N-phenylbenzohydroxamic Acid Research Articles

A Statistical Model of the Extraction-Process Parameters of Uranium–N-Phenylbenzohydroxylamine–Trioctylphosphine Oxide Complex in Chloroform Solution

Abstract The solvent extraction of uranium has been carried out with chloroform solutions of N-phenylbenzohydroxamic acid (BPHA) and Trioctylphosphine oxide (TOPO). The experiments were statistically planned to quantitatively assess the effect of the concentration of BPHA, the concentration of TOPO and the aqueous-phase pH of the solution on the percentage extraction of uranium. In addition, the interactional influence of the above-mentioned variables was also studied. A regression equation has been developed which successfully predicts the percentage extraction of uranium with the values of the variables lying between the selected range of experiments.

Effect of micelles on the acid hydrolysis of N-phenylbenzohydroxamic acid

The effect of cationic (cetylpyridinium bromide and cetylpyridinium chloride) anionic (sodium dodecyl sulfate and lithium dodecyl sulfate) and non-ionic (Brij-35 and Triton-X-100) micelles on the acid-catalyzed hydrolysis of N-phenylbenzohydroxamic acid in 20 vol.% dioxane medium has been investigated. The kinetic results are explained by both pseudo-phase and Piszkiewicz cooperativity models.

Micellar Rate Effects on Alkaline Hydrolysis of Hydroxamic Acids

Abstract The kinetics of alkaline hydrolysis of N-phenylbenzohydroxamic acid and its para-substituted derivatives (X–C6H4–CO–N(OH)C6H5; X = H, CH3, OCH3, NO2, F) have been investigated in the presence and absence of cationic (ethyl hexadecyl)dimethylammonium bromide) and anionic (sodium-1-dodecanesulfonate and lithium dodecyl sulfate) surfactants at 55 °C in 5% (v/v) dioxane–water medium. A catalytic effect was found with cationic surfactants and an inhibitory effect in the presence of anionic surfactants was observed. The rate-surfactant profiles can be analyzed in terms of pseudo-phase and Piszkiewicz models.

High-performance liquid chromatography with electrochemical detection for the determination of vanadium(V) in river water and mussel samples

A highly sensitive method has been developed for the determination of vanadium(V) by reversed-phase liquid chromatography with electrochemical detection at −0.60V vs. Ag AgCl . The metal complex with N-phenylbenzohydroxamic acid was separated on a C 18 (ODS) column; the mobile phase was a 1:1 ( v v ) mixture of acetonitrile-acetate buffer (0.02 mol l −1, pH 3.5) containing 0.05 mol l −1 potassium nitrate. The elution peak due to the vanadium(V) complex appeared on the chromatogram, and the peak height was proportional to the concentration of the metal ion in the range of 3.0 − 100.0 ng ml −1. The detection limit for vanadium(V) was 1.0ng ml −1. The method has been applied to the determination of vanadium in two river water samples and one mussel homogenate with precise results.

Kinetic Studies of Alkaline Hydrolysis of N-Phenylbenzohydroxamic Acid in the Presence of Micelles

Kinetic Studies of Alkaline Hydrolysis of N-Phenylbenzohydroxamic Acid in the Presence of Micelles

Medium Effects on Alkaline Hydrolysis of N-Phenylbenzohydroxamic Acid

Medium Effects on Alkaline Hydrolysis of N-Phenylbenzohydroxamic Acid

Kinetics of the Alkaline Hydrolysis of N-Phenylbenzohydroxamic Acid

Kinetics of the Alkaline Hydrolysis of N-Phenylbenzohydroxamic Acid

Determination of vanadium in clam tissue (Citterea sp.) by normal-phase high-performance liquid chromatography with N-phenylbenzohydroxamic acid.

