83376-94-7

Upstream product

• 59-02-9 vitamin E 
• 3141-58-0 tert-butoxy radical 
• 94-36-0 dibenzoyl peroxide 
• 2525-38-4 2,6-di-tert-butyl-4-phenylphenoxyl 
• 59-02-9 d-α-Tocopherol 
• 59-02-9 Tocopherol 
• 16183-00-9 5-hexen-1-yl radical 
• 33574-06-0 (4-Methoxybenzoyl)oxyl radical 
• 20137-67-1 2,6-di-tert-butyl-4-methoxyphenoxyl radical 
• 6858-01-1 2,6-di-tert-butyl-4-methylphenoxy radical 

Downstream Products

• 59-02-9 vitamin E 
• 335199-67-2 α-tocopherol-o-quinonemethide 
• 59-02-9 Tocopherol 
• 6858-01-1 2,6-di-tert-butyl-4-methylphenoxy radical 
• 20137-67-1 2,6-di-tert-butyl-4-methoxyphenoxyl radical 

Relevant academic research and scientific papers

Modeling the Co-Antioxidant Behavior of Monofunctional Phenols. Applications to Some Relevant Compounds

A study on the regeneration of α-tocopherol (vitamin E) by phenolic co-antioxidants in homogeneous hydrocarbon solution is reported. The behavior of some relevant phenols such as BHA, BHT, and trans-resveratrol appears to be nicely predicted by a model based on the knowledge of kinetic and thermochemical data concerning the various reactants. Despite its good reputation as an antioxidant, trans-resveratrol was found only moderately effective (kinh = 2.0 × 105 M-1 s -1 in chlorobenzene at 303 K) and unable to recycle vitamin E.

Effect of Solvation on the Bond Dissociation Energies of Phenolic Antioxidants

The effect of solvent on the bond dissociation energies (BDEs) of the oxygen-hydrogen bond in substituted phenolic antioxidants has been investigated by means of an EPR technique.On changing the solvent from benzene to tert-butanol the BDE's were found to increase by ca. 2.2 kcal/mol for phenols without ortho substituents, by ca. 1 kcal/mol for 2,6-dimethyl substituted phenols while in 2,6-di-tert-butyl phenols they seem to be substantially unaffected.This behaviour has been interpreted by admitting that the BDE increase observed in tert-butanol is essentially due to the solvation of the hydroxylic hydrogen which stabilises the phenol, leaving the energy of the phenoxyl radical unaltered.Thus, solvation effects are expected to be large with unhindered phenols and relatively unimportant in phenols containing bulky substituents in the proximity of the OH group.

Mechanism of Antioxidant Reaction of Vitamin E. Charge Transfer and Tunneling Effect in Proton-Transfer Reaction

In order to shed light on the mechanism of proton-transfer reactions, a kinetic and ab initio study of the antioxidant action (intermolecular proton transfer) of vitamin E derivatives has been carried out.The second-order rate constants (ks's)

Absolute kinetics of hydrogen abstraction from α-tocopherol by several reactive species including an alkyl radical

Laser flash photolysis and competitive techniques have been employed to study the reactions of α-tocopherol with various radicals and ketone triplets in solution. For example benzophenone triplets abstract hydrogen with rate constants of 5.1 × 109 and 3.7 × 109 M-11 s-1 in benzene and benzene/1.3 M methanol. Similar near-diffusion-controlled values were obtained for several other ketone triplets, as well as tert-butoxyl and 4-methoxybenzoyloxyl radicals. Deuterium kinetic isotope effects are frequently very small, reflecting the expected lack of selectivity of fast reactions. The reactivity of the 5-hexenyl radical toward α-tocopherol was examined by studying the competition of this process with the radical cyclization to the cyclopentylmethyl radical. The value of (1.7 ± 0.2) × 106 M-1 s-1 (at 70 °C in benzene) for this hydrogen atom abstraction from α-tocopherol makes this process exceptionally fast in comparison with the limited available rate data for reactions of carbon-centered radicals with other phenols.

KINETIC STUDY OF THE REACTION OF BENZOYL PEROXIDE WITH PHENOLIC COMPOUNDS. A TECHNIQUE FOR THE EVALUATION OF PHENOLIC O-H BOND DISSOCIATION ENERGIES

From kinetic data concerning the reaction of benzoyl peroxide (POB) with several phenolic antioxidants (ArOH): POB + ArOH -> C6H5CO2. + C6H5CO2H + ArO., it is shown that differences in the phenolic O-H bond dissociation energies may be obtained.In the particular case of α-tocopherol (α-TH), a stabilization energy defined with respect to phenol: D(C6H5O-H) - D(α-T-H) = 10 kcal.mol-1 has been estimated in heptanol as solvent.It would correspond for α-TH to an O-H bond dissociation energy around 78 kcal.mol-1.

Antioxidant Activity of 1-Thio-α-tocopherol and Related Compounds. EPR, ENDOR, and UV-Visible Absorption Spectra of Some of the Derived Phenoxyl Radicals

The inhibition of the azobis(isobutyronitrile) thermally autoxidation of styrene at 30 deg C by 1-thio-α-tocopherol and related 6-hydroxythiochromans has shown that these compounds trap fewer than 2.0 peroxyl radicals per molecule (between 1.0 and 1.8) and that they are only slightly less reactive toward peroxyl radicals than structurally related 6-hydroxychromans.A number of thiochromanoxyl radicals were generated photolytically, and their EPR and ENDOR spectra were recorded.The ENDOR cavity is unique in that it allows photolysis of the sample, and this represents the first report on the ENDOR spectra of transient radicals that must be continuously generated by photolysis.The hyperfine splittings for thiochromanoxyls are similar to those of chromanoxyls radical, but their g values are higher by 0.0008.The UV-visible absorption spectrum of the thiotocopheroxyl radical has a band maximum at 488 nm, well above the 413 nm of α-tocopheroxyl.An addendum reports that 5-hydroxy-2,4,6,7-tetramethylbenzofuran is only ca. 10percent as active toward peroxyl radicals at 30 deg C as structurally related 2,3-dihydro-5-hydroxybenzofurans, the latter being a class of phenols which we have previously shown to be the most active in trapping peroxyl radicals.5,6 An improved synthesis of 1-thio-α-tocopherol and a correction to earlier reports regarding purported syntheses of this compound are also included.