Permanganate value

Permanganate value Legislation and controls Oxidation with permanganate... 

Fig. 3. Correlation between amino acid concentration and permanganate values in alkaline medium...

Potassium permanganate under RCRA definition meets the criteria of an ignitable waste, and if discarded is considered a ha2ardous waste. The reportable quantity (RQ) (220) for potassium permanganate is 45.4 kg (100 lbs) and releases into the environment greater than this value must be reported to the U.S. Coast Guard National Response Center. 

Both ions can be removed by oxidation and subsequent filtration. Aeration is adequate for iron(II) oxidation at above pH 6, but the oxidation of manganese(II) is much too slow, even at higher pH values, for effective removal. Potassium permanganate or chlorine dioxide is frequently used for the oxidation of manganese however, their use must be foHowed by coagulation prior to filtration because of the formation of coHoidal Mn02. 

Terephthalic acid has been obtained from a great many /)-disubstituted derivatives of benzene or cyclohexane by oxidation with permanganate, chromic acid, or nitric acid. The following routes appear to have preparative value from />-toluic acid, />-methylacetophenone,2 or dihydro-/)-tolualdehyde by oxidation with permanganate from f>-cymene by oxidation with sodium dichromate and sulfuric acid from />-dibromobenzene or from /i-chloro- or -bromobenzoic acid by heating at 250° with potassium and cuprous cyanides and from />-dibromo-benzene, butyllithium, and carbon dioxide. ... 

This result clearly indicates that the reaction proceeds virtually to completion. It is a simple matter to calculate the residual Fe(II) concentration in any particular case. Thus consider the titration of 10 mL of a 0.1 M solution of iron(II) ions with 0.02M potassium permanganate in the presence of hydrogen ions, concentration 1M. Let the volume of the solution at the equivalence point be lOOmL. Then [Fe3 + ] =0.01M, since it is known that the reaction is practically complete, [Mn2 + ] = x [Fe3 + ] = 0.002M, and [Fe2 + ]=x. Let the excess of permanganate solution at the end-point be one drop or 0.05 mL its concentration will be 0.05 x 0.1/100 = 5 x 10-5M = [MnO ]. Substituting these values in the equation ... 

An approximate value of the volume of permanganate solution required can be computed from the weight of sodium oxalate employed. In the first titration about 75 per cent of this volume is added, and the determination is completed at 55-60 °C. Thereafter, about 90-95 per cent of the volume of permanganate solution is added at the laboratory temperature. 

Procedure. Dissolve a weighed portion of the substance in which the amount of iron is to be determined in a suitable acid, and evaporate nearly to dryness to expel excess of acid. Dilute slightly with water, oxidise the iron to the iron(III) state with dilute potassium permanganate solution or with a little bromine water, and make up the liquid to 500 mL or other suitable volume. Take 40 mL of this solution and place in a 50 mL graduated flask, add 5 mL of the thiocyanate solution and 3 mL of AM nitric acid. Add de-ionised water to dilute to the mark. Prepare a blank using the same quantities of reagents. Measure the absorbance of the sample solution in a spectrophotometer at 480 nm (blue-green filter). Determine the concentration of this solution by comparison with values on a reference curve obtained in the same way from different concentrations of the standard iron solution. 

Measure the absorbance A of the above three solutions of potassium dichromate and of potassium permanganate, each solution separately, at both 440 nm and 545 nm in 1 cm cells. Calculate e in each case and record the mean values for Cr2Oj and MnO at the two wavelengths. 

Kinetic isotope effect. The oxidation of benzaldehyde by permanganate ions is believed to occur by hydride abstraction. What value of k /kD do you predict for C6H5CHO/ C6H5CDO For C6H5CHO/C6D5CHO ... 

The data are the E ° values for the half-reactions, which are given in the problem. Under standard conditions, permanganate is reduced to Mn at the cathode, and water is oxidized at the anode ... 

The result has three decimal places because the ° value is accurate to three decimal places, and the correction is a subtraction. The low concentration of H3 in pure water reduces this cell potential nearly to zero, but the reaction is still spontaneous, so permanganate can oxidize water. Solutions of potassium permanganate slowly deteriorate and cannot be stored for long times. The reaction is slow enough, however, that significant oxidation does not occur over days or weeks. 

H02C(CH2) C02H it was found that beyond a certain point the increment in the rate coefficient for an increases of one in n is constant at 5.2 x 10 l.mole . sec which compares with a value of 5.73 x 10 1.mole . sec for n-paraffin oxidation (p. 293). It is clear that carboxylic acids behave as paraffins except that a slight retardation due to the inductive effect of -CO2H is apparent. Permanganate behaves in much the same way and some examples of carboxylic acid oxidation have been cited in the section on hydrocarbons. 

A comprehensive account of the oxidation of benzylamine by both neutral and alkaline permanganate has been published recently . The neutral amine is the active reductant at all pH values and at pH 9.9 good second-order kinetics were obtained. Under these conditions the stoichiometry is... 

Hi) The value of Fj is greater with permanganate than with ceric systems. With the latter, the value of Fj is lower for perchloric acid than for sulphuric acid media. 

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