Iodine In Carbon Tetrachloride Research Articles

Separating Vibrational Coherences in Ground/Excited Electronic States of Solvent/Solute Following Non-Resonant/Resonant Impulsive Excitation.

In a quest to track down the origin of coherent vibrational motions observed in femtosecond pump-probe transients, whether they arise from ground/excited electronic state of solute or are contributed by the solvent, we demonstrate a method for extricating vibrations under resonant and non-resonant impulsive excitations using a diatomic solute in condensed phase (iodine in carbon tetrachloride) with aid of spectral dispersion of the chirped broadband probe. Most importantly, we show how a sum over intensities for a select region of detection wavelengths and Fourier transform of data over select temporal window untwine contributions from vibrational modes of different origins. Thus, in a single pump-probe experiment, vibrational features specific to solute as well as solvent are disentangled that are otherwise spectrally overlapping and are non-separable in conventional (spontaneous/stimulated) Raman spectroscopy employing narrowband excitation. We envision wide-ranging applications of this method to unveil vibrational features in complex molecular systems.

Evaluation of electrical conductivity and thermal diffusivity of vanadyl naphthalocyanine

Metal phthalocyanines have attracted much attention because of their potential application in electronic devices, optical data storage, photoconductors and sensors [1, 2]. They are also very good candidates for high density optical data recording (ODR) media due to their thermal and chemical stability and facility for synthetic modification. An essential requirement for the ODR material is the long wavelength absorption. Metal naphthalocyanines absorb at a longer wavelength than the phthalocyanines because of their additional benzoannulation [3]. For constructing practical ODR devices the thermal properties of the organic dyes are of considerable importance [4–7]. It is also necessary to investigate the electrical properties of metal naphthalocyanines prior to their utilization in optoelectronic devices. Although there are a number of reports on the optical properties of metal naphthalocyanines [8, 9], only very few investigations are found on the electrical properties of these interesting materials. In the present study, we report the electrical conductivity and thermal diffusivity of pristine and iodine doped vanadyl naphthalocyanine (VONc). VONc was synthesized and purified by the method reported by Yanagi et al. [9]. The compound was characterized by elemental analysis, IR and electronic spectra. The data were in good agreement with those reported in the literature [3]. VONc was doped with iodine in the solution phase [10, 11] by stirring 100 mg of powdered sample with a saturated solution of iodine in carbon tetrachloride for 48 h. The doped material was filtered and washed with carbon tetrachloride to remove excess iodine. The iodine doped vanadyl naphthalocyanine (VONcI) was dried at 360 K in vacuo for 2 h. The pellet samples of 5.0 mm diameter and 0.8 mm thickness were prepared at a pressure of 2000 kg cm−2. The electrical conductivity was measured in a shielded cell under dynamic vacuum in the temperature range 100–450 K using a Keithley model 617 electrometer. The samples studied were heated to 375 K and cooled to ambient temperature before measurement, to avoid the interference of moisture and adsorbed oxygen. A photoacoustic method was used to measure the thermal diffusivity of the pellet samples (see Fig. 1). The light source used was a 488 nm radiation from an Ar+ laser (Liconix-5000 series) at a power level of 30 mW. The laser beam was chopped by a mechanical chopper (Stanford Research System model SR 540). By varying the chopping rate the characteristic frequency ( fc) was determined by front surface illumination of the sample. The Arrhenius plot of the temperature dependence of electrical conductivity (σ ) for VONc and VONcI are shown in the Fig. 2. In the pristine sample, the temperature dependence is very weak below 300 K. Above this temperature the behavior is in accordance with an Arrhenius relationship. The increase in conductivity at higher temperature must be due to an enhancement in carrier density with increase in thermal energy. The activation energies at different temperature ranges are given in Table I. The electrical conductivity of vanadyl naphthalocyanine increases when doped with iodine. The behavior of VONcI indicates that considerable changes have

