ENTHALPIES OF INTRAMOLECULAR HALOGEN–HYDROXYL INTERACTIONS

1965 ◽  
Vol 43 (3) ◽  
pp. 650-659 ◽  
Author(s):  
A. W. Baker ◽  
A. T. Shulgin
Keyword(s):  
Carbon Tetrachloride ◽  
Temperature Dependence ◽  
Kcal Mole

Enthalpies of halogen–hydroxyl interactions have been evaluated for the 2-halophenols in carbon tetrachloride. These values, in −kcal/mole, corrected for the temperature dependence of absorptivity coefficients, are Cl = 1.44, Br = 1.21, and I = 1.08. From enthalpy differences measured in unsymmetrical 2,6-dihalophenols, it is shown that the interaction in 2-fluorophenol lies between those in 2-bromophenol and 2-iodophenol, thus reaffirming the order Cl > Br > F > I.

13C NMR-spektroskopische Untersuchungen an Äthylaluminiumverbindungen / 13C NMR Spectroscopic Investigations of Ethylaluminium Compounds

1976 ◽  
Vol 31 (6) ◽  
pp. 730-736 ◽  
Author(s):  
R. Rottler ◽  
C. G. Kreiter ◽  
G. Fink
Keyword(s):  
Temperature Dependence ◽  
Exchange Reaction ◽  
13C Nmr ◽  
Line Shape ◽  
Nmr Spectra ◽  
Exchange Process ◽  
Kcal Mole ◽  
Line Shapes ◽  
Calculated Line ◽  
C Nmr

The 13C NMR spectra of the ethylaluminium compounds [Al(C2H5)xCl3_x]2 x = 1, 1,5, 2 and 3 are presented and factors governing the temperature dependence of the line shape are discussed. The exchange reaction of terminal ethyl groups for chlorine ligands and ethyl ligands, resp., in ethylaluminium-sesquichloride was investigated by fitting the calculated line shapes to the observed spectra.The energy of activation of this exchange process was determined as to be 12,3 ‡ 1,5 kcal/mole. The synthesis of 13C2-[Al(C2H5)Cl2]2 is described.

Conductivity and Viscosity of the Tetrabutylammonium Bromide – Carbon Tetrachloride System

1972 ◽  
Vol 50 (10) ◽  
pp. 1600-1603 ◽  
Author(s):  
K. F. Denning ◽  
James A. Plambeck
Keyword(s):  
Carbon Tetrachloride ◽  
Temperature Dependence ◽  
Tetrabutylammonium Bromide ◽  
Viscosity Measurements ◽  
Ratio Range

Conductivity and viscosity measurements have been made on tetra-n-butylammonium bromide – carbon tetrachloride solutions for the mole ratio range 1:40 to 1:2 at temperatures from 25 to 40 °C. At any individual concentration, both conductivity and viscosity follow an Arrhenius type temperature dependence. Viscosity increases exponentially with tetrabutylammonium bromide concentration while conductivity has a maximum at approximately 1:5 mole ratio R4NBr–CCl4.

Thermotransport of Noble Metal Impurities in Lead

1972 ◽  
Vol 27 (1) ◽  
pp. 138-140 ◽  
Author(s):  
George A. Sullivan ◽  
Sune Larsson ◽  
Per T. Thernquist
Keyword(s):  
Steady State ◽  
Temperature Dependence ◽  
Noble Metal ◽  
Temperature Gradients ◽  
Electronic Contribution ◽  
Kcal Mole ◽  
Cold Side ◽  
Heat Of Transport ◽  
Metal Impurities ◽  
Significant Temperature

Abstract Steady-state distributions of Au, Ag and Cu tracers in Pb wafers subjected to temperature gradients have been determined. The effective heats of transport were + 5.8 ± 1.1 for Ag, - 0.5 ± 0.3 for Au, and of the order of + 35 for Cu (all in kcal/mole, positive values denoting the impurity migrating to the cold side of the Pb wafer). No significant temperature dependence of the heats of transport could be detected. The results are difficult to reconcile with existing theories of the intrinsic and electronic contribution to the heat of transport.

Temperature dependence of proton magnetic resonance solvent shifts. 3,5-Dichlorosalicylaldehyde in carbon tetrachloride and benzene

1968 ◽  
Vol 46 (19) ◽  
pp. 3110-3112 ◽  
Author(s):  
G. Kotowycz ◽  
T. Schaefer
Keyword(s):  
Carbon Tetrachloride ◽  
Temperature Dependence ◽  
Proton Magnetic Resonance ◽  
Benzene Solution ◽  
Chemical Shifts ◽  
Relative Temperature ◽  
Proton Shift ◽  
Solvent Shifts ◽  
Solvent Molecules ◽  
Proton Chemical Shifts

The ring proton chemical shifts of 3,5-dichlorosalicylaldehyde as a function of temperature in carbon tetrachloride and benzene solutions indicate that if there is association with solvent molecules in benzene solution, then there is also association with carbon tetrachloride solvent molecules. The aldehydic proton shift shows a much smaller (relative) temperature dependence in the carbon tetrachloride solution.

