Bromides potentiometric titration

There is also evidence for stable 3,4-adducts from the X-ray analysis of 2-amino-4-ethoxy-3,4-dihydropteridinium bromide, the nucleophilic addition product of 2-aminopteridine hydrobromide and ethanol (69JCS(B)489). The pH values obtained by potentiometric titration of (16) with acid and back-titration with alkali produces a hysteresis loop, indicating an equilibrium between various molecular species such as the anhydrous neutral form and the predominantly hydrated cation. Table 1 illustrates more aspects of this anomaly. 2-Aminop-teridine, paradoxically, is a stronger base than any of its methyl derivatives each dimethyl derivative is a weaker base than either of its parent monomethyl derivatives. Thus the base strengths decrease in the order in which they are expected to increase, with only the 2-amino-4,6,7-trimethylpteridine out of order, being more basic than the 4,7-dimethyl derivative. 

Bases on the data of curve of the potentiometric titrations of [AuBr ] ions by thiourea (Thio), it consistently replaces bromide ions in [AuBr ] ion. They are formed mixed bromide-thiourea complexes of Au(III) AuBr Thio, AuBiyr/iio AuBrThio, AuBrThioJ. ... 

The amount of potassium bromide remaining in the recrystallized potassium glycidate is determined by potentiometric titration using a silver electrode. 

Elemental composition H 1.25%, Br 98.75%. The normality of the acid may be measured by titration against a standard solution of a base using a suitable color indicator or by potentiometric titration. The bromide ion, Br, may be measured quantitatively by ion chromatography after appropriate dilution. Concentration of HBr gas in air may be measured by passing a known volume of air through water and determining concentration of acid in aqueous solution by titration or ion chromatography. Alternatively, HBr gas may be analyzed by GC or GC/MS. A very polar column should be used for such measurements. An FID or a TCD type detector may be used for GC analysis. 

According to visible spectra (Figure 6) and potentiometric titration, the concentration of bromide ion decreases gradually as toluene oxidation proceeds, but the total amount of bromide ion after treating the solution with alkali remains constant (Figure 7). The bromide ion converted to organic bromides (benzyl bromide) during the oxidation can be hardly... 

Allan S. Hay During the autoxidation of p-xylene catalyzed by cobalt acetate bromide, a potentiometric titration for bromide ion of an aliquot of the reaction mixture at 0°C. shows that only a fraction of the bromide is present in ionic form. If the titration is performed at room temperature, there is a gradual drift of the end point until it finally corresponds to the calculated total amount of bromide. The implication thus is that benzylic bromides are present during the reaction, and at room temperature during the titration they are slowly solvolyzed. 

Table 5), and several are now being used, or are potentially useful, for measuring key ocean elements. The most common use of direct potentiometry (as compared with potentiometric titrations) is for measurement of pH (Culberson, 1981). Most other cation electrodes are subject to some degree of interference from other major ions. Electrodes for sodium, potassium, calcium, and magnesium have been used successfully. Copper, cadmium, and lead electrodes in seawater have been tested, with variable success. Anion-selective electrodes for chloride, bromide, fluoride, sulfate, sulfide, and silver ions have also been tested but have not yet found wide application. 

EXAMPLE 15-1 Consider the titration of arsenic(III) with bromate. In a hydrochloric add solution containing excess bromide, the end point can be determined potentiometrically by using the bromine-bromide couple as the potential-determining system. Alternatively, the same titration can be followed amperometrically by measuring the diffusion-controlled current due to excess bromine slightly beyond the end point. At an initial concentration of 5 x 10 M arsenic(III), the potentiometric titration can barely be carried out, because several minutes are required for electrode equilibrium at each point of the titration. The amperometric method gives a successM end point even at 5 x 10 M arsenic(III), the whole titration taking only a few minutes. ////... 

The oxide-solubility parameters obtained in the bromide melt by the method of potentiometric titration are collected in Table 3.7.13. It should be noted that their reproducibilities (confidence ranges) are appreciably worse than those in the molten alkali-metal chlorides. Lower values of oxide... 

We have also investigated the solubilities of MgO and CaO in molten potassium halides at 800 °C [197] to elucidate the effect of anion composition of the halide melt on metal-oxide solubility. The MgO was found to be practically insoluble in chloride and bromide melts, and the iodide-melt could not be investigated owing to intense iodine evolution from strongly acidic solutions. In contrast, CaO solubility products were determined successfully in all the potassium halide melts at 800 °C, by the potentiometric titration method. The corresponding potentiometric titration curves are shown in Fig. 3.7.16. 

The manganate ion is not reduced by bromide ion but is reduced slowly by iodide ion and quickly by vanadyl(IV) or hexacyano-ferrate(II) ions. When the latter two ions are used as reductants, especially with the potassium complex, green products are obtained rapidly and in high yield. The green species is unstable in solution and is apparently in equilibrium with the reactants. With potassium salts, the solubility of the product is low, and the reaction is driven to completion. Potentiometric titrations show that a one-electron reduction occurs to produce the green species, which has been characterized by analysis and optical and e.s.r. spectroscopy. It is a mixed-valence species similar to the heteropoly blues of molybdenum and tungsten. E.s.r. spectra suggest that the extra electron is fairly well trapped on a specific vanadium atom, and the complex is therefore a class II mixed-valence species.8... 

