Extraction and Spectrophotometric Determination of Iron(III) by 1-phenyl-2-methyl-3-hydroxy-4-pyridone

The extraction and spectrophotometric determination of iron (III) by 1-phenyl-2-methyl-3-hyd:roxy-4-pyridone (HX) are described. At pH > 1.5 97°/o of the iron(III) can be extracted. A quantitative reextraction of iron from the organic phase is possible with an acid concentraicm higher than 1 M. The composition of the iron(III)-HX complex formed tn the organic phase was investigated spectrophotometrically, radiometrically and by a quantitative analysis of the isolated species. In the aqueous phase iron(III) and HX form three different complexes, depending on the initial iron(III)HX concentration ratio and the pH of the solution. They are the violet Fex2+, the orange-red Fex2+ and the orange-yellow FeX3. The latter is identical with the complex found in the organic phase

Characterization of Isothiocyanato Niobates(V) Isolated from Solutions for the Spectrophotometric Determination of Niobium

From aqueous solutions containing niobium(V), sulphuric acid and an excess of thiocyanate, under the conditions for the spectrophotometricdetermination of niobium, the compounds [(C6H5)4P]2 [NbO(NCS)s], [(C6Hs)4As]2 [NbO(NCS)s] and [(C2Hs)4N]2 [NbO(NCS)5) were isolated either by crystallization or by extraction with diethyl ether and evaporation o·f the extracts. (C2H2N2S3)2H[Nb(NCS)a] was isolated from an ether extract only. The compounds have been characterised by analytical data, .infrared spectra, magnetic and conductivti.ty measurements. In all the compounds the thiocyanate groups bond through the nitrogen atom

Application of 1-(4-Tolyl)-2-methyl-3-hydroxy-4-pyridone for the Extraction and Spectrophotometric Determination of Iron(III)

The application of 1-(4-tolyl)-2-methyl-3-hydroxy-4-pyridone (HY) to the extraction and spectrophotometric determination of iron (III) are described. In the aqueous phase iron (III) and HY form two different complexes; FeY2+ and FeY2+, depending on the iron-HY concentration ratio and the pH of the solution. It was found that only the FeY2+ complex is extracted into chloroform

Extraction and Spectrophotometric Determination of Iron(III) by 1-phenyl-2-methyl-3-hydroxy-4-pyridone

The extraction and spectrophotometric determination of iron (III) by 1-phenyl-2-methyl-3-hyd:roxy-4-pyridone (HX) are described. At pH > 1.5 97°/o of the iron(III) can be extracted. A quantitative reextraction of iron from the organic phase is possible with an acid concentraicm higher than 1 M. The composition of the iron(III)-HX complex formed tn the organic phase was investigated spectrophotometrically, radiometrically and by a quantitative analysis of the isolated species. In the aqueous phase iron(III) and HX form three different complexes, depending on the initial iron(III)HX concentration ratio and the pH of the solution. They are the violet Fex2+, the orange-red Fex2+ and the orange-yellow FeX3. The latter is identical with the complex found in the organic phase

Solvent Extraction of Copper as a Thiocyanate Complex. Reducing Effect of Thiocyanate

Extraction of copper(II) from sulphuric and hydrochloric acid Solutions containing an excess of thiocyanate ions with tetraphenylphosphonium (TPP) chloride and cetyltrimethylammonium (CTMA) bromide in chloroform was investigated. The optimum conditions for quantitative extraction (over 99%) by both extractants were determined. The extraction behaviour of CTMA was found to be more efficacious than that of TPP because a low excess of thiocyanate and extractant was required and extraction was feasible even from a higher concentration of sulphuric acid. The formation of an extractable copper(II) thiocyanate complex with CTMA could also be determined spectrophotometrically by measuring the absorbance of the organic phase at 409 nm. The presence of ascorbic acid decreased the absorbance at 409 nm but the formed copper(I) thiocyanate was quantitatively extracted with CTMA, independently of the ascorbic acid concentration. Thiocyanate ions also exercised a reducing effect on copper(II) at pH > 1.3; with increasing pH and/or prolonged shaking time of the aqueous and organic phases, the reducing effect increased. The composition of the extracted copper(II) complex was determined by the distribution and spectrophotometric methods. The molar ratio Cu:SCN:TPP (CTMA) of the extracted complex was 1:4:2; accordingly, its composition was [TPP]2 [Cu(SCN)4] or [CTMA]2 [Cu(SCN)4]

Extraction and Formation of Iron(III) Thiocyanate Complexes: Application for Spectrophotometric Determination of Iron

Extraction of iron(III) from sulphuric and hydrochloric acid solutions containing an excess of thiocyanate ions with tetraphenylphosphonium (TPP) chloride and cetyltrimethylammonium (CTMA) bromide in chloroform was investigated. Optimum conditions for extraction by both extractants were determined. The extraction behaviour of CTMA was found to be more efficacious than that of TPP because less thiocyanate and extractant was required. Better extraction efficiency of CTMA can be attributed to surface-active properties of this substance. Formation of an extractable iron(III) thiocyanate complex with CTMA or TPP was also determined spectrophotometrically by measuring the absorbance of the organic phase at 473 nm or 506 nm, respectively. The composition of the extracted iron(III) complexes was determined by distribution and spectrophotometric methods. The molar ratio Fe:SCN:TPP of the extracted complex was 1:4:1; accordingly, its composition was [TPP][Fe(SCN)4]. The molar ratio Fe:CTMA of the extracted complex was 1:3. The molar ratio Fe:SCN in the complex extracted with CTMA could not be determined because of the turbidity in solutions containing less than 0.01 mol dm–3 thiocyanate ion, but it was concluded that the composition of the extracted complex was [CTMA]3[Fe(SCN)6]

