Kinetics and mechanism in the decomposition of CCl4 in a radio-frequency pulse discharge

In the decomposition of CCl₄ in an r.f. pulse discharge the observation of time-resolved absorption spectra of the CCl radical allowed concentration measurements and a kinetic and mechanistic investigation of the system. Kinetic spectroscopy and end product analysis, with computer simulation of proposed mechanisms, indicates that the major decomposition reaction is CCl₄»CCl+3Cl (Cl₂+Cl), with a minor contribution from CCl₄»CCl₂+2Cl. Radical concentrations were of the order of 10^–7 mol dm^–3 (10¹⁴ molec. cm^–3). CCl removal was kinetically second order with a rate coefficient value of (3.7±8)×10¹⁰ mol^–1 dm^–3 s^–1 at 295±3 K at gas pressure 0.1 torr.     

Molecular structure of trichlorophosphazo compounds from ab initio calculation and chlorine-35 NQR spectroscopy data

The molecular structures of trichlorophosphazo compounds Cl₃P=NR with R = C(CH₃)₃, C(C₂H₅)₃, C(CF₃)₃, CCl(CF₃)₂, CCl₂CF₃, CCl₃, CCl₂CCl₃, and CCl(CCl₃)₂ were analyzed by combined consideration of the results of ab initio MP2/6-31G* calculations and previously measured ³⁵Cl NQR frequencies. The conformational peculiarity of these molecules caused by the relative spatial orientations of the P-Cl and N-C bonds is reflected in the calculated geometric parameters of the Cl₃P=NC fragments and in the pattern of ³⁵Cl quadrupole resonance spectra for PCl₃ groups. For these atomic groups, the ³⁵Cl NQR frequencies were brought in correlation with the charges of the chlorine atoms found by quantum-chemical calculations.     

Plasma-chemical reactions in weakly decomposed CCl4

For the case of weak feed gas decomposition, where the concentration of CCl₄ exceeds those of decomposition and built-up products, the emission of CCl* is shown to originate from dissociative excitation of CCl₄. With electron concentration measured independently, the kinetics of CCl₄ decomposition has been extracted from the time dependence of the CCl* intensity. Supported by EPR determinations of radical concentrations in rapidly flowing CCl₄ and CCl₄/O₂ afterglows, the primary decomposition reaction is shown to be the electron impact dissociation into CCl₃ and Cl. Its rate constant (k ₁=4×10^–8 cm³s^–1) indicates strongly that dissociative electron attachment is the main reaction channel at least at r.f. power densities just above the threshold of a self-maintaining discharge. At extremely low mean electron energies the emission of a continuum is observed, which is tentatively ascribed to the radiative CCl₃-Cl recombination.     

Effect of the carbon atom coordination on the thermoactivated motion of the carbon-bonded trichloromethyl group

The reorientational motion of the trichloromethyl group depending on the environment of the carbon atom is considered based on the chlorine-35 nuclear quadrupole resonance (NQR) data. The study is performed for CCl₃ groups bonded to tri- and tetracoordinated carbon atoms in the crystalline compounds CCl₃CCl=NR (R = CH₂C₆H₅ and CCl₃CCl₃) and CCl₃CXClN=CClC₆H₄NO_2-n (X = H and Cl).₃₅Cl NQR studies of thermoactivated motion in 70 solid trichloromethyl-containing compounds are summarized. The ranges of activation energies of CCl₃ reorientations at tri- and tetracoordinated carbon atoms were determined to be 10-50 and 30-90 kJ/mole, respectively, the activation energy being markedly greater in the latter case. CCl₃ reorientations may be completely frozen by the bulky substituents which may be present along with CCl₃ in the tetracoordinated carbon bonds. Translated fromZhurnal Strukturnoi Khimii, Vol. 41, No. 4, pp. 737-746, July-August, 2000     

Effect of the carbon atom coordination on the thermoactivated motion of the carbon-bonded trichloromethyl group

The reorientational motion of the trichloromethyl group depending on the environment of the carbon atom is considered based on the chlorine-35 nuclear quadrupole resonance (NQR) data. The study is performed for CCl₃ groups bonded to tri- and tetracoordinated carbon atoms in the crystalline compounds CCl₃CCl=NR (R = CH₂C₆H₅ and CCl₃CCl₃) and CCl₃CXClN=CClC₆H₄NO_2-n (X = H and Cl).₃₅Cl NQR studies of thermoactivated motion in 70 solid trichloromethyl-containing compounds are summarized. The ranges of activation energies of CCl₃ reorientations at tri- and tetracoordinated carbon atoms were determined to be 10-50 and 30-90 kJ/mole, respectively, the activation energy being markedly greater in the latter case. CCl₃ reorientations may be completely frozen by the bulky substituents which may be present along with CCl₃ in the tetracoordinated carbon bonds. Translated fromZhurnal Strukturnoi Khimii, Vol. 41, No. 4, pp. 737-746, July-August, 2000     

