced by the copper-zinc couple, or sulphur dioxide. Perchloric acid can be titrated with —iV-alkali, using phenolphthalein as indicator. The perchlorates can be converted into chlorides by heat and the chlorides determined volumetrically or gravimetrically they can be reduced to chloride by titanous sulphate 28 and titration of the excess of titanous sulphate with standard permanganate they can be fused with zinc chloride and the amount of chlorine liberated can be measured in terms of the iodine set free from a soln. of potassium iodide and they can be... 

The Oxy-Acids of the Halogens Perchlorates and Periodates Chlorates, Bromates, and lodates Chlorites Hypochlorites, Hypobromltes, and Hypolodites—Acids and Salts of Sulphur, Selenium, and Tellurium of Molybdenlum, Tungsten, and Uranium—Perchromates, Persulpbates, Perborates, and Percarbonates. 

The lower members of the homologous series of 1. Alcohols 2. Aldehydes 3. Ketones 4. Acids 5. Esters 6. Phenols 7. Anhydrides 8. Amines 9. Nitriles 10. Polyhydroxy phenols 1. Polybasic acids and hydro-oxy acids. 2. Glycols, poly-hydric alcohols, polyhydroxy aldehydes and ketones (sugars) 3. Some amides, ammo acids, di-and polyamino compounds, amino alcohols 4. Sulphonic acids 5. Sulphinic acids 6. Salts 1. Acids 2. Phenols 3. Imides 4. Some primary and secondary nitro compounds oximes 5. Mercaptans and thiophenols 6. Sulphonic acids, sulphinic acids, sulphuric acids, and sul-phonamides 7. Some diketones and (3-keto esters 1. Primary amines 2. Secondary aliphatic and aryl-alkyl amines 3. Aliphatic and some aryl-alkyl tertiary amines 4. Hydrazines 1. Unsaturated hydrocarbons 2. Some poly-alkylated aromatic hydrocarbons 3. Alcohols 4. Aldehydes 5. Ketones 6. Esters 7. Anhydrides 8. Ethers and acetals 9. Lactones 10. Acyl halides 1. Saturated aliphatic hydrocarbons Cyclic paraffin hydrocarbons 3. Aromatic hydrocarbons 4. Halogen derivatives of 1, 2 and 3 5. Diaryl ethers 1. Nitro compounds (tertiary) 2. Amides and derivatives of aldehydes and ketones 3. Nitriles 4. Negatively substituted amines 5. Nitroso, azo, hy-drazo, and other intermediate reduction products of nitro com-pounds 6. Sulphones, sul-phonamides of secondary amines, sulphides, sulphates and other Sulphur compounds... 

The most trustworthy method for the gravimetric estimation of a pure thiosulphate is oxidation to sulphuric acid, for example by means of chlorine or bromine, or by the addition of an alkali salt of a halogen oxy-acid, and then precipitation with barium chloride. 

Confirmatory evidence of the probable correctness of the formula Na2Sa04 is supplied by electrical conductivity measurements on aqueous solutions and comparison of the results with those given by the normal salts of the other sulphur oxy-acids, namely Na2S04, Na2S03, Na2S203 and NajSa-Og. All these salts dissociate in two stages. Cryoscopic measurements with the sodium salt also indicate the formation of three ions per molecule. 

Sulphur and NItrogen —Nitrogen Sulphides, Sulphammonium, Hoxasulpli-amido, Cliloro- and Bromo-sulphides, Thiazyl Salta—Amides of the Sulphur Oxy-acids—Sulphonic Acids—Sulphur Compounds of Hydroxylaimno and Hydrazine. 

This solution of hyposulphite of lime, like the first, is employed in the preparation of a new quantity of vermilion of antimony. The mother-liquors, charged with sulphurous acid, are again neutralised in the large reservoir by a new proportion of sulphide and oxy-sulphide of calcium, and so on, until the liquors become so much loaded with chloride of calcium that it becomes necessary to throw them away, or to reserve them for some other purpose. But this take place only after twenty or thirty operations. 

Ottesen (1975) demonstrated the effect on catalyst activity of a number of known catalyst poisons. His results showed that 1 ppm of sulphur poisons 0.004% of nickel, 1 ppm of phosphorus poisons 0.0007% of nickel, 1 ppm of bromine poisons 0.00125% of nickel, 1 ppm of nitrogen poisons 0.00144% of nickel and 1 part per thousand of oxy acids poisons 0.0046% of... 

If a-phellandrene be oxidised by potassium permanganate, the principal body resulting is a-oxy-/3-isopropyl glutaric acid. If /3-phellandrene be oxidised, closely related acids result, but if a 1 per cent, solution of permanganate be used and the oxidation effected very carefully in the cold, with the terpene always in excess, a glycol, CjoHjg(OH)2, results, which when dehydrated with dilute sulphuric acid yields tetrahydro-cuminic aldehyde. 

Pyrite and arsenopyrite have similar oxidation and self-induced collectorless flotation behavior. It is generally suggested that anodic oxidation of pyrite occurs according to reactions (2-24) in acidic solutions (Lowson, 1982 Heyes and Trahar, 1984 Trahar, 1984 Stm et al., 1991 Chander et al., 1993). The oxidation of pyrite in basic solutions takes place according to reactions (2-25). Since pyrite is flotable only in strong acidic solutions, it seems reasonable to assume that reaction (2-24) is the dominant oxidation at acidic solutions. Whereas pyrite oxidizes to oxy-sulfur species with minor sulphur in basic solutions. 

Because arsenopyrite is floatable in acidic conditions and non-floatable in basic conditions (see Fig. 2.16), it seems reasonable to assume that reactions (2-63) or (2-28) and (2-29) are dominant oxidation in acidic solutions. Elemental sulphur is responsible for the hydrophobicity of arsenopyrite in acidic media. In alkaline solutions, reactions (2-64) and (2-65) may be dominant resulting in the formation of oxy-sulfur species and arsenate species with minor sulphur. 

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