Secondary Kinetic Isotope Effects in Oxidative Addition of Benzyl Bromide to Dimethylplatinum(II) Complexes

2013 ◽  
Vol 32 (9) ◽  
pp. 2593-2598 ◽  
Author(s):  
Marzieh Dadkhah Aseman ◽  
Mehdi Rashidi ◽  
S. Masoud Nabavizadeh ◽  
Richard J. Puddephatt
Keyword(s):  
Isotope Effects ◽  
Oxidative Addition ◽  
Benzyl Bromide ◽  
Kinetic Isotope Effects ◽  
Kinetic Isotope

scholarly journals Formation of Enamines via Catalytic Dehydrogenation by Pincer-Iridium Complexes

2019 ◽  
Author(s):  
Xiawei Zhang ◽  
Santanu Malakar ◽  
Karsten Krogh-Jespersen ◽  
Faraj Hasanayn ◽  
Alan Goldman
Keyword(s):  
Isotope Effects ◽  
Oxidative Addition ◽  
Kinetic Isotope Effects ◽  
Catalytic Dehydrogenation ◽  
Iridium Complexes ◽  
Tertiary Amines ◽  
Iridium Catalysts ◽  
Kinetic Isotope ◽  
Dehydrogenation Mechanism

Efficient pincer-ligated iridium catalysts are reported for the dehydrogenation of simple tertiary amines to give enamines, and for the dehydrogenation of β-functionalized amines to give the corresponding 1,2-difunctionalized olefins. Experimentally determined kinetic isotope effects in conjunction with DFT-based analysis support a dehydrogenation mechanism involving initial pre-equilibrium oxidative addition of the amine α C-H bond followed by rate-determining elimination of the β-C-H bond.<br>

Carbon-13 kinetic isotope effects. IV. The effect of temperature on k12/k13 for benzyl halides in bimolecular reactions

1968 ◽  
Vol 46 (11) ◽  
pp. 1825-1829 ◽  
Author(s):  
Jan Bron ◽  
J. B. Stothers
Keyword(s):  
Temperature Dependence ◽  
Temperature Effect ◽  
Isotope Effects ◽  
Benzyl Bromide ◽  
Kinetic Isotope Effects ◽  
Effect Of Temperature ◽  
Large Temperature ◽  
Bimolecular Reactions ◽  
Kinetic Isotope ◽  
Benzyl Halides

The temperature dependence of the 13C kinetic isotope of the α-carbon in benzyl bromide (1) and in 1-bromo-1-phenylethane (2) has been measured for reaction with alkoxide ion. For these bimolecular displacements, a relatively large temperature effect was found, comparable to that reported for other SN2 processes. A reexamination of the reaction of 2 with EtO− has shown an earlier value for k12/k13 to be in error.

scholarly journals Formation of Enamines via Catalytic Dehydrogenation by Pincer-Iridium Complexes

2019 ◽  
Author(s):  
Xiawei Zhang ◽  
Santanu Malakar ◽  
Karsten Krogh-Jespersen ◽  
Faraj Hasanayn ◽  
Alan Goldman
Keyword(s):  
Isotope Effects ◽  
Oxidative Addition ◽  
Kinetic Isotope Effects ◽  
Catalytic Dehydrogenation ◽  
Iridium Complexes ◽  
Tertiary Amines ◽  
Iridium Catalysts ◽  
Kinetic Isotope ◽  
Dehydrogenation Mechanism

Efficient pincer-ligated iridium catalysts are reported for the dehydrogenation of simple tertiary amines to give enamines, and for the dehydrogenation of β-functionalized amines to give the corresponding 1,2-difunctionalized olefins. Experimentally determined kinetic isotope effects in conjunction with DFT-based analysis support a dehydrogenation mechanism involving initial pre-equilibrium oxidative addition of the amine α C-H bond followed by rate-determining elimination of the β-C-H bond.<br>

scholarly journals The catalytic mechanism of the Suzuki-Miyaura reaction

2021 ◽  
Author(s):  
Juliet macharia ◽  
Chetan Joshi ◽  
Joseph Izzo ◽  
Victor Wambua ◽  
Sungjin Kim ◽  
...  
Keyword(s):  
Catalytic Mechanism ◽  
Palladium Complex ◽  
Isotope Effects ◽  
Oxidative Addition ◽  
Kinetic Isotope Effects ◽  
Boronic Acids ◽  
Aryl Halides ◽  
Kinetic Isotope ◽  
Aryl Bromides ◽  
Insight Into