The salinity can be determined with five significant figures from conductivity measurements as well as by potentiometric titration of chloride - - bromide in m g of sea water with v ml of t molar silver nitrate. Thereby the chlorinity is given by ... 

Considerable interest has been shown in analytical methods for the determination of algin (68, 72, 78, 101, 158, 171, 21A, 292). Improvements were made in the Lefevre-Tollens hydrochloric acid decarboxylation method by McCready, Swenson, and Maclay (135, 143) to make it more adaptable to routine determinations. Kenyon and coworkers (148, 262, 271, 272) in a series of articles compared various methods for the determination of the carboxyl content of sugar acids. These included the calcium acetate-acetic acid method, the potentiometric titration method in the presence of sodium bromide, decarboxylation and determination of the isolated furfural. Percival and Ross (70, 187) described improvements in the colorimetric carbazole determination of algin. New analytical methods include the oxidation of algin with cerium sulfate (W) and Perlin s (188) recent report of the quantitative thermal decomposition of algin at 255 C. 

Generally, methods are based on solvent extraction of the additive followed by analysis for the extracted additive by a suitable physical technique such as visible spectrophotometry of the coupled antioxidant, redox spectrophotometric methods, ultraviolet spectroscopy, infrared spectroscopy, gas chromatography, thin-layer chromatography or column chromatography. In general, direct chemical methods of analysis have not foimd favour. These include potentiometric titration with standard sodium isopropoxide in pyridine medium or reaction of the antioxidant with excess standard potassium bromide-potassium bromate (ie. free bromine) and estimation of the unused bromine by addition of potassium iodide and determination of the iodine produced by titration with sodium thiosulphate to the starch end-point. ... 

Detection of the end-point by potentiometric titration using a silver/ silver chloride or silver silver bromide indicator electrode and a platinum reference electrode is particularly valuable when highly coloured solutions are being titrated and also for titration of small quantities. The following procedure is generally applicable ... 

Mixture of Potassium Bromide for Infants, B.P.Cy Potentiometric titration 0 01190 g KBr. 

Mohamed GG, Ali TA, El-Shahat ME, Al-Sabagh AM, Migahed MA (2010) New screen-printed ion-selective electrodes for potentiometric titration of cetyltrimethylammonium bromide in different civilic media. Electroanalysis 22 2587—2599... 

In variants based on the determination of alcoholyzable halogen, chlorine and bromine have been determined69 by solvolysing the sample in a sealed tube with sodium butoxide. The resulting chloride or bromide was determined by argentimetric titration, with visual, or preferably potentiometric, indication of the end-point. 

Electrodes suitable for the potentiometric determination of surfactants are either specially designed liquid or solid membrane electrodes or ion-selective electrodes that in addition to being selective to a particular ion, also quantitatively respond to surfactants. For example, a nitrate ion-selective electrode responds to anionic surfactants, a calcium ion-selective electrode is sensitive to quaternary ammonium salts, and a barium ion-selective electrode can be used for assaying polyethoxylates [43], In some cases it is possible for one to perform potentiometric determination of a counter-ion, e.g. one can titrate alkylpyridinium chloride or bromide salts with silver nitrate solution using silver wire as an indicator electrode [38]. 

The potentiometrlc titration with perchloric acid in dioxane is the method of choice to assay clldinium bromide (6). The sample is dissolved in glacial acetic acid, an excess of mercuric acetate is added, and the titration with O.IN HCIO4 in dioxane is carried out. The equivalence point is determined potentiometrically. Each ml of O.lN HCIO4 is equivalent to 43.24 mg of clldinium bromide. 

The potentiometric detection of the endpoint of precipitation titrations is very often used because not many visual indicators are available, in particular when mixtures of analytes are titrated. Halides, cyanide, sulfide, chromate, mercaptans, and thiols can be titrated with silver nitrate, using the silver sulfide-based ISE. Also complex mixtures, such as sulfide, thiocyanide, and chloride ions, or chloride, bromide, and iodide ions, can be titrated potentio-metrically with silver(I) ions. When the solubility of a compound formed during titration is too high, nonaqueous or mixed solvents are used, for example,... 

The modified titration curves of the fractionated (MA-St)n aqueous NaCl at various ionic strengths from 0.009 to 0.27 resembled the potentiometric behaviors of the maleic acid copolymer with n-butyl vinyl ether and poly(methacrylic acid) in aqueous salts. There was no precipitation or turbidity in the deionized polymer solution, except in aqueous NaCl of 0.27 M. The conformational transition from the compact to extended coil form was seen in diagp ams of the intrinsic viscosity vs. qp and the reduced viscosity in the range 0.1 < aj < 0.4 was independent of polymer concentration. Both the potentiometric and viscometric titration data showed that the pH-induced conformational transition of (MA-St)n in aqueous NaCl is due to intramolecular interaction. The unperturbed molecular dimensions were calculated from the viscosity data and the acid compact form of this copolymer was found to be not so compact as the conformations of globular proteins. Dilatometry did also indicate existence of the transition,and the transition was observed in aqueous solutions of various salts chlorides, bromides, perchlorates and thiocyanates of Na" ", K" ", Rb" ", Cs" " and... 

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