A normal-phase high-performance liquid chromatography (HPLC) method for the selective determination of vanadium with N-phenylbenzohydroxamic acid (PBHA) is described. The Vv-PBHA complex was preconcentrated by solvent extraction into trichloromethane and injected on to a silica gel column for HPLC, with a mobile phase of methanol-trichloromethane (3 + 97) containing 9.4 x 10(-4) mol dm-3 PBHA. The detection limit for vanadium by the proposed method was 8.3 and 1.7 micrograms dm-3 for phase-volume ratios of 5:1 and 20:1 (aqueous-to-organic), respectively. Vanadium has been determined in clam tissue with satisfactory precision.

Electrochemistry of iron(III) tris-hydroxamate complexes: Kinetic and thermodynamic studies

The reaction of reduction of iron(III) complexes with N-methylbenzohydroxamic acid and N-phenylbenzohydroxamic acid, studied by cyclic voltammetry, is quasi-reversible and the global rate constants at the standard potential have been determined. The formation constants of iron(III) and iron(II) complexes have been determined. The iron(II) complex with benzohydroxamic acid is probably followed by the dissociation of the weakly bound iron(II) complex. The influence of the N-substituents has also been analysed.

Physicochemical Studies of Complexes of Transition Metal Ions with N-Phenylbenzohydroxamic Acid

Physicochemical Studies of Complexes of Transition Metal Ions with N-Phenylbenzohydroxamic Acid

Differential-pulse polarographic determination of copper and iron in biological and river-water samples as their N-phenylbenzohydroxamic acid complexes by gas-stirred solvent extraction with ethyl acetate

A simple and rapid method for the simultaneous determination of CuII and FeIII in biological and river-water samples has been developed. The method utilizes the extraction of metal–N-phenylbenzohydroxamic acid complexes into ethyl acetate, followed by direct determination by differential-pulse polarography (DPP) in the organic medium (1.5 ml). Two well defined DPP peaks appear at –0.17 and –0.59 V versus the Ag–AgCl reference electrode for CuII and FeIII, respectively. Both the extraction and oxygen-removal steps in the analytical scheme can be performed by passing nitrogen through the two phases. This feature enhances the time efficiency and simplifies the method of solvent extraction with polarographic detection. Detection limits (signal to noise ratio = 3) are 20 ng ml–1 for CuII and 10 ng ml–1 for FeIII in the original aqueous phase, and both DPP peak heights are directly proportional to metal concentrations in the aqueous phase of up to 10 µg ml–1. Except for VV, common metal ions examined do not interfere with the simultaneous determination of the two metal ions.

Extraction-Spectrophotometric Determination of Fluoride Using N-Phenylbenzohydroxamic Acid

Abstract Fluoride gives a very stable complex with scandium and, hence, by determining the unreacted scandium, the fluoride content can be calculated. Excess scandium is reacted with an ethanolic solution of N-benzoylphenylhydroxylamine (BPHA) at pH 6.0, and the scandium-BPHA complex is extracted into isoamyl alcohol. Scandium is determined spectrophotometrically after adding xylenol orange. Beer's law for fluoride is obeyed in the range of 0.05 –1.5 ppm; the molar absorptivity is 1.94×104 1 mol−1 at 565 nm. The procedure is applicable for the determination of fluoride in various types of samples.

Reactions of dioxomolybdenum(VI) hydroxamate and thiohydroxamate complexes with organohydrazines. Structures of oxohydrazido(2−) complexes [MoO(N 2Ph 2)(PhC(X)N(Me)O) 2], where X = O and S, and of the bis-diazenido complex [Mo(N 2Ph) 2(PhC(S)N(Me)O) 2

