15773-14-5

Upstream product

• 527-60-6 Mesitol 
• 81388-53-6 2,4,6-trimethylphenoxide anion 
• 50349-73-0 benzotriazole N-oxyl radical 
• 1169875-48-2 6-trifluoromethyl-1H-1,2,3-benzotriazol-N-oxyl 
• 1169875-50-6 C₇H₆N₃O 
• 1310558-96-3 3-quinazolin-4-one-N-oxyl radical 
• 1310558-97-4 3-benzotriazin-4-one-N-oxyl radical 
• 6858-01-1 2,6-di-tert-butyl-4-methylphenoxy radical 
• 15773-12-3 2,6-Dimethoxyphenoxyl radical 
• 3315-32-0 2,4,6-tri-tert-butylphenoxyl 
• 6119-32-0 4-methoxyphenoxyl 

Downstream Products

• 119-61-9 benzophenone 
• 527-60-6 Mesitol 
• 36197-06-5 2,6-dimethyl-p-quinone methide 
• 51114-00-2 sodium 2,4,6-trimethylphenoxide 
• 15773-12-3 2,6-Dimethoxyphenoxyl radical 
• 3315-32-0 2,4,6-tri-tert-butylphenoxyl 
• 6119-32-0 4-methoxyphenoxyl 
• 6858-01-1 2,6-di-tert-butyl-4-methylphenoxy radical 

Relevant academic research and scientific papers

Importance of π-stacking interactions in the hydrogen atom transfer reactions from activated phenols to short-lived N-oxyl radicals

A kinetic study of the hydrogen atom transfer from activated phenols (2,6-dimethyl- and 2,6-di-tert-butyl-4-substituted phenols, 2,2,5,7,8- pentamethylchroman-6-ol, caffeic acid, and (+)-cathechin) to a series of N-oxyl radical (4-substituted phthalimide-N-oxyl radicals (4-X-PINO), 6-substituted benzotriazole-N-oxyl radicals (6-Y-BTNO), 3-quinazolin-4-one-N-oxyl radical (QONO), and 3-benzotriazin-4-one-N-oxyl radical (BONO)), was carried out by laser flash photolysis in CH3CN. A significant effect of the N-oxyl radical structure on the hydrogen transfer rate constants (kH) was observed with kH values that monotonically increase with increasing NO-H bond dissociation energy (BDENO-H) of the N-hydroxylamines. The analysis of the kinetic data coupled to the results of theoretical calculations indicates that these reactions proceed by a hydrogen atom transfer (HAT) mechanism where the N-oxyl radical and the phenolic aromatic rings adopt a π-stacked arrangement. Theoretical calculations also showed pronounced structural effects of the N-oxyl radicals on the charge transfer occurring in the π-stacked conformation. Comparison of the kH values measured in this study with those previously reported for hydrogen atom transfer to the cumylperoxyl radical indicates that 6-CH3-BTNO is the best N-oxyl radical to be used as a model for evaluating the radical scavenging ability of phenolic antioxidants.

Absolute rate constants for some intermolecular reactions of α-aminoalkylperoxyl radicals. Comparison with alkylperoxyls

(Graph Presented) Seven α-aminoalkylperoxyl radicals have been generated by 355 nm laser flash photolysis (LFP) of oxygen-saturated di-tert-butyl peroxide containing mono-, di-, and trialkylamines and a dialkylarylamine. All these peroxyls possess absorptions in the near-UV (strongest for the trialkylamine-derived peroxyls) which permits direct monitoring of the kinetics of their reactions with many substrates. The measured rate constants for hydrogen atom abstraction from some phenols and oxygen atom transfer to triphenylphosphine demonstrated that all seven α- aminoalkylperoxyls have similar reactivities toward each specific substrate. More importantly, a comparison with literature data for alkylperoxyls shows that α-aminoalkylperoxyls and these alkylperoxyls have essentially the same reactivities. The combination of LFP and alkylamines provides a quick, reliable method for determining absolute rate constants for alkylperoxyl radical reactions, an otherwise laborious task.

Synthesis and inhibitory activity of alkyl(hydroxyaryl)amines

The reaction of ω-(4-hydroxyaryl)haloalkanes with various nitrogen-containing agents afforded primary, secondary, and tertiary amino derivatives of 2,6-dialkylphenols. For the compounds synthesized, the reaction rate constants with peroxide radicals were

Synthesis and antioxidant activity of alkyl 3-(4-hydroxyaryl)propyl sulfides

4-Alkylthiopropylphenols were synthesized from corresponding 2,6-dialkylphenols via the allyl derivative. A comparative study of the antioxidant activity of the prepared compounds was carried out in five model systems. The rate constants for the reactions

Synthesis and study of the antiradical activity of substituted hydroxybenzylamines and their hydrogen chloride salts

Different alkylated hydroxybenzylamines and their hydrogen chloride salts were synthesized. The rate constants of their reactions with peroxide radicals k1 and the stoichiometric factors of inhibition f were measured in the initiated oxidation of cumene and methyl oleate. Copyright

Abnormal solvent effects on hydrogen atom abstractions. 1. The reactions of phenols with 2,2-diphenyl-1-picrylhydrazyl (dpph?) in alcohols

Rate constants, kArOH/dpph?,s, for hydrogen atom abstraction from 13 hindered and nonhindered phenols by the diphenylpicrylhydrazyl radical, dpph?, have been determined in n-heptane and a number of alcoholic and nonalcoholic, hydrogen-bond accepting solvents. Abnormally enhanced values of kArOH/dpph?,s have been observed in alcohols. It is proposed that this is due to partial ionization of the phenols and a very fast electron transfer from phenoxide anion to dpph?. The popular assessment of the antioxidant activities of phenols with dpph? in alcohol solvents will generally lead to an overestimation of their activities.

