Peroxides organic, titration

The measured responses included uv spectra (to measure the concentration of remaining phenol), the carbon concentration (measured as non-purgeable organic carbon, or NPOC), the peroxide (by titration), and the pH in a few cases HPLC was used to measure the concentrations of oxidation intermediates. 

Control experiment. This is not necessary if the sodium peroxide is known to be chlorine-free. If there is any doubt on this point, the whole operation should be repeated precisely as before, but omitting the organic halogen compound. A small thiocyanate titration value may be found, and this should be deducted from all determinations in which the above quantity of the particular batch of sodium peroxide is used. 

To determine the exact peroxide content of benzoyl peroxide (and of other organic peroxides) the following procedure may be employed. Place about 0 05 g. of the sample of peroxide in a glass-stoppered conical flask add 5-10 ml. of acetic anhydride (A.R. or other pure grade) and 1 g. of powdered sodium iodide. Swirl the mixture to dissolve the sodium iodide and allow the solution to stand for 5-20 minutes. Add 50-75 ml. of water, shake the mixture vigorously for about 30 seconds, and titrate the liberated iodine with standard sodium thiosulphate solution using starch as indicator. 

The hberated iodine, as the complex triiodide ion, may be titrated with standard thiosulfate solution. A general iodometric assay method for organic peroxides has been pubUshed (253). Some peroxyesters may be determined by ferric ion-catalyzed iodometric analysis or by cupric ion catalysis. The latter has become an ASTM Standard procedure (254). Other reducing agents are ferrous, titanous, chromous, staimous, and arsenite ions triphenylphosphine diphenyl sulfide and triphenjiarsine (255,256). 

Other examples are the use of osmium(VIII) oxide (osmium tetroxide) as catalyst in the titration of solutions of arsenic(III) oxide with cerium(IV) sulphate solution, and the use of molybdate(VI) ions to catalyse the formation of iodine by the reaction of iodide ions with hydrogen peroxide. Certain reactions of various organic compounds are catalysed by several naturally occurring proteins known as enzymes. 

All monomers, surfactants, buffers, and chain transfer agents were used as provided. Water was deionized. Purchased organic peroxides were all reagent grade. Organic peroxides were prepared from the reaction products of acyl chlorides and sodium peroxide. Activity was determined by iodometric titration. 

A Perkin-Elmer Model 21 infrared spectrophotometer was used to detect and to estimate the hydroxylic and carbonyl functions in the oxidized product mixtures. The organic hydroperoxide and peroxide functional groups in the product mixtures were determined by an iodine liberation and titration procedure (11). In order to get reproducible results, it is necessary to pretreat the olefins with about 10 weight % activated silica or alumina for several hours with agitation to remove adventitious peroxides and impurities. Sodium bisulfite solution rapidly destroys hydroperoxides but does not destroy peroxides completely. The hydroperoxides and peroxides decomposed extensively during attempted distillation at about 1 mm. of Hg partial vacuum. We had some success in concentration by liquid chromatography over silica gel the unconverted olefins are eluted with n-hexanes, and a hydroperoxide-peroxide... 

Further experiments (159), including gas titrations, reactivity studies, and spectroscopic evidence, led to the formulation of the intermediate, earlier postulated (158) to be an oxygenated cobaltocene adduct, as the organic peroxide structure 63, in which the dioxygen bridge once again links the cyclopentadiene ligands in an exo fashion. This complex... 

K2Cr207 is not as strong an oxidant as KMn04 or Ce4+. It is employed chiefly for the determination of Fe2+ and, indirectly, for species that will oxidize Fe2+ to Fe3+. For indirect analyses, the unknown is treated with a measured excess of Fe2+. Then unreacted Fe2+ is titrated with K2Cr207. For example. CIO7, NOj, Mn04, and organic peroxides can be analyzed this way. Box 16-1 describes the use of dichromate in water pollution analysis. 

Theoretically, the Karl Fischer reagent can be used for the determination of any organic functional group that will undergo a quantitative and stoichiometric reaction to produce or consume water under conditions that do not interfere with the titration. These include alcohols, carboxylic acids, acid anhydrides, carbonyl compounds, primary and secondary amines, nitriles, and peroxides. 

The recovery of iodine from waste liquids.—E. Beilsteini2 recovered iodine from laboratory residues by evaporation to dryness with an excess of sodium carbonate and calcination until the organic matter is all oxidized. The mass is dissolved in sulphuric acid and treated with the nitrous fumes, obtained by treating starch with nitric acid, until all the iodine is precipitated. The iodine is washed in cold water, dried over sulphuric acid, and sublimed. Other oxidizing agents less unpleasant than the nitrous fumes employed by F. Beil stein—e.g. hydrogen peroxide—-were recommended by G. Torossian for the residues obtained in copper titrations. F. Beilstein s process is applicable to soluble but not to insoluble, oxidized forms of ioffine. F. D. Chattaway... 

A variety of oxidizing agents such as Cr(VI), Ce(IV), Mo(VI), NO3, NH2OH, and organic peroxides can be determined by reaction with a measured excess of standard iron(II) solution. Standard potassium dichromate is frequently used for the back-titration. 

Iodide ion is a moderately effective reducing agent. In its applications, a standard solution of sodium thiosulfate is used to titrate the iodine liberated by reaction of the analyte with an unmeasured excess of potassium iodide. Some substances determined by using iodo-metric method are 104 , lOs", BrOs, ClOs, Br2, CI2, O2, O3, Cu " ", N02, and organic peroxide. 

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