Application of 1-(4-Tolyl)-2-methyl-3-hydroxy-4-pyridone for the Extraction and Spectrophotometric Determination of Iron(III)

The application of 1-(4-tolyl)-2-methyl-3-hydroxy-4-pyridone (HY) to the extraction and spectrophotometric determination of iron (III) are described. In the aqueous phase iron (III) and HY form two different complexes; FeY2+ and FeY2+, depending on the iron-HY concentration ratio and the pH of the solution. It was found that only the FeY2+ complex is extracted into chloroform

Extraction and Characterization of Niobium(V) Thiocyanate Complexes

Extraction of niobium(V) from sulphuric and hydrochloric acid Solutions containing an excess of thiocyanate ions with tetraphenylphosphonium (TPP) and tetraphenylarsonium (TPA) chloride into chloroform was investigated. The maximum extraction of niobium from sulphuric acid Solutions was about 91% and from hydrochloric acid Solutions about 94%. Chloride ions produced a moderate synergistic effect. Niobium(V) was quantitatively extracted (over 99%) from sulphuric and hydrochloric solutions only if chloride ions were also in excess and a lower excess of thiocyanate and extractant was required than in extraction without addition of chloride. The optimal conditions for the quantitative extraction of niobium were 0.2-0.5 M H2SO4 or 0.2-4 M HCl, 0.2-0.7 M thiocyanate and more than 4 M chloride in the aqueous phase, and TPP (TPA) concentration in the organic phase higher than 3 x 10-3 M. The extracted complexes in chloroform had an absorption maximum at 390 nm or at 390 and 320 nm, depending on the composition of the aqueous phase. Absorption spectra were studied as a function of H2SO4, HCl, thiocyanate and chloride concentrations in the aqueous phase. The optimal conditions for the spectrophotometric determination of niobium by measuring the absorbances of the organic phase at 390 nm were 1-2 M HCl, 0.1-0.5 M thiocyanate and TPP (TPA) chloride in chloroform of at least 5 x 10-3 M. A total chloride concentration lower than 2.2 M had no effect on absorbance. The mechanism of extraction based on the formation of ion-associated compounds between the onium cation and the thiocyanatoniobate(V) or mixed ligand chlorothiocyanatoniobate(V) anion is discussed

Application of 1-(4-Tolyl)-2-methyl-3-hydroxy-4-pyridone to the Spectrophotometric Determination of Vanadium(V)

The application of 1-(4-tolyl)-2-methyl-3-hydroxy-4-<pyridone (HY) for the spectrophotometric determination of V(V) by extraction into chloroform was ~nvestigated. lit was found that depending on the extraotion condiltions three types of complexes are formed. At pH 1.2-2.5 an orange complex of the composition V02Y ·HY with a maximum absorption at 500 ([]Jm is formed. However, at 1.2-2.0 M hydrogen ion concentration and in .the presence of an excess of chloride ions a blue complex V02Cl(HY)2 with maximum absorption at 625 nm was found. In the presence of an excess of perchlorate i01I1s and at 0.2-1.0 M hydrogen ion concentration a blue complex V02Cl04(HY)3 with maximum absorption at 605 was found. Solutions of these complexes show great stability and they follow the Lambert-Beer\u27s law. Procedures for the determination of vanadium at either 500 or 625 nm are very simple fast and selective. The compositions of the complexes have been characterized m chloiroform solution. They were also isolated in crystalline form and iinderntified by elemental analysis and infrared spectroscopy

Application of 1-(4-Tolyl)-2-methyl-3-hydroxy-4-pyridone to the Spectrophotometric Determination of Vanadium(V)

The application of 1-(4-tolyl)-2-methyl-3-hydroxy-4-<pyridone (HY) for the spectrophotometric determination of V(V) by extraction into chloroform was ~nvestigated. lit was found that depending on the extraotion condiltions three types of complexes are formed. At pH 1.2-2.5 an orange complex of the composition V02Y ·HY with a maximum absorption at 500 ([]Jm is formed. However, at 1.2-2.0 M hydrogen ion concentration and in .the presence of an excess of chloride ions a blue complex V02Cl(HY)2 with maximum absorption at 625 nm was found. In the presence of an excess of perchlorate i01I1s and at 0.2-1.0 M hydrogen ion concentration a blue complex V02Cl04(HY)3 with maximum absorption at 605 was found. Solutions of these complexes show great stability and they follow the Lambert-Beer\u27s law. Procedures for the determination of vanadium at either 500 or 625 nm are very simple fast and selective. The compositions of the complexes have been characterized m chloiroform solution. They were also isolated in crystalline form and iinderntified by elemental analysis and infrared spectroscopy