Carbon Tetrachloride Solution Research Articles

Photochemical intercalation in graphite

Free radicals can be produced by photochemical reactions. Due to their strongly oxidizing properties they promote the intercalation of many compounds into graphite with formation of acceptor compounds. Metal chlorides, e.g. FeCl 3 or SnCl 4, were intercalated from their solutions in carbon tetrachloride, 1,2-dichloroethane or their mixtures upon irradiation with ultraviolet light. The formation of radicals under these conditions was proven experimentally. The advantages of this method as well as some serious disadvantages are discussed. Solvent is always co-intercalated, the products are often relatively badly ordered, and stage-fidelity was difficult to achieve. Metal-organic compounds, such as (CH 3) 3 SnCl, have been intercalated in the same way. Also metal carbonyls, which undergo photolysis, can be hotochemically intercalated from solution in benzene or THF.

Influence of shear on polymer adsorption kinetics.

Kinetics of poly(methylmethacrylate) adsorption onto a single surface from dilute carbon tetrachloride solution is reported. From stagnant solution the well-known steady-state plateau level of mass adsorbed is approached at long times. However, the mass adsorbed resumes its rise when moderate shear flow is initiated. For adsorption onto an initially bare surface, at a shear rate of 3 ${\mathrm{sec}}^{\mathrm{\ensuremath{-}}1}$, there is no sign of plateau on the logarithmic time scale.

Concentration dependent depolarized Rayleigh scattering of dimethylformamide-h7 and -d7 in CCl4 solution

The formulas derived in our previous paper on the first moments of far-infrared and depolarized Rayleigh spectra are applied to the study of dimethylformamide (DMF) and its deuterated derivative in carbon tetrachloride solution. Changes in the peak and average frequencies of the R(ω) representation of the depolarized Rayleigh wing data are measured as a function of concentration and compared to limited far-infrared absorbance spectra of the more dilute solutions. The measured average frequencies of the DRS data agree well with those calculated from the area under the imaginary correlation function divided by time, and with the values calculated from the first term in the series expression for ω̄ in terms of fourth and higher even moments. Collisional contributions to the spectral moments complicate the determination of mean square torques and orientational correlations from the DRS spectra. The first and second moments were found to be larger than the theoretical values for purely reorientational scattering and were fairly independent of concentration. The data suggest that the additional scattering is due to a dipole–induced dipole contribution to the polarizability αi⋅Ti j⋅αj.

Ultratrace Determination of Metals with Dithizone by Thermal Lens Spectrophotometry

A pump-probe thermal lens instrument was constructed, evaluated, and applied to the determination of metals after extraction with dithizone in carbon tetrachloride. An argon-ion laser operated at 514.5 nm, with a power of just 22 mW at the cuvette position and chopped at 2 Hz, and a He-Ne laser were used as a pump and probe, respectively. The thermal lens effect was measured by a pinhole-photodiode and a lock-in amplifier. Evaluation of the setup with an iodine solution in carbon tetrachloride gave a minimum detectable absorbance of 5 × 10−6 (S/N = 3), the upper limit of the dynamic range being 5.7 × 10−3. Relative standard deviation was about 3%. Calibration curves and limits of detection for several metal dithizonates were obtained. From extractions of cadmium dithizonate at concentrations lower than 2 ng mL−1, a LOD of 8 pg mL−1, corresponding to an absolute LOD of 4 fg of cadmium in the probe volume, was achieved.

FT-far-infrared spectroscopic studies of solute-solvent interactions and molecular dynamics in solutions of methanol, N-methyl formamide and N,N-dimethyl formamide

Quantitative measurements of the optical constants (4–170 cm−1) of three organic liquids and their dilute solutions in carbon tetrachloride have been interpreted in terms of molecular relaxation processes arising from solute-solute and solute-solvent interactions. The behaviour of CH3OH and NMF on dilution is quite different from that of DMF, emphasizing the importance of “hydrogen bonding” potentials in the former two liquids.

Spectroscopic studies of solute–solute and solute–solvent interactions in solutions containing N,N-dimethylformamide

Infrared, far-infrared and Raman spectra of N,N-dimethylformamide are reported for the liquid and across the whole concentration range in carbon tetrachloride solution. The data reflect important differences between the long-ranged and short-ranged behaviour of the solute–solute and solute–solvent intermolecular potentials. In particular, the far-infrared spectrum is dominated by short-ranged interactions which vary only marginally with concentration and which are probably controlled by geometrical factors. On the other hand, the Raman and infrared band shapes are drastically affected by at least two types of dephasing process, including resonance energy transfer and the effects of concentration fluctuations, both probably mediated through strong longer ranged dipolar interactions. Molecular tumbling motion is severely hindered in the liquid and gets faster on dilution, presumably owing to the removal of intermolecular correlations.

