Oxidation by sulfuric acid

Because Br and I are oxidized by sulfuric acid, phosphoric acid is used in the preparation of HBr and HI ... 

Figure 1. Parts of the surface of source TEG (a, b) and TEG oxidized by sulfuric acid and subjected to thermal shock at 8000C (b) part of the surface of TEG particle oxidized by nitric acid and subjected to thermal shock at 80(fiC (d).

TEG structure refinement has distinctly observed in electron microscopy studies of the oxidized TEG powders subjected to the repeated thermal shock. In this case the size of TEG macropores was equal to 1.5-2 pm that is essentially lower that for source TEG. Figure 2 presents SEM images of the source TEG particle (a) and TEG particle oxidized by sulfuric acid and re-exfoliated at 800°C (b). 

Nitric oxide is reduced to nitrous oxide by sulfurous acid ... 

Solutions of Se8+ in 100% H2S04 may be prepared by heating selenium in the acid at 50-60°C the element is oxidized by sulfuric acid [Eq. (4.221)]. The Se42+ 343 can also be oxidized to Se82+ 344 by selenium dioxide. 

Oxidation by sulfuric acid, sulfur(VI) oxide or other sulfur(VI) derivatives... 

It is evident that alkylbenzenes are too resistant to one-electron oxidation by sulfuric acid. However, cation radical formation can be achieved in sulfuric acid by ultraviolet irradiation. Hexamethyl-... 

If citric acid is oxidized by sulfuric acid alone, then as pointed out by Wiig [207], who investigated this reaction in a detail, citric acid decomposes into carbon monoxide, water and acetonedicarboxylic acid... 

Mercuric Sulfate. Mercuric s Af2iX.e.[7783-35-9] HgSO, is a colorless compound soluble ia acidic solutions, but decomposed by water to form the yellow water-iasoluble basic sulfate, HgSO 2HgO. Mercuric sulfate is prepared by reaction of a freshly prepared and washed wet filter cake of yellow mercuric oxide with sulfuric acid ia glass or glass-lined vessels. The product is used as a catalyst and with sodium chloride as an extractant of gold and silver from roasted pyrites. 

Nickel sulfate also is made by the reaction of black nickel oxide and hot dilute sulfuric acid, or of dilute sulfuric acid and nickel carbonate. The reaction of nickel oxide and sulfuric acid has been studied and a reaction induction temperature of 49°C deterrnined (39). High purity nickel sulfate is made from the reaction of nickel carbonyl, sulfur dioxide, and oxygen in the gas phase at 100°C (40). Another method for the continuous manufacture of nickel sulfate is the gas-phase reaction of nickel carbonyl and nitric acid, recovering the soHd product in sulfuric acid, and continuously removing the soHd nickel sulfate from the acid mixture (41). In this last method, nickel carbonyl and sulfuric acid are fed into a closed-loop reactor. Nickel sulfate and carbon monoxide are produced the CO is thus recycled to form nickel carbonyl. 

Manufacture and Processing. Until World War II, phthaUc acid and, later, phthaUc anhydride, were manufactured primarily by Hquid-phase oxidation of suitable feedstocks. The favored method was BASF s oxidation of naphthalene [91-20-3] by sulfuric acid ia the presence of mercury salts to form the anhydride. This process was patented ia 1896. During World War I, a process to make phthaUc anhydride by the oxidation of naphthalene ia the vapor phase over a vanadium and molybdenum oxide catalyst was developed ia the United States (5). Essentially the same process was developed iadependendy ia Germany, with U.S. patents being granted ia 1930 and 1934 (6,7). 

Reduction. Just as aromatic amine oxides are resistant to the foregoing decomposition reactions, they are more resistant than ahphatic amine oxides to reduction. Ahphatic amine oxides are readily reduced to tertiary amines by sulfurous acid at room temperature in contrast, few aromatic amine oxides can be reduced under these conditions. The ahphatic amine oxides can also be reduced by catalytic hydrogenation (27), with 2inc in acid, or with staimous chloride (28). For the aromatic amine oxides, catalytic hydrogenation with Raney nickel is a fairly general means of deoxygenation (29). Iron in acetic acid (30), phosphoms trichloride (31), and titanium trichloride (32) are also widely used systems for deoxygenation of aromatic amine oxides. 

