High Frequency Titrations Research Articles

High frequency titration of polyelectrolytes

High frequency titration of polyelectrolytes

Radiochromatographic and high-frequency titration studies on ethylthiourea complexes of palladium(II) and platinum(II)

Some solid palladium(II) and platinum(II) complexes of ethylthiourea (Etu) were prepared. Those with stoichiometry M(Etu) 4A 2 (AClO 4, BF 4, CF 3COO) and M(Etu) 4X 2 (XCl, Br, I) behave in solution as 1:2 electrolytes; the complexes MEtuX 2 (XCl, Br, I) are non-electrolytes, presumably with a dimeric halogen-bridged structure. High-frequency titrations indicated the formation of halide complexes with a ratio of Etu:M of 1:1, 2:1 and 4:1 in acidic, aqueous and dimethylformamide (DMF) solutions, respectively; Pd gives also the 3:1 complexes in DMF. By paper chromatographic elution of mixtures of the complexes and 35S-labelled ethylthiourea with aqueous solutions (0.5–5.0 M) of the corresponding NaA or NaX salts, the migrating species M(Etu *) 4X 2 and M(Etu *) 4A 2 were observed. In the case of the chlorides and bromides, two complex species migrating on the chromatographic paper in compact and distinct spots were observed: one with an R F value almost equal to that of the M(Etu *) 4 2+ species, the other with a much lower R F value. With increasing NaX concentrations of the eluting solution, the first complex decreases until it disappears and the second increases up to 100% for solutions 4–5 M in NaX. The second species can be considered as a square pyramidal five-coordinated complex, [ML 4X] +.

Apparatus for the recording of automatic high frequency titrations

A new type of oscillometer made from a series of solid state circuits suitable for automatic titration and recording is described. The apparatus is simple and easy to build in the laboratory. The output potential of the recorder is obtained by unbalancing a differential amplifier. A peak, having height proportional to the frequency of the oscillating circuit is obtained at each addition of the reagent, added by means of an electric burette. The two branches of the titration curve are obtained by joining the tops of the peaks. Reactions of precipitation, neutralization, complexation and oxidation-reduction were carried out in order to check the apparatus. The system has been shown to permit a good reproducibility of results even at long time intervals. The system developed has been directed furthermore to automatic continuous monitoring of remote laboratory and pollution control.

Apparatus for the recording of automatic high frequency titrations

Summary A new type of oscillometer made from a series of solid state circuits suitable for automatic titration and recording is described. The apparatus is simple and easy to build in the laboratory. The output potential of the recorder is obtained by unbalancing a differential amplifier. A peak, having height proportional to the frequency of the oscillating circuit is obtained at each addition of the reagent, added by means of an electric burette. The two branches of the titration curve are obtained by joining the tops of the peaks. Reactions of precipitation, neutralization, complexation and oxidation-reduction were carried out in order to check the apparatus. The system has been shown to permit a good reproducibility of results even at long time intervals. The system developed has been directed furthermore to automatic continuous monitoring of remote laboratory and pollution control.

Zur halogenaddition an cyclopentadien

By means of high frequency titration, the effects of conductivity for the intermediates of electrophilic addition of halogen to cyclopentadiene in different solvents and solvent mixtures have been determined. Based on the change of conductivity and in the case of the addition of bromine derived from the analysis of products, the experiments characterizes the intermediate state and the function of counter-ion in the concurrence-reactions of addition and polymerization.

A paper chromatographic investigation of the thiourea complexes of copper(I) silver(I) and gold(I)

Several thiourea complexes of formula M 1Tu x A (M I = Cu(I), Ag(I) and A = ClO 4, BF 4, CF 3COO, CH 3COO or HCOO; or M 1 = Au(I) and A = ClO 4, BF 4, CF 3COO, Cl or Br; Tu = thiourea) were prepared; the maximum Tu:M ratio is 3:1 for Cu(I) and Ag(I) and 2:1 for Au(I). The same maximum of 3:1 is observed on high frequency titration of the Ag(I) salts with thiourea in methyl cellosolve. Some of these complexes, undecomposed and in compact spots, may be eluted on chromatographic paper with a mixture of ketones and an aqueous solution of the corresponding sodium salt, or with a mixture of alcohols and an aqueous solution of the corresponding free acid. The Tu:M ratio is 5:2 for Cu(I) perchlorate and fluoroborate in ketones, while it is always 2:1 for the other complexes of Cu(I), Ag(I) and Au(I), irrespective of the anion, the solvent and the amount of aqueous solution in the mixture. The composition of the eluted complexes was determined by a radiochemical method after exchange with 35S-labelled thiourea. The R F values of the eluted complexes depend on the anion, the solvent and the amount of aqueous solutions in the mixture.

Aluminium(III)-iminodiacetic acid complexes in 0·M sodium perchlorate medium

Complex formation by aluminium(III) and iminodiacetic acid has been investigated in a constant ionic strength medium (0·5M NaClO 4) at 25°C by means of potentiometric titrations with a glass electrode. In the same ionic medium and temperature over all formation constants of the acid have been determined. log β 1L=9·17±0·01 log β 2L=11·73±0·01 log β 3L=13·49±0·01 At pH between 2 and 3·5 and in the chosen concentration ranges (2·43 ⩽ C M ⩽ 7·29 mM; 1·57 ⩽ C L ⩽ 12·7 mM) the experimental data can be explained by the formation of two mononuclear complexes according to the equilibria: Al 3++L 2−⇋AIL + log β 1=8·10±0·012 Al 3++2L 2−⇋AIL 2 − log β 2=15·07±0·03. The stochiometric ratio of these equilibria are in agreement with the data obtained from high frequency titrations.

