Potassium peroxodisulphate

Potassium peroxodisulphate (K2S2Og) also oxidizes sulphoxides to sulphones in high yield, either by catalysis with silver(I) or copper(II) salts at room temperature85 or in pH 8 buffer at 60-80 °c86-88. The latter conditions have been the subject of a kinetic study, and of the five mechanisms suggested, one has been shown to fit the experimental data best. Thus, the reaction involves the heterolytic cleavage of the peroxodisulphate to sulphur... 

Potassium peroxodisulphate decomposes violently when it is heated above 100°C by releasing oxygen. The same violent decomposition takes place at temperatures lower than 100°C, if water is present. The salt combusts spontaneously if soda is present. 

Potassium peroxodisulphate reacts violently with hydrazine in a basic medium. The danger is aggravated by the formation of nitrogen, which can represent a risk of overpressure if the apparatus used creates the substances containment. 

Moist potassium peroxodisulphate was accidentally exposed to traces of potassium hydroxide. It combusted spontaneously, causing the installations to catch fire. It is impossible to put out a fire involving this peroxydic compound with carbon dioxide or extinguishing powders although these agents are suitable for fires of chemical substances. Only water, which is usually not recommended in this case, can put out this type of fire. 

Potassium pemnanganate Potassium nitrite Potassium nitrate Potassium sulphite Potassium stannate IV Potassium sulphate Poptassium metabisulphite Potassium peroxodisulphate Potassium tellurate (IV) Potassium pyrophosphate... 

Mark G, Schuchmann MN, Schuchmann H-P, von Sonntag C (1990) The photolysis of potassium peroxodisulphate in aqueous solution in the presence of tert-butanol a simple actinometer for 254 nm radiation. J Photochem Photobiol A Chem 55 157-168 Mark G, Korth H-G, Schuchmann H-P, von Sonntag C (1996) The photochemistry of aqueous nitrate revisited. J Photochem Photobiol A Chem 101 89-103 Mark G, Tauber A, Laupert R, Schuchmann H-P, Schulz D, Mues A, von Sonntag C (1998) OH-radical formation by ultrasound in aqueous solution, part II. Terephthalate and Fricke dosimetry and the influence of various conditions on the sonolytic yield. Ultrason Sonochem 5 41-52 MarkG, Schuchmann H-P, von Sonntag C (2000) Formation of peroxynitrite by sonication of aerated water. J Am Chem Soc 122 3781-3782... 

Schuchmann H-P, von Sonntag C (1988) The oxidation of methanol and 2-propanol by potassium peroxodisulphate in aqueous solution free-radical chain mechanisms elucidated by radiation-chemical techniques. Radiat Phys Chem 32 149-156 Schwarz HA, Bielski BHJ (1986) Reactions of H02 and 02 with iodine and bromine and l2 and I atom reduction potentials. J Phys Chem 90 1445-1448... 

Alternatively, mix a drop of the acidified test solution on a spot plate with 2 drops 01m potassium peroxodisulphate solution and 1 drop 01m silver nitrate solution, and allow to stand for 2-3 minutes. Add a drop of the diphenylcarbazide reagent. A violet or red colour is formed. 

Ammonium or potassium peroxodisulphate Solid (NH4)2S208 or K2S208 is added to a dilute solution of manganese(II) ions, free of chloride. The solution is acidified with dilute sulphuric acid, and a few drops of dilute silver nitrate (which acts as a catalyst) are added on boiling a reddish-violet solution is formed, owing to the presence of permanganate ... 

It must be emphasized that these reactions take place only in acid media. Add solid potassium peroxodisulphate and dilute sulphuric acid to the neutralized soda extract of the mixed halides contained in a conical flask heat the flask to about 80°, and aspirate a current of air through the solution with the aid of a filter pump until the solution is colourless (Fig. IV.2. T is a drawn out capillary... 

Do not mistake precipitated silver sulphate for silver chloride. In a modification of this method, lead dioxide is substituted for potassium peroxodisulphate. Acidify the solution with acetic acid, add lead dioxide, and boil the mixture until bromine and iodine are no longer evolved. Filter, and test the filtrate, which should be colourless, with silver nitrate solution and dilute nitric acid. 

Potassium peroxodisulphate (01m). Dissolve 27 0 g potassium peroxo-disulphate K2S208, in water and dilute to l litre. 

Aliphatic amines, such as diethylamine, and amino acids, such as glycine and glutamic acid, do not show any specific absorption (Fig. 70). In this case, a photo-oxidation (using a low-pressure mercury lamp and a potassium peroxodisulphate solution as oxidant) could lead to nitrate formation (Fig. 71), easily determined by UV spectrophotometry (see Chapter 4). 