Spectroscopic study of vinylidene chloride—Vinyl chloride copolymers

Summary Deuteration technique was applied to study the micro structures of copolymer series VDC/VC by infrared spectroscopy and high resolution NMR. The CH₂ bending modes of chlorine atom containing polymers assigned as follows; –CCl₂CH₂CCl₂– 1405 cm^–1 (cryst.) and 1410 cm^–1 (amorph.), –CHClCH₂CCl₂– 1422 cm^–1, –CHClCH₂CHCl– 1428 cm^–1 (cryst.) and 1432 cm^–1 (amorph.) –CHClCH₂CH₂CHCl– 1445 cm^–1 and –CCl₂CH₂CH₂CCl₂– 1448 cm^–1. This infrared interpretation shows that only the head to tail addition occurs in the copolymerisation. Nine peaks of the methylene protons were observed clearly in the NMR spectra of the copolymers. The study of the deuterated copolymers revealed that the effects of the chemical groups until the third at both sides from the marked methylene and the stereo configuration of long VC part should be considered to assign the NMR spectra. The CCl₂ group made the chemical shift of the methylene proton to appear at lower magnetic field and the CHCl group gave the opposite behavior.

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Zusammenfassung Mit deuterierten Monomeren wurde die Mikrostruktur der Copolymerenserie Vinyliden-Chlorid/Vinyl-Chlorid im Infraroten und mit hochauflösender Kernresonanz untersucht. Für die Biegeschwingung der Chloratome enthaltenden Polymeren der Methylengruppe ergeben sich folgende Werte: –CCl₂CH₂CCl₂– 1405 cm^–1 (krist.) und 1410 cm^–1 (amorph.), –CHClCH₂CCl₂– 1422 cm^–1, –CHClCH₂CHCl– 1428 cm^–1 (krist.) und 1432 cm^–1 (amorph.), –CHClCH₂CH₂CHCl– 1445 cm^–1 und –CCl₂CH₂CH₂CCl₂– 1448 cm^–1.Diese Interpretation des Infraroten zeigt, daß nur die Kopf-Schwanz-Addition bei der Copolymerisation stattfindet. Neun Maxima des Methylenprotons wurden deutlich in den NMR-Spektren der Copolymeren beobachtet. Die Untersuchungen an den deuterierten Copolymeren zeigen, daß die Effekte der chemischen Gruppen bis zur dritten nach beiden Seiten vom markierten Methylen und die Stereokonfiguration von langen Vinyl-Chlorid-Anteilen betrachtet werden müssen, um die NMR-Spektren zu beschreiben. Die CCl₂-Gruppe läßt die chemische Verschiebung des Methylen-protons bei geringeren magnetischen Feldern und die CHCl-Gruppe bei höheren erscheinen.

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With 5 figures in 13 details and 4 tables     

Redox reactions between organic halo-compounds and ferrous cations in isopropanol

Summary Halo-compounds of which the half-wave reduction potential is equal to or less negative than that of carbon tetrachloride, are reduced by tetrachloroferrate(II) anions. The bimolecular rate constants measured at 250 in isopropanol are 2 × 10^–5 M^–1 s^–1 and 1 × 10^–4 M^–1 s^–1 respectively for CCl₄ and CCl₃CO₂Me.     

Radical telomerization of 3,3,3-trifluoro-1-propene with carbon tetrachloride

Telomerization of 3,3,3-trifluoropropene with CCl₄ was carried out in the presence of Fe(CO)₅ in combination with dimethylformamide (DMF) or hexamethylphoshoric triamide (HMPA) with formation of the telomers CCl₃(CH₂CHCF₃)_nCl, n=1–3, as the main products. Chromatography-mass spectrometry showed the presence of CCl₃CH₂CH(CCL₃)CF₃, a product of recombination of the adduct radical and CCl₃, in the reaction mixture, which confirms the radical nature of the process. The structure of all the reaction products was confirmed by¹³C NMR and (or) mass spectrometry.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1807–1811, August, 1990.     

