Spectrophotometric determination of vanadium(V) as a mixed thiocyanate-4-pyridone complex

The spectrophotometric determination of vanadium(V) as a mixed thiocyanate-3-hydroxy-2-methyl-1-phenyl-4-pyridone (HX) complex and as a mixed thiocyanate-3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone (HY) complex is described. The extracted complexes in chloroform have a maximum absorbance at 450 and 650 nm. The optimal conditions for the extraction and spectrophotometric determination of vanadium(V) are determined. The solutions of the V-SCN-HX and V-SCN-HY complexes in chloroform obey Beer's law in the range 1–10 ppm of vanadium, and are stable for at least 24 hr. The molar absorptivity of the method is 6.8 × 10³ liters mol^?1 cm^?1. The molar ratio V:SCN:HX (HY) of the extracted complex is 1:1:2.     

Spectrophotometric determination of titanium(IV) with 1-phenyl-2-methyl-3-hydroxy-4-pyridone

Analytical and Bioanalytical Chemistry -     

N-甲基-4-羟基-5-苯基-2-吡啶酮的合成

以丙二酸和二氯亚砜为起始原料,经氯代、环合、催化氢化及烷基化反应合成了新化合物——N-甲基-5-苯基-4-羟基-2-吡啶酮,总收率38.7％,其结构经1H NMR,IR和EI-MS表征.     

Structure and chemistry of 4-hydroxy-6-methyl-2-pyridone

The structure of 4-hydroxy-6-methyl-2-pyridone formed by the reaction of 6-methyl-2H-pyran-2,4(3H)-dione and ammonia is characterized. A method is discussed for the structure determination of pyridone type compounds. Reaction of 4-hydroxy-6-methyl-2-pyridone with an equivalent amount of benzenesulfonyl chloride gives 4-benzenesulfonyloxy-6-methyl-2-pyridone. With two equivalent amounts of benzenesulfonyl chloride, 2,4-dibenzenesulfonyloxy-6-picoline is formed. 4-Hydroxy-6-methyl-2-pyridone is preferentially attacked by electrophiles at the 3 position.     

Solvent extraction of molybdenum(VI) with 1-Phenyl-2-methyl-3-hydroxy-4-pyridone

Summary The extraction of molybdenum(VI) from aqueous hydrochloric or perchloric acid solution by 1-phenyl-2-methyl-3-hydroxy-4-pyridone (HX) dissolved in chloroform has been studied. Molybdenum(VI) is quantitatively extracted from aqueous solution in the range 0.001–1M hydrogen ion concentration. Outside this range, the extraction of molybdenum decreases and at 10M acid concentration or at pH>6 practically all the molybdenum remains in the aqueous phase. Molybdenum can be stripped with 10M HCl. The composition of the extracted molybdenum(VI) species was found to be MoO₂X₂. This complex, dissolved in chloroform, has a maximum absorbance at 317 nm and a molar absorptivity of 2.5×10⁴ 1 · mole^–1 · cm^–1. Owing to this property, molybdenum can be determined spectrophotometrically directly in the organic phase.

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Zusammenfassung Die Extraktion von Mo(VI) aus wäßriger Salzsäure oder Perchlorsäure mit 1-Phenyl-2-methyl-3-hydroxy-4-pyridon (HX) in chloroformischer Lösung wurde untersucht. Sie erfolgt quantitativ bei 0,001–1-molarer H-Ionenkonzentration. Außerhalb dieses Bereiches fällt die Extraktionsrate ab und aus 10-m Säure bzw. bei pH>6 bleibt praktisch alles Molybdän in der wäßrigen Phase. Mit 10-m Salzsäure kann man Mo abtrennen. Die Zusammensetzung der extrahierten Mo-Verbindung entspricht der Formel MoO₂X₂. Dieser in Chloroform gelöste Komplex hat ein Absorptionsmaximum bei 317 nm und eine molare Extinktion von 2,5 · 10⁴l · Mol^–1 cm^–1. Demzufolge läßt sich Molybdän unmittelbar in der organischen Phase spektrophotometrisch bestimmen.

     

C-acylation of heterocyclic keto-enols Communication 9. Acetyl derivatives of 4-hydroxy-6-methyl-1-phenyl-2(1H)-pyridone

Conclusions A study was made of the acetylation of 4-hydroxy-6-methyl-1-phenyl-2(1H)-pyridone with acetic acid in presence of polyphosphoric acid and of phosphoryl chloride. The structures of the C- and O-acetyl derivatives obtained were proved by independent synthesis and from IR and UV spectral data.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1605–1607, September, 1966.     

Extractive spectrophotometric determination of molybdenum as a thiocyanate-2-acetylpyridinethiosemicarbazone complex

A new spectrophotometric method for the determination of molybdenum is based on the extraction of the orange red molybdenum thiocyanate-2-acetylpyridinethiosemicarbazone complex into chloroform from hydrochloric acid. The complex has an absorption maximum at 470 nm with a molar absorptivity of 1.7 × 10⁴ liters mol^?1 cm^?1. Beer's law is valid from 0.1 to 6.5 ppm of molybdenum. The equilibrium shift method indicated a 1:4:2 complex. The method has been used successfully for the determination of molybdenum in molybdenum steels.     

