Catalyzed oxidation of 2,6-dimethylphenol in Triton X- 100 micellar solution

The oxidative coupling reaction of 2,6-dimethylphenol with H2O2 catalyzed by a copper(Ⅱ) Schiff complex in aqueous and Triton X-100 micellar solution under mild conditions was investigated. The kinetics of formation of 3,3′,5,5′-tetramethyl-4,4′-diphenoquinone (DPQ) was studied. Rate constant k2 were obtained. The optimum pH for DPQ generation reaction is 7.25. The main product was DPQ in aqueous buffer solution, but PPE and the oxidized products of PPE remained in Triton X-100 micellar solution.     

5-(2′-Carboxyphnyl) Azo-8-quinolinol as a Sensitive Reagent for Extractive Spectrophotometric Determination of Nickel

Abstract

A new sensitive extractive spectrophotometric method for the determination of nickel in sub-microgram level is discussed. 5-(2′-carboxyphenyl) azo-8-quinolinol reats with nickel at pH 5.2 to 6.1 to produce a wine red complex extractable in isomayl alcohol. The complex is stable for 24 hrs. Beer's law is obeyed in the range 0.04 to 0.60 ug of nickel per ml. The molar absorptivity and Sandell's sensitivity of the method are 5.5 × 10⁴1. mol^?1 cm^?1 and 0.001 μg cm^?2, respectively, at wavelength of maximum absorption (λ max 540 nm). Effects of diverse ions and variables have been studied in detail. The method has been applied to the determination of nickel in alloys like manganin, constantan, german silver, bronze, steel and in geological samples. Features of the method include high sensitivity, excelllent reproducibility and reliability.     

Spectrophotometric determination of acidity constants of 4-(2′-thiazolylazo)-resorcinol (TAR) in water-organic mixtures

<正>The acidity constants of TAR in different water-organic solvent binary mixtures at 25℃have been determined spectrophotometrically. DATa ANalysis(DATAN) program was used for calculations of the acidity constants and pure spectra of all formed species and their concentration distribution diagram in applied pH interval.Results show that there are a fairly inverse relationship between acidity constants and the mole fraction of the organic solvent in the binary mixtures.Effects of solvent composition on the pK_as and pure spectrum of each component are also discussed.     

Spectrophotometric study of the complexation equilibria of cobalt(II) with 4-(5′-methyl-3′-isoxazolylazo)-resorcinol and determination of cobalt(II)

The reaction of cobalt(II) with 4-(5′-methyl-3′-isoxazolylazo)-resorcinol (MIAR) in 4% v/v ethanol-water medium at I = 0.1 M (NaClO₄) was investigated spectrophotometrically. Graphical and numerical calculation methods were used to establish the equilibria in solution and to evaluate the stability constant of the complexes formed (log β₁₀₁ = 7.48±0.06, log β₁₁₁ = 12.77 max 12.99, log β₁₀₂ = 16.41±0.07). The optimum conditions for the spectrophotometric determination of Co(II) with MIAR were established and the method applied to its determination in some low alloy steels and hydrofining catalysts.     

Micellization and surface activity of Triton X-100 in water–orthophosphoric medium

The adsorption isotherms of Triton X-100 for air/water–orthophosphoric acid interfaces were determined by the stripping method. The surface chemical parameters, Γ_max, F and ΔG°_A, and the aggregation ones, CMC and the ΔG_M, are determined in different H₂O/H₃PO₄ mixtures. For concentrations higher than 4 M, the values of the CMC, ΔG_M, Γ_max and ΔG°_A increase with increasing acid concentrations due to the occurring changes in the medium structure. ©2000 Académie des sciences / Éditions scientifiques et médicales Elsevier SASsurface tension / non-ionic surfactant / micellization / orthophosphoric acid     

Spectrophotometric Determination of Carbon Disulfide Using Bis(4-(4′-Nitrophenyl)azo-2-Nitrophenyl) Disulfide

Bis(4-(4-nitrophenyl)azo-2-nitrophenyl) disulfide (NADS) has been synthesized for the first time and proposed for the indirect photometric determination of carbon disulfide by dithiocarbamic acid. The reaction, which involves the breaking of the disulfide bond with the formation of colored azothio anions, is carried out in a mixture of dimethylsulfoxide and n-butanol. The high value of the apparent molar absorptivity (2 × 10⁵) is probably due to the autocatalytic character of the reaction. Using NADS, procedures for the determination of carbon disulfide in the atmospheric air of populated areas and in the model gas mixtures designed for the calibration of gas analyzers have been developed and certified. The procedures show high sensitivity and good reproducibility.     

