Polarographic behaviour of 2-benzilidenimino-benzohydroxamic acid (2-BIBH) and 2-BIBH-Mo(VI) system

The polarographic behaviour of 2-benzilideniminobenzohydroxamic acid (2-BIBH) solutions and of 2-BIBH solutions in the presence of Mo(VI) have been studied by using differential pulse polarography and cyclic voltammetry. The polarographic characteristics of the resulting waves have been studied and possible mechanisms of the processes involved have been proposed. A linear relationship has been observed betweenI _p and Mo(VI) concentration in the range 2×10^–6 to 1.6×10^–5 M when using 3×10^–4 M 2-BIBH. Standard deviations of 5.6×10^–8 and 1.2×10^–8 M were found for 3×10^–6 and 8 × 10^–6 M Mo(VI), respectively.     

Natural radiative lifetimes in the2 S 1/2 and2 D 3/2, 5/2 sequences of neutral copper

Natural radiative lifetimes have been measured of the 3d ¹⁰ ns ² S _1/2 (n=6?10) and of the 3d ¹⁰ nd ² D _{3/2, 5/2} (n=5?9) sequences by using two step excitation of copper atoms in an atomic beam. The states investigated were populated by the light from two pulsed dye lasers pumped by the same Nd:YAG laser. The lifetimes of the² D sequence increase regularly with increasing principal quantum number. This is not the case for the² S series, because of configuration interaction in the² P series. In addition the lifetime of the 3d ¹⁰5p ² P _3/2 state has been measured together with its branching ratio.     

A kinetic study of the reaction of fluorine atoms with CH3F,CH3Cl,CH3Br,CF2H2, CO,CF3H,CF3CHCl2, CF3CH2F,CHF2CHF2, CF2ClCH3, CHF2CH3, and CF3CF2H at 295 ± 2 K

A variety of relative and absolute techniques have been used to measure the reactivity of fluorine atoms with a series of halogenated organic compounds and CO. The following rate constants were derived, in units of cm³ molecule^?1 s^?1: CH₃F, (3.7 ± 0.8) × 10^?11, CH₃Cl, (3.3 ± 0.7) × 10^?11; CH₃Br, (3.0 ± 0.7) × 10^?11; CF₂H₂, (4.3 ± 0.9) × 10^?12; CO, (5.5 ± 1.0) × 10^?13 (in 700 torr total pressure of N₂ diluent); CF₃H, (1.4 ± 0.4) × 10^?13; CF₃CCl₂H (HCFC-123), (1.2 ± 0.4) × 10^?12; CF₃CFH₂ (HFC-134a), (1.3 ± 0.3) × 10^?12, CHF₂CHF₂ (HFC-134), (1.0 ± 0.3) × 10^?12; CF₂ClCH₃ (HCFC-42b), (3.9 ± 0.9) × 10^?12, CF₂HCH₃ (HFC-152a), (1.7 ± 0.4) × 10^?11; and CF₃CF₂H (HFC-125), (3.5 ± 0.8) × 10^?13. Quoted errors are statistical uncertainties (2σ). For rate constants derived using relative rate techniques, an additional uncertainty has been added to account for potential systematic errors in the reference rate constants used. Experiments were performed at 295 ± 2 K. Results are discussed with respect to the previous literature data and to the interpretation of laboratory studies of the atmospheric chemistry of HCFCs and HFCs. © 1993 John Wiley & Sons, Inc.     

A spectrokinetic study of CH2I and CH2IO2 radicals

The UV absorption spectrum and kinetics of CH₂I and CH₂IO₂ radicals have been studied in the gasphase at 295 K using a pulse radiolysis UV absorption spectroscopic technique. UV absorption spectra of CH₂I and CH₂IO₂ radicals were quantified in the range 220–400 nm. The spectrum of CH₂I has absorption maxima at 280 nm and 337.5 nm. The absorption cross-section for the CH₂I radicals at 337.5 nm was (4.1 ± 0.9) × 10^?18 cm² molecule^?1. The UV spectrum of CH₂IO₂ radicals is broad. The absorption cross-section at 370 nm was (2.1 ± 0.5) × 10^?18 cm² molecule^?1. The rate constant for the self reaction of CH₂I radicals, k = 4 × 10^?11 cm³ molecule^?1 s^?1 at 1000 mbar total pressure of SF₆, was derived by kinetic modelling of experimental absorbance transients. The observed self-reaction rate constant for CH₂IO₂ radicals was estimated also by modelling to k = 9 × 10^?11 cm³ molecule^?1 s^?1. As part of this work a rate constant of (2.0 ± 0.3) × 10^?10 cm³ molecule^?1 s^?1 was measured for the reaction of F atoms with CH₃I. The branching ratios of this reaction for abstraction of an I atom and a H atom were determined to (64 ± 6)% and (36 ± 6)%, respectively. © 1994 John Wiley & Sons, Inc.     