For TKN determination, the photo-oxidation is carried out in the presence of an oxidant solution (potassium peroxodisulphate K2S208 buffered to pH 9). In this case, organic and inorganic nitrogen compounds are converted into nitrate. The concentration of TKN is equal to the difference between nitrate measured after photo-oxidation ([NOX]f), and nitrate measured before ([NOX]/). It is based on the following relation ... 

Some improvements have been proposed, such as the use of photo-oxidation as an alternative to chemical digestion, as it has been successfully used for similar applications [23-26], In order to minimise the photo-oxidation time, the UV light source (high-, medium- or low-pressure mercury lamp) can be associated with oxidants (hydrogen peroxide or potassium peroxodisulphate). Generally, the converted forms (orthophosphates) are determined by off-line analysis, but can also be measured by flow injection or sequential injection analysis [27,28]. 

Then, an oxidant solution (40 g/L potassium peroxodisulphate K2S2O8) is added to the sample for the photoconversion (15 min irradiation times) of the organic phosphorus forms into orthophosphates. Orthophosphates are then determined by UV-visible spectrophotometry. 

It must be emphasized that these reactions take place only in acid media. Add solid potassium peroxodisulphate and 2m sulphuric acid to the neutralized soda extract of the mixed halides contained in a conical flask heat the... 

Sugar latexes based on saccharide derivatives, such as 3-MDG, 1- or 3-MDG and IDTF are synthesised in batch and semi-continuous emulsion polymerisation. The polymerisations are carried out at 60 or 70 deg.C initiated by potassium peroxodisulphate (KPS), in the presence of... 

Polymerisation of vinyl toluene in quaternary microemulsions containing cetyltrimethylammonium bromide as the cationic surfactant was studied using laser Raman spectroscopy and dilatometry. The influences of water soluble (potassium peroxodisulphate, ammonium peroxodisulphate) and oil-soluble (azobisisobutyronitrile, benzoyl peroxide) initiators, monomer, surfactant, cosurfactants (n-alcohol and bifunctional alcohols) and temperature on the rates of polymerisation, energy of activation, particle diameter, number of polymer particles, molecular weight of polyvinyl toluene and number of polymer chains per latex particle were investigated. The dependencies of the kinetic and latex size parameters on the initiators and co-surfactants are discussed in terms of the efficiency of the initiators in initiating the polymerisation and on the interfacial partitioning behaviour of various co-surfactants. 19 refs. 

Potassium persulphate solution DUute 5mL of sulphuric add (4.5mol/L reagent 1 of the phosphate determination in Section 10.2.5.4) with water to 100 mL. Add and dissolve S g of potassium peroxodisulphate, K2S20g. Store this solution at room temperature in a polyethylene bottle protected from direct sunlight. The reagent is stable for about one week. 

Oxidizing reagent Dissolve 50 g of potassium peroxodisulphate and 30 g of boric acid in IL of 0.375 mol/L (15.00 g/L) NaOH. Store this solution at room temperature in a tightly closed polyethylene bottle wrapp>ed with aluminium foil. The mixture is stable for several... 

The oxidation of organic nitrogen compounds with potassium peroxodisulphate was introduced by Koroleff (1969,1973) and has subsequently become a recommended standard... 

Potassium peroxodisulphate, K2S2O8 The persulphate used in this procedure should have a low nitrogen content. Suitable reagents are from Merck (No. 1.05092 with a maximum of 0.001 % N) and BDH Analar (No. 10 218 with a maximum of 0.0005 % NH3). Both reagents have been tested and found to contain ca. 0.00045 % N. One or two recrystallizations will improve the quality of analytical grade reagents to the above level or better. Dissolve 16g of the persulphate in lOOmL of pure water at 70-80 °C. Cool the clear solution to almost 0 °C and filter. Dry the recrystallized salt in a desiccator over anhydrous CaCl2. The recovery is about 80 %. 

Oxidizing solution Dissolve 10 g of the purified potassium peroxodisulphate (K2S2O8), and 6 g of boric acid, H3BO3, in 1L of the 0.075 mol/L NaOH reagent. Store the oxidant in a tightly closed polyethylene bottle in the dark and at < 8 C. The solution is stable for several weeks. 

Woo, L. and Maher, W., Determination of phosphorus in turbid waters using alkaline potassium peroxodisulphate digestion, Analytica Chimica Acta 315, 123, 1995. 

Ethyl everninate is hydroxylated to ethyl 5-hydroxyeverninate by oxidation with potassium peroxodisulphate (see Scheme 13). 

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