Association constants for the electron-donor–acceptor complexes of indole and 1-methylindole with 1-(2,4,6-trinitrophenyl)propan-2-one from nuclear magnetic resonance shift measurements. An anomalous scatchard plot

Changes (Δ) in the chemical shifts of the protons in the n.m.r. spectrum of the electron acceptor 1-(2,4,6-trinitrophenyl)propan-2-one (A) as a function of added electron donor (D) have been measured for D = indole and D = 1-methylindole, in carbon tetrachloride solution. Although the Scatchard plot (Δ/[D]0vs.Δ) for the methyl probe in the system involving indole is of an unusual shape, it yields values for parameters on the basis of a double equilibrium involving the formation of DA and D2A which are consistent with values for the other 1H probes and also for values of the corresponding 1-methylindole system. The effect of the probable n-merisation of D molecules on the values of the constants for the association of D with A has been estimated.

Kinetics of polymer adsorption measured in situ at the solid—liquid interface: Utility of the infrared total internal reflection method

The method of infrared spectroscopy in attenuated total reflection (IR-ATR) has been used to study kinetics of polymethylmethacrylate (PMMA) adsorption from dilute carbon tetrachloride solution onto a germanium prism at 27.0°C. By using a combination of deuterated and protio PMMA, it was possible to monitor the initial buildup of the adsorbed layer of one polymer species, followed by the time-dependent displacement of this species when the ambient polymer solution was changed. Data are presented for the displacement of adsorbed deuterated polymer of molar mass 57,000 g by protio polymer of molar mass 400,000 g, and for the displacement of adsorbed protio polymer of molar mass 64,000 by deuterated polymer of molar mass 57,000 g. Although it was not possible to repeat experiments quantitatively, the qualitative conclusion is that in both situations PMMA of molecular weight ca 60,000 g mol −1 displayed a residence time on the germanium surface of at least several hours. It was possible by this method to measure the kinetic exchange that underlay an overall equilibrium amount of polymer adsorbed.

Molecular motions in poly (ethylene oxide) solutions

The motions of solvent and molecules in solutions of poly(ethylene oxide) have been investigated by neutron inelastic scattering measurements. Both the concentration dependence and the influence of the molecular weight of the PEO molecules were studied. It is shown that there exists a strong concentration dependent interaction between a PEO molecule and the surrounding water which affects both the translational and the rotational motions of the water molecules. Thus there is a clear indication of the presence of a hydration shell around each PEO molecule within which the motions of the water molecules are strongly hindered. In carbon tetrachloride solutions the results indicate that there exists a weak interaction of hydrodynamic origin between solvent and solute molecules.

Reorientational relaxation in liquid 1,4‐dioxane as studied by Raman spectroscopy

AbstractThe anisotropic Raman spectra of liquid 1,4‐dioxane have been recorded at several temperatures and at different concentrations of aqueous and carbon tetrachloride solutions. The rotational dynamics of the 1,4‐dioxane molecules under these conditions is discussed in terms of appropriate correlation functions, reorientational relaxation times and second‐order rotational spectral moments.

The solution-state conformations of iodoacetone and ω-iodoacetophenone

A comparison of the experimental dipole moments of iodoacetone and ω-iodoacetophenone in n-hexane, carbon tetrachloride and benzene solution at 30.0°C with the values calculated (with inclusion of induced moments through space) for both cis and gauche conformers gives estimates of their ( cis):( gauche) conformational ratios in these media. Molecular mechanics calculations show that the cis conformers of iodoacetone and ω-iodoacetophenone are nearly uniplanar, whereas the gauche-conformers of these compounds are characterized by (OCCH 2I) dihedral angles of 100.5 and 98.5°, respectively.

Far infrared spectra of the tetrahydrocarbons CBr4 and CCl4

Far infrared spectra of carbon tetrabromide in solutions of carbon tetrachloride has been measured at 20 °C in the wave number range 15–250 cm−1. The apparent dipole moments for CCl4 and CBr4 have been calculated as 0.15 and 0.31 D, respectively, on the assumption that the apparent dipole moment arises entirely from the octopole moment (Ω) of the neighboring molecules. Ω for CCl4 and CBr4 has been determined to be (13±1)×10−34 and (18±3)×10−34 esu, respectively. These values agree closely with those estimated from transition temperatures in solids composed of these molecules.

Effects of reaction conditions on bromination of atactic poly(propylene)

AbstractEffects of various reaction conditions on bromination of atactic poly(propylene) (APP) in carbon tetrachloride solution were studied. It was found that with the increase of the reaction time the extent of bromination increases. Also with an increased dilution of APP the rate of bromination increased following a bromination order of 0.66 with respect to APP concentration. This has been ascribed to initial replacement of the hydrogen at the tertiary carbon atoms followed by enhanced ease of abstraction from the neighbouring secondary and primary carbon atoms. The apparent activation energy was found to be 11.9 kcal/mol. The rate of bromination increases with an increase of the APP: Br2 molar ratio up to 1 : 1, beyond which the rate becomes independent of this ratio. Mechanism of bromination appears to be an initial substitution of tertiary H‐atoms by bromine radicals followed subsequently by replacement of secondary and primary H‐atoms via either progressive substitution or elimination‐addition. IR spectra confirm the presence of bromine in the samples.

