74978-25-9

Upstream product

• 128-39-2 2,6-di-tert-butylphenol 
• 40084-31-9 2,6-Di-tert-butyl-4-iodophenol 
• 1139-52-2 4-bromo-2,6-di-tert-butylphenol 
• 88-26-6 3,5-di-tert-butyl-4-hydroxybenzyl alcohol 
• 20017-39-4 (3,5-di-tert-butyl-4-hydroxyphenyl)phenylcarbinol 
• 91-10-1 1,3-dimethoxy-2-hydroxy-benzene 
• 26378-36-9 2-tert-butyl-3-(4-nitrophenyl)-1,2-oxaziridine 
• 955-02-2 2,6-di-tert-butyl-4-diazo-2,5-cyclohexadien-1-one 
• 128-37-0 2,6-di-tert-butyl-4-methyl-phenol 
• 2607-52-5 2,6-di-tert-butyl-4-methylene-2,5-cyclohexadien-1-one 
• 527-35-5 2,3,5,6-tetramethylphenol 
• 90388-37-7 N-(2,4-dichloro-6-oxo-2,4-cyclohexadien-1-ylidene)-4-nitrobenzamide 
• 137649-10-6 C₄₄H₆₄O₃ 
• 87-97-8 2,6-di-tert-butyl-4-methoxymethylene-phenol 

Downstream Products

• 181648-66-8 2,6-Di-tert-butyl-4,4-bis-(3,5-di-tert-butyl-4-hydroxy-phenyl)-cyclohexa-2,5-dienone 

Relevant academic research and scientific papers

A nonheme peroxo-diiron(iii) complex exhibiting both nucleophilic and electrophilic oxidation of organic substrates

The complex [FeIII2(μ-O2)(L3)4(S)2]4+(L3= 2-(4-thiazolyl)benzimidazole, S = solvent) forms upon reaction of [FeII(L3)2] with H2O2and is a functional model of peroxo-diiron intermediates invoked during the catalytic cycle of oxidoreductases. The spectroscopic properties of the complex are in line with those of complexes formed with N-donor ligands. [FeIII2(μ-O2)(L3)4(S)2]4+shows both nucleophilic (aldehydes) and electrophilic (phenol,N,N-dimethylanilines) oxidative reactivity and unusually also electron transfer oxidation.

Transformation of Formazanate at Nickel(II) Centers to Give a Singly Reduced Nickel Complex with Azoiminate Radical Ligands and Its Reactivity toward Dioxygen

The heteroleptic (formazanato)nickel bromide complex LNi(μ-Br)2NiL [LH = Mes-NH-N═C(p-tol)-N═N-Mes] has been prepared by deprotonation of LH with NaH followed by reaction with NiBr2(dme). Treatment of this complex with KC8led to transformation of the formazanate into azoiminate ligands via N-N bond cleavage and the simultaneous release of aniline. At the same time, the potentially resulting intermediate complex L′2Ni [L′ = HN═C(p-tol)-N═N-Mes] was reduced by one additional electron, which is delocalized across the π system and the metal center. The resulting reduced complex [L′2Ni]K(18-c-6) has aS=1/2ground state and a square-planar structure. It reacts with dioxygen via one-electron oxidation to give the complex L′2Ni, and the formation of superoxide was detected spectroscopically. If oxidizable substrates are present during this process, these are oxygenated/oxidized. Triphenylphosphine is converted to phosphine oxide, and hydrogen atoms are abstracted from TEMPO-H and phenols. In the case of cyclohexene, autoxidations are triggered, leading to the typical radical-chain-derived products of cyclohexene.

Enantiospecific Synthesis of Nepetalactones by One-Step Oxidative NHC Catalysis

An efficient oxidative NHC-catalyzed one-step transformation of (S)-or (R)-8-oxocitronellal to nepetalactone (NL) in enantio- A nd diastereomerically pure form has been developed. Several new and "easy to make" N-Mes-or N-Dipp-substituted 1,2,4-triazolium salts carrying nitroaromatic groups on N1 were synthesized and evaluated as precatalysts in combination with base and stoichiometric organic oxidant. Under optimized conditions, NLs are accessible in very good yields and diastereomerically pure under mild conditions. The oxidant used could be recovered and recycled under operationally simple conditions.

Structure, Spectroscopy, and Reactivity of a Mononuclear Copper Hydroxide Complex in Three Molecular Oxidation States

Structural, spectroscopic, and reactivity studies are presented for an electron transfer series of copper hydroxide complexes supported by a tridentate redox-active ligand. Single crystal X-ray crystallography shows that the mononuclear [CuOH]1+ core is stabilized via intramolecular H-bonds between the H-donors of the ligand and the hydroxide anion when the ligand is in its trianionic form. This complex undergoes two reversible oxidation processes that produce two metastable "high-valent"CuOH species, which can be generated by addition of stoichiometric amounts of 1e- oxidants. These CuOH species are characterized by an array of spectroscopic techniques including UV-vis absorption, electron paramagnetic resonance (EPR), and X-ray absorption spectroscopies (XAS), which together indicate that all redox couples are ligand-localized. The reactivity of the complexes in their higher oxidation states toward substrates with modest O-H bond dissociation energies (e.g., 4-substitued-2,6-di-tert-butylphenols) indicates that these complexes act as 2H+/2e- oxidants, differing from the 1H+/1e- reactivity of well-studied [CuOH]2+ systems.