Hydrogen-bonding effects on the properties of phenoxyl radicals. An EPR, kinetic, and computational study

The effect of 1,1,1,3,3,3-hexafluoropropan-2-ol (HFP) on the properties of phenoxyl radicals has been investigated. HFP produces large variations of the phenoxyl hyperfine splitting constants indicative of a large redistribution of electron spin density, which can be accounted for by the increased importance of the mesomeric structures with electric charge separation. The conformational rigidity of phenoxyl radicals with electron-releasing substituents is also greatly enhanced in the presence of HFP, as demonstrated by the 2 kcal/mol increase in the activation energy for the internal rotation of the p-OMe group in the p-methoxyphenoxyl radical. By using the EPR equilibration technique, we have found that in phenols the O-H bond dissociation enthalpy (BDE) is lowered in the presence of HFP because it preferentially stabilizes the phenoxyl radical. In phenols containing groups such as OR that are acceptors of H-bonds, the interaction between HFP and the substituent is stronger in the phenol than in the corresponding phenoxyl radical because the radical oxygen behaves as an electron-withdrawing group, which decreases the complexating ability of the substituent. In phenols containing OH or NH2 groups, EPR experiments performed in H-bond accepting solvents showed that the interaction between the solvent and the substituent is much stronger in the phenoxyl radical than in the parent phenol because of the electron-withdrawing effect of the radical oxygen, which makes more acidic, and therefore more available to give H-bonds, the OH or NH2 groups. These experimental results have been confirmed by DFT calculations. The effect of HFP solvent on the reactivity of phenols toward alkyl radicals has also been investigated. The results indicated that the decrease of BDE observed in the presence of HFP is not accompanied by a larger reactivity. The origin of this unexpected behavior has been shown by DFT computations. Finally, a remarkable increase in the persistency of the α-tocopheroxyl radical has been observed in the presence of HFP.

A quantitative approach to the recycling of α-tocopherol by coantioxidants

A systematic investigation is reported on the regeneration of α-tocopherol (α-TOH) in homogeneous solution by coantioxidants in order to better understand the mechanism and the factors responsible for the effectiveness of this process. The current availability of thermochemical data concerning the reactants involved in the regeneration reactions, as well as a large number of the kinetic constants for the various reactions involved, allowed us to rationalize the experimental observations collected so far. Three limiting cases have been considered. The first case is that of a coantioxidant irreversibly regenerating α-TOH, where the effectiveness of the recycling process depends on the magnitude of the rate constant kr. The second case is that of a coantioxidant reversibly recycling α-TOH, where regeneration can only be observed if the bond dissociation enthalpy value of the coantioxidant is lower or at least close to that of the O-H bond of α-tocopherol. The third case is that of a catechol derivative (chosen as a model compound for polyphenolic antioxidants), where recycling of α-TOH is feasible even though the BDE value is significantly higher than that of vitamin E. In this case, the driving force for the recycling process is the removal of the semiquinone radical from the catechol derivative by the α-tocopheroxyl radical, which makes the regeneration of α-TOH practically irreversible.

Kinetic solvent effects on hydrogen-atom abstractions: Reliable, quantitative predictions via a single empirical equation

The rate of hydrogen-atom abstraction from XH by a radical, Y·, can be solvent-dependent. In many cases, the kinetic solvent effect (KSE) is directly related to hydrogen-bonding interactions between XH and the solvent. The relative hydrogen-bond acceptor (HBA) properties of solvents are given by β2/H constants of Abraham et al. (Abraham, M. H.; Grellier, P. L.; Prior, D. V.; Morris, J. J.; Taylor, P. J. J. Chem. Soc. Perkin Trans. 2 1990, 521-529). Room-temperature rate constants for hydrogen-atom abstraction, kXH/Y·/S, have been determined in a number of solvents, S, where XH refers to several substituted phenols, tert-butyl hydroperoxide or aniline and Y· is a tert-alkoxyl radical. In all cases, plots of log(kXH/Y·/S/M-1 s-1) versus β2/H gave excellent linear correlations, the slopes of which, MXH, were found to be proportional to the hydrogen-bond-donating (HBD)ability of XH, as scaled with α2/H parameters of Abraham et al. (Abraham, M. H.; Grellier, P. L.; Prior, D. V.; Duce, P. P.; Morris, J. L.; Taylor, P. J. J. Chem. Soc., Perkin Trans. 2 1989, 699-711), with MXH = - 8.3α2/H. This leads to a general empirical equation which quantifies KSEs at room temperature: log kXH/Y·/S = log kXH/Y·O - 8.3α2/Hβ2/H, where kXH/Y·/O refers to the rate constant in a non-HBA solvent for which β2/H = 0, generally a saturated hydrocarbon. Since MXH depends only on XH, rate constants for hydrogen-atom abstraction from XH by any Y· can be accurately predicted in any of the several hundred solvents for which β2/H is known on the basis of one single measured rate constant, provided α2/H for XH is known or measured. HBA solvents can have profound effects on some of the reactions and thermodynamic properties of hydroxylic substrates including: (i) reaction product profiles (ii) antioxidant activities, (iii) Hammett-type correlations, and (iv) O-H bond dissociation enthalpies. Finally, literature data (Nielsen, M. F.; Hammerich, O. Acta Chem. Scand, 1992, 46, 883-896) on KSEs for two proton-transfer reactions are shown to be correlated by the same equation which correlates KSEs for hydrogen-atom transfers.

Reaction of superoxide with phenoxyl-type radicals

Radiolytically generated phenoxyl radicals derived from the structurally similar phenols cresol, tyrosine, tyramine and tyrosol were reacted with O2·- [k = (1-4.5) × 109 dm3 mol-1 s-1 by pu