Determination of thiosulfate at the 10 −6 M level by its oxidation with iodine in an organic phase and spectrophometric measurement of triiodide

A highly sensitive method is proposed for the determination of thiosulfate based on the oxidation of aqueous thiosulfate (100 or 200 ml) by iodide in 4 ml of carbon tetrachloride. The excess of iodine was extracted into 8 ml of aqueous iodide solution as triiodide to be measured spectrophotometrically; the thiosulfate could therefore be indirectly highly concentrated and determined selectively. The side-reaction of thiosulfate in a large volume of solution with the hypoiodite formed from the iodine in carbon tetrachloride could be compensated for by adding a certain amount of extra thiosulfate. A linear calibration graph with a negative slope was obtained over the concentration ranges 1.1 × 10 −7–1 × 10 −5 M (12 ppb-1.12 ppm) for 100 ml of thiosulfate solution and 6 × 10 −8 – 5 × 10 −6 M (6.7 ppb-0.56 ppm) for 200 ml of thiosulfate solution. The proposed method was successfully applied to the determination of various amounts of thiosulfate in hot-spring and lake-water samples.

Preparation of η5-pyranyltricarbonylmanganese complexes and pyrylium triiodide salts from cyclomanganated chalcones and alkynes

Derivatives of [[1- phenyl-2- phenylcarbonyl- kO] ethenyl- kC 1] tetracarbonylmanganese , i.e. chalcone (1, 3-diphenylprop-2-en-1-one) cyclomanganated at the β-position, undergo insertion reactions with alkynes under reflux in carbon tetrachloride to give [2,4-diphenylpyranyl- η 5]Mn(CO) 3 derivatives, the reaction being highly regioselective in the case of unsymmetrical alkynes. Reaction of the pyranyl-Mn(CO) 3 complexes with iodine in carbon tetrachloride gives pyrylium triiodide salts in excellent yield. The reaction of one pyranyl complex, [2-(4-chlorophenyl)-6-phenyl-4(4-trifluoromethylpheny)pyranyl- η 5]tricarbonylmanganese ( 2d), with Na[Fe(CO) 2Cp], gave the demetallated ring-opened isomers E, E-1-phenyl-3-(4-trifluoromethylphenyl)-5-(4-chlorophenyl)penta-2, 4-dien-1-one ( 10a) and E, E-1-(4-chlorophenyl)-3-(4-trifluoromethylphenyl)-5-phenylpenta-2,4-dien-1-one ( 10b). X-ray crystal structure determinations of [2-methyl-4,6-diphenylpyranyl- η 5]tricarbonylmanganese ( 5) and 2,6-diphenyl-4-(4-trifluoromethylphenyl)pyrylium triiodide ( 3b) are described, the former being the first reported for a pyranyl- η 5 metal complex.

Electrical conductivity and thermal diffusivity of zinc naphthalocyanine

Naphthalocyanine and its metal complexes are candidate materials for molecular electronic devices such as optical storage media, electrochromic displays and sensors [1,2]. Yanagi et al. [3] have investigated the molecular orientation of vacuum deposited zinc naphthalocyanine (ZnNc) by infrared (IR) spectroscopy, electronic spectroscopy and X-ray diffraction (XRD). Here we report the results of our study on the electrical conductivity and thermal diffusivity of ZnNc and iodine doped ZnNc. ZnNc was synthesized and purified by the method reported by Kaplan et al. [4]. The compound was characterized by elemental analysis, IR and electronic spectra. The data were in agreement with those reported in the literature [3]. ZnNc samples were doped with iodine in the solution phase by stirring 100 mg of powdered ZnNc with a saturated solution of iodine in carbon tetrachloride. The doped material was filtered and washed with carbon tetrachloride to remove excess iodine. This sample was dried at 360 K in vacuo as reported in the case of cobalt phthalocyanine [5]. The samples for measurement were formed into pellets of diameter 5.0 mm and thickness 1.1 mm at a pressure of 2000 kg cm -2. The electrical conductivity was measured in a shielded cell under dynamic vacuum in the temperature range 100-450 K using a Keithley model 617 electrometer. Thermal diffusivity of the pellets was measured by a photoacoustic technique, using 488 nm Ar ÷ laser beam at 26 mW power level. The laser beam was chopped using a Stanford Research System model SR 540 chopper, and front surface illumination was used for finding out the characteristic frequency f~. The schematic diagram of the experimental set up used for determination of the thermal diffusivity by the photoacoustic technique is shown in Fig. 1. The electrical conductivity of pristine ZnNc shows an increase in conductivity with temperature, the Arrhenius plots showing two linear regions of different activation energies, as shown in Fig. 2. The plot does not give any clear indication of a sharp transition. The activation energies in different temperature ranges are given in Table I. Doping with iodine enhances the electrical conductivity. For the iodine doped samples the Arrhenius plot gives two distinct regions with activation energies 0.05 eV and 0.14eV The enhanced electrical conductivity may be due to charge