Spectroscopic characterization of 2-naphthylcarbene

The 308 nm excimer laser flash photolysis of 2-naphthyldiazomethane produces triplet 2-naphthylcarbene (λ_max = 362 nm) which decays with the observed pseudo-first-order rate constants (k_exptl) of 5.54 ± 0.03 × 10⁶; 3.33 ± 0.4 × 10⁶; 1.64±0.02 × 10⁷; and 3.05±0.4 × 10⁶ s^-1 in n-pentane, 2,2,4-trimethylpentane (2,2,4-TMP), benzene and Freon 113 respectively. In hydrocarbon solvents the observed decay of triplet 2-naphthylcarbene is correlated with the pseudo-first-order growth of the 2-naphthylmethyl radical (λ_max = 378 nm). Direct kinetic measurements of the reaction of triplet 2-naphthylcarbene in 2,2,4-TMP with cyclohexane, styrene, methanol and carbon tetrachloride yielded bimolecular quenching rate constants of 1.48 ± 0.04 × 10⁶;4.33 ± 0.1 × 10⁷;7.25 ± 0.5 × 10⁶; and 3.35 ± 0.07 × 10⁶M^-1S^-1. It is also found that 2-naphthylcarbene reacts with acetonitrile (k_q = 5.28 ± 0.1 × 10⁵ M^-1 s^-1) to form a nitrile ylide intermediate with a λ_max = 372 nm. These results are interpreted in terms of a rapid singlet-triplet 2-naphthylcarbene equilibrium.     

CdIn2S2Se2: A new semiconducting compound

The optical and electrical properties of CdIn₂S₂Se₂, a new layered semiconducting compound, were examined in the temperature range 10–300 K. The absorption edge at room temperature is observed at 1.95 eV, with a temperature shift of about 4.6 × 10⁻⁴ eV/K. Electrical transport is due to electrons, whose temperature independent density is about 3 × 10¹⁷ cm⁻³. The room-temperature mobility is 130 cm²/Vs, independent of the conduction direction. However, measurements parallel and perpendicular to c-axis show different linear decreases of the mobility with reciprocal temperature. Au/CdIn₂S₂Se₂/In Schottky diodes were produced.     

Gas phase reactions of SiF2 with F2 and Cl2

Reactions of SiF₂ radicals have been studied in a fast-flow system. Rate constants at 295 K of (4.7±0.3)×10⁻¹³ cm³ molecule⁻¹ s⁻¹ for the reaction of SiF₂ + F₂, and (5.1±0.6)×10⁻¹³ cm³ molecule⁻¹ s⁻¹ for SiF₂ + Cl₂ were obtained. No reaction was observed with O₂ and H₂. SiF₂ was detected by laser-induced fluorescence, and lifetime observations and an excitation spectrum are reported.     

Vibrational relaxation of NH2|X2B1(O,v2, O)| radicals

Energy transfer processes in NH₂ radicals have been studied using the sensitive laser-induced fluorescence (LIF) technique. The NH₂ radicals were generated by infrared multiple-photon dissociation (IR MPD) of monomethylamine (CH₃NH₂), and the state-selected NH₂(v″₂ = 1) decay was observed by the LIF detection of [NH²]. The vibrational relaxation processes studied are NH₂(v″₂ = 1) + M → NH₂(v″₂ = O)+M, with M  He, Ne, Ar, Kr, H₂, D₂, CO, O₂, and total decay rate of NH₂(v″₂ = 1) in the presence of excess of CH₃NH₂. Rate constants of (3.41±0.03)×10⁻¹³, (1.75±0.09)×10⁻¹³, (3.03±0.08)× 10⁻¹³, (3.58±0.06)×10⁻¹³, (13.4±0.5)×10⁻¹³, (4.70±0.19)×10⁻¹³, (4.3±0.3)×10⁻¹³, (5.9±-0.4)×10⁻¹³, (9.2±0.5)×10⁻¹³), and 8.4×10⁻¹¹ cm³ molecule⁻¹ s⁻¹ were determined for the vibrational deactivation of NH₂(v″₂ = 1) by He, Ne, Ar, Kr, H², D₂, N₂, CO, O₂, and CH₃NH₂, respectively. The effect of the different collision partners on the relaxation rate is discussed. The results can be qualitatively well understood in terms of strong vibration—rotation coupling, due to the small moment of inertia of the NH₂ radicals.     