Spectrophotometric determination of molybdenum(V) by extraction of its 2-(2′-furyl)-3-hydroxychromone complex

A simple method is described for the rapid spectrophotometric determination of molybedenum in synthetic and industrial samples containing 0.1-5% Mo. Molybdenum is reduced with ascorbic acid at room temperature in 1 mol dm^–3 H₂SO₄ and extracted with chloroform after adding 2-(2-furyl)-3-hydroxychromone (FHC). The yellow colour of the 1 2 Mo-FHC complex is measured at 414 nm against a reagent blank. Beer's law is obeyed over the range 0-2.7 g Mo cm^–3 of solvent phase. The molar absorptivity and Sandell's sensitivity are 5.18 × 10⁴ dm³ mol^–1 cm^–1 and 0.0018 g Mo cm^–2, respectively. Relative standard deviations are 0.2% for solutions and 0.5–1.5% for solid samples. Interference from tungsten and tin is removed by adding citrate and EDTA, respectively, while niobium and tantalum are masked by fluoride. Many elements such as V, Fe, Ti, U, Mn, Cr, Co, Ni, Re, Ru, Pt, Rh, Se, Au, Bi, Zr, Th, Ce, As and Al do not interfere even in large amounts, but antimony always interferes. Among the anions and complexing agents, only thiocyanate interferes seriously.     

Synthesis of new heterocycles through the reaction of β-lapachone with 1,2-diamines using Triton X-100 surfactant as catalyst in aqueous medium

An efficient and an environmentally benign protocol has been developed for the synthesis of new naphtha-azaquinoxaline and naphtha-benzoquinoxaline derivatives from the reaction of β-lapachone, a naturally occurring 1,2-naphthoquinone with various 1,2-diamines using surfactant as catalyst in aqueous medium. This method has advantage of easy handling and good yield of products in shorter time. The structures were assigned with the help of analytical and ¹H, ¹³C NMR, IR, and mass spectral studies.     

Influences of Triton X-100 on Hemoglobin Behaviors in Hemoglobin/Acyclovir/Triton X-100/H2O System

The influences of Triton X-100 on hemoglobin （Hb） behaviors were studied by the methods of UV-Vis spectrum, fluorescence spectrum, HPLC, conductivity, zeta potential and negative-staining transmission electron microscope in Hb/acyclovir/Triton X-100/H2O system. With the increase of Triton X-100 concentration in the system, the percentage of the free acyclovir increased from 58%--63% to 90%--94%. The static quenching constant and the association number of acyclovir to Hb decreased. The fluorescence spectrum, conductivity, zeta potential, fluorescence polarization and negative-staining morphology of Hb tended to recover to those of the original state of Hb in the same concentration of Hb. The interaction between Triton X-100 and Hb is stronger than that between acyclovir and Hb. Most Triton-X-100 was associated with Hb at low Triton X-100 concentration. But the interaction of Triton X-100 with Hb was apparently dominant in high Triton X-100 concentration. The Hb structure was unfolded and finally denatured.     

Indirect Spectrophotometric Determination of Sulphide with the Complex of Cd(Ⅱ)-5-Br-PADAP-CPB

ampornoNTh6SpetemofCd-&Br-PADAPis~SenSitbo(s=l.4Xlotl.mol-l.CIn-'),ltwaSuSUaIly~todet6rInintal-[1],butitedotodboboeofitsWatertheOlUbuny,italSocanbeodtodetermineodboinwater8oforbobytheuseOfnthe8ufor[2J.Intthework,catiOnisuthetantwasedinCd-5Br-PADAPsy8tem,itssensitivityndthenduzn~tionwavelengthhaofthecomplexcanbeincred2O%and2onInreSpeivelybycom-P8tisonwithliteratureL2J.TheapplicaiOnOfdsterwicomplexspstemtosperOPhOtomethedeterminaiOnofsulPhidefromitseboOfdecreaseinabeorPtboonth…     

Spectrophotometric and thermal lens determination of aluminum with 3-sulfo-5-nitro-4′-diethylamino-2,2′-dihydroxyazobenzene

The conditions of the spectrophotometric and thermal lens determination of aluminum with sulfo-5-nitro-4′-diethylamino-2,2′-dihydroxyazobenzene have been compared. The limit of spectrophotometric detection of aluminum in aqueous solutions has been found to be 8 ng/mL. On the basis of the conditions of spectrophotometric determination, the conditions for thermal lens determination have been proposed (532.0 nm, exciting radiation power of 42 mW); they provide a decrease of the detection limit down to 0.6 ng/mL and an increase of the sensitivity coefficient by an order of magnitude. It has been shown that, in the case of the thermal lens determination of aluminum in water-organic mixtures (50 vol % of dimethyl sulfoxide or 30 vol % acetonitrile), the sensitivity coefficient is respectively 9.1 and 6.3-fold higher as compared with the thermal lens determination in water. As a result, the detection limits are reduced 2.5 and 10-fold, respectively. Aluminum has been determined by thermal lens spectrophotometry in Moscow’s tap water using the standard addition method, its concentration being 0.79 ± 0.07 mg/L, which is above the threshold limit value of the aluminum content of drinking water.     

