Kinetic Isotope Effects as a Mechanistic Tool for the Elucidation of the Rate-Determining Step(s) in the Transition-Metal-Ion-Mediated Activation of CH/CC Bonds. Ethylene Loss from Metastable 4-Octyne/M⊕ Complexes in the Gas Phase

1990 ◽  
Vol 29 (5) ◽  
pp. 509-510 ◽  
Author(s):  
Christian Schulze ◽  
Helmut Schwarz
Keyword(s):  
Transition Metal ◽  
Gas Phase ◽  
Metal Ion ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Transition Metal Ion ◽  
Rate Determining Step ◽  
Kinetic Isotope

The thermally induced rearrangements of 2-vinyloxirane

1976 ◽  
Vol 54 (21) ◽  
pp. 3364-3376 ◽  
Author(s):  
Robert J. Crawford ◽  
Stuart B. Lutener ◽  
Robert D. Cockcroft
Keyword(s):  
Carbon Monoxide ◽  
Gas Phase ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Thermally Induced ◽  
Rate Determining Step ◽  
Kinetic Isotope ◽  
Carbonyl Ylide ◽  
Structural Isomerization ◽  
Kinetics Of

The kinetics of the gas phase thermolysis of 2-vinyloxirane (4) have been studied over the temperature range 270–310 °C. The racemization of chiral 4 occurs six times faster than the structural isomerization to 2,3-dihydrofuran, (E)- and (Z)-2-butenal, and 3-butenal. The butenals undergo a slow thermolysis to propene and carbon monoxide. cis-Deuterio- and trans-3-deuterio-vinyloxirane have been synthesized and their interconversion is slow. Deuterium kinetic isotope effects on mono- and dideuterio-4 suggest that for the formation of the butenals the rate determining step involves rupture of the oxirane C—O bond. The dihydrofuran is produced by thermolysis of the oxirane C—C bond. The preferred mechanistic interpretation is that a carbon–oxygen diradical serves as an intermediate for butenal formation, and that a carbonyl-ylide is involved in the formation of the dihydrofuran.The relative rates, at 307.4 °C, of cis–trans-5-isomerization:dihydrofuran formation:racemization: butenal formation for 3-deuterio-2-vinyloxirane are 1.0:0.88:40.2:5.94, respectively.

Vinyl ether hydrolysis. XIII. The failure of I-strain to produce a change in rate-determining step

1980 ◽  
Vol 58 (2) ◽  
pp. 124-129 ◽  
Author(s):  
Y. Chiang ◽  
W. K. Chwang ◽  
A. J. Kresge ◽  
S. Szilagyi
Keyword(s):  
Vinyl Ether ◽  
Acid Catalysis ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Mineral Acid ◽  
Buffer Solutions ◽  
Rate Determining Step ◽  
Kinetic Isotope ◽  
Acetic Acid Buffer ◽  
Hydrolysis Of

Rates of hydrolysis of 1-ethoxy-3,3,5,5-tetramethylcyclopentene and 1-methoxy-2,3,3,5,5-pentamethylcyclopentene measured in mineral acid and formic and acetic acid buffer solutions show general acid catalysis and give large kinetic isotope effects in the normal direction (kH/kD > 1). This indicates that these reactions proceed by the conventional mechanism for vinyl ether hydrolysis in which proton transfer from the catalyzing acid to the substrate is rate-determining, and that the I-strain in these substrates is insufficiently great to shift the reaction mechanism to rapidly reversible substrate protonation followed by rate-determining hydration of the ensuing cationic intermediate.

Measurements of Solvent and Secondary Kinetic Isotope Effects for the Gas-Phase SN2 Reactions of Fluoride with Methyl Halides

1994 ◽  
Vol 116 (8) ◽  
pp. 3609-3610 ◽  
Author(s):  
Richard A. J. O'Hair ◽  
Gustavo E. Davico ◽  
Jale Hacaloglu ◽  
Thuy Thanh Dang ◽  
Charles H. DePuy ◽  
...  
Keyword(s):  
Gas Phase ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Methyl Halides ◽  
Sn2 Reactions ◽  
Kinetic Isotope
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