Quenching of I (2P1/2) by halogen cyanides

Relaxation rate constants for the collisional deactivation of I (²P_1/2) by halogen cyanides were measured by time resolved atomic absorption. The values obtained were (1.2 ± 0.1) × 10^?15, (5.2 ± 0.7) × 10^?15, and (2.6 ± 0.4) × 10^?14 cm³ molecule^?1 s^?1 for ClCN, BrCN, and ICN, respectively. Quenching efficiencies are discussed in view of the stability of linear molecules to form the transient complex as well as the similarities assumed between halogen cyanides and interhalogen diatomic molecules.     

Inclusion Complex between Local Anesthetic/2-hydroxypropyl-β-cyclodextrin in Stealth Liposome

The drugs delivery system in the treatment of diseases has advantages such as reduced toxicity, increased availability of the drug, etc. Therefore, studies of the supramolecular interactions between local anesthetics (LAs) butamben (BTB) or ropivacaine (RVC) complexed with 2-hydroxypropyl-β-cyclodextrin (HP-βCD) and carried in Stealth liposomal (SL) are performed. ¹H-NMR nuclear magnetic resonance (DOSY and STD) were used as the main tools. The displacements observed in the ¹H-NMR presented the complexion between LAs and HP-βCD. The diffusion coefficients of free BTB and RVC were 7.70 × 10⁻¹⁰ m² s⁻¹ and 4.07 × 10⁻¹⁰ m² s⁻¹, and in the complex with HP-βCD were 1.90 × 10⁻¹⁰ m² s⁻¹ and 3.64 × 10⁻¹⁰ m² s⁻¹, respectively, which indicate a strong interaction between the BTB molecule and HP-βCD (98.3% molar fraction and Ka = 72.279 L/mol). With STD-NMR, the encapsulation of the BTB/HP-βCD and RVC/HP-βCD in SL vesicles was proven. Beyond the saturation transfer to the LAs, there is the magnetization transfer to the hydrogens of HP-βCD. BTB and RVC have already been studied in normal liposome systems; however, little is known of their behavior in SL.     

Determination of Albumin Using the Chemiluminescence of Tb3+/K2S2O8 System

A new chemiluminescence system of Tb³⁺/K₂S₂O₈ was developed for the determination of albumin. Some experimental conditions were examined and optimized. The linear ranges of the calibration curves are 5.0 × 10^?9–5.0 × 10^?6 mol/L for bovine serum albumin, 5.0 × 10^?8–1.0 × 10^?5 mol/L for human serum albumin and 2.5 × 10^?7–1.0 × 10^?5 mol/L for ovalbumin, and the corresponding detection limits are 1.9 × 10^?9 mol/L, 1.5 × 10^?8 mol/L, and 1.5 × 10^?7 mol/L, respectively. The method was applied to the determination of albumin in human serum samples, and the results were in agreement with those obtained by the bromcresol green method. The relative errors for the analytical results were from ?2.0% to 4.3%.     

Determination Co2+ in vitamin B12 based on enhancement of 2-(4-substituted-phenyl)-4,5-di(2-furyl) imidazole and H2O2 chemiluminescence reaction

In this paper, three kinds of imidazole derivatives, 2-(4-methylphenyl)-4,5-di(2-furyl) imidazole (MDFI), 2-(4-nitrophenyl)-4,5-di(2-furyl) imidazole (NDFI), and 2-(4-tert-butylphenyl)-4,5-di(2-furyl) imidazole (t-BDFI) were synthesized. In an alkaline medium, the chemiluminescence (CL) reaction of imidazole derivatives with H₂O₂ has been investigated. It was also found that MDFI/H₂O₂ and t-BDFI/H₂O₂ systems gave strong CL. When Co²⁺ was added into the two CL systems, the CL intensity was remarkably enhanced. In the optimum conditions, the CL intensity is linearly related to the logarithm of concentration of Co²⁺. The linear ranges are 5 × 10⁻⁹–2.5 × 10⁻⁷ mol/L for MDFI/H₂O₂ system and 5 × 10⁻⁹–2.5 × 10⁻⁷ mol/L for t-BDFI/H₂O₂ system, and the corresponding detection limits are 1.2 × 10⁻⁹ mol/L and 1.1 × 10⁻⁹ mol/L, respectively. The method was applied to the determination of Co²⁺ in vitamin B₁₂ injection. Furthermore, the CL mechanism was also discussed.     

