Iodine trichloride in glacial acetic acid as an oxidizing titrant

A systematic study of the redox reactions of iodine trichloride with various inorganic ions in glacial acetic acid medium is described. Sodium sulphite, arsenic trichloride, antimony trichloride, iron(II) perchlorate and mecury(I) perchlorate were examined. Potentiometric and amperometric methods were used to follow the reduction of iodine trichloride, which yields different products according to the type of reductant.     

Trifluoromethyl sulphonic acid as a titrant in glacial acetic acid systems

Trifluoromethyl sulphonic acid in glacial acetic acid has been compared with perchloric acid in glacial acetic acid as a titrant in a limited number of cases. It does not appear that the reagent is likely to compete seriously with perchloric acid in non-aqueous titrimetry. Although comparable to perchloric acid in acid strength in acetic acid as well as in instrument response, it is unlikely that the considerably higher cost can be justified on the grounds of freedom from precipitate formation alone and no other advantageous feature has been observed which could justify this.

Abstract

Trifluoromethylsulfonsäure in Eisessig wurde mit Perchlorsäure in Eisessig als Titrationsmittel verglichen. Es scheint nicht wahrscheinlich, dass das Reagens ernsthaft mit Perchlorsäure als Titrationmittel in nichtwässrigem Medium konkurrieren kann. Das Reagens ist zwar mit Perchlorsäure vergleichbar, soweit es die Stärke (in Essigsäure) und das Ansprechen des Instrumentes betrifft; es ist aber unwahrscheinlich, dass sich die beträchtlich höheren Kosten lediglich wegen Nichtauftretens von Niederschlägen rechtfertigen lassen. Dies ist der einzige auffindbare Vorteil.     

Aqueous acetic acid as a medium for the facile use of ferroin as redox indicator in the presence of perchloric acid

Ferroin cannot be used as an indicator in perchloric acid medium because of precipitation of ferroin perchlorate. There is no precipitation, however, if the solution contains 30%(v/v) of acetic acid.     

Non-photochemical laser-induced nucleation of supercooled glacial acetic acid

Non-photochemical laser-induced nucleation (NPLIN) of glacial acetic acid (GAA) is demonstrated. The fraction of samples nucleated depends linearly on peak laser power density at low powers (<100 MW cm(-2)) with a threshold of (9.0 ± 4.2) MW cm(-2); at higher laser powers the fraction reaches a plateau of 0.75 ± 0.24 (2σ uncertainties). A simple model based on polarizability of pre-nucleating clusters gives a value of the solid-liquid interfacial tension γ(SL) = 15.5 mJ m(-2). It is hoped that the results will stimulate new developments in experimental and theoretical studies of cluster structure and nucleation in liquids.     

The use of vanadium-sulphosalicylic acid complex as a redox indicator

In a previous communication it was reported that vanadium^V gives an intense turquoise-blue colour with sulphosalicylic acid in concentrated sulphuric acid and that the colour reaction is specific and very sensitive for the detection of vanadium^V. During our studies on the nature of the complex, it was found that vanadium^IV gives a negative colour test and that the blue colour developed by the reagent with vanadium^V is discharged on the addition of a reducing agent like iron^II, uranium^IV or hydroquinone. It was also observed that the blue colour is restored by the addition cerium^IV solution. This reversible property of the complex has been further investigated to see if the complex can be used as a redox indicator.     

Titration of basic groups in ion-exchange resins with perchloric acid in glacial acetic acid

A non-aqueous titrimetric procedure is described for the determination of basic functional groups in ion exchange resins.     

The use of 2,6-dichlorophenol-indophenol as indicator in iodometric titrations with ascorbic acid

2,6-Dichlorophenol-indophenol can be used as an indicator in iodometric methods, provided that near the end-point the solutions can be buffered with potassium hydrogen carbonate, so that ascorbic acid can be used as the titrant. Procedures for the determination of iodine, chlorine, bromine, hypochlorite, Chloramine T, bromate, iodate, permanganate, dichromate, copper(II), hydrogen peroxide, peroxydisulphate, thiosulphate, sulphite, sulphide, hydrazine and formaldehyde are described.     

Amphiphilically stabilized block copolymer particles via heterophase polymerization in glacial acetic acid

Radical heterophase polymerization of styrene in glacial acetic acid initiated with either 2,2′-azobisisobutyronitrile or poly(ethylene glycol)-azo initiators and in the presence of poly(methyl methacrylate) or poly(ethylene glycol) macromonomers is described for the first time ever. It turned out to be a convenient route to amphiphilically stabilized block copolymer dispersions. These block copolymers, after the polymerization in glacial acetic acid, can be easily transferred to other continuous phases which are selective solvents for one of the different constituent blocks. Electron microscopy results are presented regarding the morphology of the block copolymer particles in glacial acetic acid, water, and in a mixture of tetralin, cis-decalin, and tetrachlormethane. Depending on the particular composition of the block copolymers and the nature of the continuous phase, the changes in the morphology for a given block copolymer can be quite dramatic.     

