Understanding the transition states of phosphodiester bond cleavage: Insights from heavy atom isotope effects

Biopolymers ◽  
2003 ◽  
Vol 73 (1) ◽  
pp. 110-129 ◽  
Author(s):  
Adam G. Cassano ◽  
Vernon E. Anderson ◽  
Michael E. Harris
Keyword(s):  
Bond Cleavage ◽  
Isotope Effects ◽  
Heavy Atom ◽  
Transition States ◽  
Phosphodiester Bond

Heavy Atom Kinetic Isotope Effects in HCN Elimination from Some Tricyanides in Methanol [1]

1978 ◽  
Vol 33 (12) ◽  
pp. 1496-1502
Author(s):  
Fouad M. Fouad ◽  
Patrick G. Farrell
Keyword(s):  
Transition State ◽  
Opposite Direction ◽  
Isotope Effects ◽  
Heavy Atom ◽  
Transition States ◽  
Kinetic Isotope Effects ◽  
The Other ◽  
Kinetic Isotope ◽  
Solvent Isotope ◽  
Solvent Isotope Effects

AbstractRates of HCN elimination from polycyanides N,N-dimethyl-4-(1,2,2-tricyanoethyl)-aniline (1), 9-cyano-9-dicyanomethyl fluorene (2), 1,1-diphenyl-1,2,2-tricyanoethane (3), and 2-phenyl-1,1,2-tricyanopropane (4) have been studied in methanol. Elimination from 1 occurs via (E 1 c B)R, mechanism. On the other hand olefin formation from 2-4 has been shown to occur via (E 1)anion pathway. Heavy atom kinetic isotope effects indicated that product stability is not the sole factor controlling the transition state geometries. Values of k12/k14 were found to be in the order 2 > 3 > 4 > 1 which implied transition states with more carbanion-like structure in the opposite direction. Solvent isotope effects and enthalpies of activation were also determined and discussed in terms of transition states geometries.

Hydrolysis of Phosphotriesters:  Determination of Transition States in Parallel Reactions by Heavy-Atom Isotope Effects

2001 ◽  
Vol 123 (38) ◽  
pp. 9246-9253 ◽  
Author(s):  
Mark A. Anderson ◽  
Hyunbo Shim ◽  
Frank M. Raushel ◽  
W. W. Cleland
Keyword(s):  
Isotope Effects ◽  
Heavy Atom ◽  
Transition States ◽  
Parallel Reactions ◽  
Hydrolysis Of

Probing transition states of concerted rearrangements for synchronicity: Use of heavy-atom kinetic isotope effects

1986 ◽  
Vol 138 (1-2) ◽  
pp. 107-112
Author(s):  
Henry J. Shine ◽  
Lidia Kupczyk-Subotkowska ◽  
Witold Subotkowski ◽  
Ewa Gruszecka
Keyword(s):  
Isotope Effects ◽  
Heavy Atom ◽  
Transition States ◽  
Kinetic Isotope Effects ◽  
Kinetic Isotope

Theoretical Simulations of Heavy-Atom Kinetic Isotope Effects in Aliphatic Claisen Rearrangement

2020 ◽  
Vol 124 (51) ◽  
pp. 10678-10686
Author(s):  
Yuqing Xu ◽  
Kin-Yiu Wong ◽  
Meishan Wang ◽  
Desheng Liu ◽  
Wenkai Zhao ◽  
...  
Keyword(s):  
Claisen Rearrangement ◽  
Isotope Effects ◽  
Heavy Atom ◽  
Kinetic Isotope Effects ◽  
Kinetic Isotope ◽  
Theoretical Simulations

The influence of charge on nuclear magnetic resonance isotope effects

1987 ◽  
Vol 65 (12) ◽  
pp. 2707-2712 ◽  
Author(s):  
Roderick E. Wasylishen ◽  
Neil Burford
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Isotope Effects ◽  
Heavy Atom ◽  
Coupling Constants ◽  
Molecular Orbital Calculations ◽  
Isoelectronic Series ◽  
Deuterium Isotope Effects ◽  
Charged Ions ◽  
Nuclear Magnetic

Deuterium isotope effects on the 31P shielding constants and spin–spin coupling constants in the isoelectronic series, PH2−, PH3, PH4+, are examined. Also, deuterium isotope effects on the nuclear magnetic resonance parameters of SnH3− are examined and compared with our earlier results on SnH4 and SnH3+. The experimental results are analyzed using the models of Jameson and Osten. In each isoelectronic series it is found that the isotope effects on the heavy atom chemical shifts are largest for the negatively charged ions and essentially zero for the positively charged ions, as predicted by recent molecular orbital calculations. The primary isotope effects on J(A,H) are positive for all species containing lone-pair electrons, otherwise Δp1J(A,H) is negative. The primary and secondary isotope effects on J(Sn,H) in the SnH3− ion are the largest reported to date.

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