Direkter nachweis der ionaren zwischenstufe bei der elektrophilen bromaddition an olefine

By means of high frequency titration, the “effects of conductivity” for the intermediates of electrophilic addition of bromine to olefinic compounds in polar solvents and solvent mixtures have been determined. The change of conductivity depends on solvation by the different solvents. The results characterize the intermediate of the reaction as an equilibrium between ion pairs and self-solvated ions.

High frequency titration methods in the investigation of complex formation

High frequency titration is a valuable tool in the study of complex formation in solutions, and the breaks in the titration curves can be used, in conjunction with the results of other physical methods, to determine the composition of the complexes formed. High frequency titration and other methods have been used to study the complexes formed by thorium, indium, plutonium(V) and boron with various complexing agents, and to develop methods for the determination of thorium and yttrium in rare earth mixtures, and of indium in the presence of zinc, cadmium, aluminium, nickel and cobalt.

High frequency titrations of polydicarboxylic acid copolymers: Polyitaconic acid‐Co‐styrene and polymaleic acid‐Co‐styrene

AbstractA useful method, more rapid and more accurate than elemental analysis, has been developed to determine the composition of copolymers of itaconic anhydride and maleic anhydride with styrene. The method involves a high frequency titration of the sample. The method can also be used to detect traces of acidic impurities in polymers and in the identification of mixtures of similar acidic copolymers. Titration indicates that the acid segments in the copolymers of itaconic acid–styrene, maleic acid–styrene, and the homopolymer polyitaconic acid act as dibasic acids. The method appears to have a sensitivity that permits identification and approximate resolution of two carboxylate species in the same polymer.

Determination of some cations by high frequency titration technique using potassium chromate as precipitant

Estimations of lead, barium, thallium and silver have been carried out in aqueous or ethanol-water media using a 30 Mc. unit. It has been found that lead and barium can be estimated by both direct and reverse titrations in aqueous medium. In case of silver and thallium (I), the addition of an equal volume of ethanol or methanol to the solution to be titrated was found essential for accuracy and reproducibility. Limits of tolerance for some ionic constituents which are frequently associated with these cations have also been determined. Thallium has been estimated by both direct as well as reverse titrations, but in case of silver, reverse titrations gave low results. The method requires much less time for the estimations as compared to other methods and the results fall within the ordinary limits of accuracy required.

A novel instrument for dielectric measurements with applications to chemical analysis

A novel instrument for the measurement of dielectric constant, loss and conductivity at high frequencies is described. It can be used for high frequency titrations and in other chemical applications. With cells of specific design measurements can be made up to = 100 and tan δ = 0.25 at a frequency of 3 Mc/s. The method is moderately simple as it depends on the phase characteristic of a patented auxiliary tuned circuit controlling an oscillator. Measurements are easily made and the instrument has been used to introduce automatic methods into distillation and extraction processes.

Determination of Macro Amounts of Fluoride by Steam Distillation and High-Frequency Titration.

Determination of Macro Amounts of Fluoride by Steam Distillation and High-Frequency Titration.

A study of some solvents as media for the high frequency titration of weak acids

Six solvents, with different basicities and dielectric constants, were studied to determine their suitability as media for high frequency (HF) titrations of weak acids. There is no definite correlation between the slopes of the HP response and conductance curves and the two properties, dielectric constant or basicity, of the solvent. The apparent strength of the acid or base in these solvents is not due to any single solvent property but it is a combination of the properties of the solute and the solvent. In general, from this and other papars, solvents with relatively high dielectric constants and very weakly basic properties are most likely to be successful solvents for non-aqueous HF and conductance titrations.

High frequency titration of Al 3+ with Ba(OH) 2.

High frequency titration of Al 3+ with Ba(OH) 2.

High frequency titrations of silver and thallium (I) with sodium tetraphenylborate.

High frequency titrations of silver and thallium (I) with sodium tetraphenylborate.

High frequency titrations. I. The silver-thiocyanate reaction

High frequency titrations. I. The silver-thiocyanate reaction

High Frequency Titrations of Silver and Thallium(I) with Sodium Tetraphenylborate

High Frequency Titrations of Silver and Thallium(I) with Sodium Tetraphenylborate

High frequency titration and estimation of ions: Determination of silver

High frequecy titration has been found to be a highly suitable technique for the volumetric estimation of silver with potassium chloride, potassium bromide, potassium iodide, ammonium thiocyanate, 2-mercaptobenyothiazole and bismuthiol II. The results have been accurate when the amount of silver present was not more than 15 mg. Titration of potassium cyanide with silver nitrate gives an end-point corresponding to the complex K[Ag(CN) 2]. Reverse titration fails to give any sharp break. Mercaptobenzimidazole, bismuthiol I and potassium chromate were not suitable reagents in these determinations.

High frequency titrations: The silver-thiocyanate reaction

A high frequency (oscillometric) method for the titrimetric determination of small amounts of silver at dilutions down to 1 4000 M with ammonium or potassium thiocyanate is described. Reverse titrations in the same order of dilution are also feasible. Oscillometric studies on the formation of soluble mercuric thiocyanate and of the sparingly soluble zinc tetracyanatomercuriate(l1) are in progress.