Kinetics of Dialkylaminium Cation Radical Reactions: Radical Clocks, Solvent Effects, Acidity Constants, and Rate Constants for Reactions with Hydrogen Atom Donors

1995 ◽  
Vol 117 (45) ◽  
pp. 11124-11133 ◽  
Author(s):  
John H. Horner ◽  
Felix N. Martinez ◽  
Osama M. Musa ◽  
Martin Newcomb ◽  
Haifa E. Shahin
Keyword(s):  
Hydrogen Atom ◽  
Solvent Effects ◽  
Rate Constants ◽  
Cation Radical ◽  
Radical Reactions ◽  
Acidity Constants ◽  
Radical Clocks ◽  
Kinetics Of

Kinetics of reactions of para-substituted phenyl isocyanates with amines and alcohols

1991 ◽  
Vol 56 (8) ◽  
pp. 1662-1670 ◽  
Author(s):  
Ivan Danihel ◽  
Falk Barnikol ◽  
Pavol Kristian
Keyword(s):  
Transition State ◽  
Solvent Effects ◽  
Rate Constants ◽  
Substituent Effects ◽  
Steric Effects ◽  
Stopped Flow ◽  
Partial Charges ◽  
Hammett Correlation ◽  
One Step ◽  
Kinetics Of

The reaction of para-substituted phenyl isocyanates with amines and alcohols was studied by stopped-flow method. The Hammett correlation obtained showed that the sensitivity of the above mentioned reactions toward substituent effects is the same as that of analogous reactions of phenyl isothiocyanates (ρ ~ 2). The rate constants of these reactions were found to be affected more by steric effects than by solvent effects. An one step multicentre mechanism with partial charges in transition state has been proposed for the title reactions.

Picosecond radical kinetics. Rate constants for ring openings of 2-aryl-substituted cyclopropylcarbinyl radicals

1999 ◽  
Vol 77 (5-6) ◽  
pp. 1123-1135 ◽  
Author(s):  
Martin Newcomb ◽  
Seung-Yong Choi ◽  
Patrick H Toy
Keyword(s):  
Aromatic Ring ◽  
Rate Constants ◽  
The Other ◽  
Radical Reactions ◽  
Methyl Radicals ◽  
Kinetic Methods ◽  
Mechanistic Probe ◽  
Radical Rearrangements ◽  
Kinetics Of

The kinetics of ring openings of a series of eight (trans-2-arylcyclopropyl)methyl radicals (1) were studied by indirect kinetic methods using Barton's PTOC esters as radical precursors and reaction with PhSeH as the competition reaction. The substituents were CF3, F, Me, and OMe located on both the para and meta positions of the aromatic ring. Syntheses of the radical precursors and the products of the radical reactions are described. Kinetics were determined between -43 and 25°C in four cases (CF3 and OMe substituents) and at 0 and 25°C in the other four cases. The rate constants at 25°C ranged from 1.0 × 1011 s-1 (p-CH3) to 4.1 × 1011 s-1 (p-CF3). The relatively large acceleration of the p-CF3 group, ca. 2.5 times as fast as the parent system with Ar = Ph, correlates well with Adam's ΔD substituent parameters but not with other radical substituent parameters. These calibrated radical rearrangements provide a new set of ultrafast reactions that can be applied in mechanistic probe studies.Key words: cyclopropylcarbinyl radical, kinetics, PTOC esters, benzeneselenol.

Polar substituent and solvent effects on the kinetics of radical reactions with thiols

1996 ◽  
Vol 37 (33) ◽  
pp. 5845-5848 ◽  
Author(s):  
Christopher Tronche ◽  
Felix N. Martinez ◽  
John H. Horner ◽  
Martin Newcomb ◽  
Martin Senn ◽  
...  
Keyword(s):  
Solvent Effects ◽  
Radical Reactions ◽  
Polar Substituent ◽  
Kinetics Of

ChemInform Abstract: Polar Substituent and Solvent Effects on the Kinetics of Radical Reactions with Thiols.

ChemInform ◽  
2010 ◽  
Vol 27 (46) ◽  
pp. no-no
Author(s):  
C. TRONCHE ◽  
F. N. MARTINEZ ◽  
J. H. HORNER ◽  
M. NEWCOMB ◽  
M. SENN ◽  
...  
Keyword(s):  
Solvent Effects ◽  
Radical Reactions ◽  
Polar Substituent ◽  
Kinetics Of
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