The six-coordinate cis-oxohydrazido(2−) molybdenum(VI) complexes [MoO(N 2Ph 2)(PhC(S)N(Me)O) 2] ( 1) and [MoO(N 2Ph 2)(PhC(O)N(Me)O) 2] ( 3) were prepared by reaction of N, N-diphenylhydrazine with the appropriate cis-dioxomolybdenum(VI) precursor. The thiohydroxamato and hydroxamate coligands differ only in their S- and O-donor atoms. A bis-hydrazide(2−) complex, [Mo(N 2Ph 2) 2(PhC(S)N(Me)O) 2] ( 2) and a bis-diazenido complex [Mo(N 2Ph) 2(PhC(S)N(Me)O) 2] ( 4) were also prepared. Crystal data are as follows: 1: monoclinic, P2 1/ c, a = 12.182(2), b = 11.238(1), c = 20.035(2) Å, β = 90.75(1)°, U = 2742.5 Å 3, Z = 4. R = 0.038 and R w = 0.041 for 3945 observed reflections. 3: triclinic, P 1 , a = 12.060(4), b = 17.795(7), c = 14.025(5) Å, α = 93.67(2), β = 108.35(2), γ = 91.41(2)°, U = 2847.8 Å 3, Z = 4. R = 0.062 and R w = 0.084 for 5056 observed reflections. 4: monoclinic, C2/ C, a = 24.775(12), b = 9.030(5), c = 14.322(7) Å, β = 109.72(8), U = 3016.2 Å 3, Z = 4. R = 0.059 and R w = 0.056 for 1731 observed reflections. The geometries of the cis-MoO(N 2Ph 2) fragment in 1 and 3 are similar and indicative of multiply bonded oxo and hydrazide(2−) groups, disposed some 103° relative to each other. The CO oxygen donor in 3 and CS sulfur donor in 1 are not in the same configuration with respect to the cis-[MoO(N 2Ph 2)] fragment. In the cis-bis-diazenido complex ( 4) the two multiply bonded N 2Ph groups have an essentially linear MoNN geometry and an angle of 92.2° between them. The two thiohydroxamate sulfur atoms are trans to each other and 2.469(2) Å from the Mo atom. Preliminary attempts to obtain [(PhN 2) 2MoL 2] bis-diazenido species led to the isolation of partially characterized products which probably contain μ-ethoxo bridged (PhN 2) 2Mo fragments, cocrystallized in the case of L = PhC(O)N(Ph)O −, with benzanilide, PhC(O)N(Ph)H. These observations led to the production of benzanilide from N-phenylbenzohydroxamic acid by reaction with phenylhydrazine or hydrazine in the presence of trace quantities of [MoO 2(acac) 2].

Selective determination of tantalum in ores by extraction with N-phenylbenzohydroxamic acid in toluene

A method for tantalum(V) spectrophotometric determination in a non-aqueous phase is proposed. Tantalum(V) is extracted with N-phenylbenzohydroxamic acid into toluene from a 5M hydrochloric acid solution. The colour is then developed by addition of 4-(2-pyridylazo)-resorcinol (PAR) solution in N,N-dimethylformamide and pyridine to an aliquot of the extracted phase. The Ta(V)-PAR complex gives an absorption maximum at 547 nm with a molar absorptivity of 3.88 ± 0.04 . 104 l mol-1 cm-1. The method has been applied to the selective determination of tantalum in ores with good accuracy and precision.

Determination of total carbonate by ligand exchange

An indirect spectrophotometric method is described for the determination of carbonate, based on the decoloration of dilute chloroform solutions of uranium(VI)-N-phenylbenzohydroxamic acid by shaking them with an aqueous solution of anions. Several variables affecting the decoloration (pH, shaking time, etc.) were investigated. The carbonate concentration range over which the decoloration of the chloroform solutions showed a linear dependence (30–100 µg ml–1 of carbonate in the aqueous phase) and the interferences caused by other ions were also studied. The proposed method was applied to the determination of carbonate in mineral and sea waters and pharmaceutical samples and the results obtained showed good agreement with those obtained using the back-titration method of Gripenberg.

Extraction and spectrophotometric determination of zirconium(IV) with N-phenylbenzohydroxamic acid and phenylfluorone

N-Phenylbenzohydroxamic acid reacted with zirconium(IV) in 3.5 M hydrochloric acid to give a colourless complex that could be extracted into chloroform. The chloroform extract of the zirconium(IV) complex, on a second extraction from a dilute hydrochloric acid medium (0.5 M) in the presence of phenylfluorone and acetone, formed an intensely coloured complex with an absorption maximum at 534 nm. The molar absorptivity under optimum conditions was 1.125 × 104 dm3 mol–1 cm–1. The system obeyed Beer's law up to 7 p.p.m. of zirconium(IV) in the extract. Large amounts of many cations and anions, including a ten-fold molar excess of vanadium(IV), iron(III) and molybdenum(VI), were tolerated. Equimolar amounts of aluminium(III), fluoride, phosphate and vanadium(V) were also tolerated. A slight interference from titanium(IV) and niobium(V) was observed when the mole ratio of zirconium(IV) to foreign ion exceeded 1.0 : 0.3. The method was applied successfully to the determination of zirconium(IV) in zircon sand.

