scholarly journals THE REACTION OF tert-BUTOXY RADICALS WITH 2,6-Di-tert-BUTYL-4-METHYLPHENOL AND 2,6-Di-tert-BUTYLPHENOL

1963 ◽  
Vol 41 (11) ◽  
pp. 2807-2815 ◽  
Author(s):  
K. U. Ingold
Keyword(s):  
Carbon Tetrachloride ◽  
Isotope Effect ◽  
Satisfactory Agreement ◽  
Deuterium Isotope Effect ◽  
Tert Butyl

The products of the reaction of t-butoxy radicals with 2,6-di-t-butyl-4-methylphenol and 2,6-di-t-butylphenol in carbon tetrachloride have been analyzed quantitatively. There is a satisfactory agreement between the measured and calculated yields of t-butanol with both phenols. The deuterium isotope effect (kh/kd) for abstraction of the phenolic hydrogen from 2,6-di-t-butyl-4-methylphenol is about 6.4.

Sterically Hindered Aromatic Compounds. VI. A Remote ε-Deuterium Kinetic Isotope Effect in the Solvolysis of Perdeutero-2,4,6-tri-tert-butylbenzyl Chloride

1975 ◽  
Vol 53 (21) ◽  
pp. 3171-3174 ◽  
Author(s):  
L. Ross C. Barclay ◽  
John R. Mercer ◽  
Peter J. MacAulay
Keyword(s):  
Transition State ◽  
Isotope Effect ◽  
Aromatic Compounds ◽  
Kinetic Isotope Effect ◽  
Inductive Effect ◽  
Steric Effects ◽  
Deuterium Isotope Effect ◽  
Tert Butyl ◽  
Kinetic Isotope ◽  
Sterically Hindered

2,4,6-Tri-tert-butylbenzyl chloride deuterated at the three tert-butyl groups was synthesized. Conductimetric solvolysis studies of the normal and perdeutero-2,4,6-tri-tert-butylbenzyl chloride at 30.06 °C in 80% ethanol–water provides evidence for an inverse remote ε-deuterium isotope effect, kH/kD = 0.873−0.874. Under the same conditions the α-deuterium isotope effect was kH/kαD = 1.166 per deuterium, indicative of limiting solvolytic behavior. The remote ε-deuterium isotope effect for the perdeutero compound is discussed in terms of the inductive effect of deuterium and steric effects on the transition state conformation.

THE INHIBITED AUTOXIDATION OF STYRENE: PART I.THE DEUTERIUM ISOTOPE EFFECT FOR INHIBITION BY 2,6-DI-tert-BUTYL-4-METHYLPHENOL

1962 ◽  
Vol 40 (9) ◽  
pp. 1851-1864 ◽  
Author(s):  
J. A. Howard ◽  
K. U. Ingold
Keyword(s):  
Isotope Effect ◽  
Rate Constants ◽  
Activation Energies ◽  
Deuterium Isotope Effect ◽  
Apparent Absence ◽  
Elementary Reactions ◽  
Tert Butyl ◽  
Rapid Exchange ◽  
Phenolic Inhibitor

Most previous work on the inhibition of autoxidation by phenols has indicated that the reaction involves abstraction of the phenolic hydrogen. However, the apparent absence of any appreciable deuterium isotope effect made it difficult to believe that abstraction could be rate controlling. The present work using styrene as the substrate, 2,6-di-tert-butyl-4-methyl-phenol as the inhibitor, and azo-bis-isobutyronitrile as the initiator has shown that this reaction has an unexpectedly large isotope effect, e.g. ~10.6 at 65 °C. Previous failures to detect an isotope effect are attributed to the rapid exchange of deuterium which takes place between deuterated phenols and traces of moisture or other hydroxyl-containing compounds present in the substrate. Rate constants and activation energies for some of the elementary reactions in the inhibited and uninhibited oxidation of styrene have been measured. It is suggested that a compound which functions in the same way as a weak phenolic inhibitor is formed in the apparently uninhibited oxidation.

Partial kinetic ‘resolution’ resulting from a deuterium isotope effect

1991 ◽  
Vol 0 (12) ◽  
pp. 801-802 ◽  
Author(s):  
Panayiotis Anastasis ◽  
Raymond Duffin ◽  
Christopher Gilmore ◽  
Karl Overton
Keyword(s):  
Isotope Effect ◽  
Kinetic Resolution ◽  
Deuterium Isotope Effect
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