Investigation of the stereochemistry of iron-carbon.alpha. bond cleavage when phenylcyclopropane is generated by .gamma.-ionization of stereospecifically deuterated C5H5(CO)2FeCHDCHDCH(OCH3)C6H5 complexes. A transition-state model for transfer of the carbene ligand from C5H5(CO)2Fe:CHR+ to alkenes

1991 ◽  
Vol 113 (3) ◽  
pp. 939-944 ◽  
Author(s):  
Maurice Brookhart ◽  
Yumin Liu
Keyword(s):  
Transition State ◽  
Bond Cleavage ◽  
State Model

Nitro–Nitrite Isomerization and Transition State Switching in the Dissociation of Ionized Nitromethane: A Threshold Photoelectron–Photoion Coincidence Spectroscopy Study

2009 ◽  
Vol 15 (2) ◽  
pp. 157-166 ◽  
Author(s):  
Brandon Ferrier ◽  
Anne-Marie Boulanger ◽  
David M.P. Holland ◽  
David A. Shaw ◽  
Paul M. Mayer
Keyword(s):  
Transition State ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Bond Cleavage ◽  
Cleavage Reaction ◽  
Nitrite Ion ◽  
Methyl Nitrite ◽  
Bond Cleavage Reaction ◽  
Entropy Of Activation ◽  
Lower Entropy

Threshold photoelectron–photoion coincidence (TPEPICO) spectroscopy has been employed to investigate the competition between bond cleavage and rearrangement reactions in the dissociation of ionized nitromethane, 1. Modeling TPEPICO breakdown diagrams with a combination of RRKM theory and ab initio calculations at the G3 level of theory allowed the derivation of the activation energy for the isomerisation of 1 to ionized methyl nitrite, 2, 82 kJ mol−1. In addition, evidence was found for a transition state switch in the bond cleavage reaction in 1 leading to CH3• + NO2+. As internal energy increases, the effective transition state for this reaction becomes tighter (i.e. is characterized by a lower entropy of activation, Δ‡S). Fitted thresholds for NO+ and CH2OHO+ ions, originating from the isomeric methyl nitrite ion, are consistent with G3 level ab initio calculations.

Aglycon mimicking: Glycoside bond cleavage transition state mimics based on hydroxypyrrolidine inhibitors

1995 ◽  
Vol 36 (36) ◽  
pp. 6541-6544 ◽  
Author(s):  
Gitte Mikkelsen ◽  
Troels V. Christensen ◽  
Mikael Bols ◽  
Inge Lundt ◽  
Michael R. Sierks
Keyword(s):  
Transition State ◽  
Bond Cleavage ◽  
Glycoside Bond

ChemInform Abstract: Transition-State Model for Subtilisin-Catalyzed Transesterifications of Secondary Alcohols.

ChemInform ◽  
2010 ◽  
Vol 30 (31) ◽  
pp. no-no
Author(s):  
Tadashi Ema ◽  
Ryoichi Okada ◽  
Minoru Fukumoto ◽  
Masahito Jittani ◽  
Mikiko Ishida ◽  
...  
Keyword(s):  
Transition State ◽  
State Model ◽  
Secondary Alcohols

scholarly journals A Two Transition State Model for Radical−Molecule Reactions:  Applications to Isomeric Branching in the OH−Isoprene Reaction

2007 ◽  
Vol 111 (25) ◽  
pp. 5582-5592 ◽  
Author(s):  
Erin E. Greenwald ◽  
Simon W. North ◽  
Yuri Georgievskii ◽  
Stephen J. Klippenstein
Keyword(s):  
Transition State ◽  
State Model

The Influence of the 2-Alkoxy Group and of C-5 Substituents on the Direction of Reductive Cleavage of 2-Alkoxytetrahydrofurans by AlH2Cl in Ether Solution

1972 ◽  
Vol 50 (10) ◽  
pp. 1502-1512 ◽  
Author(s):  
P. C. Loewen ◽  
Miss L. P. Makhubu ◽  
R. K. Brown
Keyword(s):  
Transition State ◽  
Alkyl Group ◽  
Steric Effect ◽  
Bond Cleavage ◽  
Alkoxy Group ◽  
Ring Cleavage ◽  
Relative Ease ◽  
Ether Solution ◽  
A Minor ◽  
Minor Extent

The AlH2Cl hydrogenolysis of ether solutions of 2-alkoxytetrahydrofurans in which the alkoxy group is either CH3O, C2H5O, i-C3H7O, or t-C4H9O, gives only those products resulting from ring C—O bond cleavage. However, substituents at C-5 of 2-methoxytetrahydrofuran exert a strong effect on the ratio of ring to exo C—O bond cleavage. Thus, alkyl (electron donor) groups at C-5 promote an increase in the amount of exo cleavage, the proportion increasing from 62.5 to 100% as the C-5 alkyl group is changed from CH3 to t-C4H9. In contrast, electron withdrawing substituents, CH3OCH2— and C6H5, at C-5 favor ring cleavage to the extent of 93 and 84% respectively.The results are interpreted in terms of the influence that these substituents exert through their electronic properties on the relative ease of attainment of the transition state leading to either ring C—O or exo C—O bond cleavage. However, evidence is provided to show that the bulk steric effect of these substituents also controls, though to a minor extent, the proportion of ring to exo cleavage.

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