Temperature Dependence of Deuterium Isotope Effect in Fluorescence of Aromatic Hydrocarbons

1971 ◽  
Vol 55 (10) ◽  
pp. 5126-5127 ◽  
Author(s):  
E. C. Lim ◽  
H. R. Bhattacharjee
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Aromatic Hydrocarbons ◽  
Deuterium Isotope Effect

The Complex between Chloromethane and Benzene

1986 ◽  
Vol 41 (1-2) ◽  
pp. 208-210 ◽  
Author(s):  
Daniel Rupp ◽  
Edwin A. C. Lucken
Keyword(s):  
Raman Spectroscopy ◽  
Temperature Dependence ◽  
Nuclear Quadrupole Resonance ◽  
Isotope Effect ◽  
Crystalline Phase ◽  
Enthalpy Of Fusion ◽  
Deuterium Isotope Effect ◽  
Quadrupole Resonance ◽  
Nuclear Quadrupole

35Cl Nuclear Quadrupole Resonance, NQR, spectra of mixtures of Chloromethane and Benzene, with relative molar compositions in the range 1:3 to 3:1, and at temperatures in the range 77 K to 180 K, reveals the presence of a new crystalline phase, in addition to that of pure Chloromethane. The temperature-dependence and the deuterium isotope effect of this new resonance show that the chloromethane molecule is much more labile in the new crystalline phase than in pure chloromethane. The existence of the new crystalline phase is confirmed by Differential Thermal Approach, DTA, which in addition provides evidence that the complex has a 1:1 composition and that the enthalpy of fusion is ≈ 660 cal./mole. Raman spectroscopy provides further evidence of the existence of the complex.

DEUTERIUM KINETIC ISOTOPE EFFECTS: V TEMPERATURE DEPENDENCE OF β-DEUTERIUM EFFECTS IN WATER SOLVOLYSIS OF ISOPROPYL COMPOUNDS

1961 ◽  
Vol 39 (10) ◽  
pp. 1989-1994 ◽  
Author(s):  
K. T. Leffek ◽  
R. E. Robertson ◽  
S. E. Sugamori
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Isotope Effects ◽  
Zero Point ◽  
Kinetic Isotope Effects ◽  
Methyl Groups ◽  
Deuterium Isotope Effect ◽  
Point Energy ◽  
Kinetic Isotope ◽  
Enthalpy Of Activation

The secondary β-deuterium isotope effect (kH/kD) has been measured over a range of temperature for the water solvolysis reactions of isopropyl methanesulphonate, p-toluenesulphonate, and bromide. In these cases the isotope effect is due to a difference in entropies of activation of the isotopic analogues rather than a difference in the enthalpies of activation. It is suggested that the observed isotope effect is due to internal rotational effects of the methyl groups in the isopropyl radical, and the lack of an isotope effect on the enthalpy of activation is accounted for by a cancellation of an effect from this source and one from zero-point energy.

Hydrolysis of α-bromoisobutyrate ion in water

1967 ◽  
Vol 45 (18) ◽  
pp. 2071-2077 ◽  
Author(s):  
B. N. Hendy ◽  
W. A. Redmond ◽  
R. E. Robertson
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Deuterium Isotope Effect ◽  
Detailed Mechanism ◽  
Temperature Range ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

The temperature dependence of the rate of hydrolysis of α-bromoisobutyrate ion in water was determined over a temperature range 9–37 °C. From these data corresponding values of ΔH≠, ΔS≠, and ΔCP≠ have been derived. The implication of these terms, together with corresponding data for hydrolysis in D2O and for the secondary deuterium isotope effect from the hydrolysis of (CD3)2CBrCOO−, provide a basis for reexamining the detailed mechanism with particular reference to accompanying solvent reorganization.

Charge Development and Mechanism in Disrotatory Ring Opening of Cyclopropyl Bromides

1974 ◽  
Vol 52 (14) ◽  
pp. 2660-2665 ◽  
Author(s):  
Jan Han Ong ◽  
Ross Elmore Robertson
Keyword(s):  
Transition State ◽  
Temperature Dependence ◽  
Temperature Coefficient ◽  
Isotope Effect ◽  
Ring Opening ◽  
Deuterium Isotope Effect ◽  
Enthalpy Of Activation ◽  
Cis And Trans ◽  
Hydrolysis Of

The temperature dependence of the rates of hydrolysis of cis- and trans-2-vinylcyclopropyl bromides has been determined in water. The temperature coefficient of the enthalpy of activation (ΔCp≠) for both compounds was unusual (−27 and −35 cal mol−1 deg−1). From this fact, it was concluded that the charge development at the transition state was low, in agreement with the conclusions of Clark and Smale (19). The slightly inverse α-deuterium isotope effect (kH/kD = 0.994) is consistent with that conclusion.

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