Kinetics of cyclopropyl radical reactions. 1. Absolute rate constants for some addition and abstraction reactions

1984 ◽  
Vol 106 (17) ◽  
pp. 4877-4881 ◽  
Author(s):  
Linda J. Johnston ◽  
J. C. Scaiano ◽  
K. U. Ingold
Keyword(s):  
Rate Constants ◽  
Radical Reactions ◽  
Absolute Rate ◽  
Kinetics Of

Absolute Rate Constants for Alkoxycarbonyl Radical Reactions

1998 ◽  
Vol 63 (4) ◽  
pp. 1226-1232 ◽  
Author(s):  
Pavel A. Simakov ◽  
Felix N. Martinez ◽  
John H. Horner ◽  
Martin Newcomb
Keyword(s):  
Rate Constants ◽  
Radical Reactions ◽  
Absolute Rate

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.

Synthesis and spin trapping kinetics of new alkyl substituted cyclic nitrones

1982 ◽  
Vol 60 (12) ◽  
pp. 1514-1522 ◽  
Author(s):  
D. L. Haire ◽  
Edward G. Janzen
Keyword(s):  
Comparative Study ◽  
Rate Constants ◽  
Spin Trap ◽  
Spin Trapping ◽  
Absolute Rate ◽  
Cyclic Nitrones ◽  
The Absolute ◽  
Kinetics Of

Three new nitrones, 5-n-propyl-5-methyl-1-pyrroline-N-oxide (PMPO), 5-n-hexyl-5-methyl-1-pyrroline-N-oxide (HMPO), and 5-n-decyl-5-methyl-1-pyrroline-N-oxide (DeMPO), amphiphilic versions of the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), have been synthesized. A comparative study of the absolute rate constants for formation and decay of the tert-butoxyl spin adducts to these cyclic nitrones as well as 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (M4PO) has been undertaken using esr kinetic techniques.

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