Isotope effects in proton-transfer reactions. An ion cyclotron resonance determination of the equilibrium deuterium isotope effect in the bichloride ion

1987 ◽  
Vol 91 (3) ◽  
pp. 554-557 ◽  
Author(s):  
J. W. Larson ◽  
T. B. McMahon
Keyword(s):  
Proton Transfer ◽  
Isotope Effect ◽  
Cyclotron Resonance ◽  
Isotope Effects ◽  
Transfer Reactions ◽  
Ion Cyclotron Resonance ◽  
Deuterium Isotope Effect ◽  
Ion Cyclotron ◽  
Proton Transfer Reactions

Gas-Phase Basicity of Formaldehyde by the Thermokinetic Method

2000 ◽  
Vol 6 (2) ◽  
pp. 109-112 ◽  
Author(s):  
Guy Bouchoux ◽  
Danielle Leblanc
Keyword(s):  
Fourier Transform ◽  
Proton Transfer ◽  
Equilibrium Constant ◽  
Gas Phase ◽  
Cyclotron Resonance ◽  
Transfer Reactions ◽  
Ion Cyclotron Resonance ◽  
Proton Transfer Reactions ◽  
Ft Icr

A series of proton transfer reactions monitored in a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer allows the determination of the gas-phase basicity ( GB) and the proton affinity ( PA) of formaldehyde. The values determined by the thermokinetic method, GB(CH2O) = 681.5 ± 0.7 kJ mol−1 and PA(CH2O) = 711.5 ± 2.1 kJ mol−1 are in excellent agreement with data originating from proton transfer equilibrium constant determinations or from G2 calculations.

Proton transfer reactions between ortho-methyl substituted derivatives of 4-nitrophenylphenylcyanomethane and nitrogen bases in acetonitrile solvent

1988 ◽  
Vol 66 (6) ◽  
pp. 1454-1458 ◽  
Author(s):  
Kenneth T. Leffek ◽  
Przemyslaw Pruszynski
Keyword(s):  
Proton Transfer ◽  
Isotope Effect ◽  
Rate Constants ◽  
Isotope Effects ◽  
Equilibrium Constants ◽  
Activation Parameters ◽  
Transfer Reactions ◽  
Methyl Groups ◽  
Methyl Group ◽  
Proton Transfer Reactions

Equilibrium constants, rate constants, primary deuterium isotope effects, and activation parameters have been measured for the proton transfer reactions in acetonitrile solvent of 4-nitrophenylphenylcyanomethane and 2-methyl-4-nitrophenylphenyl-cyanomethane with tetramethylguanidine base and for the reactions of 2-methyl-4-nitrophenylphenylcyanomethane and 2,6-di-methyl-4-nitrophenylphenylcyanomethane with 1,5-diazabicyclo[5.4.0]undec-7-ene base. Introduction of the ortho-methyl groups in the substrate molecule caused significant reductions in the equilibrium and rate constants. The expected rise in the kinetic primary deuterium isotope effect was not observed when the first ortho-methyl group was introduced, but a 20% increase did accompany the introduction of the second ortho-methyl group. Enthalpy of activation measurements indicated that there was no increase in the proton tunnelling contribution to the isotope effect when the amount of steric hindrance is increased with ortho-methyl groups.

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