Radical addition of polychloromethanes toα,α-dichlorovinyl compounds

Conclusions The reaction of CCl₄ and CHCl₃ with CCl₂=CHR, where R=(CH₂)₃H (I) and (CH₂)₃Cl (II), gives compounds of type HCCl₂CH(CCl₃)R, and the adducts HCCl₂CH(CCl)₂CH₂CH₂CH₂Cl (V) from (I) and HCCl₂CH·(CCl₃)CH₂CH₂CHCl₂ (VIII) from (II).From CCl₄ and CC1₂=CHCH₂CH₂CH=CH₂, besides the usual addition product CCl₂=CHCH₂CH₂CHClCH₂· CCl₃, is formed 1,1-dichloro-2-(trichIoromethyl)-5-(chloromethyl)cyclopentane due to stabilization of the CCl₂CH(CCl₃)R radical by intramolecular addition to the CH=CH₂ group and the subsequent cleavage of chlorine.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1569–1574, July, 1975.     

The molecular structure of cyan trichloride ClN=CClCl

The geometric structure of cyan trichloride has been derived by gas phase Electron Diffraction methods. The r_α^o-parameters are (in Å and deg.): r_NC: 1.266(5), r_NCl: 1.683(10), r_CCl: 1.718(6), φ_CNCl: 117.11(40), φ_NCCl,cis: 127.52(40) and φ_NCCl,trans: 118.68(50).     

Infrarot-Spektren und Normalkoordinatenanalyse von Salzen mit den AnionenX 3CSO 3 − (X=H,D, F,Cl)

Zusammenfassung Die IR-Spektren verschiedener Salze mit den Anionen CH₃SO₃ ^–, CD₃SO₃ ^–, CF₃SO₃ ^– und CCl₃SO₃ ^– sowie ein Raman-Skektrum des Ag[CF₃SO₃] werden mitgeteilt. Für die gen. Anionen sowie CH₃PO₃ ^2– und CD₃PO₃ ^2– wird mit einem für alle Ionen ähnlichen allgemeinen Valenzkraftfeld eine Normalkoordinatenanalyse durchgeführt. An den A₁-Schwingungen von CF₃SO₃ ^– und CCl₃SO₃ ^– sind mehrere Koordinaten beteiligt; eine charakterisische CS-Valenzschwingung tritt in diesen Ionen nicht auf.

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Infrared spectra and normal coordinate analysis of compounds with the anionsX ₃CSO₃ ^– (X=H, D, F, Cl)

The infrared spectra of several salts with the anions CH₃SO₃ ^– CD₃SO₃ ^–, CF₃SO₃ ^–, and CCl₃SO₃ ^– and Raman data for Ag[CF₃SO₃] are reported. A normal coordinate analysis using a GVFF is performed for these anions as well as for CH₃PO₃ ^2– and CD₃PO₃ ^2–. The A₁ modes of CF₃SO₃ ^– and CCl₃SO₃ ^– are mixed; consequently no characteristic CS stretching vibration occurs.

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Mit 3 Abbildungen     

Intramolecular Hindrances to CCl3 Reorientations in CCl3PCl4 and (CCl3)2PCl3 Crystals

The trigonal bipyramidal structure of trichloromethyl-tetrachlorophosphorane CCl₃PCl₄ and bis(trichloromethyl)trichlorophosphorane (CCl₃)₂PCl₃ molecules with apical CCl₃ groups is responsible for steric hindrances to reorientations of these groups around the C–P bond. The intramolecular barriers to CCl₃ reorientations calculated for the two phosphoranes (Hartree–Fock method using the 6-31G(d) basis set) are 105.9 kJ/mole and 106.6 kJ/mole, respectively. These internal barriers are high enough to block the reorientational motion of the CCl₃ groups, as found previously by ³⁵Cl NQR for the stated crystals.     

Absolute partial and total electron ionization cross sections for CCl4 from threshold up to 180 eV

Electron impact ionization of carbon tetrachloride was studied as a function of electron energy from threshold up to 180 eV. A double-focusing mass spectrometer system in combination with an improved electron impact ion source was used, alleviating the problems of ion extraction from the source and the transmission of the extracted ions through the mass spectrometer system. Absolute partial ionization cross sections for the occurrence of CCl ₃ ⁺ , CCl ₂ ⁺ , CCl⁺, Cl ₂ ⁺ , Cl⁺, C⁺, CCl ₃ ²⁺ , and CCl ₂ ²⁺ have been determined. In addition, the total ionization cross-section function of CCl₄ is reported and compared with theoretical predictions based on a classical binary encounter approximation. Using nth root extrapolation the following ionization energies of the doubly ionized fragment ions have been derived: AE(CCl ₃ ²⁺ )=30.4±0.3 eV; and AE (CCl ₂ ²⁺ )=31.8±0.3 eV. In accordance with theoretical predictions and previous results, no stable CCl ₄ ⁺ has been detected, however, metastable dissociation processes CCl ₄ ⁺ CCl ₃ ⁺ have been observed.     

