Tsugikatsu Odashima

SOLVENT EXTRACTION OF ALUMINIUM, GALLIUM AND INDIUM WITH 4-ACYL-3-PHENYL-5-1SOXAZOLONES

Abstract Five 4-acyl-3-phenyl-5-isoxazolones (AcyPI or HL) including three new compounds, 4-(4-toluoyl)-, 4-(4-fuluorobenzoyl)- and 4-(4-nitrobertzoyl(-3-phenyl-5-isoxazolones (TPI, FBPI and NBPI, respectively), were synthesized. The extraction of aluminium(III), gallium(IH) and indium (III) into benzene with the synthesized AcyPI has been investigated. The acid dissociation constants, Ka, and the partition coefficients, Kν, of AcyPI and the extraction constants, Kax, of their metal complexes were determined. The introduction of an electron-withdrawing fluoro or nitro group to the 4-position of the benzene ring in the acyl moiety of AcyPI was very effective for increasing the Kν. value of AcyPI, but scarcely affects the Kν value. The extracted species were ML3 in all the extraction systems, where M denotes the metal ion.

Synthesis and chromogenic properties of water-soluble substituted 2-pyridyl-3′-sulphophenylmethanone 2-pyridylhydrazones and spectrophotometric and analogue derivative spectrophotometric determination of trace amounts of cobalt with 2-pyridyl-3′-sulphophenylmethanone 2-(5-nitro)pyridylhydrazone

Three water-soluble hydrazones, in which the 5-position of the pyridine ring in the hydrazine moiety of 2-pyridyl-3′-sulphophenylmethanone 2-pyridylhydrazone (PSPH) was substituted a methyl, chloro or nitro group, have been synthesised and their chromogenic properties and reactivities with metal ions investigated. The acid dissociation constants (Ka) of the synthesised hydrazones were determined spectrophotometrically. These values obeyed Hammetts law, the inductive effect of the substituents being found to reflect the pKa values. Of the synthesised hydrazones, 2-pyridyl-3′-sulphophenylmethanone 2-(5-nitro)pyridylhydrazone (PSNPH) is the most sensitive for cobalt(II) determination. It reacts with cobalt(II) to form a 1 : 2 (metal to ligand) complex. This complex is rapidly oxidised above pH 2 to give a stable cobalt(III) complex with an absorption maximum at 496 nm. Beers law is obeyed over the range 0.05–1.0 µg ml–1 of cobalt and the apparent molar absorptivity of the complex is 5.69 × 104 l mol–1 cm–1 at 496 nm. A sensitive and practical spectrophotometric method for the determination of trace amounts of cobalt with PSNPH is proposed and has been successfully applied to the determination of cobalt in steel samples. The method may be made more sensitive by employing an analogue derivative spectrophotometric technique.

Spectrophotometric and analogue derivative spectrophotometric determination of cobalt with 2,2′-dipyridyl-2-benzothiazolylhydrazone

2,2′-Dipyridyl-2-benzothiazolylhydrazone (DPBH) reacts with cobalt(II) to form a 1:3 (metal:ligand) complex having an absorption maximum at 530 nm in weakly acidic to alkaline media. The complex, once formed; remains stable even when its solution is acidified by addition of hydrochloric acid. The complex is extractable into chloroform, benzene and 4-methylpentan-2-one. The chloroform extract has an absorption maximum at 504 nm and gives a constant absorbance in the pH range 2.0–9.3. Apparent molar absorptivities and sensitivities for an absorbance of 0.001 in the proposed procedures without and with extraction are 2.50 × 104 l mol–1 cm–1, 2.35 ng cm–2 and 3.43 × 104 l mol–1 cm–1, 1.72 ng cm–2, respectively. Both proposed methods are selective for cobalt and especially in the method without extraction none of the other ions usually encountered interfere in the cobalt determination. Application of one of the proposed methods to the determination of cobalt in standard iron and steel samples and further sensitisation of the methods by employing analogue derivative spectrophotometry are also described.

Solvent extraction of some tervalent lanthanoids with 4-acyl-3-phenyl-5-isoxazolones

ABSTRACT The solvent extraction of some tervalent lanthanoid ions (Ln3+) with five 4-acyl-3-phenyl-5-isoxazolones (AcyPI or HL),i.e. 4-acetyl-, 4-benzoyl-, 4- (4-toluoyl)-, 4- (4-fluorobenzoyl) - and 4-(4-nitrobenzoyl)-3-phenyl-5-isoxazolones (API,BPI, TPI, FBPI and NBPI respectively) into benzene was studied in the presence of tri-n-butylphosphate (TBP). The extracted species were (Ln3+) (L-)3 (TBP)2 for AcyPI.

Synthesis and chromogenic properties of water-soluble hydrazones, spectrophotometric and analogue derivative spectrophotometric determination of trace amounts of iron with 2-pyridyl-3′-sulphophenylmethanone 2-pyrimidylhydrazone (PSPmH) and kinetic studies of the complex formation of iron(II) with PSPmH

Three water-soluble hydrazones have been synthesised and their chromogenic properties and reactivities with metal ions investigated. One of them, 2-pyridyl-3-sulphophenylmethanone 2-pyrimidythydrazone (PSPmH), has been utilised for the spectrophotometric determination of iron. Iron(II) reacts with PSPmH to form a stable 1 : 2 (metal to ligand) complex having absorption maxima at 379 and 580 nm in the pH range 7.3–10.0. The apparent molar absorptivities of the complex are 4.79 × 104 and 1.18 × 104 l mol–1 cm–1 at 379 and 580 nm, respectively. A selective spectrophotometric method is proposed for the determination of iron at parts per million levels and has been applied successfully to the analysis of water samples. The sensitivity of the method can be increased significantly by employing analogue derivative spectrophotometry, iron determination at parts per billion levels being feasible. Further, the formation reaction of the iron(II)-PSPmH complex has been investigated by a stopped-flow spectrophotometric technique. The rate for the complex formation is proportional to each of the concentrations of iron(II) and PSPmH and independent of the hydrogen ion concentration. On this basis the 1 : 1 complex formation between Fe2+ and undissociated PSPmH is assumed to be the rate-determining step. The rate constant for the complex formation at an ionic strength of 0.2 and at 25 °C is 1.3 × 105 l mol–1. The activation parameters for the complex formation are as follows: Ea= 44.3 kJ mol–1, ΔH‡= 41.8 kJ mol–1, ΔS‡=–6.48 J K–1 mol–1 and Δ‡= 43.9 kJ mol–1.