Nuclear magnetic resonance studies. X. Determination of the thermodynamic parameters of the self-association of tricyclic aromatic aldehydes in solution

1967 ◽  
Vol 45 (3) ◽  
pp. 213-219 ◽  
Author(s):  
Gurudata ◽  
R. E. Klinck ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Temperature Dependence ◽  
Thermodynamic Parameters ◽  
Aromatic Aldehydes ◽  
The Self ◽  
Kcal Mole ◽  
Magnetic Resonance Studies ◽  
Self Association

The temperature dependence of the formyl proton shieldings of 9-anthraldehyde and 9-phenanthraldehyde in chloroform solutions has been measured. Four concentrations in the range 0.5–5.0 mole % were examined over the temperature interval − 60 to + 90 °C. From these results, the enthalpies and entropies of formation have been estimated for the complex formed by the self-association of two aldehyde molecules. The calculations indicate the ΔH and ΔS values to be − 1.9 ± 0.3 kcal/mole and − 6 ± 1 e.u., respectively. These results are compared with other available data.

Temperature dependence of chemical shifts of protons in hydrogen bonds. Experimental evidence on an intramolecular hydrogen bond

1968 ◽  
Vol 46 (17) ◽  
pp. 2865-2868 ◽  
Author(s):  
T. Schaefer ◽  
G. Kotowycz
Keyword(s):  
Hydrogen Bond ◽  
Carbon Tetrachloride ◽  
Chemical Shift ◽  
Hydrogen Bonds ◽  
Temperature Dependence ◽  
Intramolecular Hydrogen Bond ◽  
Chemical Shifts ◽  
Hydroxyl Proton ◽  
Intramolecular Hydrogen ◽  
Strong Intramolecular Hydrogen Bond

A temperature dependence of the chemical shift of the hydroxyl proton in the strong intramolecular hydrogen bond in 3,5-dichlorosalicylaldehyde is observed in carbon tetrachloride and benzene-d6 solutions. Its magnitude of 0.25 to 0.30 × 10−2 p.p.m. per ° C over a range of 100 °C is in agreement with the model described by Muller and Reiter (1).

Kinetics of the direct chlorination of carbon

1970 ◽  
Vol 23 (4) ◽  
pp. 725 ◽  
Author(s):  
JD Blackwood ◽  
BD Cullis
Keyword(s):  
High Temperature ◽  
Carbon Tetrachloride ◽  
Partial Pressure ◽  
Reaction Times ◽  
Not Given ◽  
Kcal Mole ◽  
Predominant Species ◽  
Flow Apparatus ◽  
Wood Char ◽  
Kinetics Of

Carbon, in the form of a wood char activated by treatment with air and chlorine, has been chlorinated directly at temperatures between 600� and 800� and at chlorine pressures between 3.5 and 20 atm in a flow apparatus to produce carbon tetrachloride as sole reaction product. The rate of formation R of carbon tetrachloride can be expressed by the equation R = ilpa where il is the rate constant for the chemisorption of chlorine on carbon and pa is the partial pressure of chlorine. The rate is also dependent on the nature of the carbon, high temperature carbons being less reactive. The energy of activation for the process is 25 kcal mole-1. When carbon tetrachloride is decomposed in a carbon bed, tetrachloroethylene, hexachloroethane, chlorine, and carbon are formed as products, the predominant species depending on the conditions. This indicated that the overall reaction is not given by the simple equation C + 2Cl2 + CCl4 (I) and, on prolonged reaction times, yields of carbon tetrachloride well below the amount expected at equilibrium for this reaction confirm the finding. pa denotes the partial pressure of Cl2, pb that of CCl4, pc that of C2C14, and pa that of CzCl6.The subscript numerals to i and j refer to the equation numbers in the text.

SPECTROSCOPIC STUDIES OF ALCOHOLS: II. THE CONFORMATION OF 2-HALOETHANOLS IN CARBON TETRACHLORIDE SOLUTION

1964 ◽  
Vol 42 (2) ◽  
pp. 326-339 ◽  
Author(s):  
P. J. Krueger ◽  
H. D. Mettee
Keyword(s):  
Carbon Tetrachloride ◽  
Equilibrium Constants ◽  
Spectroscopic Studies ◽  
Kcal Mole ◽  
Band Shift ◽  
Carbon Tetrachloride Solution ◽  
Hydrogen Bond Interactions ◽  
Conformational Equilibria ◽  
Intramolecular Hydrogen ◽  
Conformational Free Energy

Of the five conformers predicted for 2-haloethanols, only two (halogen and OH trans and gauche) can be positively identified by high resolution infrared spectroscopy. From the temperature dependence of the relative intensities of the fundamental OH stretching bands of the trans and gauche forms of the compounds XCH2CH2OH2 where X = F, Cl, Br, and I, the gauche conformers are shown to be energetically favored in dilute carbon tetrachloride solution, with enthalpy differences between the two conformers of 2.07 ± 0.53, 1.20 ± 0.09, 1.25 ± 0.08, and 0.81 ± 0.09 kcal/mole respectively. Equilibrium constants and the conformational free energy and entropy differences are reported. Inter- and intra-molecular OH … X hydrogen-bond interactions are found to be similar in that the enthalpy increases in the order X = I < Br < Cl < F, and is linearly related to a decrease in the fundamental OH band shift, in contrast to the Badger–Bauer relationship. The molecular and thermodynamic factors governing conformational equilibria involving intramolecular hydrogen bonds are discussed.

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