Iodine monochloride in anhydrous acetic acid as an oxidizing agent

A systematic study of the redox reactions of iodine monochloride with various inorganic ions in glacial acetic acid medium is described. Sodium sulphite, mercury(I) perchlorate, antimony trichloride, arsenic trichloride and iron(II) perchlorate were examined. Potentiometric and amperometric methods were used to follow the reduction of iodine monochloride, which yields different products according to the type of reductant.     

Microcalorimetric determination of enthalpies of solution of methyl alkanes in glacial acetic acid

An empirical equation H _{s, m}=0.84n gives the enthalpy of solution of 30 branched, linear and cyclic alkanes in glacial acetic acid. The parametern is an effective carbon number which expresses the number of carbon atoms in the longest chain plus one half of the pendant methyl groups.     

Complex formation and fluorescence : Part II The use of 8-hydroxyquinoline-5-sulfonic acid as an indicator

The use of fluorescent 8-hydroxyquinoline-5-sulfonic acid complexes in titrations was examined. The disappearance of the fluorescence of these metal complexes, upon titration with a stronger, nonfluorescing complexing agent can be used to indicate endpoints in both complexometric titrations and acid-base titrations.     

Mercury-mercurous acetate indicator electrode for potentiometric titrations in anhydrous acetic acid

The authors describe a metallic mercury electrode covered with a mercurous acetate coating, its preparation, its use as an indicator electrode in anhydrous acetic acid neutralization titrations and its properties as compared with other electrodes used for the same purpose.     

Facile synthesis of novel dihydroquinoline-3,3-dicarbonitriles in the presence of glacial acetic acid as a catalyst under solvent-free conditions

A series of novel dihydroquinoline derivatives were synthesized using malononitrile, 2-aminobenzoic acid, and benzaldehydes in the presence of a catalytic amount of acetic acid, without the use of any additional cocatalyst, under solvent-free conditions. The reaction is characterized by high efficiency, easy workup, simple purification of the products, and availability of catalyst.     

Metal(II)-promoted hydrolysis of pyridine-2-carbonitrile to pyridine-2-carboxylic acid. The structure of [Cu(pyridine-2-carboxylate)2] · 2H2O

Pyridine-2-carbonitrile (2-CNpy) undergoes Cu(II) or Co(II)-promoted hydrolysis to pyridine-2-carboxamide (piaH) and/or pyridine-2-carboxylic acid (pycH). The pathway of pycH formation depends on the presence of 2-amino-2-hydroxymethyl-1,3-propanediol (AL¹) and on the central atom. In the absence of AL¹, Co(II) or Cu(II) ions mediate piaH formation under mild reaction conditions in the first hydrolytic step. Cu(II) ions assist in piaH transformation to pycH by subsequent reflux. In the presence of AL¹ and Co(II), a Co(II) complex containing pyoxaL¹ (2-(2-pyridinyl)-4,4-bis(hydroxymethyl)-2-oxazoline) is formed in the first stage; subsequent decomposition of pyoxaL¹ under the reflux yields pycH. Under similar conditions, no solid Cu(II) complex with pyoxaL¹ can be isolated, but a Cu(II) complex with coordinated pyc⁻ anions precipitates from the reaction mixture. The synthesis, spectral and magnetic properties of the complexes [Co(H₂O)₂ (piaH)₂]Cl₂, [Co(H₂O)₂(pyc)₂] · 2H₂O, [Cu(H₂O)₂(piaH)₂]Cl₂, [Cu(pyc)₂] and [Cu(pyc)₂] · 2H₂O, including the structure determination of the latter one, are described.     

A study of the reactivity of copper nanopowders in their reaction with glacial acetic acid

The reactivity of copper nanopowders obtained by mechanical treatment or electric explosion of a conductor was studied in their reaction with glacial acetic acid. Two parameters were used to evaluate the reactivity: heat effect of the reaction and the maximum rate of heat release.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 12, 2004, pp. 1937–1941.Original Russian Text Copyright © 2004 by Mikubaeva, Kobotaeva, Sirotkina.     

Methyl violet as an indicator of perfluorosulfonic membrane acid properties

Sorption of methyl violet from an aqueous solution by a perfluorosulfonic membrane is accompanied by the indicator protonation. Changes in the absorption spectra of the indicator and the corresponding color transitions, which are consistent with the shape of the isotherm of water adsorption by the membrane, characterize it as a strong solid acid.     

The use of cacotheline as an oxidation-reduction indicator before the volumetric oxidation of iron

Caotheline may be used as an oxidation-ieduction indicator in the removal of stannous tin with cerio sulfate befor the titration of ferrous non