Mössbauer effect studies on sodium hexa/carboxylato/ ferrates/III/

Mössbauer spectra of a series of the complexes of the type Na₃[Fe/RCOO/₆]xH₂O /R=H, CH₃, C₂H₅, C₆H₅/ has been recorded at 298±2 K. All display a quadrupole doublet with isomer shift and quadrupole splitting values in agreement with high spin iron/III/ octahedral geometry. The quadrupole splitting show an increasing trend with increasing polarizability of the substituent anion /RCOO^–/. A linear correlation between quadrupole splitting values and the /Fe–O/ stretching frequencies has also been observed.     

Mutual separation of210Po,210Bi,and210Pb with solvent extraction using copper dithizonate −CCl4 and dithizone −CCl4 solutions

Displacement-extraction of tracer concentrations of²¹⁰Po in 1.0M (H, Na)NO₃ solutions has been studied by using copper dithizonate–CCl₄ solutions. Furthermore, based on the results of the displacement-extraction of polonium, a mixture of²¹⁰Po,²¹⁰Bi, and²¹⁰Pb of tracer concentrations in 1.0M (H, Na)NO₃ solutions could be satisfactorily separated with successive extractions by copper dithizonate–CCl₄ and dithizone–CCl₄ solutions in acidic conditions.     

Structure of the CCl3CCl=NCH2C6H5 molecule and reorientations of its CCl3 group, according to ab initio calculations

The optimal geometry of the isolated CCl₃CCl=NCH₂C₆H₅ molecule and the intramolecular barrier to reorientations of its trichloromethyl group are calculated by the RHF/6-31G* and B3LYP/6-31G* methods. The barrier found (14.1 kJ mol^?1) is compared to that determined previously by ³⁵Cl NQR for a crystal of this compound, which allows estimation of the contribution of intermolecular interactions to braking of this motion of the CCl₃ group. The structural features of the molecule of this compound are consistently manifested in quantum-chemical calculations and NQR spectra.     

Reaction of 1-Aryl-1,3,4,4-tetrachloro-2-azabuta-1,3-dienes with aminoazoles

Reactions of polychlorinated 2-aza-1,3-dienes of the general formuls ArCCl=NCCl=CCl₂ with 3(5)-aminopyrazoles, 3(5)-amino-1,2,4-triazoles, and 5-aminotetrazole led to the formation of substituted pyrazolo[1,5-a][1,3,5]triazines, [1,2,4]triazolo[1,5-a][1,3,5]triazines, and 2-azido-1,3,5-triazine derivatives whose structure was reliably established by spectral methods and X-ray analysis.     

Nuclear quadrupole interaction at133Cs in some barium compounds

Nuclear quadrupole interaction frequencies at¹³³Cs following the electron-capture decay of¹³³Ba for BaSO₄, Ba/BrO₃/2 and Ba/NO₃/2 were obtained by measuring the perturbation of 356–81 keV cascade of¹³³Ba. Nuclear quadrupole interaction frequencies for BaSO₄ and Ba/BrO₃/2 are 17.2 Mrad sec^–1 and 14.6 Mrad sec^–1, respectively, while no perturbation of 356–81 keV cascade was observed in case of Ba/NO₃/2. Further the possibility of any after-effects of electron-capture decay is ruled out through the measurement of 276–161 keV gamma-gamma directional correlation.     

Conformational features of Cl3P=NC(CF3)3 and Cl3P=NCCl(CCl3)2 molecules according to results of non-empirical calculations

Non-empirical RHF/6-31G* and MP2/6-31G* quantum chemical methods are used to calculate the molecular structure of trichlorophosphazene compounds: Cl₃P=NC(CF₃)₃ (I) and Cl₃P=NCCl(CCl₃)₂ (II). The corresponding geometric parameters obtained from the calculations are compared with X-ray diffraction analysis data reported in the literature. Conformational differences between the molecules of I and II, previously found by X-ray diffraction in the crystals of these compounds, are confirmed by non-empirical calculations of the molecules in the free state. The features of their geometry caused by intramolecular interactions are discussed.     

Infrared and Raman spectroscopic investigations of δ2-oxazolin-5-ones

The infrared and Raman Spectra of saturated and unsaturated ²-oxazolin-5-ones (azlactones) have been studied for CCl₂, CHCl₃, i-PrOH, and t-BuOH solutions and for the solid phase. Frequency assignments have been made for C=O bond stretching in the region 1825–1770 cm^–1 and for a mixed C=C and C=N vibration at 1690–1550 cm^–1. All of the azlactones showed an intense, characteristic absorption in a narrow range near 900 cm^–1 which was assigned to a deformation vibration of the oxazolone ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1133–1136, August, 1989.