Extraction and spectrophotometric determination of titanium(iv) with 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone

Titanium(IV) in sulphuric, perchloric and hydrochloric acid media reacts with 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone (HY) to give a complex which is extractable into chloroform. The composition of the extractable complex depends on the acidity of the aqueous phase and on which mineral acid is used. The mixed titanium-perchlorate-HY complex which is formed in the presence of excess of perchlorate is the most suitable for the spectrophotometric determination of titanium. The molar absorptivity of the complex is 1.6×10⁴1·mole^–1·cm^–1 at 355 nm. The optimum titanium concentration range is 0.5–6,g/ml. The method has been successfully applied to the determination of titanium in samples of bauxite and alumina refractory.     

Extraction and complex formation of niobium(V) with 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone

The extraction of niobium(V) from aqueous hydrochloric and sulphuric acid solutions with 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone (HY) dissolved in chloroform is described. Niobium(V) can be quantitatively extracted with HY in the form of two different complexes depending on the chloride ion concentration in the aqueous phase. At a low chloride concentration or without chloride in the aqueous phase niobium(V) is extracted with HY in the form of Nb(OH)₃Y₂ and at a high chloride concentration as a mixed Nb(OH)₃ClY complex. Niobium extraction with HY enables the separation of niobium(V) from zirconium(IV) and hafnium(IV). The formation of a mixed chloro-4-pyridone complex is also applicable for the spectrophotometric determination of niobium in the organic phase at the maximum absorption at 350 nm.     

Extraction and complex formation of thorium(IV) with 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone

The extraction of thorium(IV) from aqueous hydrochloric and nitric acid solution by 3-hydroxy-2-methyl-1-(4-tolyl)-4-pyridone (HY) dissolved in chloroform has been studied. Thorium(IV) is quantitatively extracted at pH > 3.8 from the hydrochloric acid solution containing an excess of chloride ions, and at pH > 2.5 from nitric acid solution containing an excess of nitrate ions. Extracted thorium can be quantitatively stripped with 1 M hydrochloric or nitric acid. The separation of protactinium from thorium is described. The mechanism of thorium extraction has been studied. The composition of the extractable thorium complexes depends on the HYTh concentration ratio and on the kind of mineral acid present in the aqueous phase. The solid complex ThCl₃Y·HY was isolated and its composition verified by chemical analysis.     

Spectrophotometric determination of molybdenum as a mixed thiocyanate-monooctyl α-anilinobenzylphosphonate complex

A sensitive method for the spectrophotometric determination of molybdenum is described. Molybdenum is reduced with ascorbic acid in hydrochloric acid solution, and complexed with thiocyanate ions, and the complex formed is extracted with monooctyl α-anilinobenzylphosphonate (MOABP) in chloroform. The molar absorptivity of the method is 5858 l mole^-1 cm^-1 at 470 nm. Beer's law is obeyed in the range 0.7–28 μg Mo ml^-1. Few metals interfere; the separation of the interfering elements is discussed. The composition of the extracted complex is Mo(SCN)₅·3 MOABP.     

A mass spectrometric study of 4-hydroxy-6-methyl-2-pyridone and its derivatives

The mass spectra of 4-hydroxy-6-methyl-2-pyridone, its N-methyl and N-phenyl derivatives, and also their 4-O-acetyl and 3-C-acyl derivatives have been studied. The proposed fragmentation pathways were supported by comparison of the mass spectra and in some cases by the spectra of deutero analogues. A strong N-phenyl group effect has been found, which in the case of N-phenyl-4-hydroxy- and N-phenyl-4-acetoxy-6-methyl-2-pyridones promotes the formation of the stable [M—H]+ and [M—CH₃CO]+ ions respectively. These ions are not characteristic of the N—H and N—Me analogues.     

Nitration of 1-methyl-2-pyridone

Nitration of 1-methyl-2-pyridone with 70% nitric acid or fuming nitric acid at 0–20°C proceeds in the 3 and 5 positions to give a mixture of mononitro isomers, the structures of which were proved by PMR spectroscopy. Mainly 3,5-dinitro-1-methyl-2-pyridone is formed by the action of fuming nitric acid or a nitrating mixture at 90°.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1671–1673, December, 1973.     

Spectrophotometric determination of iron with 1-hydroxy-4-sulpho-2-naphthoic acid

1-Hydroxy-4-sulpho-2-naphthoic acid (H(3)L) is proposed as a spectrophotometric reagent for determination of iron. It gives a red-brown chelate, FeL(6-)(3), with lambda(max) 500-520 nm at pH 8 ( = 3.3 x 10(3) l. mole(-1). cm(-1)). In this wavelength region the reagent has no absorption. Most common cations and oxo-anions do not interfere. In the determination of iron in polymetallic iron ores and aluminium alloys the relative error and relative standard deviation of the method were found to be better than 1 and 0.5%, respectively. 1-Hydroxy-4-sulpho-2-naphthoic acid seems to be a more sensitive and accurate reagent for iron than 5-sulphosalicylic acid, and the number of interfering ions is smaller than in the 1,10-phenanthroline or thiocyanate methods.