56501-19-0

Upstream product

• 732-26-3 2,4,6-tri-tert-butylphenoxol 
• 3315-32-0 2,4,6-tri-tert-butylphenoxyl 
• 101-38-2 2,6-dichloroquinone-4-chloroimide 
• 67-56-1 methanol 

Downstream Products

• 719-22-2 2,6-Di-tert-butyl-1,4-benzoquinone 
• 3383-21-9 3,5-di-tert-butyl-o-benzoquinone 

Relevant academic research and scientific papers

Combining Structural with Functional Model Properties in Iron Synthetic Analogue Complexes for the Active Site in Rabbit Lipoxygenase

Iron complexes that model the structural and functional properties of the active iron site in rabbit lipoxygenase are described. The ligand sphere of the mononuclear pseudo-octahedral cis-(carboxylato)(hydroxo)iron(III) complex, which is completed by a tetraazamacrocyclic ligand, reproduces the first coordination shell of the active site in the enzyme. In addition, two corresponding iron(II) complexes are presented that differ in the coordination of a water molecule. In their structural and electronic properties, both the (hydroxo)iron(III) and the (aqua)iron(II) complex reflect well the only two essential states found in the enzymatic mechanism of peroxidation of polyunsaturated fatty acids. Furthermore, the ferric complex is shown to undergo hydrogen atom abstraction reactions with O-H and C-H bonds of suitable substrates, and the bond dissociation free energy of the coordinated water ligand of the ferrous complex is determined to be 72.4 kcal·mol-1. Theoretical investigations of the reactivity support a concerted proton-coupled electron transfer mechanism in close analogy to the initial step in the enzymatic mechanism. The propensity of the (hydroxo)iron(III) complex to undergo H atom abstraction reactions is the basis for its catalytic function in the aerobic peroxidation of 2,4,6-tri(tert-butyl)phenol and its role as a radical initiator in the reaction of dihydroanthracene with oxygen.

Electron transfer between protonated and unprotonated phenoxyl radicals

(Chemical Equation Presented) The reaction of phenoxyl radicals with acids is investigated. 2,4,6-Tri-tert-butylphenoxyl radical (13), a persistent radical, deteriorates in MeOH/PhH in the presence of an acid yielding 4-methoxycyclohexa-2,5-dienone 18a and the parent phenol (14). The reaction is facilitated by a strong acid. Treatment of 2,6-di-tert-butyl-4-methylphenoxyl radical (2), a short-lived radical, generated by dissociation of its dimer, with an acid in MeOH provides 4-methoxycyclohexa-2,5-dienone 4 and the products from disproportionation of 2 including the parent phenol (3). A strong acid in a high concentration favors the formation of 4 while the yield of 3 is always kept high. Oxidation of the parent phenol (33) with PbO2 to generate transient 2,6-di-tert-butylphenoxyl radical (35) in AcOH/H2O containing an added acid provides eventually p-benzoquinone 39 and 4,4′-diphenoquinone 42, the product from dimerization of 35. A strong acid in a high concentration favors the formation of 39. These results suggest that a phenoxyl radical is protonated by an acid and electron transfer takes place from another phenoxyl radical to the protonated phenoxyl radical, thus generating the phenoxyl cation, which can add an oxygen nucleophile, and the phenol (eq 5). The electron transfer is a fast reaction.

Mechanism of the Gibbs Reaction. 3. Indophenol Formation via Radical Electrophilic Aromatic Substitution (SREAr) on Phenols

Different products are formed, depending on the para substituent (R) when 2,6-dichlorobenzoquinone N-chloroimine (1b) reacts with the anion of the 4-substituted phenol (2).If the group R can leave as a cation (i.e., R is an electrofugal leaving group) such as H, CH2NMe2, CH2OH, etc., then the reaction yields indophenol (3), the normal Gibbs product.If the group R cannot leave as a cation such as CH3, the final product of the reaction will be type 10, 1,1-disubstituted 2,5-cyclohexadienone.If the group R is OH or NH2, then the reaction gives the corresponding benzoquinone 4 or benzoquinone imine 1 and 2,6-dichlorobenzoquinone imine (1d).In all these cases the reaction proceeds at a 1:1 stoichiometry.If, however, the group R can leave as an anion (i.e., R is a nucleofugal leaving group) such as halogen, alkoxy, or OCH2Ph, then the reaction proceeds at a 1:2 stoichiometry.In this case the reaction of a second mole of phenolate with type 26 intermediate yields the indophenol product 3 and the oxidized product of the phenol.If the two ortho positions of the phenolate are substituted then the oxidized product of the phenol will be the corresponding benzoquinone.The mechanism of the reaction has been studied by kinetic and nonkinetic (NMR) methods.It has been concluded that the first step of the mechanism is a single electron transfer (SET) from the phenolate to the benzoquinone N-chloroimine 1b which is the rate-determining process in most of the cases.In some of the nucleofugal cases the final oxidation, involving the second mole of phenolate, is the rate-determining step.For the radical reaction three different alternatives are suggested: a combination of radicals in a solvent cage (direct reaction) and two different chain reactions (chain A and chain B).Quantum chemical calculations revealed that the direct reaction and the chain A mechanisms were energetically more favored than chain B.The reaction shows an extremely large para selectivity although the substitution does follow a radical mechanism.

Oxidation of Phenols with Iodine in Alkaline Methanol

The use of iodine as an oxidizing agent for phenolic compounds has been explored.The reaction has been conducted in methanol containing such alkali as potassium hydroxide and, depending on the nature of the substituents and on the amount of iodine employed, leads to iodination, oxidation to give a stable phenoxy radical, oxidative dimerization, or benzylic oxidation.In general the reaction proceeds smoothly at room temperature, and under appropriate conditions yields of products are good to excellent.Oxidative dimerization of 2,4- and 2,6-di-tert-butylphenols invol-ves iodination followed by iodine-catalyzed dimerization.The oxidation of 4-methylphenols with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in methanol has been carried out for comparison.