Distribution of Spin Density on Phenoxyl Radicals Affects the Selectivity of Aerobic Oxygenation of Phenols

Phenoxyl radical was generally suggested as the intermediate during copper-catalyzed aerobic oxygenation of phenols. However, the substrate-dependent selectivity has not been well interpreted, due to insufficient characterization of the radical intermediate under reaction conditions. When studying the CuCl-LiCl-catalyzed aerobic phenol oxidation, we obtained EPR spectra of phenoxyl radicals generated by oxidizing phenols with the preactivated catalyst. Upon correlation to the selectivity of benzoquinone, the hyperfine coupling constant of para-site proton (aH, para) was found to be better than the Hammett constant. The catalysis mechanism was studied based on EPR detection and the reaction results of phenoxyl radicals under N2 or O2 atmosphere. It appeared that the chemoselectivity depended on the attack of activated dioxygen on phenoxyl radicals, and the activation of dioxygen by [CunCln+1]- (n = 1, 2, 3) was suggested as the rate-determining step. Understanding of the substrate-dependent selectivity contributed to predicting the chemoselectivity in the aerobic oxidation of phenols.

Phenol Oxidation by a Nickel(III)–Fluoride Complex: Exploring the Influence of the Proton Accepting Ligand in PCET Oxidation

In order to gain insight into the influence of the H+-accepting terminal ligand in high-valent oxidant mediated proton coupled electron transfer (PCET) reactions, the reactivity of a high valent nickel–fluoride complex [NiIII(F)(L)] (2, L=N,N’-(2,6-dimethylphenyl)-2,6-pyridinecarboxamidate) with substituted phenols was explored. Analysis of kinetic data from these reactions (Evans–Polanyi, Hammett, and Marcus plots, and KIE measurements) and the formed products show that 2 reacted with electron rich phenols through a hydrogen atom transfer (HAT, or concerted PCET) mechanism and with electron poor phenols through a stepwise proton transfer/electron transfer (PT/ET) reaction mechanism. The analogous complexes [NiIII(Z)(L)] (Z=Cl, OCO2H, O2CCH3, ONO2) reacted with all phenols through a HAT mechanism. We explore the reason for a change in mechanism with the highly basic fluoride ligand in 2. Complex 2 was also found to react one to two orders of magnitude faster than the corresponding analogous [NiIII(Z)(L)] complexes. This was ascribed to a high bond dissociation free energy value associated with H?F (135 kcal mol?1), which is postulated to be the product formed from PCET oxidation by 2 and is believed to be the driving force for the reaction. Our findings show that high-valent metal–fluoride complexes represent a class of highly reactive PCET oxidants.

Method for synthesizing and preparing 3,3',5,5'-tetraalkyl-4,4'-biphenyl quinone

The invention relates to a method for synthesizing and preparing 3,3',5,5'-tetraalkyl-4,4'-biphenyl quinone. According to the method, a novel bis(2-hydroxyloxo-1,10-o-phenanthroline minus monovalent anion)binuclear cuprous (I) complex is added into a synthesis reaction system, and the 3,3',5,5'-tetraalkyl-4,4'-biphenyl quinone is synthesized and prepared from 2,6-dialkyl phenol in a high-selectivity manner under the conditions that a temperature is relatively low, the reaction time is relatively short, a reaction solvent is economical and air serves as an oxidant.

Functional models of nonheme diiron enzymes: Reactivity of the μ-oxo-μ-1,2-peroxo-diiron(iii) intermediate in electrophilic and nucleophilic reactions

The reactivity of the previously reported peroxo-adduct [FeIII2(μ-O)(μ-1,2-O2)(IndH)2(solv)2]2+ (1) (IndH = 1,3-bis(2-pyridyl-imino)isoindoline) has been investigated in nucleophilic (e.g., deformylation of alkyl and aryl alkyl aldehydes) and electrophilic (e.g. oxidation of phenols) stoichiometric reactions as biomimics of ribonucleotide reductase (RNR-R2) and aldehyde deformylating oxygenase (ADO) enzymes. Based on detailed kinetic and mechanistic studies, we have found further evidence for the ambiphilic behaviour of the peroxo intermediates proposed for diferric oxidoreductase enzymes.

Concerted proton-electron transfer oxidation of phenols and hydrocarbons by a high-valent nickel complex

The high-valent nickel(iii) complex Ni(pyalk)2+ (2) was prepared by oxidation of a nickel(ii) complex, Ni(pyalk)2 (1) (pyalk = 2-pyridyl-2-propanoate). 2 and derivatives were fully characterized by mass spectrometry and X-ray crystallography. Electron paramagnetic resonance spectroscopy and X-ray photoelectron spectroscopy confirm that the oxidation is metal-centered. 2 was found to react with a variety of phenolic and hydrocarbon substrates. A linear correlation between the measured rate constant and the substrate bond dissociation enthalpy (BDE) was found for both phenolic and hydrocarbon substrates. Large H/D kinetic isotope effects were also observed for both sets of substrates. These results suggest that 2 reacts through concerted proton-electron transfer (CPET). Analysis of measured thermodynamic parameters allows us to calculate a bond dissociation free energy (BDFE) of ～91 kcal mol-1 for the O-H bond of the bound pyalk ligand. These findings may shed light onto CPET steps in oxidative catalysis and have implications for ligand design in catalytic systems.

Hydrogen Atom Transfer Oxidation by a Gold-Hydroxide Complex

AuIII-oxygen adducts have been implicated as intermediates in homogeneous and heterogeneous Au oxidation catalysis, but their reactivity is under-explored. Complex 1, ([AuIII(OH)(terpy)](ClO4)2, (terpy = 2,2′:6′,2-terpyridine), readily oxidized substrates bearing C-H and O-H bonds. Kinetic analysis revealed that the oxidation occurred through a hydrogen atom transfer (HAT) mechanism. Stable radicals were detected and quantified as products of almost quantitative HAT oxidation of alcohols by 1. Our findings highlight the possible role of AuIII-oxygen adducts in oxidation catalysis and the capability of late transition metal-oxygen adducts to perform proton coupled electron transfer.