Abstract: Experimental and theoretical 13C kinetic isotope effects are utilized to obtain atomistic insight into the catalytic mechanism of the Pd(PPh3)4 catalyzed Suzuki-Miyaura reaction of aryl halides and aryl boronic acids. Under catalytic conditions, we establish that oxidative addition of aryl bromides occurs to a 12-electron monoligated palladium complex (Pd(PPh3)). For aryl iodides, the first irreversible step in the catalytic cycle precedes oxidative addition and is shown to be binding of the iodoarene to Pd(PPh3). Our results suggest that the commonly proposed oxidative addition to the 14-electron Pd(PPh3)2 complex can occur only in the presence of excess added ligand or under stoichiometric conditions. The transmetalation step, under catalytic conditions, is shown to proceed via a tetracoordinate boronate (8B4) intermediate with a Pd-O-B linkage.

Model Calculations of Kinetic Isotope Effects in Nucleophilic Substitution Reactions

1974 ◽  
Vol 52 (6) ◽  
pp. 903-909 ◽  
Author(s):  
Jan Bron
Keyword(s):  
Transition State ◽  
Isotope Effects ◽  
Benzyl Bromide ◽  
Kinetic Isotope Effects ◽  
Substitution Reactions ◽  
Model Calculations ◽  
Kinetic Isotope ◽  
Proposed Model ◽  
Standard Reaction ◽  
Deuterium Isotope Effects

The results of calculations indicate that a previously proposed model for the transition state in "borderline" substitution reactions can be generalized and, as a result, the observed differences in the carbon-13 and deuterium isotope effects of SN1, SN2, and "borderline" reactions rationalized. Although the conclusions may apply more generally, the standard reaction investigated is the solvolysis of benzyl bromide. The importance of resonance interaction with the phenyl ring, the significance of the product- or reactant-like character of the transition state, and the influence of the magnitude of force constants in determining isotope effects are examined. The temperature dependence of kinetic isotope effects in solvolysis is also investigated.

Oxidative Addition of Ethyl Iodide to a Dimethylplatinum(II) Complex: Unusually Large Kinetic Isotope Effects and Their Transition-State Implications

2010 ◽  
Vol 29 (23) ◽  
pp. 6359-6368 ◽  
Author(s):  
S. Masoud Nabavizadeh ◽  
Sepideh Habibzadeh ◽  
Mehdi Rashidi ◽  
Richard J. Puddephatt
Keyword(s):  
Transition State ◽  
Isotope Effects ◽  
Oxidative Addition ◽  
Kinetic Isotope Effects ◽  
Ethyl Iodide ◽  
Kinetic Isotope

CARBON-13 KINETIC ISOTOPE EFFECTS IN BIMOLECULAR REACTIONS

1962 ◽  
Vol 40 (10) ◽  
pp. 2007-2011
Author(s):  
J. B. Stothers ◽  
A. N. Bourns
Keyword(s):  
Isotope Effects ◽  
Benzyl Bromide ◽  
Kinetic Isotope Effects ◽  
Bimolecular Reaction ◽  
Alcohol Solution ◽  
Ionic Character ◽  
Compound I ◽  
Bimolecular Reactions ◽  
Kinetic Isotope ◽  
Methoxide Ion

Carbon-13 kinetic isotope effects have been measured for the bimolecular reaction of 1-phenyl-1-bromoethane (I) and benzyl bromide (II) with alkoxide ion in alcohol solution. Compound I gave an effect, k12/k13, of 1.0032 ± 0.0005 for reaction with ethoxide ion in ethanol, while II gave k12/k13 = 1.0531 ± 0.0004 for reaction with methoxide ion in methanol. These surprisingly different effects are tentatively interpreted in terms of a model for the transition state having varying degrees of ionic character.

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
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