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.

Neutral Solvolysis of Acyl Carbon and the Temperature Dependence of the Kinetic Solvent Isotope Effect

1975 ◽  
Vol 53 (6) ◽  
pp. 869-877 ◽  
Author(s):  
B. Rossall ◽  
R. E. Robertson
Keyword(s):  
Temperature Dependence ◽  
Isotope Effect ◽  
Solvent Isotope Effect ◽  
Acyl Carbon ◽  
Rate Of Hydrolysis ◽  
Solvent Isotope ◽  
Neutral Conditions ◽  
Hydrolysis Of

The temperature dependence of the rate of hydrolysis of benzoic, phthalic, and succinic anhydrides have been determined in H2O and D2O under "neutral" conditions. Corresponding data have been obtained for methyl trifluoroacetate. While both series supposedly react by the same BAc2 mechanism, remarkable differences are made obvious by this investigation. Possible sources of such differences are proposed.

Studies in Solvolysis. Part VII. The Neutral Hydrolysis of Methyl Perchlorate

1975 ◽  
Vol 53 (20) ◽  
pp. 3106-3115 ◽  
Author(s):  
Ross Elmore Robertson ◽  
Adrianna Annesa ◽  
John Marshall William Scott
Keyword(s):  
Heat Capacity ◽  
Carbon Atom ◽  
Temperature Dependence ◽  
Thermodynamic Parameters ◽  
Isotope Effect ◽  
Perchlorate Ion ◽  
Rate Of Hydrolysis ◽  
Leaving Groups ◽  
Hydrolysis Of

The temperature dependence of the rate of hydrolysis of methyl perchlorate has been measured and the entropy (ΔS≠), enthalpy (ΔH≠), and heat capacity (ΔCp≠) of activation calculated. The measurements confirm that the perchlorate ion is superior to all other leaving groups in water. The isotope effect related to the hydrolysis of methyl-d3 perchlorate has been measured at three temperatures and shown to be inverse. The thermodynamic parameters and the isotope effect were examined with respect to the mechanism of substitution at a primary carbon atom.

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.

Untersuchungen zur Reaktion der Alkoholdehydrogenase mit Tritium-markierten Substraten

1966 ◽  
Vol 21 (6) ◽  
pp. 540-546 ◽  
Author(s):  
Dieter Palm
Keyword(s):  
Alcohol Dehydrogenase ◽  
Temperature Dependence ◽  
Isotope Effect ◽  
Substrate Binding ◽  
Isotope Effects ◽  
Direct Interaction ◽  
Enzyme Complex ◽  
Temperature Range ◽  
Yeast Alcohol Dehydrogenase ◽  
Rate Controlling Step

Unexpectedly, the isotope effect of ethanol-1-Τ as a substrate of yeast alcohol dehydrogenase, increases with rising temperature from kH/kT = 3.2 at 5 —15°C to 3.8—4.7 at 20 —35 °C. This suggests a change of the rate controlling step as proposed by MÜLLER-HILL and WALLENFELS, who investigated the temperature dependence of the activation energies in this temperature range. A comparison of the affinities of propanol and butanol with the isotope effects of the corresponding tritium labelled compounds (propanol-1-Τ 6.7 at 25 °C, butanol-1-Τ 6.8 at 25 °C) supports the proposal, that during substrate binding, there must be a direct interaction between the enzyme complex and hydrogen which is removed in the reaction. These influences are less pronounced for the ethanol homologues which are bound less tightly to the enzyme. Therefore the H transfering step proper gives a greater contribution to the overall experimental 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.

scholarly journals Solvent Deuterium Isotope Effect on the Rate of the Uncatalyzed Hydrolysis of Phenyl Dimethyl Orthoformates.

1987 ◽  
Vol 41a ◽  
pp. 93-97 ◽  
Author(s):  
Markku Lahti ◽  
Jozef Kowalewski ◽  
Arnold Maliniak ◽  
Lauri Niinistö ◽  
L. Niinistö
Keyword(s):  
Isotope Effect ◽  
Deuterium Isotope Effect ◽  
Hydrolysis Of

Notizen: Solvent Deuterium Isotope Effect on Hydrolysis of Nd3+ Ion

1977 ◽  
Vol 32 (12) ◽  
pp. 1493-1495 ◽  
Author(s):  
Masunobu Maeda ◽  
Toshihiko Amaya ◽  
Hidetake Kaeihana
Keyword(s):  
Isotope Effect ◽  
Heavy Water ◽  
Formation Constant ◽  
Water System ◽  
Glass Electrode ◽  
Mononuclear Complex ◽  
Deuterium Isotope Effect ◽  
Light Water ◽  
Water Solutions ◽  
Hydrolysis Of

The hydrolysis equilibria of Nd3+ ion in light- and heavy-water solutions containing 3 mol dm-3 (Li)ClO4 as an ionic medium were studied at 25 °C by measuring the lyoniumion concentration with a glass electrode. Analysis of the emf data indicated the formation of only the mononuclear complex Nd(OL)2+ in both light and heavy water. The formation constant *β2,1 was smaller in D2O (log *β2,1 = —16.54 ± 0.04) than in H2O (log *β2,1 = —15.90 ± 0.06). The formation constant K2,1 for the heavy-water system (log K2,1 = 12.28) had a larger value than that for the light-water system (log K2,1 = 11.86).

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