Koch Ro- ction. C-6-neoacids are readily available from amyl alcohols by the Koch reaction. Greater than 95% 2,2-dimethylbutyric acid [595-37-9] was obtained from 2-methyl-1-butene at 304 kPa (3 atm) CO and 35°C for 1 h with cupric oxide and sulfuric acid catalyst (31). Likewise,... 

Sulfur dichloride is oxidized by sulfur trioxide or chlorosulfuric acid [7790-94-5] (qv) to form thionyl chloride ... 

Stannous Sulfate. Stannous sulfate (tin(Il) sulfate), mol wt 214.75, SnSO, is a white crystalline powder which decomposes above 360°C. Because of internal redox reactions and a residue of acid moisture, the commercial product tends to discolor and degrade at ca 60°C. It is soluble in concentrated sulfuric acid and in water (330 g/L at 25°C). The solubihty in sulfuric acid solutions decreases as the concentration of free sulfuric acid increases. Stannous sulfate can be prepared from the reaction of excess sulfuric acid (specific gravity 1.53) and granulated tin for several days at 100°C until the reaction has ceased. Stannous sulfate is extracted with water and the aqueous solution evaporates in vacuo. Methanol is used to remove excess acid. It is also prepared by reaction of stannous oxide and sulfuric acid and by the direct electrolysis of high grade tin metal in sulfuric acid solutions of moderate strength in cells with anion-exchange membranes (36). 

Copper(II) sulfate monohydrate [10257-54-2] CuS04-H2 0, which is almost white in color, is hygroscopic and packaging must contain moisture barriers. This product is produced by dehydration of the pentahydrate at 120—150°C. Trituration of stoichiometric quantities of copper(II) oxide and sulfuric acid can be used to prepare a material of limited purity. The advantages of the monohydrate as opposed to the pentahydrate are lowered freight cost and quickness of solubilization. However, these advantages are offset by the dustiness of the product and probably less than one percent of copper sulfate is used in the monohydrate form. 

The use of molybdenum catalysts in combination with hydrogen peroxide is not so common. Nevertheless, there are a number of systems in which molybdates have been employed for the activation of hydrogen peroxide. A catalytic amount of sodium molybdate in combination with monodentate ligands (e.g., hexaalkyl phosphorus triamides or pyridine-N-oxides), and sulfuric acid allowed the epoxidation of simple linear or cyclic olefins [46]. The selectivity obtained by this method was quite low, and significant amounts of diol were formed, even though highly concentrated hydrogen peroxide (>70%) was employed. 

Figure 4-13 shows an example from a three-dimensional model simulation of the global atmospheric sulfur balance (Feichter et al, 1996). The model had a grid resolution of about 500 km in the horizontal and on average 1 km in the vertical. The chemical scheme of the model included emissions of dimethyl sulfide (DMS) from the oceans and SO2 from industrial processes and volcanoes. Atmospheric DMS is oxidized by the hydroxyl radical to form SO2, which, in turn, is further oxidized to sulfuric acid and sulfates by reaction with either hydroxyl radical in the gas phase or with hydrogen peroxide or ozone in cloud droplets. Both SO2 and aerosol sulfate are removed from the atmosphere by dry and wet deposition processes. The reasonable agreement between the simulated and observed wet deposition of sulfate indicates that the most important processes affecting the atmospheric sulfur balance have been adequately treated in the model. 

Poly(2-methoxy, 5-(2 -ethylhexyloxy)-1,4-phenylene vinylene) MEH-PPV Emission peak = 605 nm p-type doping by sulfuric acid (H2SO4) -type doping by sodium (electron donor) Iodine (I2) = electron acceptor = > oxidizing agent... 

Sulfide minerals can also be oxidized by the acidic ferric sulfate solutions produced (as shown in the last two equations), with the formation of elemental sulfur ... 

Conversion and the mean rate of reaction were obtained by titrating the liquid recovered from the bed for total acidity before and after dissolved S02 and sulfurous acid were oxidized to sulfuric acid. The difference between these measurements allowed calculation of the S02 conversion. An extension of the Haure study (Metzinger et al., 1992) added gas phase analysis and a check of the results through a sulfur balance. Computer control of flow interruption and acquisition of the S02 analyzer readings were also added. 

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