Separation and microdetermination of rare earth metals with N-phenylbenzohydroxamic acid and Xylenol Orange

A simple, sensitive and selective method for solvent extraction and spectrophotometric determination of lanthanum(III), praseodymium(III), neodymium(III) and samarium(III) is described. The rare earth metals are extractable into chloroform solution of N-phenylbenzohydroxamic acid (PBHA) at pH9–10. Various parameters are studied to optimize the extraction conditions. Stoichiometry of the complexes and the effect of various ions is discussed. The molar absorptivity is found to increase from 65,000 to 93,000 1·mol−1· cm−1 with the increase in atomic number of the rare earths. The stability constants of the complexes, separation factors and pH5 0 are discussed.

Extraction and spectrophotometric determination of molybdenum(VI) with N-phenylbenzohydroxamic acid and phenylfluorone

N-Phenylbenzohydroxamic acid reacts with molybdenum(VI) in 3.5–6.0 M hydrochloric acid to give a complex that is extractable into chloroform. The chloroform extract of the molybdenum complex, on second extraction from a dilute hydrochloric acid medium (0.2–0.3 M) in the presence of phenylfluorone and ethanol, forms an intensely coloured complex possessing an absorption maximum at 518 nm. Job's method of continuous variation reveals that the complex is Mo(VI)—2NPBHA—PF. The molar absorptivity under optimum conditions is 7.4 × 104 cm3 mol−1 cm−1. The system obeys Beer's law up to 0.6 ppm of molybdenum(VI). Considerable amounts of many cations and anions can be tolerated. The interference from vanadium(IV) and vanadium(V) can be eliminated by the addition of sodium metabisulphite, whereas the interference from titanium(IV) is mitigated by oxalate ions. The method has been successfully applied for the determination of molybdenum in a standard steel sample.

Extraction, Spectrophotometric and atomic Absorption Spectrophotometric Determination of Tellurium with N-Phenyl Benzohydroxamic Acid

Abstract Solvent extraction, spectrophotometric and atomic absorption spectrophotometric determination of tellurium-(IV) in nanogram levels are described. The tellurium(IV) forms yellow colored complex with N-phenylbenzohydroxamic acid (PBHA) which is extractable into chloroform from 7 M HCI04. Te-PBHA complex has a maximum absorbance at 345 nm with the molar absorptivity 3.5 × 104 1 mol−1 cm−1 and Sandell's sensitivity 0.00365 μg/cm2. The tellurium(IV) is also determined in the range of 0.01 – 0.08 ppm by flameless atomic absorption spectrophotometry using GEC HG 900 vapor generation accessay. Effect of molarity, reagent concentrntions, diverse ions on the extraction of tellurium complex were studied. The tellurium was determined in presence of selenium and also in standerd samples.

Spectrophotometric determination of thiocyanate following complexation with mercury(II) and N-phenylbenzohydroxamic acid

A simple solvent extraction and spectrophotometric method for the determination of trace amounts of thiocyanate is described. Thiocyanate is selectively separated from other ions by reaction with mercury(II). The excess of mercury(II) is determined using N-phenylbenzohydroxamic acid (PBHA) at pH 6.8 and the thiocyanate concentration calculated. Mercury(II) complexes rapidly with PBHA in ethanol and is further extracted into chloroform. Beer's law is obeyed for thiocyanate in the range 0–10 p.p.m. at 550 nm for a fixed amount, 20 p.p.m., of mercury(II). The method has been applied to the determination of thiocyanate in human blood serum, urine and some organoisothiocyanate samples.