Permanganates reductions

When testing for a tannin reserve or tannin index, the presence of natural color aids detection. Testing for tannin is simple and relatively accurate using either a permanganate reduction test (development of permanent purple color) or lignin/tannic acid polymer test (tungstate blue color). 

A)Permanganate Reduction. The pink color shall.persist for at least 30 mins when 0.5 ml of O.IN K permanganate soln is added to a 100 ml graduate contg the sample. The graduate is stoppered and the soln is thoroughly mixed before it is allowed to stand at 13°... 

Yebra-Biurrun, M. C., R. M. Cespon-Romero, and A. Moreno-Cid. 2001. Flow injection flame AAS determination of ascorbic acid based on permanganate reduction. At. Spectrosc. 22 346-349. 

Example The permanganate reduction in acidic solution shown in the previous example would be converted to basic solution as follows using the three steps above ... 

Expected ratio of permanganate reductant is 0.30 1 for N2H5 and 1.68 1 for NH3OH. These stoichiometries indicate competition for a free radical intermediate. 

Reduction of acid permanganate. Add a few ml. of dil. HgSO to 1 ml. of a solution of oxalic acid or of an oxalate. Warm gently and add a dilute solution of KMn04 drop by drop and note the decolorisation. 

Reduction of potassium permanganate. To a solution of uric acid in aqueous NajCO add KMnO solution drop by drop a brown precipitate of MnOj is produced immediately in the cold. 

Secondary alcohols (C q—for surfactant iatermediates are produced by hydrolysis of secondary alkyl borate or boroxiae esters formed when paraffin hydrocarbons are air-oxidized ia the presence of boric acid [10043-35-3] (19,20). Union Carbide Corporation operated a plant ia the United States from 1964 until 1977. A plant built by Nippon Shokubai (Japan Catalytic Chemical) ia 1972 ia Kawasaki, Japan was expanded to 30,000 t/yr capacity ia 1980 (20). The process has been operated iadustriaHy ia the USSR siace 1959 (21). Also, predominantiy primary alcohols are produced ia large volumes ia the USSR by reduction of fatty acids, or their methyl esters, from permanganate-catalyzed air oxidation of paraffin hydrocarbons (22). The paraffin oxidation is carried out ia the temperature range 150—180°C at a paraffin conversion generally below 20% to a mixture of trialkyl borate, (RO)2B, and trialkyl boroxiae, (ROBO). Unconverted paraffin is separated from the product mixture by flash distillation. After hydrolysis of residual borate esters, the boric acid is recovered for recycle and the alcohols are purified by washing and distillation (19,20). 

The most important manganese(V) compound is K MnO, a key intermediate in the manufacture of potassium permanganate. Potassium manganate(V) is an easily crystallized salt obtained by reduction of potassium permanganate using sodium sulfite in strong sodium hydroxide solution. This was the first compound to be recognized as exclusively pentavalent. 

Phenol can be oxidi2ed and hence removed, ie, to levels <20 / g/L, from wastewater (248). Moreover, addition of potassium permanganate to the return activated sludge results in reduction of odors issued from the aeration tanks of conventional activated sludge wastewater treatment plants without any change occurring to the microbiology of the system (249). 

Bromide ndIodide. The spectrophotometric determination of trace bromide concentration is based on the bromide catalysis of iodine oxidation to iodate by permanganate in acidic solution. Iodide can also be measured spectrophotometricaHy by selective oxidation to iodine by potassium peroxymonosulfate (KHSO ). The iodine reacts with colorless leucocrystal violet to produce the highly colored leucocrystal violet dye. Greater than 200 mg/L of chloride interferes with the color development. Trace concentrations of iodide are determined by its abiUty to cataly2e ceric ion reduction by arsenous acid. The reduction reaction is stopped at a specific time by the addition of ferrous ammonium sulfate. The ferrous ion is oxidi2ed to ferric ion, which then reacts with thiocyanate to produce a deep red complex. 

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