Permanganate sample preparation

A methoxyaldehyde, m.p. 52-53°, of unassigned structure is reported in the patent literature [6] as the product from the reaction of 2-methoxy-5,6,7,8-tetrahydronaphthalene with N-methylformanilide and phosphorus oxychloride. This reaction in our hands gave a 50% yield of methoxyaldehyde (VII), m.p. 51 6-52°, whioh was oxidized with potassium permanganate in acetone solution to 3-methoxy-5,6,7,8-tetrahydro-2-naphthoic acid. The structure of the latter was established by mixture m.p. with an authentic sample prepared [7] by converting 3-hydroxy-5,6,7,8-tetrahydro-2-naphthoic acid to the... 

Mercury Determine as directed under Mercury Limit Test, Appendix TUB, using the following as the Sample Preparation Transfer 2.0 mL of sample into a 50-mL beaker add 10 mL of water, 1 mL of 1 5 sulfuric acid, and 1 mL of a 1 25 potassium permanganate solution cover with a watch glass boil for a few seconds and cool. 

Sample Preparation Transfer 5 g of sample into a 250-mL Erlenmeyer flask, and continue as directed in the second full paragraph for Sample Solution under Arsenic Limit Test, Appendix IIIB, beginning with add 5 mL of sulfuric acid and a few glass beads. After the sample has been digested and the solution diluted to 35 mL, as directed therein, add 1 mL of a 1 25 solution of potassium permanganate, and mix. 

Sample Preparation Transfer 10.0 g of sample into a 100-mL beaker, dissolve in 15 mL of water, add 2 drops of phenolphthalein TS, and while constantly stirring, slowly neutralize with 1 2 hydrochloric acid. Add 1 mLof 1 5 sulfuric acid and 1 mL of a 1 25 solution of potassium permanganate, cover the beaker with a watch glass, boil for a few seconds, and cool. 

Samples of the nonionic and zwitterionic surfactants used were prepared in this laboratory and had a purity better than 99.5%. Sodium dodecyl sulfate was a sample prepared and purified in this laboratory. No minimum in the surface tension was found near the CMC. The dodecyl trimethylammonium bromide was a sample from Palmer Research Co. Ltd., showing a minimum of about 1 mNm 1 at the CMC. Water distilled from alkaline permanganate was used to prepare all solutions. All experiments were done at 25 °C where water had a surface tension of 72.25 mNm-1. 

Prepare 5M sodium hydroxide solution using analytical grade material test a 10 mL sample for reducing agents by adding a drop of the permanganate solution no green coloration should develop. 

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. 

Preparation of Manganese(IV) Oxide Sol. Add a 2% hydrogen peroxide solution to 5 ml of a potassium permanganate solution containing 14 g of salt per litre of solution until the violet colour disappears. Write the equation of the reaction. To determine the end of the reaction, proceed as follows add a few drops of a saturated sodium chloride solution to a small sample and heat it. If a violet colour is noticeable, add more hydrogen peroxide solution to the main solution. 

A stock solution of 3.0% potassium permanganate in 10% nitric acid (prepared fresh daily) was used to stabilize the mercury collected in the rinses from the sampling train. The stabilized solutions were then returned to TraDets Columbus, Ohio laboratory for analysis. 

Methanol Prepare a Sample Solution by diluting 10 mL of sample to 100 mL with water. Prepare a Standard Solution in water containing 40 p.g of methanol in each milliliter. Add 0.2 mL of 10% phosphoric acid and 0.25 mL of 1 20 potassium permanganate solution to 1 mL of each solution. Allow the mixtures to stand for 15 min, then add 0.3 mL of 1 10 sodium bisulfite solution to each, and shake until colorless. Slowly add 5 mL of ice-cold 80% sulfuric acid, keeping the mixtures cold during the addition. Add 0.1 mL of 1 100 chromotropic acid solution, mix, and digest on a steam bath for 20 min. 

Lead Determine as directed for Method I in the Atomic Absorption Spectrophotometric Graphite Furnace Method under Lead Limit Test, Appendix IIIB, using a 10-g sample. Methanol Transfer 1 drop of sample to a test tube, add 1 drop of 1 20 phosphoric acid and 1 drop of 1 20 potassium permanganate solution mix and allow to stand for 1 min. Add, dropwise, 1 10 sodium bisulfite solution until the permanganate color disappears. If a brown color remains, add 1 drop of the phosphoric acid solution. Add 5 mL of freshly prepared chromotropic acid TS to the colorless solution, and heat it in a water bath at 60° for 10 min. No violet color appears. 

Transfer 20 mL of sample into a 500-mL separator, add a solution of 20 g of sodium hydroxide in 50 mL of water, stopper the separator, and wrap it securely in a towel for protection against the heat of the reaction. Shake the mixture vigorously for about 5 min, cautiously opening the stopcock from time to time to permit the escape of air. Continue shaking the mixture vigorously until a homogeneous liquid results, then distill, and collect about 25 mL of the distillate. Add 1 drop of dilute phosphoric acid (1 20) and 1 drop of a 1 20 solution of potassium permanganate to 1 drop of the distillate. Mix, allow to stand for 1 min, and add, drop wise, a 1 20 solution of sodium bisulfite until the color disappears. If a brown color remains, add 1 drop of the dilute phosphoric acid. Add to the colorless solution 5 mL of a freshly prepared 1 2000 solution of chromotropic acid in 75% sulfuric acid, and heat on a steam bath for 10 min at 60°. No violet color appears. 

---