Tb3+ PVC-Membrane Electrode Based on 2-{2-(2-Anilinocarbothioyl)hydrazino)-2-oxoacetyl}-N-phenyl-1-hydrazine Carbothioamide

Abstract

The polyvinyl chloride (PVC) membrane containing 2-{2-(2-anilinocarbothioyl)hydrazino)-2-oxoacetyl}-N-phenyl-1-hydrazinecarbothioamide (AHC) as a suitable iophore exhibits a Nernstian response for Tb³⁺ ions over a wide concentration range (1.0 × 10^?6 to 1.0 × 10^?2 M) with a slope of 19.6 ± 0.3 mV per decade and a limit of detection of 6.8 × 10^?7 M in the pH range 3.5–8.5. The proposed sensor revealed very good selectivities (expect for the Pr³⁺ and Ho³⁺ ions) for a wide variety of other metal ions. The practical utility of the electrodes has been demonstrated by its use for the determination of Tb³⁺ in different solutions.     

Aromatic protonation—4: On the 1H-2H exchange of three 9-n-alkylanthracenes on reaction with CF3CO2[2H] and FSO3[2H]

The reactions of 9-methyl-, 9-ethyl- and 9-propyl-anthracene with CF₃CO₂[²H] in C[²H]Cl₃ and with FSO₃[²H] in SO₂ClF have been investigated. Using 4 equivalents of CF₃CO₂[²H] at 50° ¹H-²H exchange was observed only for the 10-H and the side-chain α-hydrogens, and on using 8 and 12 equivalents at 50° also for the aromatic α-hydrogens. Treatment of the substrates with FSO₃[²H] at -60° leads to the stable 9-alkyl-[10-²H]-10-anthracenium ions. On warming up to ?25° a slow ¹H-²H exchange of only the 10-¹H of these anthracenium ions is observed. A mechanism for the ¹H-²H exchange of the aromatic and the side-chain α-hydrogens of the 9-alkylanthracenes is presented.     

Rate coefficients and ClO radical yields in the reaction of O(1D) with CClF2CCl2F,CCl3CF3, CClF2CClF2, and CCl2FCF3

Rate coefficients, k, and ClO radical product yields, Y, for the gas‐phase reaction of O(¹D) with CClF₂CCl₂F (CFC‐113) (k₂), CCl₃CF₃ (CFC‐113a) (k₃), CClF₂CClF₂ (CFC‐114) (k₄), and CCl₂FCF₃ (CFC‐114a) (k₅) at 296 K are reported. Rate coefficients for the loss of O(¹D) were measured using a competitive reaction technique, with n‐butane (n‐C₄H₁₀) as the reference reactant, employing pulsed laser photolysis production of O(¹D) combined with laser‐induced fluorescence detection of the OH radical temporal profile. Rate coefficients were measured to be k₂ = (2.33 ± 0.40) × 10^?10 cm³ molecule^?1 s^?1, k₃ = (2.61 ± 0.40) × 10^?10 cm³ molecule^?1 s^?1, k₄ = (1.42 ± 0.25) × 10^?10 cm³ molecule^?1 s^?1, and k₅ = (1.62 ± 0.30) × 10^?10 cm³ molecule^?1 s^?1. ClO radical product yields for reactions (2)–(5) were measured using pulsed laser photolysis combined with cavity ring‐down spectroscopy to be 0.80 ± 0.10, 0.79 ± 0.10, 0.85 ± 0.12, and 0.79 ± 0.10, respectively. The quoted errors in k and Y are at the 2σ (95% confidence) level and include estimated systematic errors. © 2011 Wiley Periodicals, Inc.

1 This article is a U.S. Government work and, as such, is in the public domain of the United States of America

Int J Chem Kinet 43: 393–401, 2011     

穴醚[2, 2, 2]和穴醚[2, 2]对镉离子萃取行为的研究

本文研究了穴醚[2,2,2]和穴醚[2,2]在硝基甲烷中对镉的萃取行为。探讨了溶剂、穴醚浓度,碱浓度,无机酸浓度,盐效应及共存离子对镉萃取的影响。实验结果表明,硝基甲烷ε=35.6,μ=3.4德拜宜作为穴醚的溶剂。当穴醚[2,2,2]——硝基甲烷的浓度为2×10~(-3)M,Me_4NOH浓度为4×10~(-2)M时对镉的萃取最为有利。无机酸的引入使穴醚质子化程度加大,盐效应对镉的萃取无明显影响。十八种共存离子对镉萃取无干扰,因而选择性高。实验结果为用穴醚[2,2,2]萃取镉提供了依据。     