Spectrophotometric Determination of Thiosulfate Based on an Oxidation Reaction in the Presence of Formaldehyde with Iodine in the Organic Phase

Abstract Aqueous thiosulfate was shaken in the presence of large amounts of sulfuric acid and formaldehyde with iodine in carbon tetrachloride; thereby, one mol of thiosulfate reacted with one mol of iodine. The organic phase was separated, the excess of iodine was extracted into an aqueous iodide solution as triiodide and the absorbance of the liberated triiodide was measured at 350 nm. The calibration plot obtained for thiosulfate did not form a linear graph and was not affected by a change in the volume of 10 to 27 cm3 of the sample solution. The proposed method could be applied to the determination of thiosulfate in the concentration ranges 5 × 10−7—3.4 × 10−5 mol dm−3 (0.056—3.81 ppm) for a 10 cm3 thiosulfate solution and 1.9 × 10−7—1.36 × 10−5 mol dm−3 (0.021—1.52 ppm) for a 25 cm3 thiosulfate solution. Good recoveries of thiosulfate from hot-spring and lake-water samples, to which various known amounts of thiosulfate had been added, was achieved and the relative standard deviation was 0.86% at the 5.42 × 10−6 mol dm−3 (0.608 ppm) thiosulfate level when applied to a hot-spring sample.

Piezoelectric determination of traces of thiourea

A method was developed for the determination of thiourea based on the reaction of the latter with a solution of iodine in carbon tetrachloride at pH 7, followed by measuring the frequency change of a gold-plated piezoelectric crystal caused by the unreacted iodine. The frequency change is proportional to thiourea concentration over the range 1 × 10 −7−6 × 10 −6 mol l −1 (7.6–457 ng ml −1). The relative standard deviation was 1.4% for six measurements of 6 × 10 −7 mol 1 −1 (46 ng ml −1) thiourea.

Determination of thiosulphate at trace levels using an iodide ion-selective electrode

Aqueous thiosulphate was shaken with a solution of iodine in carbon tetrachloride. The organic phase was separated, the excess of iodine extracted into an aqueous sulphite solution and the iodide liberated was measured with an iodide-selective electrode. It was possible to determine thiosulphate in various concentration ranges by changing only the concentration of the standard iodine in carbon tetrachloride solution. A linear calibration graph was obtained over the concentration range 4 × 10–7–8 × 10–6M thiosulphate and the relative standard deviation was 0.92% at the 6 × 10–6M thiosulphate level. Good recoveries of thiosulphate from natural water samples were achieved using the proposed method.

Ion-selective electrodes in organic functional group analysis: Micro- and submicro-determination of thiocarbonyl and thiol groups using the silver/sulphide and iodide electrodes

Thiocarbonyl and thiol groups in organic compounds are determined by reaction with 1N iodine in carbon tetrachloride in the presence of pyridine, whereby 4 equivalents and 1 equivalent of iodide ion are quantitatively released per group, respectively. The iodide ions in an aqueous extract are potentiometrically titrated with silver nitrate using the solid-state silver/sulphide selective electrode. The results obtained with samples down to 70μg show an average recovery of 98.6% and no interferences are caused by unsaturated functions. Measurement of the iodide ion using the iodide ion-selective electrode and the known addition technique gives results with an absolute error of 2%.