Extraction-spectrophotometric determination of copper with 2-thiophenealdehyde-2-benzothiazolylhydrazone

Abstract A sensitive and selective extraction-spectrophotometric method is proposed for the determination of small amounts of copper. The method is based on the formation of a copper(II)-TBTH complex, which is extractable in benzene from the acetate buffered solution of pH 5.1. The extract is stable for at least 2 h. The complex system conforms to Beers law for up to 12 μg of copper in 10.0 ml of the benzene extract at 422 nm. The molar absorptivity is 4.4·l0 4 l mol −1 cm −1 . Common cations do not interfere.

Spectrophotometric and analogue derivative spectrophotometric determination of micro-amounts of iron with 2,2′-dipyridyl-2-benzothiazolylhydrazone

The synthesis of 2,2′-dipyridyl-2-benzothiazolylhydrazone (DPBH), characteristics, reactions with various metal ions and its application in the selective determination of iron are presented. DPBH reacts with iron(II) to form a stable 1:3 metal to ligand complex having absorption maxima at 427 and 615 nm in 0.4% Triton X-100 solution. A solution of the complex gives a constant absorbance in the pH range 4.5–8.4 at 427 nm and 3.0–9.6 at 615 nm. The molar absorptivity, sensitivity for an absorbance of 0.001 and relative standard deviation for 10.3 µg of iron (10 replicates) are 3.41 × 104 and 1.23 × 104 l mol–1 cm–1, 1.64 and 4.54 ng cm–2, and 0.7 and 0.5% at 427 and 615 nm, respectively. Application of the proposed method to the determination of iron in water samples and further sensitisation of the method by employing analogue derivative spectrophotometry are also described.

Synthesis and chromogenic properties of phthalazinohydrazones and spectrophotometric and analogue derivative spectrophotometric determination of micro-amounts of nickel with 5-methylfurfural-1-phthalazinohydrazone

The synthesis of two new hydrazones is described together with the results of spectrophotometric studies of their chromogenic reactions. One of them, 5-methylfurfural-1-phthalazinohydrazone (MFPH), has been utilised for the spectrophotometric determination of nickel at the parts per million level. On the basis that nickel(II) reacts with MFPH to form a stable 1 : 2 (metal: ligand) complex, having absorption maxima at 470 and 503 nm in 2.4% Triton X-100 solution and the solution of the complex gives a constant absorbance in the pH range 7.2–10.4, a sensitive and practical method for the determination of nickel has been proposed. The molar absorptivity and the sensitivity for an absorbance of 0.001 are 3.7 × 104 l mol–1 cm–1 and 1.6 ng cm–2, respectively, the relative standard deviation for 15.3 µg of nickel (15 replicates) being 0.7%. Application of the proposed method to the determination of nickel in standard iron and steel samples and in chemicals and further sensitisation of the method by employing analogue derivative spectrophotometry are also described.

Substituted 2-thiophenealdehyde-2-benzothiazolyl-hydrazones as analytical reagents for copper

Abstract The analytical properties of 5-chloro-, 5-bromo- and 5-methyl-2-thiophenealdehyde-2-benzothiazolylhydrazone (CTBH, BTBH and MTBH, respectively), are compared with those of 2-thiophenealdehyde-2-benzothiazolylhydrazone (TBH). The acid dissociation constants have been determined, and the 5-substituent effect is discussed. The complex formation of the reagents with several metal ions has been examined spectrophotometrically. Extraction—spectrophotometric determinations of traces of copper are proposed. The copper complexes can be extracted quantitatively into benzene over wide pH ranges (from weakly acidic to alkaline medium) and the molar absorptivities are high (4–5· 104 l mol-1 cm-1). The complexes formed are 1:2 (copper:ligand) in all cases. There are few interferences from common ions except silver(I), mercury(II), thiocyanate and citrate.

Synthesis and properties of hydrazones from 3- and/or 5-nitro-2-pyridylhydrazine and heterocyclic aldehydes, characterization of their complexes and extraction-spectrophotometric determination of traces of nickel with 2-pyridinecarbaldehyde 3,5-dinitro-2-pyridylhydrazone

Abstract Four new hydrazones, 2-pyridinecarbaldehyde 3-nitro-2-pyridylhydrazone, 2-pyridinecarbaldehyde 3,5-dinitro-2-pyridylhydrazone (PA-3,5-NPH), 2-quinolinecarbaldehyde 5-nitro-2-pyridylhydrazone and 6-phenanthridinecarbaldehyde 5-nitro-2-pyridylhydrazone, were synthesized. Their properties and reactivities with metal ions and the properties of the resultant complexes were investigated spectrophotometrically and compared mutually and with those of 2-pyridinecarbaldehyde 5-nitro-2-pyridylhydrazone. Useful information on the molecular design of the hydrazone reagent was obtained. A highly sensitive and practical extraction-spectrophotometric method for the determination of nickel with PA-3,5-NPH was developed and applied successfully to the determination of nickel in steel samples.