Spectrophotometric determination of rhenium with di(2-pyridyl)ketone-2-furancarbothiohydrazone and other thiohydrazones

A simple rapid method is proposed for the determination of rhenium (as perrhenate) in which the brown-violet complex produced is measured at 546 nm. The system obeys Beer's law in the range 0.7–14.0 μg Re ml^-1; the molar absorptivity is 1.51 × 10⁴ l mol^-1 cm^-1 in ethanol and 1.64 × 10⁴ l mol^-1 cm^-1 for the complex extracted into methyl isobutyl ketone. Molybdenum (100-fold), tungsten (40-fold), copper (10-fold), and palladium (10-fold) are tolerable. Reactions of other metal ions such as Cu(II), Ni(II), Co(II) and Fe(II) with this ligand and reactions of perrhenate with analogous reagents are discussed.     

Polarographic and voltammetric determination of trace amounts of 2-nitronaphthalene

The polarographic behaviour of 2-nitronaphthalene was investigated by DC tast polarography (DCTP) and differential pulse polarography (DPP), both at a dropping mercury electrode, and differential pulse voltammetry and adsorptive stripping voltammetry, both at a hanging mercury drop electrode. Optimum conditions have been found for the determination of 2-nitronaphthalene by the given methods in the concentration ranges of 2×10^–6–1×10^–4, 2×10^–7–1×10^–4, 1×10^–8–1×10^–4 and 2×10^–9–1×10^–8 M, respectively. Practical applicability of these techniques was demonstrated by the determination of 2-nitronaphthalene in drinking and river water after its preliminary separation and preconcentration using liquid–liquid and solid-phase extraction with limits of determination of 3×10^–10 M (drinking water) and 3×10^–9 M (river water).     

A study of the reaction NO3 + NO2 + M → N2O5 + M(M = N2, O2)

The gas-phase reaction of the NO₃ radical with NO₂ was investigated, using a flash photolysis-visible absorption technique, over the total pressure range 25–400 Torr of nitrogen or oxygen diluent at 298 ± 2 K. The absolute rate constants determined (in units of 10^?13 cm³ molecule^?1 s^?1) at 25, 100, and 400 Torr total pressure were, respectively, (4.0 ± 0.5), (7.0 ± 0.7), and (10 ± 2) for M = N₂ and (4.5 ± 0.5), (8.0 ± 0.4), and (8.8 ± 2.0) for M = O₂. These data show that the third-body efficiencies of N₂ and O₂ are identical, within the error limits, and that previous evaluations for M = N₂ are applicable to the atmosphere. In addition, upper limits were determined for the rate constants of the reactions of the NO₃ radical with methanol, ethanol, and propan-2-ol of ?6 × 10^?16, ?9 × 10^?16, and ?2.3 × 10^?15 cm³ molecule^?1 s^?1, respectively, at 298 ± 2 K.     

UV absorption spectrum of CF3CFClO2 and kinetics of the self reaction of CF3CFCl and CF3CFClO2 and the reactions of CF3CFClO2 with NO and NO2

The ultraviolet absorption spectrum of CF₃CFClO₂ and the kinetics of the self reactions of CF₃CFCl and CF₃CFClO₂ radicals and the reactions of CF₃CFClO₂ with NO and NO₂ have been studied in the gas phase at 295 K by pulse radiolysis/transient UV absorption spectroscopy. The UV absorption cross section of CF₃CFCl radicals was measured to be (1.78 ± 0.22) × 10^?18 cm² molecule^?1 at 220 nm. The UV spectrum of CF₃CFClO₂ radicals was quantified from 220 nm to 290 nm. The absorption cross section at 250 nm was determined to be (1.67 ± 0.21) × 10^?18 cm² molecule^?1. The rate constants for the self reactions of CF₃CFCl and CF₃CFClO₂ radicals were (2.6 ± 0.4) × 10^?12 cm³ molecule^?1 s^?1 and (2.6 ± 0.5) × 10^?12 cm³ molecule^?1 s^?1, respectively. The reactivity of CF₃CFClO₂ radicals towards NO and NO₂ was determined to (1.5 ± 0.6) × 10^?11 cm³ molecule^?1 s^?1 and (5.9 ± 0.5) × 10^?12 cm³ molecule^?1 s^?1, respectively. Finally, the rate constant for the reaction of F atoms with CF₃CFClH was determined to (8 ± 2) × 10^?13 cm³ molecule^?1 s^?1. Results are discussed in the context of the atmospheric chemistry of HCFC-124, CF₃CFClH. © 1994 John Wiley & Sons, Inc.