Mechanism of ester formation during decarboxylation with t-butyl hypochlorite and iodine

Esters are formed from carboxylic acids and alkyl iodides upon treatment with t-butyl hypochlorite and iodine in carbon tetrachloride. Evidence is presented for a heterolytic mechanism whereby the iodine in the alkyl halide is replaced by the acyloxy-group of the acyl hypoiodite in the presence of iodine monochloride.

Reactivity of main-group–transition-metal bonds. Part I. Kinetics of lodination of tricarbonyl(η-cyclopentadienyl)(trimethylstannyl)-molybdenum and -tungsten, dicarbonyl(η-cyclopentadienyl)(trimethylstannyl)iron, and pentacarbonyl(trimethylstannyl)manganese

The kinetics of cleavage of the tin–transition-metal bond in [Me3SnMo(CO)3(cp)], [Me3SnW(CO)3(cp)], [Me3SnMn(CO)5], and [Me3SnFe(CO)2(cp)] by iodine in carbon tetrachloride have been studied (cp =η-cyclopentadienyl). The reaction is an electrophilic substitution at the metal–metal bond. The relative rates for the above four compounds are M = Fe > Mo ≈ W ≫ Mn. The simplicity of the kinetics for the iodination of these compounds probably masks the complexity of the reaction, and schemes involving charge-transfer complexes and chemical intermediates are proposed.

Studies in Solubility Parameter Theory for Mixed Solvent Systems

Data are presented for the saturation solubility and partial molal volume of iodine in a mixed benzene–cyclohexane solvent and for the saturation solubility of stannic iodide in the same solvent mixture. A successful interpretation of these data in terms of solubility parameter theory is possible if we define an effective volume fraction term. This term reflects the immediate solvent environment of the solute molecule with the preferential solvation of the solute by one of the solvent molecules. Data for iodine in a mixed carbon tetrachloride–benzene solvent mixture and for iodine in a carbon tetrachloride–perfluoroheptane mixture are also interpreted in terms of the proposed theory.

The liquid-state, iodide-selective electrode

The ion-sensitive surface of the liquid-state electrode is formed by a very thin layer of an organic liquid, adsorbed at the surface of porous graphite. The composition of this organic phase, which must be immiscible with water, can be chosen so that the electrode responds only to the activity of a certain ion in the measured aqueous sample. The performance and construction of a liquid-state electrode with solutions of iodine in carbon tetrachloride, benzene and mesitylene as the organic phase is described. The electrode is suitable for measurement of iodide activities down to 10 −6 M; it has selectivity ratios for iodide over bromide of about 10 −3 and over chloride ion of better than 10 −4. In contrast to the solid-state iodide-selective electrode (AgI/Ag 2S membrane), the liquid-state electrode is not sensitive to light at any level of the iodide activities studied, but it is sensitive to species which would reduce iodine to iodide.

Charge transfer processes with electronically excited iodine molecules

AbstractUsing an anthracene crystal as a probe, it was concluded from hole injection experiments that the 3∏+ state of iodine in carbon tetrachloride has a mean free path √Dτ in solution of (3 ± 2) · 10−6 cm. No energy transfer between iodine molecules could be detected. It was shown that photocurrents in naphthalene crystals can be generated either through reaction of naphthalene excitons with electron acceptors in solution or of excited iodine molecules in the solution with ground state naphthalene molecules in the crystal.