Complexation equilibria and spectrophotometric determination of zinc (II) with 2-(4′-methyl-2′-thiazolylazo)-4,6-dimethylphenol

2-(4′-methyl-2′-thiazolylazo)-4,6-dimethylphenol has been synthesized and its acid—base behaviour (pK_a1=0.03 ± 0.01, pK_a2=9.70±0.09) and complexation equilibria with zinc (logβ₁₀₁=6.70±0.04, logβ₁₀₂ = 13.70±0.02) studied in a 40% (v / v) ethanol—water medium at I=0.25 M NaClO₄. A spectrophotometric method for the determination of 0.2–1.5 ppm of zinc has been developed (ε=1.83 × 10⁴ 1. mol⁻¹ cm⁻¹ at 590 nm) and applied to its determination in lubricating oils.     

Spectrophotometric Method for the Determination of Cobalt with N,N′-Bis(2-Aminobenzoyl)Ethylenediamine

 A simple and direct spectrophotometric method has been developed for the determination of cobalt(II) using N,N′-Bis(2-aminobenzoyl)ethylenediamine (Baben). The method is based on the colour reaction between Baben and cobalt(II) in borax buffer (pH 9.2). The studies are carried out at 470 nm at which the calculated value of molar absorptivity is found to be 1.102 × 10⁴ L mol⁻¹ cm⁻¹. The system obeys Beer’s law over a wide range of concentration (2–20 μg/ml). The effect of interfering ions has been studied and the method was applied to the determination of cobalt in water, industrial effluents and in alloys and the results were highly satisfactory. Received May 8, 2000. Revision January 30, 2001.     

Steric Considerations in Supramolecular Inclusion of Modified β-cyclodextrins with Triton X-100 and α-bromonaphthalene

Supramolecular inclusion of modified β-cyclodextrin (β-CD) with Triton X-100 (TX) and α-bromonaphthalene (BN) was studied by fluorescence and phosphorescence measurements. Major differences were observed in the magnitude of the apparent stability constants and quenching constants of the inclusion complexes. Methyl substitution on the rims of β-CD increased the binding of TX with β-CD but was unfavorable to the protection of the phenyl group of TX from fluorescence quenching and further accommodation of BN for steric considerations. According to the overall molecular size of β-CD, TX and BN, further inclusion of BN in the cavity of β-CD occupied by TX may force the flexible tert-octyl chain of TX to deform to a greater extent and close packing complexes were obtained. Phosphorescence of BN arising from intermolecular energy transfer between BN and the phenyl group of TX was observed when the phenyl group of TX was irradiated. In the case of heptakis(2,6-di-O-methyl)-β-CD, BN failed to penetrate into the cavity because of the steric hindrance of the methyl substituents at the rim of the β-CD cavity.     

Spectrophotometric Determination of Palladium(II) With 2, 2′-Dipyridylglyoxime

Abstract

A spectrophotometric method is described for the determination of palladium with 2,2′-dipyridylglyoxime. The effects due to pH, time, solvents, reagent concentration and diverse ions are reported. A new method of reagent synthesis is also described.     

Triton X-100存在下钴与2-(2-噻唑偶氮)-5-二甲氨基苯甲酸的胶束显色反应

杂环偶氮邻苯甲酸染料是近年来新报道的一类高灵敏金属显色剂.石附朋典等首次合成并报道了这类显色剂之一的2-(2-噻唑偶氮)-5-二甲氨基苯甲酸(TAMB).并将该试剂用作EDTA滴定中的指示剂.Furukawa曾研究了TAMB与钴、镍、铜、铁等离子的显色反应. 本文简化并改进了试剂的合成方法,详细地研究了在非离子表面活性剂存在下TAMB与钴的胶束增敏显色反应.     

Triton X-100辅助合成多级孔道结构ZSM-5沸石催化剂(英文)

ZSM-5 zeolite with a hexagonal cubic morphology was synthesized by a hydrothermal method using Triton X-100, a nonionic surfactant. The samples prepared with and without the surfactant were characterized by X-ray diffraction(XRD), Fourier transform infrared spectroscopy, N2 adsorption, high resolution transmission electron microscopy(TEM), high resolution scanning electron mi-croscopy, energy dispersive X-ray analysis, and NH3 temperature-programmed desorption. The XRD patterns confirmed the formation of a pure ZSM-5 crystalline phase without secondary phases. TEM images revealed that the hexagonal cubes were made of peanut-shaped nanoparticles with voids.The catalytic activity of the zeolite samples was evaluated using the selective oxidation of benzyl alcohol with tertiary-butyl hydrogen peroxide as the oxidant at 90 °C. The surfactant-assisted prep-aration yielded a zeolite that gave a higher conversion than the one prepared in the absence of the surfactant. The catalyst was retrieved and reused four times without significant loss in activity and selectivity.