On the Reactivity of Chlorine Atoms towards Alcohols

Abstract Pulse radiolysis has been used to determine reaction rate constants of chlorine atoms with various alcohols in carbon tetrachloride solutions by competition kinetic methods taking the absorption of the complex formed in the reaction of dimethyl sulfoxide and chlorine atoms as a reference system.

Novel Transient Absorption of Irradiated DMSO in Carbon Tetrachloride as Studied by Pulse Radiolysis

Abstract Transient absorption spectra with a maximum at 400 nm have been observed in the pulse radiolysis of dimethyl sulfoxide in carbon tetrachloride solutions. The transients are attributed to the complexes formed in reaction of chlorine atom with dimethyl sulfoxide based on spectral and kinetic studies.

Infrared study of the hydrogen bonding site in a poly-functional schiff base: N( sp2) or N( sp)?

The hydrogen bond complexes between phenol derivatives and the Schiff base [(diphenylmethylene)amino]-acetonitrile have been studied by infrared spectroscopy in carbon tetrachloride solution. The thermodynamic data and the infrared spectra investigated in the ν OH, ν CN and ν CN region indicate that complex formation occurs at the nitrogen atom of the nitrile function. The hydrogen bonding site is in this case governed by the accessibility of the lone pair which is markedly higher for the N( sp) than the N( sp 2) electrons.

Proton NMR study of the interaction of water with N-methylacetamide in carbon tetrachloride solution

Proton NMR study of the interaction of water with N-methylacetamide in carbon tetrachloride solution

ChemInform Abstract: Molecular Design of Chiral Recognition Systems Based on Self Association‐Induced Non‐Equivalence.

In consideration of the flat-sheet structure known as a secondary structure of peptides and proteins, the self association of N-acyl α-amino acid derivatives may reasonably be expected to occur in non-aqueous media. To confirm the structure of dynamically formed molecular complexes, spectral studies of N-acetylvaline tert-butyl ester (1) in a carbon tetrachloride solution were carried out. A split of the amide NH resonance into two 1H nmr signals for the D and L enantiomers, termed self-induced non-equivalence, was observed when the solute was enantiomerically enriched in the solution. A concentration study of 1H and 13C-NMR showed the diastereomeric dimers, whose associative interactions are bidentate NH--O=C (ester) hydrogen bonds, to be in the enantiomeric solutions. Ir spectra confirmed the stability difference between the diastereomeric dimers by an external comparison of optically pure and racemic samples in the carbon tetrachloride solution.The association stereoselectivity of solute 1 was applied to the design of chromatographic phase systems. When racemic solute 1 is injected into a non-chiral silica gel column using mobile phase solvent containing chiral solute 1 as an additive component, the racemate should interact with chiral solute 1 added to the mobile phase solvent, while passing through the column, to form transient diastereomeric dimers as observed in solution, and be separated. Self association-induced resolution was confirmed experimentally using radiolabelled solute 1 and the radioactivity detection.Attempts were made to widen the scope of application involved in the hydrogen-bond association mode to chiral recognition through the development of other resolving agents. N-Acetylvaline tert-butylamide was found to separate the homologues of N-acyl α-amino acid esters. Tartaric esters and amides were found capable of separating a variety of enantiomeric compounds in non-aqueous media.

Nearly free rotation of water and ammonia in alkanes and other weakly interacting solvents

The weak hydrogen-bonding interactions between water, ammonia, and some alcohols as solutes and alkanes, alkenes, and carbon tetrachloride as solvents are explored. The nature of the interaction is indicated by the intensities, positions, and widths of the OH and NH stretching bands. The alkane solutions differ qualitatively from the alkane and carbon tetrachloride solutions. In the alkane solutions, water and ammonia show free rotation with a correlation time of a bit less than 0.1 ps. In the other solvents, stronger solute-solvent interactions determine the band shape.

Electron-donor–electron-acceptor association constants of pyrene with 2,4,6-trinitrotoluene in solution determined by 1H-nuclear magnetic resonance from non-linear Scatchard plots

The chemical shifts of the ring and methyl protons of 2, 4, 6-trinitrotoluene have been measured as a function of the concentration of added pyrene in solutions in carbon tetrachloride at 33.5 °C. Simple analysis at the 95 % confidence level yields association constants K= 8.42 ± 0.1 and 7.92 ± 0.1 kg mol–1 from these two probes, respectively. Allowance for ‘additional unspecific shielding’ increases these values to K= 9.10 ± 0.05 and 8.84 ± 0.06 kg mol–1. Alternatively, analysis based on a double equilibrium forming complexes with stoichiometry DA and D2A results in association constants K1= 8.7 ± 0.2 and 8.4 ± 0.3 kg mol–1, and K2= 0.23 ± 0.05 and 0.31 ± 0.07 kg mol–1 from HAr and HMe, respectively. Thus, whilst the model of a simple 1:1 association is untenable, the data do not provide a clear choice between the second and third models in this particular system.