Study of electrophilic substitution reactions at the olefinic carbon atom Communication 4. Kinetics and stereochemistry of the reaction of cis-and trans-?-chlorovinyl-mercury chlorides with iodine in carbon tetrachloride and benzene

1. The kinetics of the reaction of trans-β-chlorovinylmercury chloride with iodine was studied in nonpolar solvents-carbon tetrachlorine and benzene. 2. In nonpolar solvents the reaction proceeds without conservation of the geometrical configuration. Each of the isomers ofβ-chlorovinylmercury chloride gives the same equimolar mixture of trans- and cis-1,2-chloroiodoethylenes.

The interaction of iodine with dimethyl-sulphoxide in carbon tetrachloride solutions

The infra-red, visible and ultra-violet spectra of solutions of DMSO and iodine in carbon tetrachloride were studied at 20°C and the ratio of DMSO to iodine concentrations was changed from 2 to 20, 00. The results confirm the existence of a molecular complex DMSO. I 2. The reversible formation of the tri-iodide ion is related to a change of polarity in the medium when a relatively large amount of DMSO is present, due to the high dielectric constant of the latter as compared to carbon tetrachloride, which induces the ionization of the complex.

108. Aromatic reactivity. Part XXIII. Cleavage of aryl–tin bonds by iodine in carbon tetrachloride

The first page of this article is displayed as the abstract.

Iodine Complexes in Inert Solvents. III. Iodine Complexes with Methanol, Ethanol, or Diethyl Ether in Carbon Tetrachloride

Thermodynamic and spectroscopic constants, obtained by a spectrophotometric method, are reported for complexes of methanol, ethanol, and diethyl ether with iodine in carbon tetrachloride. It is shown that the heats of formation of the complexes are nearly identical with values obtained by a nonspectroscopic method. From the spectroscopic and nonspectroscopic data for solutions of methanol, ethanol, and diethyl ether with iodine or with iodine and carbon tetrachloride, it is concluded that the activity coefficients for the iodine and the alcohols are independent of their concentrations and that in these cases the alcohols do not solvate the complexes even at concentrations of nearly one hundred percent alcohol. Exact molar extinction coefficients for iodine in n-heptane and in carbon tetrachloride are given in Table I, and related data in Fig. 2. There is a detailed discussion of errors due to the neglect of temperature effects, underlying bands, and volume changes on mixing the solvents. Evidence in support of ``Liquid Lattice Penetration Complex'' theory, in which it is assumed that the stabilizing forces arise from ``donor-acceptor'' interaction, is also discussed. It is found that Andrews and Keefer's linear relations between ΔF and ΔH or ΔS, for the aromatic complexes of iodine, do not hold for all iodine complexes.

Absorption Spectra of I2 and I4 in CCl4 Solution

The absorption of light by solutions of iodine in carbon tetrachloride has been investigated from 250 mμ to 600 mμ. Deviations from Beer's law occur in the region below 420 mμ. In this region the apparent extinction coefficient of the iodine is a linear function of its concentration. This can be accounted for on the basis that a weak complex of formula I4 exists in the solution in equilibrium with the diatomic molecules: 2I2=I4. The true extinction coefficient of I2 and the product of the formation constant and the extinction coefficient of I4 have been determined as a function of wavelength in this region.

The absorption of chlorine from air by solutions of olefins and iodine in carbon tetrachloride

The S tephens-M orris disc column is used to study the influence of chemical reaction upon the rates of absorption of chlorine from air by solutions of either cyclohexene or oleic acid with iodine in carbon tetrachloride. The increase in the liquid film coefficient due to chemical reaction between chlorine and cyclohexene was found to be independent of the concentration of cyclohexene, but no satisfactory correlation of the experimental results could be obtained. The fractional increase in the liquid film coefficient due to reaction between chlorine and oleic acid varied from zero to 9, and was found to be ▪ where φ is the ratio of the liquid film coefficient to the coefficient in the absence of reaction, c C is the concentration of the catalyst (iodine), c B is the concentration of oleic acid, and c i is the concentration of the dissolved chlorine at the gas-liquid interface. The units are lb. moles, feet and hours. The film theory is unable to predict the effect of the chemical reaction on the liquid film coefficient.